Pest Activity -- April 20, 2001

Pest Activity > Pest Activity Archives > April 20, 2001

Welcome to the Woody Ornamental Pest Scouting Report for Western Pennsylvania for April 20, 2001, brought to you by Penn State Cooperative Extension. This tape will be updated weekly with growing degree day counts and insect activity through the end of June. If you would like an email copy of this report, send your request to mcm2@psu.edu.

As of April 18, the following growing degree days using a base temperature of 50 degrees have accumulated:

Wexford	105
Uniontown	176
New Stanton	125

The cold temperatures this past week have slowed down the development of plants and insects and with the exception of Cooley Spruce Gall Adelgids there is very little change from last week's report. If the temperatures rebound to the seasonal averages the following insects should be emmerging in the next couple of weeks: Spruce Spider Mites, Birch Leafminers, Pine Spittlebugs and Boxwood Psyllids.

The adults of Cooley Spruce Gall Adelgids on Douglas Fir and Colorado Spruce in Westmoreland County were completely coveredwith white waxy filaments, thus greatly reducing pesticide efficacy. Feeding damage from his pest will cause bent or distorted needles on Douglas Fir and galls on the terminal growth of Colorado Blue and Oriental Spruce.

White Pine Weevil feeding was observed in Westmoreland County again this past week. Nursery inspectors from the PA Department of Agriculture reported egg laying has just started in Perry county. This pest is responsible for killing the terminal leader on Eastern White Pine, Spruces, and occasionally Douglas Fir. Glistening droplets of fresh sap found on the terminal leaders of white pines is the result of feeding by adult males and females. Registered insecticides applied according to label directions should be directed to the tops of the trees at this time, before the females lay eggs in the terminal leaders.

Eastern Tent Caterpillar hatched out this past week in Westmoreland, Allegheny and counties to the south. In many areas the populations of eastern tent caterpillars are on the rise from the previous couple of years. The tents are approaching 3-4 inches in length and the larvae are in early instars. The insecticide B.T. is effective against the eastern tent caterpillar when the larvae are under one inch long and sprays are directed toward the foliage surrounding the tents since the material must be ingested. If using a contact insecticide, be sure to apply when the caterpillars are feeding outside of the tents. While not practical in all situations, the tents and caterpillars can be removed by hand at this time. The best time to do this is early morning and evening, when the caterpillars are in the tents.

European Pine Sawfly eggs hatched last week in Allegheny and Westmoreland counties and the 1/8 inch long larvae can be found feeding on last year's terminal growth. Their preferred host plants are Scotch, Japanese Red and Mugho Pines. At this time the larvae are confined to a localized area and a spot treatment or physical removal will provide control.

Eriophyid mites were observed feeding on hemlocks in Westmoreland and Allegheny counties this past week. High populations of this pest will cause needles to yellow before dropping. If you noticed this occurring in the landscape or nursery last year, check now for small worm-like creatures with two pairs of legs. Eriophyid mites are much smaller than spider mites and a hand lens is required for detection. Registered insecticides applied according to label directions should be used at this time.

There is another Eriophyid Mite that feeds on white pines with severe infestations responsible for turning last years’ foliage brown. Since white pines are very sensitive to salt injury and winter desiccation it is wise to check the foliage under a stereo microscope or a 15x hand lens.

Now is the time to think about apple scab control on flowering crabapples. Recent research indicates that a combination of the fungicides Banner and Daconil provides very good control of apple scab with the first spray applied at the early pink stage and a second one applied three weeks later.

The next tape update will be on Friday, April 27th.