Pest Activity -- Woody Ornamental Integrated Pest Management at Penn State

Pest Activity -- April 9, 2004

Pest Activity > April 9, 2004

Welcome to the Woody Ornamental Pest Scouting Report for Western Pennsylvania brought to you by Penn State Cooperative Extension. This message 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 7, the following growing degree days with a base temperature of 50 degrees have accumulated.

Uniontown	81	Harbor Creek	32
New Stanton	65	Meadville	38
Pittsburgh	57	Erie	28
Franklin	36	Behrend	xx
Wexford	47	Mercer	40
Butler	33

Pest Activity

Hemlock Rust Mite

Eriophyid mites are active at lower temperatures than spider mites and the hemlock rust mite is no exception. Regularly monitored populations in Westmoreland County are increasing despite the cool temperatures. In 2002, this pest remained active through May 17 when we had 290 growing degree days. They are often found closer to the ground and on internal branch foliage. Registered controls can be found here.

Fact Sheet

White Pine Weevil

	To date, I have not found evidence of white pine weevil adult feeding on the leaders of white pines at nurseries in Westmoreland and Butler counties. Insecticidal treatments should be applied when the sap flow from the adult feeding is observed. Registered controls for this pest can be found here.
Fact Sheet

Other Insects

Emerald Ash Borer

A new exotic pest from Asia that feeds on ash trees was discovered in Michigan in July, 2002. It has already killed over 6 million ash trees in Michigan and has spread to Maryland, Virginia, and Ohio. I am including this pest in an ipm report because it has spread on firewood and infested nursery stock and has the potential to show up in Pennsylvania undetected.

Early detection, which is difficult, and quarrantine are the keys to any hope of slowing down this potentially devastating pest. Emerald ash borers are often difficult to detect, because there are few external signs or symptoms of early infestations.

When trees are still vigorous, small, vertical splits may form in the bark. These are caused by the growth of callus tissue forcing out the bark as it forms over larval galleries in the phloem. To confirm the presence of emerald ash borer, split open the cracks to check for larvae and galleries. Larval galleries are distinctly S-shaped or serpentine, and are packed tightly with frass (mixture of sawdust and excrement).

The shape of adult emergence holes in the trunk is the most distinctive diagnostic guide. The emergence holes of emerald ash borer are distinctly D-shaped (upper left) while emergence holes of clearwing borers of ash are larger (one-fourth of an inch in diameter) and round (lower right).

If you believe you have emerald ash borer, immediately call the regional office for the PA Department of Agriculture.

Diseases

Apple Scab

In the last weeks report, I noted that the correct time to apply the first of two sprays for apple scab on crabapples is pre-pink. I had a question from someone asking me to describe exactly what is "pre-pink." Here is a picture of crabapple flowers in the pre-pink stage(with the leaves stripped off to get a better picture).

Weeds

Bittercress

Now is the time to take action if you are managing lesser-seeded bittercress in the landscape. This winter-annual weed has become a nuisance in many landscape beds in Southwest Pennsylvania and will rapidy increase in number through prolific seed production. Hand-weeding is always an option with this plant as is the use of a contact herbicide, such as Reward, or a systemic herbicide like Round-up Pro.
The contact herbicide will shut the plant down quicker than the systemic, but both materials need a 2 hour window of dry weather for absorption.

The next scouting report will be on April 16 .