No. 13/August 8, 2011

Sod Webworms
The hot, dry weather of recent weeks have set us up for sod webworm damage in non-irrigated turf. High temperatures result in shorter generation times, allowing more generations and higher population numbers. Dry soils reduce the infection rate of naturally-occurring microsporidia that usually help keep larval numbers low. All of this allows more individuals to mature faster resulting in high sod webworm numbers.

White Grubs
Scouting at this time will allow control decisions to be made in areas where preventative insecticides have not been applied. Even in areas with large numbers of grubs, damage is unlikely to become evident until the second half of August.

Testing for Bacterial Leaf Scorch of Trees will be offered at the U of I Plant Clinic
Scorch may be of the noninfectious or infectious type. Environmental stress, root injury, drought, and many other factors may cause leaf margin necrosis, a condition we call scorch. It is usually widespread in a tree and is fairly uniform. Such a condition is not necessarily repeated in following years and is noninfectious. Unfortunately, we are seeing a lot of scorch symptoms on leaves brought on by this season's environmental stress.

Oak Wilt has been confirmed at the U of I Plant Clinic
As the dog days of summer begin, the appearance of obvious oak wilt symptoms throughout Illinois continues. The U of I Plant Clinic has already positively confirmed 3 cases of oak wilt this summer and is anticipating more positive cases to appear. Oak wilt is an extremely serious disease of oaks that can cause death to oaks in the red-black group (leaves with pointed tips) within a growing season and oaks in the white-bur group (leaves with rounded lobes) over several years. No oak species is immune.