No. 4/May 17, 2011
Bridal wreath spirea, or Vanhoutte spirea, is blooming throughout the state. With phenology, stages of plant development (usually bloom time) are used to predict stages in pest development.
We have received reports of large numbers of buffalo gnats, also known as black flies, attacking people particularly in the Springfield and Moline areas. Buffalo gnats are small, 1/16- to 1/8-inch-long, humpbacked black flies. They bite exposed skin, typically leaving a small, red welt.
Gypsy moth caterpillars hatch when common lilac, Syringa vulgaris, blooms. However, its main hosts, oaks, are typically just leafing out at that time. It is recommended to delay treatment until there is sufficient foliage expansion for sprays to have enough leaf surface to be effective.
Selective Control for Nimblewill Now Available
For years, homeowners and professional lawncare applicators have had to rely on non-selective herbicides such as glyphosate when controlling nimblewill (Muhlenbergia schreberi) in residential lawns. Along with the nimblewill, non-target desirable plants such as bluegrass may be seriously injured or killed if contacted by glyphosate. Finally, we have a selective herbicide option for nimblewill.
More on Stressed Spruce and Deep Planting
The U of I Plant Clinic continues to receive many spruce samples. These samples are examined and evaluated for disease, insects, and mites. The bulk of the recent samples, however, have not yielded a biotic cause of decline.