No. 11/July 12, 2013

White Grubs
With the light adult Japanese beetle emergence this year in much of the state, and the continuing periodic rains in most of the state, white grub numbers are likely to be low this year in most areas. Because masked chafer grubs are better able to survive the dry soils and high soil temperatures that we had last summer, they are likely to be more numerous this year. However, in most areas where Japanese beetles, northern masked chafers, and southern masked chafers occur together, the Japanese beetles tend to crowd them out of the prime, irrigated, turf areas.

Japanese Beetles
Adult Japanese beetles continue to be spotty throughout the state with many areas having low numbers and correspondingly minor feeding damage on trees and shrubs. We have received reports of high numbers and damage in northwestern Illinois from New Bedford, Macomb, and Wyoming, IL. There are also reports of high numbers in north-central Illinois near Rockford.

Bagworms continue to be numerous in some areas of the state. Although they continue to grow and get bigger, a high level of control can still be achieved. Pupation will occur in the second half of August in southern Illinois to early September in northern Illinois. The insects are large enough to make hand removal very effective with small populations on shorter trees and shrubs. Do not just drop them on the ground; they will climb back up the tree. Squash them or collect them and dispose of them in the trash.

Don't blame it on the dog: Dog Vomit Slime Mold
A type of slime mold that resembles dog vomit has been noted in numerous landscapes. However, your dog (or neighbor’s dog) had nothing to do with it. Slime molds are rather interesting organisms. They first appear as slimy masses ranging from a few inches to over a foot across. They can be colorful; with shades of orange, yellow green, and even some blues and purples. They also have the ability to move, however movement is too slow to watch. Over a span of several days, the slime mold masses may move short distances. The organisms eventually develop colorful, crusty fruiting bodies filled with masses of dusty spores. The spores are then dispersed to create new slime mold patches.

Why BLS is nothing to LOL about! – FYI on testing for BLS at the U of I Plant Clinic How can I diagnose Bacterial Leaf Scorch (BLS)?
How can I diagnose Bacterial Leaf Scorch (BLS)?
The problem is that BLS can be easily mistaken for other environmental, disease, or cultural problems, so diagnosis cannot be based on symptoms alone.  Some examples that might limit the water uptake of trees and cause similar symptoms to BLS are as follows: drought stress, unfavorable site, construction damage, improper planting, girdling roots, root and butt rot, and canker fungi.  Late summer or early fall is the best time to test for BLS, because this is when Xylella fastidious is most active and bacterial populations are high in the tree’s water conducting tissues.  It has been found that testing for this disease too early in the growing season can result in false negative results.  We suggest that you obtain an accurate BLS diagnosis, because this disease is affecting many high value trees across the US and infected trees can be unsightly and unsafe.

Modified Growing Degree Days (Base 50° F, March 1 through July 11)
Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Home, Yard, and Garden readers can use the links below with the degree day accumulations above to determine what insect pests could be active in their area.