Issue 12, July 26, 2016
Large numbers of Japanese beetle adults along with sporadic rainfall makes it necessary to treat preventatively for white grubs in irrigated turf in some areas of the state. Much of southern and central Illinois continue to be dry, creating conditions where white grub damage is likely in irrigated turf. Much of the rest of Illinois has had sufficient rainfall that non-irrigated turf is generally green and attractive to egg-laying Japanese beetle and masked chafers.
In areas with more rainfall and naturally green turfgrass, infestations are likely to be low with only spotty infestations requiring treatment. Scouting in early August will identify hot spots and is typically a better option economically and environmentally than is widespread preventive insecticide application.
Refer to the previous issue of this newsletter for white grub control recommendations located at http://hyg.ipm.illinois.edu/article.php?id=834. (Phil Nixon)