September 16 2005.cdr
September 16, 2005
Issue 24
INSECTS & MITES
WEED CONTROL
Gregory Hoover Ornamental Extension Entomologist
Stephen Hart Extension Specialist, Rutgers
The COOLEY SPRUCE GALL ADELGID has a complicated life cycle that involves five biological forms of the insect, three of which occur on spruce and two on Douglas-fir. This pest can live on Douglas-fir alone by continuous reproduction of the two forms with as many as five to six generations produced each year. However, it appears that those forms occurring on spruce cannot continue producing indefinitely and need to find the second host, Douglas-fir to complete the entire life cycle. On spruce, the Cooley spruce gall adelgid overwinters as immature females at the bases of terminal buds. Females resume feeding in the spring, mature, and lay several hundred eggs on the tips of lateral branches. Eggs hatch in 10-14 days into young nymphs that migrate to new growth and feed at the base of needles. Their feeding causes a gall to form on the tip of the current year's growth that soon surrounds them. This species remains in the chambers inside gall tissue throughout the summer. By mid-summer the galls dry out, turn brown, and the adelgids emerge from the opened chambers. They may migrate to Douglas-fir or remain on spruce. On Douglas-fir, heavily infested needles appear to be covered with snow. No galls are formed on Douglas fir, but feeding by the insects on the underside of the needle causes needle discoloration, needle distortion, and premature needle drop.
ANOTHER BAD YEAR FOR CRABGRASS THE SOLUTION The best way to avoid summer infestations of crabgrass is to maintain a dense and vigorous turf and apply split applications of Pre herbicides. Split applications entail applying 50 to 66% of the herbicide in midApril and a second application in early/mid June as opposed to applying a single application at the full rate in midApril. Split applications can greatly increase control levels compared to single applications. However, this year was so bad even split applications were providing only 80 to 85% crabgrass control in my research plots in mid-August. Single application were starting to fail as early as late-June.
DISEASES Bob Mulrooney Extension Plant Pathologist While conditions remain dry, most diseases are held in check, but as soon as we get some rain they will reemerge. BOTRYTIS BLIGHT. As the weather cools and more dew forms in the evenings, conditions become ideal for the development of Botrytis blight or gray mold. To reduce this fuzzy, gray fungus, keep rose gardens and flowers beds dead-headed and spray with Daconil 2787, Cleary's 3336 (thiophanate-methyl) or other labeled fungicide. RUST. In the last issue I mentioned seeing aster rust on perennial asters but neglected to tell you which one. In the past I have seen Coleosporium asterum on asters; this year it appears to be a Puccinia rust. These spots are darker and larger than the small orange-red pustules of Coleosporium rust.
UNIVERSITY OF DELAWARE
Although split herbicide applications and maintaining a vigorous turf can greatly increase levels of crabgrass control, complete control can rarely be achieved. Frequent, heavy rainfall events in July/August, especially if they follow extended dry periods, greatly reduce the chances of achieving complete control. Turfgrass Professionals must be vigilant during these months to check for breakdown of Pre crabgrass programs and spot treat escapes with postemergence (POST) herbicides if complete control is desired. Seedling crabgrass (untillered) can (Continued)
For more ion format n i on pests & practices covered in this Helpful numbers to know: Garden Line 831-8862 (for home gardeners only) New Castle County Extension 831-2506 Kent County Extension 730-4000 Sussex County Extension 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.
Weed Control (Continued) Editor’s Note: We have two issues remaining in this year’s Ornamentals Hotline. They will be published on September 23 and October 7. As we are winding down, I want to take this opportunity to thank the folks who have diligently read the biophenometers or provided weather data throughout the year.
be effectively controlled with Drive or Acclaim Xtra and Acclaim Xtra can control crabgrass up to 2 to 3 tillers in Kentucky bluegrass. In addition, both herbicides can be tank-mixed with residual herbicides to get through the remainder of the season.
New Castle County - Phil Thompson, City of Newark Kent County - Maggie Moor and Carol McClister, Kent County Extension Office Sussex County - Dean Day, Research and Education Center (maintains weather station data)
Even with the use of split herbicide applications and timely use of POST herbicides we have appeared to lose the battle to crabgrass this year. The effectiveness of POST herbicides was also reduced by the excessive heat, and many crabgrass plants were not completely controlled (plants re-grew from the crown) requiring additional applications. Hopefully, 2006 will be a better year in the battle against crabgrass.
Editor: Susan Barton Extension Horticulturist
G N I W O R G EGREE DAYS
05 3, 2 0 1 r e mb Septe F O AS
D
1) 310 = ('04 038 3 e s ou y) = e t nh ffic NA) ree Coun G n n O 04 = r o e i e l ow st ch ens 83 (' get 92) t r F is w C a x o E e 2 ty = 31 r, G = 3 (Ne ) un nte ('04 Co unty e t n c. C3063 Ke nt Co du & E ty) = (Ke h n c ear Cou Res ssex ( Su
Issue 24
INSECTS & MITES
WEED CONTROL
Gregory Hoover Ornamental Extension Entomologist
Stephen Hart Extension Specialist, Rutgers
The COOLEY SPRUCE GALL ADELGID has a complicated life cycle that involves five biological forms of the insect, three of which occur on spruce and two on Douglas-fir. This pest can live on Douglas-fir alone by continuous reproduction of the two forms with as many as five to six generations produced each year. However, it appears that those forms occurring on spruce cannot continue producing indefinitely and need to find the second host, Douglas-fir to complete the entire life cycle. On spruce, the Cooley spruce gall adelgid overwinters as immature females at the bases of terminal buds. Females resume feeding in the spring, mature, and lay several hundred eggs on the tips of lateral branches. Eggs hatch in 10-14 days into young nymphs that migrate to new growth and feed at the base of needles. Their feeding causes a gall to form on the tip of the current year's growth that soon surrounds them. This species remains in the chambers inside gall tissue throughout the summer. By mid-summer the galls dry out, turn brown, and the adelgids emerge from the opened chambers. They may migrate to Douglas-fir or remain on spruce. On Douglas-fir, heavily infested needles appear to be covered with snow. No galls are formed on Douglas fir, but feeding by the insects on the underside of the needle causes needle discoloration, needle distortion, and premature needle drop.
ANOTHER BAD YEAR FOR CRABGRASS THE SOLUTION The best way to avoid summer infestations of crabgrass is to maintain a dense and vigorous turf and apply split applications of Pre herbicides. Split applications entail applying 50 to 66% of the herbicide in midApril and a second application in early/mid June as opposed to applying a single application at the full rate in midApril. Split applications can greatly increase control levels compared to single applications. However, this year was so bad even split applications were providing only 80 to 85% crabgrass control in my research plots in mid-August. Single application were starting to fail as early as late-June.
DISEASES Bob Mulrooney Extension Plant Pathologist While conditions remain dry, most diseases are held in check, but as soon as we get some rain they will reemerge. BOTRYTIS BLIGHT. As the weather cools and more dew forms in the evenings, conditions become ideal for the development of Botrytis blight or gray mold. To reduce this fuzzy, gray fungus, keep rose gardens and flowers beds dead-headed and spray with Daconil 2787, Cleary's 3336 (thiophanate-methyl) or other labeled fungicide. RUST. In the last issue I mentioned seeing aster rust on perennial asters but neglected to tell you which one. In the past I have seen Coleosporium asterum on asters; this year it appears to be a Puccinia rust. These spots are darker and larger than the small orange-red pustules of Coleosporium rust.
UNIVERSITY OF DELAWARE
Although split herbicide applications and maintaining a vigorous turf can greatly increase levels of crabgrass control, complete control can rarely be achieved. Frequent, heavy rainfall events in July/August, especially if they follow extended dry periods, greatly reduce the chances of achieving complete control. Turfgrass Professionals must be vigilant during these months to check for breakdown of Pre crabgrass programs and spot treat escapes with postemergence (POST) herbicides if complete control is desired. Seedling crabgrass (untillered) can (Continued)
For more ion format n i on pests & practices covered in this Helpful numbers to know: Garden Line 831-8862 (for home gardeners only) New Castle County Extension 831-2506 Kent County Extension 730-4000 Sussex County Extension 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.
Weed Control (Continued) Editor’s Note: We have two issues remaining in this year’s Ornamentals Hotline. They will be published on September 23 and October 7. As we are winding down, I want to take this opportunity to thank the folks who have diligently read the biophenometers or provided weather data throughout the year.
be effectively controlled with Drive or Acclaim Xtra and Acclaim Xtra can control crabgrass up to 2 to 3 tillers in Kentucky bluegrass. In addition, both herbicides can be tank-mixed with residual herbicides to get through the remainder of the season.
New Castle County - Phil Thompson, City of Newark Kent County - Maggie Moor and Carol McClister, Kent County Extension Office Sussex County - Dean Day, Research and Education Center (maintains weather station data)
Even with the use of split herbicide applications and timely use of POST herbicides we have appeared to lose the battle to crabgrass this year. The effectiveness of POST herbicides was also reduced by the excessive heat, and many crabgrass plants were not completely controlled (plants re-grew from the crown) requiring additional applications. Hopefully, 2006 will be a better year in the battle against crabgrass.
Editor: Susan Barton Extension Horticulturist
G N I W O R G EGREE DAYS
05 3, 2 0 1 r e mb Septe F O AS
D
1) 310 = ('04 038 3 e s ou y) = e t nh ffic NA) ree Coun G n n O 04 = r o e i e l ow st ch ens 83 (' get 92) t r F is w C a x o E e 2 ty = 31 r, G = 3 (Ne ) un nte ('04 Co unty e t n c. C3063 Ke nt Co du & E ty) = (Ke h n c ear Cou Res ssex ( Su
