No. 14/August 22, 2011

Elm Sawfly
We've had a couple of reports of large numbers of elm sawfly larvae in Kankakee and Iroquois counties. These yellowish to white larvae are thick-bodied and approach 1-1/2 inches long when fully grown. They have yellowish heads and a black line running down the middle of their backs with a row of brown to black spots on each side.

Zimmerman Pine Moth
Zimmerman pine moth can be effectively controlled at this time of year. They are susceptible now in southern and central Illinois and will become susceptible to control at the end of August in northern Illinois. This insect commonly attacks at branch whorls of Scotch, Austrian, red, and other pines.

Large Wasps
There are a number of large wasps that are present in landscapes at this time of year. They are primarily interested in feeding themselves on flower pollen and collecting insects or spiders to feed their young. As such, they are very unlikely to sting people unless grabbed or stepped on when barefoot. However, their large size makes them obvious to clientele who worry about getting stung or at least ask you what they are.

My Tree is in Decline, Now What?
Most trees samples are immediately put into culture in order to isolate any fungal pathogens that may be infecting the vascular system of the tree, after they arrive at the U of I Plant Clinic. If the trees are negative for vascular, fungal pathogens, such as oak wilt (Ceratocystis fagacearum), Dutch elm disease (Ophiostoma ulmi), and Verticillium wilt (most often caused by Verticillium dahlia), the sample is carefully examined for signs of tree decline.

Update on Imprelis Herbicide
This summer, we have witnessed widespread damage to pine and spruce trees caused by the newly registered Imprelis herbicide (aminocyclopyraclor) by DuPont.