Friday, July 31, 2009

Education - 4-H'ers and FFA Students and Horticulture at the Delaware State Fair

The Delaware State Fair offers 4-H'ers and FFA students many opportunities to learn about horticulture through 4-H and FFA horticulture contests, demonstrations, and exhibits. The following are a few pictures.

Landscape - Backyards a Focus for the Cooperative Extension at the Delaware State Fair

Backyards were a focus for at the Delaware Cooperative Extension Tent at the Delaware State Fair. This included many horticultural ideas. Commercial landscapers can use this theme in designing landscapes and providing services for their clients - show your clients what their backyard can do for them.

Thursday, July 30, 2009

Landscape - Mugwort Control

The following is information on control of mugwort in landscape beds.

Many landscape beds have problems with mugwort (Artemesia vulgaris), also know as wild chrysanthemum. This is a perennial weed that is difficult to control due to its ability to spread by underground rhizomes. Leaves are similar to appearance as chrysanthemum, 2-4 inches long, 1-3 inches wide, simple, alternate, deeply lobed, and are covered with soft, white to gray hairs underneath. Leaves will also have a distinctive smell. Mugwort is most commonly introduced as a weed with nursery stock. It rarely produces viable seed and spreads almost exclusively by rhizomes.

Hand weeding is often only partially effective because complete control requires removal of all the underground rhizomes. One fairly effective control approach is to use directed applications of glyphosate, one in late summer and one in early fall. Dichlobenil (Casoron) granular herbicide, winter applied, has given good mugwort control in beds with woody plants such as junipers; however, Casoron is not labeled for all species and injury can occur on newly planted trees and shrubs. Clopyralid (Lontrel) has given up to 95% control of mugwort in some trials as a selective application. However, clopyralid is only labeled for use around the following woody species: dogwood, oak, fir, pine, red maple, spruce, sycamore, arborvitae, boxwood, juniper, some Rhododendron species, spirea, and yew. A better fit for Lontrel is suppression of mugwort in ornamental grasses where it can be used as an over-the-top application for many grass species.

Gordon Johnson, Extension Horticulture Agent, UD, Kent County

Wednesday, July 29, 2009

Landscape - Velvet Ants

You may come across velvet ants in the landscape. The following is more information on these insects.

Velvet ants are striking insects covered with red and black or orange and black "hairs". Females are wingless; males have two pairs of black wings. The female have very long stingers, the potency of the punch is reflected in the common name "cow killer wasps". Picking one up can provide a memorable experience. These wasps, seen walking determinedly across the lawn, do not have a home, so there is no place to treat. They pose no threat unless handled or stepped on by bare feet.

Velvet ant. Photo by Johnny N. Dell,

Information from "Yard Wasps" By Lee Townsend in the current edition of the Kentucky Pest News

Tuesday, July 28, 2009

Turf - Grub Control With Beneficial Nematodes

The following is information on grub control in lawns using beneficial nematodes from the University of Maryland.

Non –Chemical Control of Grubs in Lawns

The interest in non-chemical control of white grubs in lawns is increasing. Japanese beetles are laying eggs in the soil in late July through early August. The newly hatching larvae will be very susceptible to control using beneficial nematodes. Nematodes are microscopic, non-segmented worms which occur naturally in soil all over the world. Beneficial nematodes attack soil dwelling insects and leave plants alone. These predators enter the host through body openings or by penetration of the body wall. Beneficial nematodes are considered safe and EPA has waived the registration requirements for application.

When Heterorhabditis bacteriophora (Hb) nematodes sense the temperature and carbon dioxide emissions of soil-borne insects, they move toward their prey and enter the pest through its body openings. The nematodes carry an associated symbiotic bacterium (Xenorhabdus species) that kills insects within 48 hours. The bacteria is harmless to humans and other organisms and cannot live freely in nature. Several generations of nematodes may live and breed within the dead pest before emerging and seeking more pests in the soil.

Heterorhabditis bacteriophora nematodes are a good choice for white grub control at this time of year. The key is that they need a lot of water to survive in turf areas. Irrigate the day of the application or apply during periods of rain. The lawn area must be keep moist for a couple of days after an application to keep the nematodes alive. Infected grubs become slimy and discolored and turn from white-beige to red-brown within 3 to 5 days after application. Nematodes leave the grub when they reach the infectious third stage to search for new larvae. The nematode population will slowly decrease when no new hosts are present.

Checking to Make Sure Nematodes Are Alive is Essential: It’s critical when using beneficial nematodes to check the population to make sure they are alive at application time. Draw off a small sample and examine the water with nematodes under a magnification of 20X. Live nematodes will be slightly curved and moving. Dead nematodes are still and straight as a board.

Information from Stanton Gill, University of Maryland

Greenhouse and Nursery - Mum Fertilization Revisited

With mum season in mid crop, I thought it would be good to do a reprint of recommended fertilizer programs for garden mums.

It is mid season and it’s a good time to revisit your fertilizer program. Mums are heavy feeders during the first few weeks. After flowers are formed, nutrient demand diminishes. Your fertilizer program and fertilizer selection should be based on irrigation water quality, so have your irrigation water tested if it hasn’t been done and conduct regular soil tests to monitor soil fertility.

There are several ways to fertilize mums. Some growers use 100% water soluble fertilizer through a drip system, some use 100% controlled-release fertilizer and some use a combination of water soluble and controlled-release.

1) 100% Water Soluble Fertilizer Using Drip Irrigation

After plants are established using 20-20-20 the first few weeks, switch to 200-250 ppm of 20-10-20 constant feed for 3-4 applications and then rotate to a calcium nitrate based fertilizer such as 15-0-15 for 1 application, then repeat. Once plants start to show color, reduce to 100 ppm constant feed.

2) Combination of Water Soluble Fertilizer and Low Rate of Controlled Release Fertilizer

Use 250 ppm of 20-20-20 at time of planting and constant feed for first two weeks then change to 20-10-20, 300 ppm once per week and use clear water from first color until sale.

Information from the June 5, 2008 edition of the New England Greenhouse Update.

Monday, July 27, 2009

Landscape - Cedar-Quince Rust on Callery Pear

The following is information about a rust disease attacking Callery pears in Delaware.


Samples of 'Bradford' Callery pear fruit and 'Redspire' have been diagnosed with cedar-quince rust. Since pear is in the same family as hawthorn and serviceberry--usual hosts of this rust, it stands to reason that pears could be infected as well. But, pear is a new host for this common disease. Infected fruit have the elongated white tube structures that protrude and turn orange with time. It is a superficial disease that only infects the fruit. So only the appearance of plants are affected not overall health. Since Bradford pears don't set lots of fruit anyway it may be hard to spot infected ones. Since there is concern over Bradford pears setting fruit and escaping into the landscape it will be interesting to learn if infected fruit can produce normal seed and germinate.

Information from Bob Mulrooney, Extension Plant Pathologist, UD

Sunday, July 26, 2009

Landscape - Leaf Drop in Trees

The following is information on leaf drop in trees in midsummer. This is a common occurance during dry periods in many species. However, excessive premature leaf drop can be a cause for alarm indicating too much plant stress. the following is some additional information.


When the leaves of large shade trees drop during mid-season, it typically causes alarm to concerned homeowners/clients. With the ground littered with spent foliage, the conclusion often is that “their favorite shade tree is dying!” Linden, birch, and sycamore trees are often most susceptible to mid-season leaf drop. In a majority of cases, this is a normal physiological growth habit for these species. The trees commonly drop foliage in mid-season in order to reduce leaf surface area and subsequent water loss. This leaf shedding ability is especially important during typical summer droughts or when water availability in soils is limited. Neither tree health nor tree growth is usually affected.

With this said, excessive premature leaf drop can be a sign that trees are undergoing too much stress. Plants with compromised root systems will be the most affected. If you suspect such a problem, examine the root system and take measures to reduce stress. This might include use of a tree spade to aerate compacted areas, additional watering where rooting is poor, or site corrections such as improving drainage (poor drainage can affect roots in wet periods leading to additional stress when soils dry out).

Some information from the Plant and Pest Advisory newsletter from Rutgers University, other from Gordon Johnson, Extension Horticulture Agent, UD.

Landscape and Nursery - Safari for Armored Scale Control

Safari, a systemic insecticide in the neonicotinoid class has much better action on armored scales than other products. The following is more information.

SAFARI (Dinotefuran)= New Armored Scale Control

Unlike Merit, the relatively new neonicotinoid insecticide named Safari (dinotefuran) has shown promise as an effective control against armored scales. Although both Safari and Merit (imidacloprid) have systemic capabilities with the same general mode of action, Safari is significantly more water-soluble. The high water solubility is thought to be the reason for the increased armored scale controls. Armored scales primarily feed by inserting their piercing-sucking mouthparts into parenchyma cells containing chlorophyll. Since Merit predominately moves through plants by vascular tissues (phloem and xylem), it does not readily enter into cells where armored scales feed. Consequently, Merit has not shown good efficacy against pests that feed within plant cells (typically less than 30-40% control). Recent University efficacy trials have shown dramatically improved results against armored scales with soil injection or drench applications of Safari insecticide. Although this material continues to be translocated by vascular tissues, it also appears to have the ability to permeate through cell walls and membranes. Some efficacy trials have shown controls exceeding 80%!

Information from Steven K. Rettke, Ornamental IPM Program Associate, Rutgers University in the recent edition of the Plant and Pest Advisory from Rutgers University

Saturday, July 25, 2009

Landscape - Lecanium Scales

Control opportunities exist now for controlling Lecanium scales. The following is more information.

Two species of Lecanium scales are problematic in our landscapes and the next few weeks offer good management opportunities. Fletcher scale (Parthenolecanium fletcheri) affects a wide variety of coniferous plants such as Taxus, arborvitae, junipers, and even Taxodium spp.. European fruit lecanium (Parthenolecanium corni) affects a broad range of broadleaved woody plants such as redbud, hawthorn, dogwood, and oak.

Lecanium scale adults appear like little brown lumps grouped along branches. They feed on plant sap and leave a clear sticky substance (honeydew the scales' excrement) that gets on leaves, cars, etc. A black fungus called sooty mold often grows on it. European fruit lecanium has eggs (1000-3500/female) by May 9 and production occurs from 319-1328 GDD (median=654).

For Fletcher scale, eggs were noted by April 16 and continued from 171-1438 GDD (median=592). There is one generation per year. The crawler (hatchling nymph) stages look like tiny yellow-orange dots when tapped onto a white sheet of paper. Crawlers were seen in our area this past week and are later this year than the normal median crawler observations (between 850-900 GDD). The crawlers will migrate to the undersides of leaves/needles and spend the summer months there then migrate back to the branches to spend the fall and winter. They will resume growth, mate, and lay eggs the following spring.

The settled crawler stage is the best time to control lecanium scales. Many insecticidal products are registered for this purpose. Horticultural oil (1-2% v:v) applications work quite well. Occasionally, a re-application of oil is needed about 3 weeks after the initial application to ensure all crawlers have emerged and settled. Many naturally occurring parasites also control lecanium scales look for tiny holes in the adult scale's cover. Many predators like lady beetles also feed on lecanium scales. Insecticides sprayed well after crawlers have settled provide only limited effectiveness. Soil systemic insecticide applications of neonicotinoids such as imidacloprid (Merit) and Dinotefuran (Safari) work well against lecanium scales if applied in advance.

Information from Casey Sclar, IPM Coordinator, Longwood Gardens

Greenhouse - Bacterial Soft Rot on Poinsettias

As poinsettia season gets started with cuttings being rooted, greenhouse growers should watch out for bacterial soft rot. The following is more information.

We have had couple of reports of bacterial soft rot, Erwinia carotovora, showing up on poinsettias in greenhouses. E. carotovora is found everywhere and attacks stressed and weakened plants. Often the problem starts because of how the cuttings are handled. Most cuttings are produced offshore and when they arrive in the United States they are cooled by third party companies before shipment. The trucks they are shipped in are cooled to keep the poinsettia cuttings out of stress. If the cuttings are not kept cooled enough at any stage in this process then they become stressed. When the cuttings arrive at your greenhouse, reach into the box to check the temperature of the poinsettia cuttings. If cuttings feel warm, take them out and cool them down using ice packs, by misting them or by moving them into your cooler and lowering the temperature to 50°F. If you have to stick the cuttings right away, soaking them first will help reduce the temperature stress. Watering the oasis cubes or substrate before sticking also helps reduce stress on the cuttings. Do not heat the greenhouse at night for the first 2 - 3 nights. Greenhouse temperatures of 80-85°F/ 26-29°C during the day and 72°F/22°C at night are optimum for poinsettia propagation. Shading the greenhouse to 1500 - 2000 foot candles/16,140 - 21,520 lux will help reduce temperatures and stress on the cuttings. Remove all infected cuttings from the growing area. If you can get the plants past the first 4 to 5 days, you are usually “out of the woods” with this disease.

Reprinted from the Greenhouse TPM/IPM Bi-Weekly Report from the University of Maryland Cooperative Extension Central Maryland Research and Education Center

Friday, July 24, 2009

Turf - Weather Changes Mean Added Stress

Following a cool, wet, spring, turf will suffer challenges in the hot summer during dry periods. The following is an article on the subject from Rutgers University. Although it is focusing on golf courses and putting greens, the same effects will be seen on lawns and other turfgrass areas.

As the weather turns, so goes the turfgrass. Beautiful fall-like weather (I know it’s July) over the July fourth weekend really changed the dynamics on golf course putting greens in our region. Endless days of rain and overcast skies through May and June have been replaced with low humidity, high skies, cool breezes and moderate to high temperatures. Superintendents have been talking about super-saturated root zones and poor root mass for several weeks now and worrying about an abrupt change to summer heat. Those plants compromised by the wet spring were suddenly faced with a significant increase in transpiration demand. Over the last few weeks, we have seen plenty of poorly performing turfgrass on tough sites, but now we are starting to see plants that simply couldn’t keep up with the change in the weather. Putting green samples of both annual bluegrass and bentgrass are being submitted to the laboratory at a vigorous pace (25 this week). All of them have the same symptoms – slight thinning, poor growth and leaf tip scorch. The submissions came from Rehoboth Beach, Delaware to the south and out to the tip of Long Island to the north. Some samples, of course, look worse than others. Those where we find slight fungal insults - like Pythium root dysfunction or Curvularia fading out - or site related issues - like shade, compaction, or thatch - have more severe symptom expression. All of the samples; however, regardless of the source have the leaf tip scorch symptom in common. Pay close attention to the moisture needs of your turf areas moving forward and keep a careful eye towards stress related disease. There was a long period of wet and cloudy weather this spring and I think our turf may need to feel a little pain before it overcomes it.

Adapted from information by Richard J. Buckley, Director, Soil Testing and Plant Diagnostic
Services, Rutgers University

Landscape and Turf - Welcome Rainfall

We got some welcome rain over the last 2 days. The following are rainfall totals across mid-state:

Dover = 1.03 inches
Bridgeville = 0.46 inches
Ellendale = 1.72 inches
Georgetown = 0.51 inches
Harrington = 0.08 inches
Kitts Hummock = 0.12 inches
Milford = 0.62 inches
Sandtown = 0.24 inches
Smyrna = 1.94 inches
Townsend = 0.07 inches (they did get 1.0 inches on 7/16)
Viola = 0.02 inches

As you can see, rainfall has been quite variable. Some areas are still dry, others have adequate moisture from rain. It is interesting to note that areas so close can recieve such different rainfall totals. Compare the Dover and Kitts Hummock locations within just a few miles of each other.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Thursday, July 23, 2009

Landscape - Current Pests

The following are some pests currently active in DE landscapes that you should watch for.

First generation fall webworm is being found on apple, crabapple and persimmon. Don't think it's the old tent caterpillar tents! Mechanical disruption of the web now will lessen the second generation.

The “Shothole” damage from Tortoise beetle feeding is prevalent on annuals (Ipomea ,etc.) and some perennials.

Rose midge is active this year again in many locations. Look for the “blighted” shoot tips on the terminal growth only.

Powdery mildew is all over crepe myrtle, lilacs, and other shrubs and flowering trees due to warm moist conditions combined with succulent new growth. Fungicides and sanitation may be required to prevent spread or overwintering.

Cicada Killer wasps are solitary wasps and are very unlikely to sting. Males fly at people, dogs, cats, other insects, etc. but are unable to sting. Females prefer to dig holes and sting cicadas. Treatments are rarely warranted.

Information from the current edition of the Ornamentals Hotline Newsletter from the University of Delaware Cooperative Extension.

Landscape and Turf - Wet then Dry, Bad Combination of Stresses

One of the worse combination of stresses on landscape plants and turf is a very wet spring followed by a drought in summer. The following is an article on the subject.

Drought Stress after a Wet Spring

A month ago we were very wet in many areas. Now, we are starting into drought stress conditions in parts of the state (as is common in DE summers). This combination of wet-dry can be extremely damaging to landscape plants and turf. In periods of excess moisture when soils are saturated, root growth often ceases due to lack of oxygen and some roots will die. There can also be increased incidence of root rots. Upon onset of hot, dry weather, plants with weakened root systems often will wilt prematurely and will have more severe stress. In addition, planting activities done in wet soils often creates added compaction and as soils dry out, plants will have a difficult time to root out. Cool season turf growth in cool wet springs is often excessive, especially with heavy spring nitrogen fertilizer. Turf in these conditions will increase shoot growth at the expense of root growth and will also deplete energy reserves. With the return of dry weather, this turf will undergo excessive stress. Trees and shrubs that experienced root damage in wet soils this spring will have additional stresses put on them during drought periods this summer. We are seeing premature leaf drop in many trees and shrubs at this time because of this double set of stresses (wet to dry).

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Wednesday, July 22, 2009

Pests of Stressed Plants

The following are some common pests of stressed plants. We are seeing drought stress in many parts of the state now.

Aphids and whiteflies are apparently drawnt o plants with yellowing foliage. Plantsunder stress often lose some of their chlorophyll and become yellowish in color. Yellow sticky cards are often hung in greenhouses to monitor for some of these pests.

Some species of caterpillars (not gypsy moth) are “samplers” when they feed. These caterpillars will sample individual leaves to determine if they contain plant defensive chemicals such as tannins or alkaloid toxins. If these toxins are contained within the leaves, the caterpillar may find it distasteful and move on to sample other leaves. A weakened plant unders tress may not have enough energy to produce these defensive chemicals and therefore, be more attractive for these caterpillars.

The greatest concern with stressed plants in the landscape is from borer infestations. The best examples of borer-prone plants are when drought conditions and high temperatures stress non-native plants. Pine bark beetles, bronze birch borers, and the two-lined chestnut borers are all encouraged when stressed tress are forced to “shutdown”their vascular systems (xylem& phloem tissues). When trees have low sap pressure, the borers can easily penetrate and cut through vascular tissue. Furthermore, trees with compromised vascular systems cannot readily transport defensive chemicals to areas invaded by borers.

Adapted from a presentation delivered by Dr. David Shetlar (The Ohio State University Extension)@ the RCE IPM Symposium, Nov. 1995

Landscape - Hot, Dry, Weather Pests

In some parts of down state Delaware, we have not had rain for 3 weeks and drought stress is evident. Hot and dry weather will favor certain pests. The following is more information.

Hot-Dry Weather Pests

It is well known that lacebugs reach their highest populations on plants located in sunny-dry locations. There are few predators in these areas,and the shallow rooted azalea is often under drought stress. Lacebugs typically thrive under these conditions.

Scale insects also generally will do better in hotdryweather primarily because the immatures are notknocked off the plants by raindrop “bombs.” Recently hatched scale crawlers are unprotected for several days as they move about the plant looking for a place to settle down. If rains do cause the crawlers to fall to the ground, it is unlikely they will be able to climb back up the plant before they die (their short-stubby legs do notwork very well). The timing of the rainfall to suppress the scale crawlers is critical, because they typically are active for only a few days. Once they settle down and insert their mouthparts into the plant tissue, they are less vulnerable to the raindrops.

Various leaf feeding beetles and caterpillars usually prefer hot-dry conditions, not because they may get knocked off the plants (they will often simply climb back up), but since they can be infected by fungal diseases if a lot of free moisture is present. For example, the Entomophagafungus that has been decimating most of the Gypsy Moth populations for more than a decade does an excellent job of keeping these caterpillar populations in check in cool, moist springs. However, when warm and dry springs occur, this pest typically returns to become a problem again in certain areas.

One of the most common of the warm season pests is the two-spotted spider mite. These pests thrive in very dry conditions, and they will reproduce more rapidly when it is warmer. Mites are vulnerable to being dislodged by heavy rains unless they are under protective leaf covering. Invariably, the worst spider mite populations within the landscape occur when plants are sited under over-hanging structures. In moist conditions, they also can be attacked by diseases but in dry weather, these diseases are not present. In the landscape, twospotted spider mites can have between 10 to 15 generations per year.

Adapted from an article by Steven K. Rettke, Ornamental IPM Program Associate, Rutgers University

Tuesday, July 21, 2009

Landscape and Nursery - Rose Rosette Disease

We are seeing more cases of rose rosette disease in Delaware. The following is more information about this disease.

Rose rosette is endemic and eventually lethal to multiflora roses, and for that reason it has been considered for use as a biocontrol. All cultivated roses are considered to be potentially susceptible, though tolerance is variable, depending on species and cultivar.

Rose rosette is caused by a virus or a virus-like organism, according to the most recent information available. It is spread by the eriophyid mite, Phyllocoptes fructiphilus, also known as the wooly mite. Eriophyid mites are unable to fly, but they are so small they are easily blown by wind. Therefore, to help control their spread, ornamental roses should not be planted downwind of existing areas of multiflora roses. The disease can also be spread by grafting. Transmission is most likely in late spring and early summer.

Symptoms of rose rosette are variable, and may begin as a red mosaic pattern on new leaves, followed by a growth spurt resulting in red pigmented vegetative shoots producing stunted leaves and short, densely-packed red shoots in a witches’ broom. Especially on ornamental roses, many more thorns develop, and the new shoots are thicker and more succulent than normal, leaving them prone to frost damage. These plants are also more susceptible to powdery mildew. The original shoot infections will spread to roots, and then to the remaining canes.

Symptoms continue with distorted flowers with fewer petals and abnormal flower color and possible mottling. Buds may abort, deform, or develop into leaf tissue. All this may resemble effects of herbicide injury, especially glyphosphate and 2,4 D, but the plant can outgrow the herbicide injury.

Management: Remove and destroy roses with symptoms, including the rootstock. Space cultivated roses so they do not contact each other. It is considered safe to replant roses in the same area as long as all roots have been removed. Chemical control consists of miticides effective against eriophyid mites. Recommendations are to apply these weekly in June and July. Miticides for spider mites may not be effective against eriophyid mites, so check the labels carefully. Control materials include Avid, bifenthrin, horticultural oils, and insecticidal soap. Use only pesticides registered for your crop and follow all label instructions.

Reprinted from an article by Penny Wilkow in the July 17, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.

Landscape and Nursery - Rose Rosette Pictures

The following are different pictures of Rose Rosette Disease.

Witches' broom of rose rosette disease. Photo by James W. Amrine Jr., West Virginia University,

Rose rosette symptomatic inflorescence (red pannicle, accompanied by normal flowers on healthy foliage (a separate plant). Photo by James W. Amrine Jr., West Virginia University,

Rose rosette showing bright red shoots emerging in the spring. Photo by James W. Amrine Jr., West Virginia University,

Sunday, July 19, 2009

Greenhouse and Nursery - Handling Media

The following is a reprint of a good article on handling growing media.

How a mix is handled can affect the air and water content of the mix. Compaction is an important factor to consider for plant root health when handling growing media. Air space that results in good drainage can be cut in half or even eliminated by compaction. To minimize compaction, containers, cell packs and plug trays should be lightly filled and the excess brushed away. The media should not be packed down, tamped down, or the filled pots tapped down on the bench several times, and the pots and trays should not be stacked directly over one another.

Another consideration is the moisture content of the mix prior filling containers. When water is added to dry components such as peat, they hydrate and swell. This swelling helps to create more aeration by preventing the particles from nesting within one another. This is especially important in plug production. Water should be added to the mix before it is placed into the container. It is best to moisten, then mix and then allowed to set overnight prior to use. If that is not possible, waiting at least a couple of hours after adding the water will help the hydration process.

How much water to add to the mix? For peat-based mixes for large containers and bedding plant cell pak production use 1 water:1 dry substrate ratio (50% moisture content). Plug mixes should have 2 water:1 dry substrate ratio (67% moisture content). The rule of thumb is, the smaller the cell, the more water to add prior to planting.

Information from the New England Greenhouse Update Website:

Greenhouse and Nursery - Check Your Fertilizer Injector

Fertilizer injectors should be checked for accuracy on a regular basis. The following is a simple procedure to follow for checking your injector.

Procedure to check the EC of a fertilizer solution:

1) Let plain water (no fertilizer) run a little, then collect water in a clean bucket. Take a sample of the plain water from the bucket. Check the EC of the untreated water supply.

2)Mix up your fertilizer as you normally do and run it through the injector and hose. Let it run a little to be sure you get an accurate sample. Take a sample of the fertilizer-injected water from the end of the hose and use your meter or soil test laboratory to check the EC of the sample.

3) Subract the EC value of the untreated water from the EC value of the fertilizer water.

4) Compare the results to an EC chart from the fertilizer manufacturer or fertilizer bag. The chart will correlate the EC measurement with the ppm Nitrogen so you can determine if your injector and mixing procedure is accurate.

Information from the New England Greenhouse Update Website

Saturday, July 18, 2009

Landscape - Generalist Caterpillars

There are a number of generalist caterpillars that can attack landscape plants, especially annual and herbaceous perennial plants. The following is more information.

A number of caterpillar species will feed on ornamental plants in the landscape. These include the well known pest such as bagworms, fall webworms, and eastern tent caterpillars. However, some pests more commonly associated with agricultural crops will also feed on ornamental plants. These include corn earworms, cutworms, various loopers, pansyworms, hornworms, and others. These are generalist caterpillars that readily feed on many plant species. Look for them on herbaceous perennials and annual bedding plants in particular. Caterpillar damage to bedding plants can be distinguished from slug or beetle damage because caterpillars generally consume large areas of leafs including all but the largest veins. Slugs will leave a messing trail of slime and feeding damage will appear irregular. Caterpillars in hanging baskets and small plantings can often be removed by hand. Commercial operators have a number of chemical options to choose from including the pyrethroid and spinosyn class insecticides.

Adapted from an article in the current North Carolina Pest News

Landscape and Nursery - Baldcypress Rust Mite

Baldcypress rust mite is evident now on Baldcypress trees in Delaware. The following is more information.

Baldcypress rust mite (BCRM). Even with the wet spring, Taxodium foliage may be showing the russetting, bronzing, distortion, and premature leaf drop that are telltale symptoms of BCRM damage. Look for the white cast skins of these microscopic yellowish-brown with a hand lens. BCRM overwinters as mated females in bark cracks and buds of baldcypress. After bud break, females migrate to needles and lay eggs. Populations build up rapidly in warm weather and typically peak in late July to Mid-August. BCRM feed until about needle drop in mid-October, when they re-position for overwintering. Use funnel sampling to scout for BCRM and other spider/rust mites.

No need to manage BCRM in the landscape, if premature browning and leaf drop is tolerable. Treatment is warranted in container and field nurseries. Several natural enemies feed on BCRM-predatory mites, predatory thrips, and spider mite destroyers (a small lady beetle - Stethorus spp.) are a few. We found that populations of BCRM were best managed using 1250 GDD or petal fall of Kousa dogwood as early indicators. We're past that now…

2% (v:v) horticultural oil the best chemical control for BCRM. While several other researchers have noted phytotoxicity from its use on baldcypress, our mid-season oil applications have reduced BCRM without burn and may provide lecanium scale crawler control as well. Attempts to manage BCRM in the dormant stage with oil applications actually INCREASED mite populations during that season and should be avoided. Avid (abamectin) or Forbid (spiromesifen) are other miticidal choices for later in the season, but will harm some natural enemies. Many newer selective miticides such as Hexygon and Floramite have NO EFFECT on rust mites, so check the label.

Information from Casey Sclar, IPM Coordinator, Longwood Gardens

Friday, July 17, 2009

Landscape - Current Pests

The following are some current pest reports from the Ornamental's Hotline newsletter from Delaware Cooperative Extension.

We are still seeing twig dieback from earlier infections of bacterial blight on willow oak, pear, and cherry. Trim back at least 12 inches below the affected area when dry. With all the lush new growth (Saturday's sprinkle followed by sunny days), be on the lookout for aphids and whiteflies infesting the new growth of annuals and perennials. Japanese beetle populations are much lower than expected so far this year. Azalea whitefly was noted on deciduous azaleas. More lace bugs starting up on Franklinia, oak, and other species; 2nd generation Euonymus scale crawlers should be active anytime. Hort oil (as temps permit), insecticidal soap, Distance, Safari are all good options for control. Brian Kunkel ( is still looking for sites with Euonymus scale infestations.

Landscape - Invading Millipedes

Each year I get samples of millipedes that are invading houses and other structures. The following is an article on the subject. Commercial landscape companies may be asked to deal with the problem.

Millipedes are long, many segmented creatures that use their two pairs of legs per body segment to move along with deliberate speed. There are several species in Delaware with a variety of shapes and colors.

Millipedes can be very abundant in forest litter, grass, thatch, and in mulched areas. These places provide needed food, shelter, and dampness. Usually, millipedes stay out of sight unless abundant rainfall or some other event, such as the mating season, puts them on the move.

While harmless and in fact, helpful recyclers, millipedes generally are not welcomed with enthusiasm. They often invade crawl spaces, damp basements and first floors of houses at ground level. Common points of entry include door thresholds (especially at the base of sliding glass doors), expansion joints, and through the voids of concrete block walls. Frequent sightings of these pests indoors usually mean that there are large numbers breeding on the outside in the lawn, or beneath mulch, leaf litter or debris close to the foundation. Because of their moisture requirement, they usually do not survive indoors for more than a few days.


Minimize moisture & remove hiding places - The most effective, long-term measure for reducing entry of millipedes is to minimize moisture and hiding places, especially near the foundation. Leaves, grass clippings, heavy accumulations of mulch, boards, stones, boxes, stacked firewood or similar items laying on the ground beside the foundation should be removed, since these often attract and harbor pests. Items that cannot be removed should be elevated off the ground.

Seal entry points - Seal cracks and openings in the outside foundation wall, and around the bottoms of doors and basement windows. Install tight-fitting door sweeps or thresholds at the base of all exterior entry doors, and apply caulk along the bottom outside edge and sides of door thresholds. Seal expansion joints where outdoor patios, sunrooms and sidewalks abut the foundation. Expansion joints and gaps should also be scaled along the bottom of basement walls on the interior to reduce entry of pests and moisture from outdoors.

Insecticides - Exterior applications, in the form of barrier sprays, may help to reduce inward invasion when applied outdoors, along the bottom of exterior doors, around crawl space entrances, foundation vents and utility openings, and up underneath siding. It also may be useful to treat along the ground beside the foundation in mulch and ornamental plant beds, and a few feet up the base of the foundation wall. Heavy accumulations of mulch and leaf litter should first be raked back to expose pest hiding areas. Insecticide treatment may also be warranted along the interior foundation walls of damp crawl spaces and unfinished basements. There is no benefit from treating indoors.

One species of millipede. Photo by Gary Alpert, Harvard University,

Adapted from "Millipedes and Wood Cockroaches - Common Invaders in July" By Lee Townsend in the current edition of the Kentucky Pest News

Thursday, July 16, 2009

Landscape - Peony Blotch

The following is information on Peony blotch, a common disease of Peony in Delaware.

Peony blotch is now evident on garden and tree peony. Look for purple to dark red spots on the upper surface of the leaves and the corresponding lower surface will be chocolate brown color. The fungus, Cladosporium, will also infect the stems and produce circular spots with red borders. Be sure to remove and destroy infected leaves and stems in the fall to reduce overwintering spores. It's too late for any fungicide control this season unless you are just seeing the first blotches. The disease does not seem to affect plant health all that much, just makes a mess of the leaves.

Information from Bob Mulrooney, Extension Plant Pathologist, UD

Landscape and Nursery - Sucker Control

The following is information on sucker control in woody plants.

Many ornamental trees and shrubs will produce suckers from the stem area at the base of a plant, some from the roots. In multi-stem shrubs, these suckers will provide new stems and can serve as a means to rejuvenate plants (remove old stems, keep some new stems). However, in most trees and single stem shrubs, suckers are a drain on plant food reserves and can attract pests. In grafted plants, suckers from rootstocks will be different from the desired ornamental plant. Sucker removal by hand pruning can be time consuming in nurseries and large landscapes.

There are some chemical aids to reduce or eliminate suckers. Naphthaleneacetic Acid (NAA), a growth regulator, is labeled for some non-residential uses on ornamental plants. Apply in the dormant season or before new shoots are 12’’ long. Pelargonic acid (Scythe) is a non-selective herbicide that can be applied to suckers of woody plants. It can be used in landscapes and nurseries. Use a 5-10% solution. One caution is not to use glyphosate (Roundup and many other trade names) for sucker control or around plants with suckers. The glyphosate will be translocated into the root system of the plant and while you may not see any affect to the main plant this year, in the following year, the glyphosate will be mobilized from the root system and translocated to growing points causing poor leaf out, yellowing, reduced growth or stunting.

Gordon Johnson, Extension Agriculture Agent, UD

Wednesday, July 15, 2009

Landscape - Verticillium Wilt

As drier weather sets in, evidence of wilting in some tree species may be seen. One cause of wilting is Verticillium wilt, a fungus disease. The following is more information.

Verticillium wilt of woody plants is caused by the fungus Verticillium dahliae, or in some cases by V. albo-atrum. The fungus is capable of causing a serious vascular wilt of a wide range of woody plants. Several of our common landscape trees such as ash, katsura tree, magnolia, maple, redbud, and tuliptree are susceptible to Verticillium wilt.

Symptoms. By invading the xylem tissues of the tree, Verticillium disrupts the movement of water from the roots to the leaves. As a consequence, leaves wilt and branches die back. This often occurs one branch at a time or on one side of the tree over a period of several years, but sometimes in only a matter of months or a year. Sometimes, branches simply fail to leaf out in the spring - the result of infection the previous year. Verticillium wilt may also cause marginal browning and leaf scorch, abnormally large seed crops, small leaves, stunting, poor annual growth, and sparse foliage. However, some or all of these symptoms may also be caused by girdling roots, construction injury, bacterial leaf scorch and drought.

In the landscape and nursery, one should try to observe additional diagnostic symptoms. Usually, there is staining of xylem and cambial tissue, visible as streaks if you cut into the wood. The color of this staining will vary for different trees often being greenish black in maple, yellowish green in smoke tree, dark brown in redbud, and brown in ash and catalpa. Be aware that often young twigs and branches and some tree species simply don’t show the streaks of stained xylem tissue under the bark and that other fungi and other factors can cause staining. For a positive laboratory diagnosis of Verticillium wilt, stained vascular tissue is essential.

Disease biology. The Verticillium fungus survives as resistant, dormant microsclerotia for many years in soil, making effective crop rotation in the nursery or landscape difficult. The fungus infects plant roots through wounds, or in some cases, direct penetration of susceptible root tissue. In the nursery, the Verticillium fungus could also be transmitted from plant to plant by grafting and budding. From the root infections, the fungus spreads into the plant through the xylem. Xylem tissues become blocked so that stems and leaves no longer are supplied with adequate water and mineral elements. After the tree dies, the fungus is returned to the soil as tiny resistant fungal microsclerotia. Microsclerotia can also be spread by wind, in soil, and on equipment. Many herbaceous and weed hosts are also susceptible so it is hard to avoid contaminated soil. Verticillium wilt is favored by landscape stresses such as wounding and drought. It is possible that much of the Verticillium observed now relates back to stresses imposed by the drought last summer.

Reprinted from "Verticillium Wilt is Active in Catalpa and Smoke Tree" By John Hartman in the current edition of the Kentucky Pest News. For the full article with pictures go to

Landscape - Managing Verticillium Wilt

Relating to the recent post on Verticillium wilt in trees, the following are points to consider in managing Verticillium wilt.

1) Where Verticillium wilt has been diagnosed, only replant with disease resistant plants. Conifers such as hemlock, pine, taxus and spruce are not affected. Other trees that are typically free of this disease include: beech, birch, crabapple, mountain ash, dogwood, hackberry, hawthorn, hickory, holly, honeylocust, mountain ash, oak, pear, planetree, sweetgum, sycamore, willow, and zelkova. The red maple cultivars Armstrong, Autumn Flame, Bowhall, October Glory, Red Sunset, Scarlet and Schlessinger have also been reported as resistant.

2) Keep plants as healthy as possible. Good plant health care includes good site selection, proper transplanting, good water management, a prudent fertility program, and pruning out dead branches. Be aware that while pruning out infected branches is a useful general horticultural practice for maintaining plant vigor and aesthetics, it does not eliminate Verticillium from the plant since infections originate and spread from the roots.

3) Fungicides are not effective for control of this disease.

Information from the an article by John Hartman, UK Plant Pathologist, in the current edition of the Kentucky Pest News

Tuesday, July 14, 2009

Landscape - Cicada Killers

Cicada killers in the landscape can get home owners worried due to their large size and excavation they do in the landscape. The following is more information.

Now that cicadas are out, soon to follow are the wasps that hunt them. The cicada killer wasp uses cicadas to provision its nest. Cicadas are caught and stung by the wasp, then dragged back to the nest. The most noticeable feature is often the large amount of soil excavated and mounded outside the burrow. Once in the nest, the female wasp lays her eggs on the cicada. Soon the egg hatches and the larva feeds on the cicada. When mature, the wasp larva pupates and another generation of wasps emerges to carry on the life cycle. This is one of our most "showy" wasps and the sight and sound of a collection of them in a yard is impressive. I used to say that I had never heard of anyone being stung by one until a woman from Texas sent me an e-mail message to say that she had, indeed, been stung. However, it was really an accidental entanglement that created the situation. She seemed only slightly amused to know that she held such an honor. Since they control cicadas, these wasps can be regarded as beneficial. They are also downright interesting. Ornamentals and Turf Insect Note No. 63 ( has additional information on the biology and control of cicada killer wasps.

Cicada killer wasp and cicada. Photo by Ronald F. Billings, Texas Forest Service,

Information from the July 10, 2009 edition of the North Carolina Pest News

Turf - Controlling Nutsedge

The following is information on controlling Nutsedge in Turf.

Control options for the homeowner are rather limited; look for products with the active ingredient sulfentrazone or halosulfuron. Yellow nutsedge control options for professional applicators include Dismiss (sulfentrazone) and Sedgehammer (a.i. halosulfuron). Repeat applications will likely be required to achieve control. As with any herbicide applications at this time of year, be cautious of applications to turfgrass that is under drought or heat stress, even with the relatively cool temperatures, the soil is drying out in many areas and the turf is starting to show some stress. General recommendations are to avoid herbicide applications when temperatures are above 80 F due to the risk of burning the turf. Sulfentrazone has been implicated in causing damage to tall fescue turf in some cases, especially when applied with urea fertilizers.

Information in part from the Michigan State University Landscape Alert Site

Monday, July 13, 2009

Nursery and Landscape - Controlling Suckers

Controlling suckers in woody plants in the nursery can be time consuming by hand. There is a chemical option that could also be used in large landscapes. The following is more information.

We have had several questions on what materials to use to burn back sucker shoots on nursery plants. The wet season has resulted in a proliferation of sucker shoots. First off, do not try to use glyphopate to burn back sucker shoots. This will translocate into the plant and will cause bark splitting and possible dieback of the plant. Pelargonic acid sold as the product Scythe from Dow AgroSciences Company, can be used to burn back sucker shoots Avoid using this material on young trees with green bark. The material is applied to the sucker shoots before they become woody. The percent used is between 5 and 7%. The 5% rate is 2 quarts in 10 gallons of water. The 7% rate is 2 3/4 quarts in 10 gallons of water.

Information from the University of Maryland TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers

Sunday, July 12, 2009

Landscape and Nursery - Daylily Rust

The following is information on daylily rust, a relatively new introduced disease that can attack daylilies.

Daylily Rust

The recent introduction of a new disease has complicated the nearly trouble-free reputation of daylilies. Daylily rust, caused by the fungus Puccinia hemerocallidis, produces yellow spots or streaks on leaves and scapes, with raised pustules commonly on the undersurface releasing infectious orange spores. The frequently seen Daylily Leaf Streak, caused by the fungus Aureobasidium microstictum, begins with water-soaked brown spots usually beginning at the top of the leaf. As these work their way downward, they lengthen into brown streaks with yellow borders. A quick way to confirm Daylily Rust as the problem is to wipe a clean white tissue over the leaf lower surface – an orange stain indicates the presence of the rust spores. A severe infection on susceptible varieties may result in withering and death of the leaves, but the crown and roots are not involved.

As with other rusts, P. hemerocallidis has a life cycle that features two hosts, though it requires only the daylily to survive asexually from year to year. On daylily, the fungus produces two kinds of infectious spores – the orange urediospores, spreading disease during the growing season to other daylilies, and the darker, thicker-walled teliospores. These can survive the winter and infect the alternate host to complete the life cycle with the sexual stage. The alternate host is Patrinia, a perennial with fern-like leaves and bright yellow umbels, sometimes used as a filler for border plantings. No infection of Patrinia has been observed in the US, however, and the fungus can infect other daylilies without infecting the alternate host. Reports that Hosta can act as an alternate host have not been verified.

On daylily, disease spread is favored by warm temperatures and high humidity. Cloudy rainy weather is best. Poor air circulation and overhead watering at night should be avoided. Spores can spread by wind, windblown rain, or mechanical transfer by clothing or tools, for example.

Management: Select varieties that are more resistant.

The following list is from the Texas Cooperative Extension, Texas A & M University, April, 2004. Destroy infected leaves and those of nearby plants.

Remove shoots as close to the ground as possible. Fungicide sprays can be used when new growth emerges. In the fall, remove foliage from all plants and destroy or compost these (hot compost temperatures will eradicate the urediospores). If you are planting newly purchased daylilies in the spring, prune them back to remove possible inoculum from your landscape. Fungicides available to commercial growers for managing this disease include azoxystrobin (Heritage), propiconazole (Banner Maxx), myclobutanil (Systhane), thiophanate methyl (Cleary’s 3336 and others) or flutolanil (Contrast). Follow all label directions.

Reprinted from an article by Penny Wolkow in the July 10, 2009 edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension

Landscape - Twobanded Japanese Weevil

The following is information on twobanded Japanese weevil. Adults will be emerging during the summer in DE.

Twobanded japanese weevil adults [1267- 1897 (1555 peak) GDD base 50] feed on ash, cherry laurel, pyracantha, privet, rose, spirea, forsythia, lilac, barberry, flowering dogwood, broad-leaved evergreens, and others. This flightless weevil is light to dark brown and feeds during the day on new leaves, shoots and inner foliage, but drops to the ground when disturbed.

Remove excessive mulch to prevent overly moist soils around susceptible plants. Entomopathogenic nematodes, Heterorhabditis and Steinernema spp., offer variable control of larvae in field plots but have performed better in container soil in greenhouses. Adult chemical control includes acephate, pyrethrins, piperonyl butoxide, and cyfluthrin and imidacloprid. The twobanded Japanese weevil is resistant to sevin and malathion.

Twobanded Japanese Weevil adult. Photo from the University of Georgia Archive, University of Georgia,

Information from Brian Kunkel, Ornamental IPM Specialist, UD

Saturday, July 11, 2009

Landscape - Black Vine Weevil

Black vine weevil will be laying eggs soon in the landscape. The following is more information of this pest which is a big problem on Rhododendrons in DE.

Black vine weevil adults [87-3644 (1259 peak) GDD base 50] feed on over 100 plants such as Taxus, hemlocks, euonymus, mountain laurel and rhododendrons. Magnolia x soulangiana in full bloom signals the beginning of adult activity. This flightless weevil feeds during the night and rests at the base of plants during the day. Adults are gray to brownish black. Larvae are c-shaped, legless, and creamy colored with brownish heads. Larvae feed in early spring and emerge from pupae in late-May to June. Adults (all female) feed for 21-45 days before egg laying in July when each female oviposits about 200 eggs in the soil or leaf litter around the plant. Adult feeding appears as notches on leaves. Larvae prefer to feed on young roots, but scarce roots and moist soil results in stem feeding that can eventually girdle plants. Larvae feed until soil temperatures force them to dig deeper to overwinter.

Black vine weevil adult. Photo by Mike Reding & Betsy Anderson, USDA Agricultural Research Service,

Adult black vine weevil feeding appears as notches on leaves. Photo by Eric R. Day, Virginia Polytechnic Institute and State University,

Black vine weevil larvae. Photo by Mike Reding & Betsy Anderson, USDA Agricultural Research Service,

Information from Brian Kunkel, Ornamental IPM Specialist, UD

Friday, July 10, 2009

Landscape - Insects and Swimming Pools

Clients may complain to you about insects in swimming pools. The following is some information that you can pass on to them.

Swimming pools attract a variety of insects. Honey bees come to collect water for use in their colonies. A few aquatic insects, mostly bugs and beetles, come because water is their natural environment; to them, a swimming pool is just another pond. A few (like thrips) come as a result of disturbances – cutting hay fields or wheat. Finally, there are those that just accidentally fall into the water and cannot escape.

Honey bees need lots of water to maintain optimum hive temperature and humidity; a nearby swimming pool may be the most convenient supply, causing alarm to pool owners and users. Worker bees that find a good water source will recruit colony mates to join them. Over time, hundreds of bees may be appear. Some will fall into the water and drown but others will keep coming. They are preoccupied with this task and generally are not a threat. Dealing with bee visits to small kiddy pools can be as simple as moving the pool to a different spot in the yard every few days. Bees follow directions very strictly and if the pool is not where it should be, they will not find it easily. You can stay ahead of them with the moves.

Aquatic insects, such as backswimmer bugs and toe biters, may arrive in large numbers as they fly from ponds in which they developed to colonize other bodies of standing water. In some cases, they may be abundant enough to clog filtering systems. Usually, this mass movement lasts only a few days. Backswimmers are predators; they can give a painful bite with their piercing-sucking mouthparts. There should be no question as to what the toe biter can do. The pain from these bites is similar to a bee sting but there is no toxin.

Thrips can make a dramatic appearance. These tiny elongate yellow insects were described on one insect ID form as follows: "These little biting things covered an aboveground pool and deck. They were so thick that you could wipe them off with your hand. They have painful bites, children could not play in the pool for them." Thrips show up at pools probably drawn to water or driven there from nearby recently-cut hay fields. On normal days thrips use their abrasive mouthparts to rasp at plant tissue, especially flowers. However, they will scrape skin, perhaps as they attempt to pick up small amounts of moisture. An occasional thrips scrape probably is tolerable but lots of them do not add to the swimming experience. A strong jet of water may be used to plaster them to decks and other surfaces where they have accumulated.

Finding and managing the source of an insect problem usually is the most effective management practice but this is rarely possible or practical with swimming pool invaders. There is no safe or effective means of treating pool water to keep intentional or accidental invaders away. Covering the pool when it is not in use may be the best and only way to exclude chronic problems with unwanted creatures. Fortunately, this may be needed for only a few days at a time. The clumsy pool invaders are the easiest to handle – the few that fall in can be removed with a cleaning net or cup.

Reprinted from "Few Management Alternatives for Insects around Swimming Pools" By Lee Townsend in the current edition of the Kentucky Pest News

Landscape, Nursery, and Turf - Provaunt Insecticide

The following is information on Provaunt insecticide, one of the new low risk materials that is on the market for use in landscape, nurseries, and turf.


Provaunt, containing the active ingredients Indoxacarb, is a low risk pesticide for use in landscape and turf areas. This is also another product from Dupont Company. It controls caterpillars such as gypsy moth, bagworms, webworms, and yellowneck caterpillars. This material is not systemic. If applied for caterpillar control it is suggested that it be applied to early life stages of caterpillars.

It also is labeled for control of potato leafhopper. For foliar applications the label rate is 1.25 – 2 oz/100 gallons of water.

In turf areas it controls several species of cutworms, armyworms, sodwebworms and grasshoppers. For turfgrass it is used at very low rates of 2- 4 ounces of product per acre.

Information from Stanton Gill, Extension Specialist, Central Maryland Research and Education Center, University of Maryland Cooperative Extension

Thursday, July 9, 2009

Landscape and Turf - Spent Mushroom Soil

Spent mushroom soil is a readily available resource in Delaware as the mushroom industry is nearby. The following is information on the characteristics of spent mushroom soil.

Characteristics of SMS

Spent mushroom substrate is the composted organic material remaining after a crop of mushrooms is harvested. Mushrooms are grown in a mixture of natural products, including horse-bedded straw (straw from horse stables), hay, poultry manure, ground corn cobs, cottonseed hulls, gypsum, and other substances. This mixture is composted in piles or ricks, creating a dark brown, fibrous, and pliable organic growing media. When the composting process is complete, the media is brought into mushroom houses where it is placed into beds or trays and used as a substrate for growing mushrooms. After the mushrooms are harvested, the "spent" substrate is removed from the houses and pasteurized with steam to kill insects, pathogens, and mushroom remnants.

Spent mushroom substrate is sometimes sold immediately after it is removed from mushroom houses; in this case it is referred to as "fresh SMS". Alternatively, the SMS can be placed in windrows and further composted for several weeks or several months. This material is often called "weathered SMS" and differs in composition and appearance from fresh SMS. Some producers blend SMS with soil to produce a ready-to-use growing medium for turfgrasses and other plants.


Landscape and Nursery - Conserve Insecticide

The following is information on Conserve insecticide. This is one of the newer low risk insecticides for use in the landscape and nurseries.


Conserve SC, spinosad, is a very safe insecticide from Dow Agro Science that has been in the marketplace for several years. It is a low risk pesticide that is made through fermentation of naturally occurring fungi. It is very effective in controlling lepidopterous caterpillars, several sawfly species larvae, thrips and some leafminers. In turfgrass it can be used to control cutworms, armyworms and sodwebworms. It is labeled for use in the landscape, nursery and turfgrass areas. In nurseries it has a 4 hour REI.

This material is very gentle to beneficial organisms such as ladybird beetles, lacewings and other predators. This product has no detectable ill impact on birds or fish.

For caterpillar control such as bagworms, tent caterpillars and other leaf feeder it works well on young larvae and later instar larvae.

Information from Stanton Gill, Extension Specialist, Central Maryland Research and Education Center, University of Maryland Cooperative Extension

Wednesday, July 8, 2009

Landscape - Nuisance Fungi and Landscape Mulch

The following is information on different nuisance fungi that sometimes grow in landscape mulch.

Mulches are used in Delaware gardens and landscapes for many reasons. By suppressing vegetation near trees and shrubs, they keep mowers and string trimmers from damaging the bark. In landscape beds and in the garden, they control weeds, improve drainage, prevent soil water loss, lower soil temperatures, prevent soil erosion and, as they decompose they release minerals and leave behind humus which benefits the plants. Organic mulches generally suppress plant pathogenic fungi and enhance beneficial mycorrhizal fungi. For continuing benefits, mulches need to be reapplied periodically. However, mulches are sometimes misused, especially around trees where excessive mulch (volcano mulch) is placed against the trunk, a practice which is harmful to trees.

Earlier in June, rains and use of fresh wood chip or bark mulch in landscape beds resulted in a proliferation of nuisance fungi growing in or on the mulch. One that was prevalent is slime mold (sometimes referred to as “dog vomit fungus”) which produces yellow or whitish patches of mold which later turn gray as they dry out. This slime mold spreads over the surface of the landscape mulch, sometimes surrounding the stems of plants in the bed. Although nuisance fungi such as slime mold rarely harm plants, some homeowners and landscapers object to their appearance and thus seek ways to prevent or eliminate these fungi.

There are many examples of fungi that grow on or from landscape mulch. Examples include stinkhorns (Mutinus and other related species), bird’s nest fungus (Crucibularium), earth stars (Geastrum spp), assorted toadstools, slime molds (Physarum and other species), and the shotgun, or artillery fungus (Sphaerobolus). Of these, only the shotgun fungus is truly a nuisance because it shoots tiny black spore masses onto nearby surfaces such as home siding and cars. Fungi also permeate thick layers of dry mulch, creating a hydrophobic mulch which is not easily penetrated by water, thus causing irrigation problems. Fertility problems can result when the fungi decomposing mulch removes nitrogen from the soil which is needed by the plants.

With proper manipulation, mulches can be prevented from developing nuisance fungi while maintaining the benefits of mulch. Much work on microbes and mulch has been done at Ohio State University where they have found that hardwood mulches (commonly used in Kentucky), especially if finely ground, contain a large amount of cellulose which decomposes fairly rapidly and leads to nuisance fungi. Such mulches, if composted for a few weeks with added nitrogen, and maintained at moisture levels over 40%, will not develop nuisance fungi. Such moisture levels allow bacteria and other fungi to compete with the nuisance molds. Wet mulches are heavy and require more effort to transport; however, moisture contents of organic products up to 50% will not present excessive transport weight problems.

The following are suggestions for the landscape industry and for homeowners wishing to avoid nuisance fungi:
-Purchase composted mulch products.
-Use mulches low in wood and high in bark.
-Avoid finely ground woody products unless composted first.
I-f using fresh wood chips such as those from a tree maintenance firm, add water to the mulch and allow the pile to partially compost for six weeks. If the wood chips do not include fresh leaves, add some nitrogen to speed composting.
-Use coarse mulches, but do not apply them too deep.
-Soak all mulches with water immediately after application to enhance bacterial colonization.
-Do not apply mulch deeper than three inches.
-Do not use sour mulches (highly acidic mulches giving off an acrid odor) because they injure plants.

Reprinted with slight edits for DE from "Mulches, Mushrooms and Molds" By John Hartman in the current edition of the Kentucky Pest News

Landscape and Nursery - Bt for Caterpillar Control

The following is information on the use of Bt biological insecticide for caterpillar control in ornamental plants.

Bacillus thuringiensis (Bt)

Bt is one of the oldest and very safe materials used for control of caterpillars. The insecticide produced from this rod-shaped bacterium does not harm animals, birds, beneficial insects or humans. This material is not systemic and must be ingested by a caterpillar to cause death. When eaten by a caterpillar a crystal dissolves in the insect’s stomach and breaks down the stomach wall. The crystal can only dissolve in those insects species whose stomach contain the correct combination of pH, salts, and enzymes. It cannot dissolve the highly acidic stomach of humans. Because of the selectivity, the US EPA permits food crops sprayed with Bt to be eaten right after spraying. Bt is effective in controlling early stages of caterpillars but is rather ineffective against late instar stages of caterpillars. It can provide good control of early instars of bagworms, eastern tent caterpillars, fall webworms, yellowneck caterpillars, orange stripped oak caterpillar and several other lepidopterous species of caterpillars. Note: Bt will not control sawfly caterpillars which are in the order Hymentoptera.

Information from Stanton Gill, Extension Specialist, Central Maryland Research and Education Center, University of Maryland Cooperative Extension

Tuesday, July 7, 2009

Landscape - Flatheaded Appletree Borer

The following is information on the Flatheaded Appletree Borer, a pest of many tree species in Delaware

Flatheaded Appletree Borer, Chrysobothris femorata

Flatheaded apple tree borer adults are dark greenish brown on top (dorsal) and brown on the underside (ventral). The wings have two wavy, indented light bands. Look for the adults in sunny locations. You may find adults in the early morning sitting on the bark of a tree. The adults tend to attack stressed apple, beech, dogwood, elm, linden, oak, willows and apple trees. The last two years of drought has stressed many trees in Delaware making them susceptible to attack from this borer. Young, newly transplanted trees can be attacked and killed by this beetle.

Non-chemical Control: Keep trees healthy and vigorous and this beetle will not be a problem. It is easy to say and hard to do in a lot of situations.

Chemical Control: Apply Onyx or Astro to the main trunk of the tree.

Photo of flatheaded apple tree borer by Joseph Berger,

Information adapted from the current edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.

Landscape and Nursery - Downy Mildew on Rudbeckia

Rudbeckia, especially the cultivar "Goldsturm" has been showing susceptiblity to a number of diseases in recent years. The following is information on Downy Mildew of Rudbeckia.

Downy mildew is becoming an increasingly important problem in nurseries. The disease is caused by the fungus Plasmopara halstedii. A recent report detailed a severe outbreak of downy mildew on Rudbeckia ‘Goldsturm’ in Virginia Beach nurseries in June 2005 and 2006, when most of the crop was lost, though other Rudbeckia species and cultivars adjacent to Goldsturm were not affected.

The symptoms begin as light green spots on leaves’ upper surfaces. These mature into dark necrotic blotches, with fuzzy gray-white hyphae and spores appearing on the lower surfaces. Leaf and shoot distortions may follow. In warmer areas, the fungus can overwinter as oospores in dead plant material or soil. If it is not warm enough for inoculum to survive in infected plant debris or soil, spores will arrive by wind or through introduction of infected plant material from southern areas. New infections begin as water splashes spores to the surfaces of lower leaves. Additional spores produced in these leaves will travel by wind or water to spread the disease. Favorable temperatures for disease development are cool – 58 to 72 °F – with humidity higher than 85% at the leaf surface.

Management: Growers should scout incoming plant material carefully for signs of downy mildew. Infected plants must be removed and destroyed immediately – do not compost these. Keep nighttime temperatures in greenhouses high, and try to maintain humidity lower than 85% by proper spacing and pruning. Avoid overhead watering; keep leaves as dry as possible in the morning and early afternoon as this is when spore release and dissemination are most active. Fungicides should be used preventively. Downy mildews can develop resistance, so a combination of systemic and protectant fungicides will provide best control and avoid development of resistance. A partial listing of fungicides includes Subdue, Heritage, Phyton 27, Kocide, Dithane, and liquid copper. Professional applicators may be required.

Information from the current edition of the TPM/IPM Weekly Report for Arborists, Landscape Managers & Nursery Managers from the University of Maryland Cooperative Extension.

Monday, July 6, 2009

Landscape, Nursery, and Turf - Acelepyrn Insecticide

The following is information on Acelepyrn insecticide, a new, reduced risk insecticide for use in landscape, nurseries, and turf.

Acelepyrn from Dupont Company is very safe, new systemic material for controlling foliar feeding caterpillars, some boring caterpillars, lacebugs and some leafminers in the landscape. Acelepryn uses an entirely unique class of chemistry with a novel mode of action and active ingredient that has been classified as EPA Reduced Risk for turf applications. Acelepryn also has a low impact on non-target organisms such as beneficial arthropods as well as bees, birds, fish and mammals, and has a very low water solubility. It is the first insecticide in the new anthranilic diamide class of chemistry.

Acelepryn has been developed to provide control of caterpillars feeding on trees and shrubs. It has been reported to kill fairly late instar caterpillar stages. This material can be used for caterpillars that feed in turfgrass such as sod webworm and armyworm. It also does an excellent job of controlling white grubs, bluegrass weevil, and billbugs. For white grubs, the labels states it is applied in April through September. One application provides season long control. For billbug control, apply the material in April or May when billbugs are first observed. For tree and shrub applications it can be used as a foliar, soil or bark treatment for ornamental insect control. Since it is a systemic it will be taken up from a soil application, but it should be applied within 1 - 3 ft of the base of the plant. For foliar applications for controlling caterpillars such as bagworms the label range is 1 - 2 oz mixed in 100 gallons of water. For maximum residual control the labels states to use it at a rate of 16 oz/100 gallons of water. This would be one expensive treatment at this high rate.

Lepidoptera (caterpillars) boring into trees: Acelepryn can be applied to the trunk of trees for control of clearwing moth borer larvae such as banded ash clearwing and peachtree borer. The label states that the product should be used at 4 oz/100 gallons of water and sprayed on the trunk down to the flair of the plant. Apply the material after adult emergence.

Acelepryn contains the new active ingredient chlorantranilirole. It is used at very low application rates (0.1 lb/acre A.I.). Here is the best part: DuPont Acelepryn has been classified as a reduced risk insecticide by the EPA. It has also received the presidential green seal award.

Information from "Being Greener When Controlling Bugs" By Stanton Gill, Extension Specialist, Central Maryland Research and Education Center, University of Maryland Cooperative Extension and Professor in Landscape Technology,Montgomery College,,

Landscape - Mulch and Termites

The following is a good article on mulch and termites from the University of Maryland.

Like daffodils and dogwoods, fresh mulch is a harbinger of Spring. Whether it's traditional favorites like shredded hardwood and pine bark or specialty products like pine straw and cedar bark, gardeners and landscapers depend on organic mulches to conserve water, reduce weeds, and give gardens a tidy, orderly appearance. Subterranean termites are notorious for tunneling into wood items that are in direct contact with the soil, such as planters, fences, and trellises, and gaining access to homes via these exterior fixtures. Homeowners, mindful of this well-earned reputation, often question whether wood and bark mulches can attract and support foraging termites.

Field research at the University of Maryland, College Park, indicates that organic mulches do not attract termites to the underlying soil, nor will the termites consume mulches in any great quantity. Termites have been observed within newly purchased bags of moist mulch, as well as bags that had been allowed to sit undisturbed for a while. The warm, wet environment of these full bags is ideal for the termites, but such conditions do not exist when the mulch is applied to its recommended depth of 3-4 inches. However, foraging termites can travel within the mulch layer and could theoretically use the mulch as a bridge up over a termiticide treatment around a foundation and into a home. For this reason, it is recommended that a band of bare soil be left around foundations. Surprisingly, even pea gravel perimeters should be avoided. Termites have been shown to feed more actively at resources beneath inorganic gravel mulches, presumably because gravel and stone mulches create a cool, moist, “shadow” underground where the insects can take refuge during the heat of summer.

Reprinted from "Landscape Mulches and Subterranean Termites" by Catherine Long, Graduate Student, University of Maryland, College Park

Sunday, July 5, 2009

Landscape and Greenhouse - Bacterial Leaf Spot on Zinnia

The following is information on bacterial leaf spot of Zinnia, a disease present in landscapes at this time.

Bacterial leafspot on Zinnia has been evident in gardens for several weeks. Look for small angular brown spots with yellow borders on lower leaves. It can spread quickly with wet weather. The disease will move higher on the plants and make them look poorly by fall. There is no effective control at this time. Copper fungicides/bactericides may cause some reduction or halt spread if applied now. Be sure to check the label for safe times to apply. This bacteria can overwinter in old infected leaf tissue and is seed-born, which is the primary source of infections we see. Greenhouse growers should make efforts to eliminate this disease before plants are sold. Suspect plants should be destroyed. Protective sprays of copper may be needed if this is a persistant problem in greenhouse plant production, but be careful with rates to avoid copper injury to plants.

Bacterial leaf spot of Zinnia. Photo by Bob Mulrooney, UD.

Adapted from an article by Bob Mulrooney, Extension Plant Pathologist, UD.

Landscape - Mimosa Webworm

Mimosa webworm is active in landscapes in Delaware. The following is more information.

Mimosa webworm is an introduced pest that effects both honeylocust and mimosa. Trees in grown in nurseries may be more susceptible. There are usually two generations per year. The overwintering pupal stage gives rise to very small, gray moths that lay tiny, rose-colored eggs in late spring. Young larvae strip/skeletonize upper surfaces of leaves and produce large amounts of silk. This silk sandwiches together leaves and small branch tips. Eventually, webby masses are quite visible on the tree. Caterpillars vary in color from pinkish gray to green to dark brown and grow to about 5/8”. After feeding, larvae use silk threads to lower themselves into bark crevices or to the ground and pupate in small, white cocoons. The second generation is produced quickly in mid-late summer and there are reports of a third generation during warm years in southern mid- Atlantic locations. The earliest observed date for larvae is June th 15 in Northern DE. A GDD range of 750-3216 (avg. 1643) and full bloom of Kalmia latifolia can also be used.

Research at Purdue University indicates that isolated honeylocust trees are more commonly affected than trees grouped closely together; and observations in this region seem to confirm this. Early research indicates resistance amongst certain thornless honeylocust cultivars. 'Sunburst' is quite susceptible, while 'Moraine', 'Shademaster', and 'Imperial' were touted as less susceptible. Manual web removal is not a practical control method.

Sprays of Bacillus thuringiensis 'kurstaki' (Dipel, Bt Worm Killer, many others) may be used very early in the season if the eggs or young larvae are found during scouting and before webbing. Neem products containing azadirachtin such as Azatin, Ornazin, and Azatrol provide some feeding repellency along with larval knockdown. Conserve (a.i. spinosad) and pyrethroids are used once webs are widely observed to protect against greater damage by subsequent generations.

Mimosa webworm webbing. Both mimosa and honeylocust are attacked by the mimosa webworm. Photo by John A. Weidhass, Virginia Polytechnic Institute and State University,

Information from Casey Sclar, IPM Coordinator, Longwood Gardens

Saturday, July 4, 2009

Turf - Brown Patch Season

Summer means brown patch disease season in turfgrasses. The following is more information.

Brown patch disease will be coming active in Delaware soon, especially in tall fescue. Warm, humid weather will promote brown patch activity on cool- season turfgrasses. Perennial ryegrass is probably the most susceptible host; creeping bentgrass and tall fescue are both relatively susceptible. Sometimes we see brown patch on Kentucky bluegrass, as well.

On all grasses, affected patches are often somewhat circular and can range from several inches to two or more feet in size. On tall fescue and Kentucky bluegrass, leaves exhibit tan, irregular lesions with a thin, brown border. On creeping bentgrass and perennial ryegrass, a ring of olive- green leaf blades appears on the outside margin of the patch; these blighted leaf blades dry to a tan color. On humid mornings, the mycelium of the fungus often appears as a sparse, very light tan webbing in the lower canopy. This can be best seen with a hand lens. In some situations on perennial ryegrass, the mycelium can be quite dense, cottony, and fluffy, and grow all over the leaf blades. In this condition, it can look quite a bit like Pythium cottony blight. Since different fungicides are used against Pythium cottony blight and Rhizoctonia brown patch, knowing the identity of the disease can be quite important from a management standpoint. Laboratory diagnosis is the best option if a case of perennial ryegrass has dense mycelium that looks like Pythium blight.

Management: During the next 8-10 weeks or so, be careful with postemergence herbicides, some of which have been shown to increase brown patch activity on cool-season turfgrasses.

Tall fescue. Generally brown patch can be managed through cultural means in established tall fescue lawns. However, recent seedings of tall fescue often can suffer severe outbreaks of the disease during humid weather in summer months. These should be monitored carefully and treated with fungicide if necessary. Once these swards make it through their first summer and are well-established, they often do not need fungicide treatment to maintain sward density, although fungicides do improve overall greenness during summer. Be aware that products containing chlorothalonil and iprodione are no longer labeled for use on home lawns.

Kentucky bluegrass. Although brown patch may be active in adapted varieties of Kentucky bluegrass, brown patch rarely develops aggressively enough on this host to justify fungicide treatment.

Perennial ryegrass and creeping bentgrass. High- maintenance perennial ryegrass and creeping bentgrass swards should have preventive fungicide applications on at this point, and putting greens should continue to receive preventive applications for brown patch control through August (and possibly later, depending on weather).

There is a wide selection of fungicides with very good activity for brown patch control. See the Extension publication PPA-1, Chemical Control of Turfgrass Diseases ( for options.

Adapted from "Brown Patch Activity" By Paul Vincelli in the current edition of the Kentucky Pest News

Turf - Controlling Crabgrass Breaks

The following is general information on controlling crabgrass breaks in turf.

With the heavy rains and cool weather conditions this spring I’m expecting that a significant number of preemergence herbicide applications will fail. Above average rainfall will result in an increased dissipation of preemergence herbicide out of the crabgrass germination zone while the cool temperatures are prolonging the crabgrass germination cycle. As always, maintaining a dense and healthy turfgrass stand throughout the summer is our first and best line of defense to prevent preemergence crabgrass herbicide failures. However, if summer stresses which thin and weaken the turfgrass stand occur; postemergence herbicides may need to be utilized to control crabgrass that germinates later in the season.

Both Acclaim Extra and Drive herbicides can be used to control crabgrass breaks. However, crabgrass cannot be too large (ideally less than 2 tillers, but no more than 4 tillers). Both herbicides are most effective when applied to young actively growing crabgrass in good soil moisture conditions. Applying either herbicide to sites under drought and/or heat stress may result in reduced control of crabgrass and other summer annual grasses as well as increased potential for turfgrass injury. Weed control with both herbicides is most effective when applied with flat fan nozzles producing a fine spray droplet. I do not recommended the use of flood jets with either herbicide. Both herbicides may be applied in combination with residual preemergence herbicides. However, applying residual herbicides late in the season may interfere with overseeding operations in late summer/fall.

Information adapted from an article from Dr. Steve Hart, Extension Weed Science Specialist, Rutgers University.