Pest Activity -- April 14, 2000

Pest Activity > Pest Activity Archives > April 14, 2000

Welcome to the Woody Ornamental Pest Scouting Report for Western Pennsylvania for April 14, 2000, 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 12, the following growing degree days using a base temperature of 50 degrees have accumulated:

Fox Chapel	100
Butler	84
Uniontown	137
New Stanton	101

Aphids were again observed on the newly emerging birch leaves this week in Westmoreland County. This pest feeds on the young leaves and developing catkins and can cause distorted leaves if population levels are high. Birch leafminer, another pest of this host plant should be active in the next couple of weeks if the warming trend continues.

The continued cold weather this past week has slowed the development of European Pine Sawfly larvae. The terminal growth of Scotch, Japanese Red and Mugho Pines should be inspected for this dark green, black headed larvae which are 1/4 inch long at this time. Control measures include physical removal or a spot treatment with a pesticide labeled for control of this pest.

The cool temperatures have also affected the development of the Cooley Spruce Gall Adelgid. Immature adults observed on Douglas Fir in Westmoreland County this week again only showed white waxy thread around the perimeter of their bodies. Once the wax completely covers their entire body, the early season window for control is closed. It is important to check for this protective covering prior to applying a control measure.

White Pine Weevil feeding on terminals of Eastern White Pine was spotted again in Westmoreland and Beaver counties this past week but no egg laying has been observed to date. The terminals should be inspected for egg laying prior to applying an insecticide since control efficacy is greatly reduced once the eggs are laid and covered with pine pitch.

Eriophyid mites continue to be active on hemlocks in Westmoreland and Beaver counties. High populations of this pest will cause needles to take on a silverish appearance from the loss of chlorophyll. The occurrence of this pest has steadily increased in southwest Pennsylvania in the past few years and hemlocks should be regularly scouted for this pest in early Spring. Registered insecticides applied according to label directions should be used at this time.

Crabapples that are highly susceptible to apple scab can be sprayed at this time. Recent research indicates that a combination of the fungicides Banner and Daconil provides very good control of apple scab when applying either 3 sprays at two week intervals or 2 sprays at 3 week intervals. Initial sprays for apple scab on crabapples should be applied now. If you are considering a crabapple for a new installation, please call the extension office at 412-473-2540 for a list of disease resistant crabapples or we can be reached via e-mail at AlleghenyExt@psu.edu

I have received requests for information about the shot holes on the leaves of oaks last year. The consensus among entomologists is that a small leafmining fly is the culprit. Trees in the red oak groups are the preferred hosts but White Oaks can also be affected. The timing for control of the pest is when the newly emerging oak leaves have elongated one inch. Dave Shetlar in his P.E.S.T. newsletter states:

I have seen no data on control of this pest. However, several insecticides are effective in controlling dipterous (fly) leafminers. Most of the pyrethroids (Astro, Pounce, Scimitar, and Talstar), Conserve, Dursban, Dylox (Proxol), and Malathion are effective if the adults are present. I also have a "gut feeling" that a Cygon or Orthene application would also do the job well (Cygon is registered for scale control on oak and ortherne is registered for lepidopterous - moth - leafminers).

The next page update will be on Friday, April 21th.