No. 15/August 28, 2009
Woolly Apple Aphid
Woolly apple aphid, Eriosoma lanigerum, is common this year on crabapple, cotoneaster, strawberry, and other rose family plants. Other rose family hosts include hawthorn, mountain ash, and pyracantha.
White grubs appear to be low in number and spotty this year in central and northern Illinois. In my surveys, it has been difficult to find any grubs at all, and I have not heard of any treatable infestations.
Bagworms have about finished feeding for the year. Pupation occurs from mid-August to early September, depending on the temperature. With cooler temperatures this year, pupation may not have occurred yet in central and northern Illinois.
Scoliid wasps, family Scoliidae, feed as parasitoids on the larvae of green June beetles. With higher numbers of these beetles in many areas of Illinois this summer, we are now getting reports of large numbers of scoliid wasps.
Send Clinic Samples Soon
The University of Illinois Plant Clinic is a seasonal clinic operation. It is open May 1st each year and closes September 15th.
Pine Gall Rusts
A problem that has been popping up in nurseries and some landscape plantings is a gall that forms on pine stems. The galls are rust galls. Although much less common than the galls caused by cedar apple and related rusts, these galls also appear on stems, but on pines.
Peony Leaf Spot/Blotch
This is the time when many gardeners want to know what is causing the foliage on their peony to look so puny. Red to purple foliar blotches are caused by a fungus, Cladosporium paeoniae.
Diseases of Perennials Book
Anyone who grows perennials, for pleasure, profit, or both, can use this new book. I am speaking of Diseases of Herbaceous Perennials by Mark L. Gleason, Margery L. Daughtrey, Ann R. Chase, Gary W. Moorman, and Daren S. Mueller.