August 17 2007
INSECTS
August 17,
2007
Brian Kunkel Ornamental IPM Specialist TULIP TREE SCALE. This large scale (6 7 mm in diameter; grayish green to pinkish orange mottled with black) feeds on tulip tree, magnolia, and occasionally lindens. There is only one generation per year; crawlers emerge starting in early August; and are active from 2016 3212 [2860 peak] GDD. Crawlers,dispersed by wind or birds, find a suitable host and begin to feed. Look for honeydew and sooty mold on host plants from July through August. Honeydew attracts ants and wasps. A number of natural enemies feed on this scale, but rarely do they manage populations. Use horticultural oil, insecticidal soap, or Distance for control during crawler activity. Imidacloprid must be applied earlier in the summer so there is sufficient time for uptake. MAGNOLIA SCALE. This large, soft scale is often confused with the tulip tree scale (but feed on magnolias and Virginia creeper). Females are tan brown and smooth. Magnolia scales are often covered with a white mealy wax until crawlers emerge. Crawlers are active from 2075 3247 [2746 peak] GDD and move a short distance before settling. There is only one generation a year. Control options are the same as for tulip tree scale.
DISEASES Bob Mulrooney Extension Plant Pathologist DROUGHT DAMAGE. Leaf scorch symptoms are easily seen on affected maples, Katsura tree, oaks and broad-leaved evergreens. Tulip poplars and sycamores continue to drop the oldest leaves in response to drought. In drought stricken areas, keep newly planted trees and shrubs watered. Try to keep landscape trees and shrubs from wilting. Perennials in the garden that thrive in cool, moist conditions are looking tired and droopy such as Bergenia, astilbe, hostas, and many others. POWDERY MILDEW is appearing now on lilac and will persist until leaf drop in the fall. Powdery mildew on lilac usually does not affect plant health, just the appearance of the plants. If control is desired apply a fungicide such as Immunox, Infuse or Remedy for homeowners; commercial applicators can use Systhane, Banner Maxx, Cleary's 3336, Heritage, Compass just to name a few. RHIZOCTONIA BROWN PATCH has shown up on a number of samples after the horrid heat and humidity last week. Wait until cooler weather and low humidity arrive and the disease will disappear. It usually does not kill turf only the blades, so the turf recovers once good weather for turf growth returns.
Issue 21
What's Hot! Samples of white peach and white prunicola scale have been sent in recently. These two scales are difficult to separate without microscopic examination. Fall webworms are out in full force. Cultural control includes pruning out infested terminals or physically removing the webbing. To use insecticides, disrupt webbing first for better contact. Dogwood sawflies are in the wasp family, but look similar to a caterpillar covered with wax. They feed gregariously and can defoliate portions of the tree. Use horticultural oil, insecticidal soap, Conserve, synthetic pyrethroids, or carbaryl for control. As cicada killer wasps decline over the next few weeks, the scoliid wasp (a parasitoid of green June beetle larvae) will appear. It has a gun metal blue-black body with a rust colored abdomen with two yellow spots. Adult wasps may feed on flowers and are non-aggressive.
WEEDS Gordon Johnson Agricultural Agent, Kent County ANNUAL BLUEGRASS, Poa annua var. annua can be a very difficult weed in turf and landscape beds. To make matters worse, a perennial form Poa annua var. reptans is also found, primarily on golf greens. Annual bluegrass tolerates low
Fornfomromrae tion i
(Continued)
on pests & practices covered in this newsletter, call your County Extension Office Helpful numbers to know: Garden Line (for home gardeners only) New Castle County Extension Kent County Extension Sussex County Extension
831-8862 831-2506 730-4000 856-7303
View Hotline pictures for this issue at www.kentcoopextension.blogspot.com/
UNIVERSITY OF DELAWARE
COOPERATIVE EXTENSION
Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating. Janice A. Seitz, Director. Distributed in furtherance of Acts of Congress of March 8 and June 30, 1914. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age, or national origin.
Weeds (Continued) mowing and compaction. It is a prolific seeder and can quickly infest an area. Annual bluegrass starts to germinate in late summer as soil temperatures drop below 70°F and continues to germinate throughout the winter. Annual bluegrass is a problem in turf because it forms a weak sod, provides poor footing on athletic fields, produces unsightly seed heads, and dies out in late spring. In ornamental plantings it can compete with perennial landscape plants and groundcovers in the cool season. Control starts with reducing spread by equipment. Maintain grass or groundcover vigor to shade it out, reduce compaction with aeration, increase mowing height, and avoid overwatering that encourages annual bluegrass growth. Withholding water can help to stress and kill out annual bluegrass in some cases. Preemergence herbicides such as dithiopyr, pendimethalin, or prodiamine can be used to limit seedling germination on established cool season turf. Make the application before seed germinates in late August when soil temperatures go below 70°F. Use benefin if fall seeding is planned (wait 6 weeks). Ethofumesate (Prograss) is the only selective herbicide for postemergence annual bluegrass control in cool-season turfgrass. Apply ethofumesate during the peak of annual bluegrass germination and again just before winter. Do not use on turf containing fine fescues (cannot be used on lawns with shade mixtures for example). In landscape beds, preemergence grass herbicides will give some control late August applied, non-selective herbicides can be used spot sprayed, and clethodim (Envoy plus) can be used as a selective post-emergence control. Mesotrione (Outplay), a new herbicide being developed for turf, will good annual bluegrass control pre and post (waiting for registration). Editor: Susan Barton Extension Horticulturist
Cooperative Extension Townsend Hall Newark, Delaware 19717
GROWI DAYS7 DAESGORF EAuEgust 13, 200 NG
37 ) =25 '06 e 81 ( ous ) = 24 wn y enh geto6) Gre Count eor her e r, G = 2 6 2 Fisc Castl 6 ente w c. C 511 ('0 (Ne Edu 2 h & nty) = u earc Res sex Co ( Su s
August 17,
2007
Brian Kunkel Ornamental IPM Specialist TULIP TREE SCALE. This large scale (6 7 mm in diameter; grayish green to pinkish orange mottled with black) feeds on tulip tree, magnolia, and occasionally lindens. There is only one generation per year; crawlers emerge starting in early August; and are active from 2016 3212 [2860 peak] GDD. Crawlers,dispersed by wind or birds, find a suitable host and begin to feed. Look for honeydew and sooty mold on host plants from July through August. Honeydew attracts ants and wasps. A number of natural enemies feed on this scale, but rarely do they manage populations. Use horticultural oil, insecticidal soap, or Distance for control during crawler activity. Imidacloprid must be applied earlier in the summer so there is sufficient time for uptake. MAGNOLIA SCALE. This large, soft scale is often confused with the tulip tree scale (but feed on magnolias and Virginia creeper). Females are tan brown and smooth. Magnolia scales are often covered with a white mealy wax until crawlers emerge. Crawlers are active from 2075 3247 [2746 peak] GDD and move a short distance before settling. There is only one generation a year. Control options are the same as for tulip tree scale.
DISEASES Bob Mulrooney Extension Plant Pathologist DROUGHT DAMAGE. Leaf scorch symptoms are easily seen on affected maples, Katsura tree, oaks and broad-leaved evergreens. Tulip poplars and sycamores continue to drop the oldest leaves in response to drought. In drought stricken areas, keep newly planted trees and shrubs watered. Try to keep landscape trees and shrubs from wilting. Perennials in the garden that thrive in cool, moist conditions are looking tired and droopy such as Bergenia, astilbe, hostas, and many others. POWDERY MILDEW is appearing now on lilac and will persist until leaf drop in the fall. Powdery mildew on lilac usually does not affect plant health, just the appearance of the plants. If control is desired apply a fungicide such as Immunox, Infuse or Remedy for homeowners; commercial applicators can use Systhane, Banner Maxx, Cleary's 3336, Heritage, Compass just to name a few. RHIZOCTONIA BROWN PATCH has shown up on a number of samples after the horrid heat and humidity last week. Wait until cooler weather and low humidity arrive and the disease will disappear. It usually does not kill turf only the blades, so the turf recovers once good weather for turf growth returns.
Issue 21
What's Hot! Samples of white peach and white prunicola scale have been sent in recently. These two scales are difficult to separate without microscopic examination. Fall webworms are out in full force. Cultural control includes pruning out infested terminals or physically removing the webbing. To use insecticides, disrupt webbing first for better contact. Dogwood sawflies are in the wasp family, but look similar to a caterpillar covered with wax. They feed gregariously and can defoliate portions of the tree. Use horticultural oil, insecticidal soap, Conserve, synthetic pyrethroids, or carbaryl for control. As cicada killer wasps decline over the next few weeks, the scoliid wasp (a parasitoid of green June beetle larvae) will appear. It has a gun metal blue-black body with a rust colored abdomen with two yellow spots. Adult wasps may feed on flowers and are non-aggressive.
WEEDS Gordon Johnson Agricultural Agent, Kent County ANNUAL BLUEGRASS, Poa annua var. annua can be a very difficult weed in turf and landscape beds. To make matters worse, a perennial form Poa annua var. reptans is also found, primarily on golf greens. Annual bluegrass tolerates low
Fornfomromrae tion i
(Continued)
on pests & practices covered in this newsletter, call your County Extension Office Helpful numbers to know: Garden Line (for home gardeners only) New Castle County Extension Kent County Extension Sussex County Extension
831-8862 831-2506 730-4000 856-7303
View Hotline pictures for this issue at www.kentcoopextension.blogspot.com/
UNIVERSITY OF DELAWARE
COOPERATIVE EXTENSION
Cooperative Extension Education in Agriculture and Home Economics, University of Delaware, Delaware State University and the United States Department of Agriculture cooperating. Janice A. Seitz, Director. Distributed in furtherance of Acts of Congress of March 8 and June 30, 1914. It is the policy of the Delaware Cooperative Extension System that no person shall be subjected to discrimination on the grounds of race, color, sex, disability, age, or national origin.
Weeds (Continued) mowing and compaction. It is a prolific seeder and can quickly infest an area. Annual bluegrass starts to germinate in late summer as soil temperatures drop below 70°F and continues to germinate throughout the winter. Annual bluegrass is a problem in turf because it forms a weak sod, provides poor footing on athletic fields, produces unsightly seed heads, and dies out in late spring. In ornamental plantings it can compete with perennial landscape plants and groundcovers in the cool season. Control starts with reducing spread by equipment. Maintain grass or groundcover vigor to shade it out, reduce compaction with aeration, increase mowing height, and avoid overwatering that encourages annual bluegrass growth. Withholding water can help to stress and kill out annual bluegrass in some cases. Preemergence herbicides such as dithiopyr, pendimethalin, or prodiamine can be used to limit seedling germination on established cool season turf. Make the application before seed germinates in late August when soil temperatures go below 70°F. Use benefin if fall seeding is planned (wait 6 weeks). Ethofumesate (Prograss) is the only selective herbicide for postemergence annual bluegrass control in cool-season turfgrass. Apply ethofumesate during the peak of annual bluegrass germination and again just before winter. Do not use on turf containing fine fescues (cannot be used on lawns with shade mixtures for example). In landscape beds, preemergence grass herbicides will give some control late August applied, non-selective herbicides can be used spot sprayed, and clethodim (Envoy plus) can be used as a selective post-emergence control. Mesotrione (Outplay), a new herbicide being developed for turf, will good annual bluegrass control pre and post (waiting for registration). Editor: Susan Barton Extension Horticulturist
Cooperative Extension Townsend Hall Newark, Delaware 19717
GROWI DAYS7 DAESGORF EAuEgust 13, 200 NG
37 ) =25 '06 e 81 ( ous ) = 24 wn y enh geto6) Gre Count eor her e r, G = 2 6 2 Fisc Castl 6 ente w c. C 511 ('0 (Ne Edu 2 h & nty) = u earc Res sex Co ( Su s
