March 25 2005.cdr
March 25,
2005
INSECTS Derby Walker Extension Agent EASTERN TENT CATERPILLAR. Eastern tent caterpillar egg hatching is likely to occur when the leaves emerge from the buds of their host tree. In our area, wild cherry, flowering cherry, apples, and other fruit trees are commonly attacked. The shiny brown egg masses can be seen encircling small branches and twigs. If you had just a few egg masses, they could be hand removed through pruning. In pruning earlier in the week, I noticed the peaches are just about ready to bloom and cherries should be leafing out soon. Bt's and insecticidal soaps can be effective against small caterpillars. Often we don't notice the caterpillars until they larger and then it will take a pyrethroid, orthene, or carbaryl to kill them.
DISEASES Bob Mulrooney Extension Plant Pathologist ROSES. Now is the time to prune hybrid tea roses. Removal of old dead canes and those with obvious cankers (sunken dead spots) is a good sanitation practice. I have noticed quite a bit of winter damage in the form of excessive cane death even on roses whose crowns were well protected with mulch. Gardeners may want to wait until they see buds emerging before pruning, but most dead canes are pretty obvious now. Cane die-back seems to be much worse than the past several years on the plants I've observed. Fluctuating temperatures during the winter are probably the cause. Once pruning is finished, an application of liquid limesulfur will burn out any old cankers caused by black spot fungus or other canker forming fungi. VERONICA RUST was discovered on 'Sunny Border Blue' in a Michigan nursery last fall on plants propagated in Costa Rica. The causal fungus, Puccinia veronicae-longifoliae, does not occur in the US. Garden centers and growers may want to keep an eye out this season for plants with reddish leaves on the upper surface and obvious raised dark pustules on the under surface. It is not known if all Veronica cultivars are susceptible or how widespread the disease may be. If found, diseased stems should be pruned out and new growth sprayed with Systhane, Eagle, Banner, or similar fungicide chemistry. From the pictures I have seen, the symptoms are not subtle and should be very easy to spot.
UNIVERSITY OF DELAWARE
Issue 2
What's Hot! Old cicada damage from egg laying last season is evident on small branches and twigs of affected hosts such as oak, flowering dogwood, maple and others. Many of the old slits made in the bark still have a tuft of shredded tissue sticking out with new callus tissue surrounding the oviposition slit. Some twigs have 8-10 inches of damaged area, others only 1-2 inches. This damage was pretty widespread in New Castle County and much less in Kent and almost non-existent in Sussex. By next season most damage will be completely healed over. Dormant oils are effective against many scales, mites and aphids. There is still time to use dormant oil before leaves on most plants emerge. For the product to be effective, it must dry on the tree since it works by smothering the insect. Some plants are sensitive to oils, so read the label before applying and check to make sure plants are still dormant. Hemlock rust mite hatch has been reported in PA. This eriophyid mite feeds on the upper and lower surfaces of needles. Feeding by large mite populations causes needles to turn a light yellowish green. Damage usually occurs in spring. Look on the south side of hemlocks for off-color, yellowish needles. You will probably need a 10x hand lens to detect the minute, spindle-shaped, yellowish (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.
What’s Hot (Continued) eriophyid mites on the needles. Use a horticultural oil spray at the first sign of mite activity and damage.
Editor: Susan Barton Extension Horticulturist
Elongate hemlock scale nymphs have now been reported. This pest also produces a yellowish cast on hemlock foliage. Spray now with a dormant oil. Wait until a little later in the season (May) when more nymphs have hatched for insecticidal sprays.
G N I W O R G REE DAYS
5 , 200 5 1 arch M F AS O
DEG
5) =3 '04 ( 11 se e ou ty) = h fic n Of 4 4 ) n ree Coun n G = ow r e sio get en ('04 r che Castl t s o x i e E F ) 11 w r, G 49 nty = (Ne nte '04 = ou nty) e C C ( ou nt uc. 11 Ke nt C Ed ) = & y t (Ke rch oun C sea Re ssex u S (
2005
INSECTS Derby Walker Extension Agent EASTERN TENT CATERPILLAR. Eastern tent caterpillar egg hatching is likely to occur when the leaves emerge from the buds of their host tree. In our area, wild cherry, flowering cherry, apples, and other fruit trees are commonly attacked. The shiny brown egg masses can be seen encircling small branches and twigs. If you had just a few egg masses, they could be hand removed through pruning. In pruning earlier in the week, I noticed the peaches are just about ready to bloom and cherries should be leafing out soon. Bt's and insecticidal soaps can be effective against small caterpillars. Often we don't notice the caterpillars until they larger and then it will take a pyrethroid, orthene, or carbaryl to kill them.
DISEASES Bob Mulrooney Extension Plant Pathologist ROSES. Now is the time to prune hybrid tea roses. Removal of old dead canes and those with obvious cankers (sunken dead spots) is a good sanitation practice. I have noticed quite a bit of winter damage in the form of excessive cane death even on roses whose crowns were well protected with mulch. Gardeners may want to wait until they see buds emerging before pruning, but most dead canes are pretty obvious now. Cane die-back seems to be much worse than the past several years on the plants I've observed. Fluctuating temperatures during the winter are probably the cause. Once pruning is finished, an application of liquid limesulfur will burn out any old cankers caused by black spot fungus or other canker forming fungi. VERONICA RUST was discovered on 'Sunny Border Blue' in a Michigan nursery last fall on plants propagated in Costa Rica. The causal fungus, Puccinia veronicae-longifoliae, does not occur in the US. Garden centers and growers may want to keep an eye out this season for plants with reddish leaves on the upper surface and obvious raised dark pustules on the under surface. It is not known if all Veronica cultivars are susceptible or how widespread the disease may be. If found, diseased stems should be pruned out and new growth sprayed with Systhane, Eagle, Banner, or similar fungicide chemistry. From the pictures I have seen, the symptoms are not subtle and should be very easy to spot.
UNIVERSITY OF DELAWARE
Issue 2
What's Hot! Old cicada damage from egg laying last season is evident on small branches and twigs of affected hosts such as oak, flowering dogwood, maple and others. Many of the old slits made in the bark still have a tuft of shredded tissue sticking out with new callus tissue surrounding the oviposition slit. Some twigs have 8-10 inches of damaged area, others only 1-2 inches. This damage was pretty widespread in New Castle County and much less in Kent and almost non-existent in Sussex. By next season most damage will be completely healed over. Dormant oils are effective against many scales, mites and aphids. There is still time to use dormant oil before leaves on most plants emerge. For the product to be effective, it must dry on the tree since it works by smothering the insect. Some plants are sensitive to oils, so read the label before applying and check to make sure plants are still dormant. Hemlock rust mite hatch has been reported in PA. This eriophyid mite feeds on the upper and lower surfaces of needles. Feeding by large mite populations causes needles to turn a light yellowish green. Damage usually occurs in spring. Look on the south side of hemlocks for off-color, yellowish needles. You will probably need a 10x hand lens to detect the minute, spindle-shaped, yellowish (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.
What’s Hot (Continued) eriophyid mites on the needles. Use a horticultural oil spray at the first sign of mite activity and damage.
Editor: Susan Barton Extension Horticulturist
Elongate hemlock scale nymphs have now been reported. This pest also produces a yellowish cast on hemlock foliage. Spray now with a dormant oil. Wait until a little later in the season (May) when more nymphs have hatched for insecticidal sprays.
G N I W O R G REE DAYS
5 , 200 5 1 arch M F AS O
DEG
5) =3 '04 ( 11 se e ou ty) = h fic n Of 4 4 ) n ree Coun n G = ow r e sio get en ('04 r che Castl t s o x i e E F ) 11 w r, G 49 nty = (Ne nte '04 = ou nty) e C C ( ou nt uc. 11 Ke nt C Ed ) = & y t (Ke rch oun C sea Re ssex u S (
