Ornamentals:
Some Pine Bark Adelgid samples have been sent in this week. Look for sooty mold on the branch tips and the cottony covering that these adelgids use to cover themselves. Those who did not use dormant oil for control last winter should consider using some type of foliar spray in early May, if they have trees with damaging populations. For an update on Pine Bark Adelgid, see:
http://www.ext.vt.edu/departments/entomology/factsheets/pibadelg.html
Vegetables
Gardenders who have annual problems with seed corn maggots should consider using Diazinon at planting time. Adult seedcorn maggots (small black flies) are often found stuck to flowers in the spring because they are infested with a fungal disease that makes them sticky. See:
http://www.ext.vt.edu/departments/entomology/factsheets/casemag.html
Some more insects to be on the look out for next month:
Eric Day
Manager, Insect Identification Laboratory
(540) 231-4899
Insect:Host(s) Description Treatment timing*
FIELD AND VEGETABLE CROPS
| Insect:Host(s) | Description | Treatment timing* |
| Aphids: Any crops but in particular crucifer crops | Look for small soft-bodied insects causing the leaves to be stunted, yellowed, and /or curled. | Cut out and destroy small localized areas on plants or treat with an insecticide labeled for aphids and that particular crop. |
| Black Cutworm and other Cutworms: Many crops but in particular corn. | Medium to large caterpillars cut off plants at the base. Inspect newly planted seed beds and newly set plants. | If more than 5% of the plants are cut, control with an insecticide or bait is warranted. |
| Flea Beetle: Corn, eggplant, and many other crops | Small black beetles jumping like fleas when disturbed from the leaves of a plant. They scrape the upper epidermis layer off the leaf and sometimes the fruit, leaving a brown scar. | Spray with Sevin when damage becomes severe. |
| Imported Cabbageworm: Cabbage, broccoli, cauliflower, and other crucifers | Velvet green caterpillars with a faint yellow stripe down the back and a row of yellow spots on each side. Full grown larvae are about 32mm (1-1/4 inches) long. | Treat when caterpillar populations reach a threshold of one worm per plant, repeat every 5 to 7 days as needed. |
| Root Maggots: Many vegetable and field crops, particularly crucifer crops | White leggless maggots feed on small roots and tunnel into large roots. Plants with damage fail to develop properly. | Usually a planting time soil insecticide is needed but a soil drench after plants have been set may be effective. Replanting is effective because there is usually only one generation of maggots and the second planting is not attacked. |
FRUIT INSECTS
|
Insect:Host(s) |
Description |
Treatment timing* |
| Codling Moth: Apple and pear primarily, but cherry, peach, plums, apricots, and similar fruits are attacked | Pinkish-white caterpillars enter fruit at calyx end and tunnel all the way to the core. Adult moths are grayish-brown with irregular golden brown lines on the forewings. 1/2-3/4" wingspan. | If using pheromone traps, treat if you exceed 5/trap/week. |
| European Red Mite: Apple, pear, plum, prune, and many other trees and shrubs. | Mites are very small and range from red to green. Foliage turns a sickly bronze color as if covered by dust. | This mite is resistant to many miticides, so make sure that the chemical you will use is effective. A dormant oil is applied at the 1/2" green leaf stage or earlier in the spring is important also. |
| Green Apple Aphid: Apple, pear | Pale green nymphs on the underside of leaves and new shoots, often a problem on trees with excessive shoot growth due to overfertilization. | Treat when 50% or more of the shoots are infested. |
| Spotted Tentiform Leafminer: Apple | Young mites are serpentine changing to oval. As the larvae get older they form into a tentlike structure. | Treat young mites with Vydate or Lannate if more than 3 mines per leaf on average. |
ORNAMENTAL INSECTS
|
Insect:Host(s) |
Description |
Treatment timing* |
| Azalea Stem Borer: Azalea, rhododendron, mountain-laurel, blueberry | Look for tips dying back and yellow legless grubs up to 1/2" long boring in twigs and trunk. | Treat mid-May and mid-June with an insecticide or cut out and destroy dead and dying tips as noticed. Use of a borer paste in the holes will give some control also. |
| Boxwood leafminer: Boxwood | Adults are out April to early May. Infested leaves often appear blistered and discolored. See the March 1990 issue of the Plant Protection Newsletter for more information. | Apply insecticides for adults; apply systemic insecticides in early to late June to control larvae. |
| Bronze Birch Borer: Birch, cottonwood, poplar, aspen | Look for the top of the tree dying back and up to 1" long flat-headed borers under the bark. | Treat mid-May, and early-, mid-, and late-June; spray trunk and branches heavily and leaves lightly. |
| Camellia Scale: Camellia | Scale is light to dark brown, 1/10" long and oyster-shaped. Crawler dates are May 1-June 5; and Sept. 15-30. | Treat May 10 and 20 and/or Sept. 10 and 20. |
| Dogwood Borer: Dogwood, sometimes pecan | As many as 50 white caterpillars with brown heads living under roughened areas of the bark. | Treat mid-May, repeat at 6 week intervals 2-3 times. |
| Dogwood Twig Borer: Dogwood, elm, viburnum, and many fruit trees | A slender lemon-yellow beetle grub feeding in the center of twigs. As it feeds it makes small holes to the outside for the protrusion of frass. | In early to mid-May, apply an insecticide spray to control the adults. Prune out and destroy infested twigs. |
| Eastern tent Caterpillar: Many fruit trees, but in particular cherry | Look for conspicuous egg masses circling trees. These egg masses will be black in color and quite shiny as if varnished. The small black hairy caterpillars will hatch out in April and feed on the newly emerging leaves. | Pick off egg masses before they hatch. Treat with an insecticide as soon as the leaves have emerges enough to retain the insecticide. |
| Elm Leaf Beetles: Elm | Newly hatched larvae are yellowish with black markings, adults are olive green with two black lines. | Control newly hatched larvae in late-May and early-June. |
| Euonymus Scale: Euonymus, | Females are dark brown oyster-shaped | Treat May 10 and 20, and |
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