June 15 2007.cdr
June 15,
2007
Issue 12
INSECTS
What's Hot!
Dewey Caron Extension Entomologist NATIVE POLLINATORS. The University of DE and DE Dept. of Agric. are cooperating in a 4-year project on documenting/augmenting native bee pollinators. The project, funded by NE-SARE, is focused on farming practices that will promote diversity of pollinators. Targeted communities include vine crop growers, state parks, public gardens and organic farmers. Six new state records of bee species have already been identified in a pilot project that collected over 2500 specimens conducted to assist in securing the funding itself. Experiments on ways to increase bee nesting sites and alter cultivation practices to promote pollinator diversity are underway. It is thought that habitat loss and alteration have led to a decrease in pollinator populations so a baseline will be developed to better determine what is actually happening. Information brochures with Natural Resource Conservation Service of USDA support are being prepared to assist growers with compliance of Conservation cover guidelines and to expand pollinator-friendly management practices.
DISEASES Bob Mulrooney Extension Plant Pathologist PHOMA STEM BLIGHT on the groundcover vinca or periwinkle is very common now. The recent rain showers and humidity has been very favorable for infection. Look for gray-green foliage and black stems. Remove dead stems; plants often recover by producing new stems and filling in dead spots. Thin out beds and remove dense shade to reduce excessive wetness and increase air movement to help drying. Fungicides help if applied early in the spring and repeated every two weeks until dry weather comes. Fungicides with thiophanate-methyl (Bonomyl), mancozeb and copper should provide some control. Check fungicide labels for more information. BLACK SPOT ON ROSE is beginning to increase. If fungicide applications are delayed until symptoms are readily seen, satisfactory control becomes very difficult to obtain. Once sprays are started it is important to continue spraying regularly depending on the fungicide label. I have had good success with a two week interval with propiconazole (Banner Maxx, Infuse) or myclobutanil (Systhane, Eagle, Immunox), or triforine if applied before symptoms are seen. (Continued)
UNIVERSITY OF DELAWARE
Cottony camellia/taxus scale crawlers are active on holly. Aphids are active on a number of woody and herbaceous ornamentals. Lady beetles and parasitoids attack theses pests so use horticultural oil or insecticidal soap when and where appropriate to preserve natural enemies. Diseases are not very prevalent due to the weather and when found, the severity is usually light. Rust on crabapples is easy to spot now on susceptible cultivars. Depending on the cultivar, the raised spots are yellow-orange to red.
WEEDS Gordon Johnson Agricultural Agent, Kent County MUGWORT (Artemesia vulgaris), also know as wild chrysanthemum, is a perennial weed of landscape plantings that is difficult to control due to its ability to spread by underground rhizomes. It is in the Artemesia genus of the Aster family which contains numerous herb and ornamentals species. At a glance, leaves are similar to appearance as chrysanthemum. They are 2-4 inches long, 1-3 inches wide, simple, alternate, deeply lobed, and have a distinctive aroma. Leaf undersides are covered with soft, white to gray hairs. Mugwort has vigorous underground rhizomes and is commonly introduced as a weed with nursery stock. (Continued)
Fornfomromrae tion i
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
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.
Diseases (Continued)
Weeds (Continued)
ENTOMOSPORIUM LEAF SPOT is not only a disease of hawthorn but Photinia as well. Photinia is extensively planted in southern Delaware and often is disfigured when Entomosporium leaf spot is severe. Symptoms of leaf spot are gray to brown spots with purple to red borders, which are often numerous and can cause yellowing of leaves and eventual leaf drop. Raking up infected leaves and composting or removing from the site may help reduce disease incidence. If sprinkler irrigation is present, keep the plants from being wetted. Fungicide applications of Daconil, Infuse, or Immunox should provide some control of the new leaves but should be applied before infection occurs.
Control with hand weeding requires removal of all the underground rhizomes, which is often difficult, if not impossible, in landscape beds. Spring application (directed) of non-selective herbicides such as glyphosate (Roundup Pro and several others) will provide some suppression but not full control. Better results have been obtained with two applications of glyphosate applied several weeks apart in late summer and 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. Research has also been done on the use of Lontrel (clopyralid) for mugwort control, but results have often been disappointing. One fit for Lontrel may be suppression of mugwort in ornamental grasses where it can be used as an over-the-top application. Editor: Susan Barton Extension Horticulturist
Cooperative Extension Townsend Hall Newark, Delaware 19717
GROWI DAYS DAESGORF EJEune 11, 2007 NG
6) = 87 '06 e 42 ( ous = 9 wn enh unty) geto ) Gre eor her e Co r, G = 11 0 0 Fisc Castl ente 6 w c. C 40 ('0 (Ne 9 Edu h & nty) = u earc Res sex Co ( Su s
2007
Issue 12
INSECTS
What's Hot!
Dewey Caron Extension Entomologist NATIVE POLLINATORS. The University of DE and DE Dept. of Agric. are cooperating in a 4-year project on documenting/augmenting native bee pollinators. The project, funded by NE-SARE, is focused on farming practices that will promote diversity of pollinators. Targeted communities include vine crop growers, state parks, public gardens and organic farmers. Six new state records of bee species have already been identified in a pilot project that collected over 2500 specimens conducted to assist in securing the funding itself. Experiments on ways to increase bee nesting sites and alter cultivation practices to promote pollinator diversity are underway. It is thought that habitat loss and alteration have led to a decrease in pollinator populations so a baseline will be developed to better determine what is actually happening. Information brochures with Natural Resource Conservation Service of USDA support are being prepared to assist growers with compliance of Conservation cover guidelines and to expand pollinator-friendly management practices.
DISEASES Bob Mulrooney Extension Plant Pathologist PHOMA STEM BLIGHT on the groundcover vinca or periwinkle is very common now. The recent rain showers and humidity has been very favorable for infection. Look for gray-green foliage and black stems. Remove dead stems; plants often recover by producing new stems and filling in dead spots. Thin out beds and remove dense shade to reduce excessive wetness and increase air movement to help drying. Fungicides help if applied early in the spring and repeated every two weeks until dry weather comes. Fungicides with thiophanate-methyl (Bonomyl), mancozeb and copper should provide some control. Check fungicide labels for more information. BLACK SPOT ON ROSE is beginning to increase. If fungicide applications are delayed until symptoms are readily seen, satisfactory control becomes very difficult to obtain. Once sprays are started it is important to continue spraying regularly depending on the fungicide label. I have had good success with a two week interval with propiconazole (Banner Maxx, Infuse) or myclobutanil (Systhane, Eagle, Immunox), or triforine if applied before symptoms are seen. (Continued)
UNIVERSITY OF DELAWARE
Cottony camellia/taxus scale crawlers are active on holly. Aphids are active on a number of woody and herbaceous ornamentals. Lady beetles and parasitoids attack theses pests so use horticultural oil or insecticidal soap when and where appropriate to preserve natural enemies. Diseases are not very prevalent due to the weather and when found, the severity is usually light. Rust on crabapples is easy to spot now on susceptible cultivars. Depending on the cultivar, the raised spots are yellow-orange to red.
WEEDS Gordon Johnson Agricultural Agent, Kent County MUGWORT (Artemesia vulgaris), also know as wild chrysanthemum, is a perennial weed of landscape plantings that is difficult to control due to its ability to spread by underground rhizomes. It is in the Artemesia genus of the Aster family which contains numerous herb and ornamentals species. At a glance, leaves are similar to appearance as chrysanthemum. They are 2-4 inches long, 1-3 inches wide, simple, alternate, deeply lobed, and have a distinctive aroma. Leaf undersides are covered with soft, white to gray hairs. Mugwort has vigorous underground rhizomes and is commonly introduced as a weed with nursery stock. (Continued)
Fornfomromrae tion i
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
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.
Diseases (Continued)
Weeds (Continued)
ENTOMOSPORIUM LEAF SPOT is not only a disease of hawthorn but Photinia as well. Photinia is extensively planted in southern Delaware and often is disfigured when Entomosporium leaf spot is severe. Symptoms of leaf spot are gray to brown spots with purple to red borders, which are often numerous and can cause yellowing of leaves and eventual leaf drop. Raking up infected leaves and composting or removing from the site may help reduce disease incidence. If sprinkler irrigation is present, keep the plants from being wetted. Fungicide applications of Daconil, Infuse, or Immunox should provide some control of the new leaves but should be applied before infection occurs.
Control with hand weeding requires removal of all the underground rhizomes, which is often difficult, if not impossible, in landscape beds. Spring application (directed) of non-selective herbicides such as glyphosate (Roundup Pro and several others) will provide some suppression but not full control. Better results have been obtained with two applications of glyphosate applied several weeks apart in late summer and 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. Research has also been done on the use of Lontrel (clopyralid) for mugwort control, but results have often been disappointing. One fit for Lontrel may be suppression of mugwort in ornamental grasses where it can be used as an over-the-top application. Editor: Susan Barton Extension Horticulturist
Cooperative Extension Townsend Hall Newark, Delaware 19717
GROWI DAYS DAESGORF EJEune 11, 2007 NG
6) = 87 '06 e 42 ( ous = 9 wn enh unty) geto ) Gre eor her e Co r, G = 11 0 0 Fisc Castl ente 6 w c. C 40 ('0 (Ne 9 Edu h & nty) = u earc Res sex Co ( Su s
