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
Showing posts with label lecanium scale. Show all posts
Showing posts with label lecanium scale. Show all posts
Saturday, July 25, 2009
Friday, June 5, 2009
Landscape - Current Pests
The following are some current pests in the landscape to be on the watch for. Information is from the "What's Hot" section of the Ornamentals Hotline from the University of Delaware Cooperative Extension.
Exobasidium galls have been observed on camellias - probably also on Azalea/Rhododendron. The big clubby white new growth is striking, a truly "Ornamental" disease!
Lecanium scales (Fletcher Scale, European Fruit Lecanium) and Cottony scales (Cottony Maple, Cottony Camellia/Taxus) have begun egg laying. Watch for crawler hatch.
Emerald Ash borer was found in Kentucky this past week. Bloom of Black locust is known to correspond with EAB emergence in affected areas so keep an eye out.
Azalea bark scale females are producing the cottony egg masses. Crawlers can be treated with horticultural oil, insecticidal soap, Distance, pyrethroids, or soil drenches of imidacloprid should provide control.
Exobasidium galls have been observed on camellias - probably also on Azalea/Rhododendron. The big clubby white new growth is striking, a truly "Ornamental" disease!
Lecanium scales (Fletcher Scale, European Fruit Lecanium) and Cottony scales (Cottony Maple, Cottony Camellia/Taxus) have begun egg laying. Watch for crawler hatch.
Emerald Ash borer was found in Kentucky this past week. Bloom of Black locust is known to correspond with EAB emergence in affected areas so keep an eye out.
Azalea bark scale females are producing the cottony egg masses. Crawlers can be treated with horticultural oil, insecticidal soap, Distance, pyrethroids, or soil drenches of imidacloprid should provide control.
Friday, May 30, 2008
Landscape and Nursery - Scales to Watch For
The following is information on some scale pests you should watch for and apply control measures in the next few weeks.
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.
These soft scales appear like little brown lumps grouped along tree branches as adults. They feed in the phloem (on plant sap). Honeydew rain (clear sticky substance that is scale excrement) from the developing nymphs and adults of both species was noticeable in early May. A black fungus called sooty mold often grows on the honeydew.
Lecanium scales have one generation per year. Crawlers will start to appear in early June and 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 but horticultural oils work quite well. Occasionally, a re-application is needed about 3 weeks after the initial application to ensure that all crawlers have emerged. Many naturally occurring parasites and predators often control lecanium scales,
but parasites have been less active recently on a regional level. Still, many predators such as lady beetles feed on them. Insecticides sprayed later provide only limited effectiveness against nymphs and soil systemic insecticide applications must be properly timed.
Information from Casey Sclar, IPM Coordinator, Longwood Gardens
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.
These soft scales appear like little brown lumps grouped along tree branches as adults. They feed in the phloem (on plant sap). Honeydew rain (clear sticky substance that is scale excrement) from the developing nymphs and adults of both species was noticeable in early May. A black fungus called sooty mold often grows on the honeydew.
Lecanium scales have one generation per year. Crawlers will start to appear in early June and 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 but horticultural oils work quite well. Occasionally, a re-application is needed about 3 weeks after the initial application to ensure that all crawlers have emerged. Many naturally occurring parasites and predators often control lecanium scales,
but parasites have been less active recently on a regional level. Still, many predators such as lady beetles feed on them. Insecticides sprayed later provide only limited effectiveness against nymphs and soil systemic insecticide applications must be properly timed.
Information from Casey Sclar, IPM Coordinator, Longwood Gardens
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