Monday, December 31, 2007
The Potential of Former Poultry House Pad Soils for use as Horticultural Amendments
There are over 2400 derelict poultry houses covering 1000 acres that are out of production on the Delmarva Peninsula. Poultry houses are built over soil pads that accumulate mineral nutrients through diffusion from manure in litter over a 30-50 year period. This includes significant amounts of nitrate nitrogen (NO3-N). Once production ceases, houses are often demolished or left to slowly deteriorate. Exposed pads are subject to leaching from rainfall and high amounts of NO3-N can enter the groundwater. Research is underway to study nutrient loading at these sites and methods to recover nutrients, particularly nitrogen (N). Remediation strategies being explored include co-composting of pad soils to create synthetic soils, use of pad soils directly as a fertilizer, using pad soils for enriched topsoil products, and use of salt tolerant plants as bioremediators that would then be composted. Potential uses of these products as horticultural amendments is a part of this research. Challenges include variability in nutrient content at sites, high salt levels, inconsistency in soil particle sizes, and weight of the material.
Gordon Johnson, Extension Agriculture Agent, UD, Kent County
Thursday, December 27, 2007
Images and information from Cynthia McKenney, Texas A&M, Professor of Urban Horticulture and the University of Florida Cooperative Extension.
Wednesday, December 26, 2007
Shore flies (Scatella stagnalis) thrive in wet areas with algae where they can feed and lay their eggs. Shore flies are often confused with another greenhouse pest found in wet areas, the fungus gnat (Bradysia spp.). Unlike fungus gnats, shore flies have robust bodies, short antennae, spots on their wings, and larvae without head capsules. Shore flies are also stronger fliers than fungus gnats which live mainly on the surface of the soil. Because shore flies do not feed on plant tissues like the fungus gnat, they are considered more of a nuisance pest. However, shore flies are capable of spreading diseases like Pythium.
Eliminating breeding areas and preventing the development of algae in the greenhouse is crucial for managing shore fly populations. Do not allow standing water- especially water containing fertilizer. Practice good sanitation by keeping the greenhouse free of debris. Monitoring for larvae is difficult, but by examining algae covered areas with a good hand lens, you can find the white, wedge-shaped larvae. Monitor adult populations using sticky cards. Control the algae first. If controlling algae alone is not effective in suppressing shorefly populations, then treatments should be directed at the larval stage. Soil drench treatments include: Distance (pyriproxyfen) and Adept (diflubenzuron). Make sure the chemical is applied to a depth of one inch or more. Note: Biological controls such as predatory mites, parasitic nematodes, and Gnatrol (Bacillus thuringiensis) drenches used for fungus gnat larvae are not effective on shore flies.
Several products that can be used to control algae include:
ZeroTol Broad Spectrum Algaecide/Fungicide (hydrogen dioxide product labeled for use both on greenhouse surfaces and on plants)
Physan 20 Algaecide, Fungicide, Bactericide Virucide, (quaternary ammonium compound for use on greenhouse surfaces and on orchids, roses, and African violets)
Green-Shield Algaecide, Fungicide, Bactericide Virucide (quaternary ammonium compound for use on greenhouse surfaces)
GreenClean Granular Algaecide (Sodium Carbonate Peroxyhydrate or use on greenhouse surfaces)
Terracyte Broad Spectrum Algaecide, Fungicide (sodium carbonate peroxyhydrate for use on greenhouse surfaces and on plants)
Triathlon Algaecide, Fungicide, Bactericide (quaternary ammonium compound for use on greenhouse surfaces).
Reprinted from the article "Algae in the Greenhouse Guarantees Shore Flies" in the February 24, 2006 issue of the Greenhouse TPM/IPM Weekly Report from University of Maryland Cooperative Extension.
There are many forms of American holly for landscape use from shrubs to large trees. Selections from the Rutgers breeding program have done well as landscape trees in Delaware. They are relatively slow growing but are quite stately when mature.
Information and images from multiple extension and university sources.
Tuesday, December 25, 2007
Several legends are reported about holly. The ancient Romans considered this plant sacred. Holly was used to honor Saturn, god of agriculture, during their Saturnalia festival held near the time of the winter solstice. The Romans gave one another holly wreaths, carried it in processions, and decked images of Saturn with it. During the early years of the Christian religion in Rome, many Christians continued to deck their homes with holly to avoid detection and persecution by Roman authorities. Gradually, holly became a symbol of the holidays as Christianity became the dominant religion of the empire.
Early Roman Christians believed that the cross on which Christ was crucified was made of holly wood; the crown of thorns was created from holly leaves and the white berries became stained red by Christ’s blood. The white flowers were supposed to represent Jesus’ purity and birth.
During the Middle Ages people associated holly with good fortune. Hollies planted near homes helped protect these homes from thunder and lightning. The berries and leaves were used to ward off witches and evil spirits. It was believed that elves and fairies stayed in the holly and kept the house goblins from causing trouble. The Druids also believed in the protective power of holly, claiming that this was where the woodland spirits took winter refuge.
On the other hand, Medieval Europeans believed family bickering would result if holly entered the home prior to December 24. Holly boughs left up past the New Year would cause one misfortune for each leaf on a branch. (This also correlates with the often-practiced tradition of removing all holiday decorations prior to the New Year, to avoid bad luck.)
Medieval Europeans also believed that picking holly while it was blooming might cause death. However, plucking a piece of holly from church decorations would bring good luck all year long; holly hung in the barn would cause animals to fatten and flourish; and holly picked on December 25 would protect one from witches and evil spirits.
The Germans believed bad luck would befall anyone who stepped on the berries. They also believed that the first person to bring holly into the household each year, rules the household for the coming year.
Another popular plant at this time of year is the poinsettia. These plants are native to Mexico. Originally, these plants were cultivated by the Aztec Indians for their use in dyes and the preparation of fever remedies. This plant was introduced into the U.S. by the first ambassador to Mexico, Joel Robert Poinsett.
One of the most colorful legends associated with poinsettias dates back to ancient Mexico. Legend has it that on December 24, villagers take flowers to the church to the baby Jesus. A young child, too poor to buy flowers, was sad that he had no gift to bring. An angel appeared and told the child to pick some weeds from the roadside and bring them, since any gift given with love would be accepted. As the weeds were placed in the church, the upper leaves of the weed changed into a bright red color. The Mexicans called this weed Flores de nocha buena, or Flowers of the Holy Night. Accounts differ whether it was a girl or boy that delivered the weeds to the church.
Please note: references to particular religions or ethnic groups are not meant to be discriminatory. Information concerning these legends is intended merely for their use in educational value. The University of Kentucky does not endorse nor deny any of these claims. Educational programs of the Kentucky Cooperative Extension Service.
From the Franklin County Kentucky Horticulture Program, Kentucky Cooperative Extension, University of Kentucky
Sunday, December 23, 2007
Saturday, December 22, 2007
Friday, December 21, 2007
Click on slides for larger images.
Although scab can cause alarm because it is unfamiliar—it is not a disease that occurs every year without fail (like Botrytis!)—it is actually very nicely controlled via fungicides and cultural adjustments. The trick is to notice that it is present in the crop, so that the diseased plants may be promptly rogued out and the neighboring plants treated for their protection.
Often it is the growing areas with the highest amounts of leaf wetness where scab disease symptoms appear. Long periods of leaf wetness are needed for infection. Adjusting cultural procedures so as to reduce the length of time the foliage sits wet is important: water early in the day, use fans strategically and heat and ventilate at sunset to avoid condensation.
Among the fungicide choices, strobilurins such as Heritage and Compass alternated with Eagle, Terraguard or Strike is a strong program that conveniently guards against powdery mildew and gives some Botrytis suppression. Mancozeb-containing materials are effective but may leave high residue, so these should be used at early stages of production.
The symptoms of scab are very striking. The spots are light-colored, small, round, and blistered out from the leaf surface; often they run down a vein. There is usually a yellow halo around each spot. The fungus also infects stems, where it causes larger raised whitish oval “scabs”. Eventually these stem lesions turn brown, after the spores have matured. The most peculiar scab symptom of all is seen on plants that have stem infections, or else extremely heavily infected leaves. The shoots that have these symptoms will hyper-elongate, so that they stretch up several inches higher than the rest of the crop. This effect is due to the plant growth hormone produced by the invading fungus!
Poinsettias with scab lesions on the stems will hyperelongate. Here the (normal height) plant at the right had only moderate leaf infection, while the one on the left had “scabs” on the stem as well. Photos: Maria Tobiasz Article extracted from "Scab on Poinsettias Again This Season" by Margery Daughtrey, Cornell University Dept. of Plant Pathology, LI Horticultural Research & Extension Center in the October 2005 edition of Northeast Greenhouse IPM notes.