No. 6/June 5, 2017

Why are Yew so sad?
Yew plants are fairly pest-free once established into a landscape, and can be a wonderful addition to the right area. However we've seen a number of yew samples at the Plant Clinic in the last few weeks. Most of them come with pictures or descriptions of plants with needles turning bright yellow, then browning and eventually falling from the plant. When examined under the microscope, no pathogens or insect pests are found. Instead, corky bumps or blisters are observed, usually on the underside of the needle. These can be seen with the naked eye, though they may appear as spots.

Phil Nixon Retires
Phil retired at the end of May, 2017. We wish Phil years of enjoyment with his fish, dinosaurs, bonsai, and other hobbies in his retirement.

Waterlogged Plants
It's no secret that much of Illinois has received excessive spring rains, which has resulted in waterlogged soils and flooding. It is important to understand what is happening to plants growing in these conditions and what to expect later. I look at this as "a wait-and-see situation." Many herbaceous plants are experiencing injury symptoms now. Visible injury symptoms on trees and shrubs may not occur for a year or more.

Deer tick, the northern subspecies of the blacklegged tick, spreads Lyme disease, perhaps the fastest rising, most under-reported serious disease in the U.S. There have been an estimated 300,000 cases of Lyme disease annually in the U.S. in recent years. June is the month most likely to get Lyme disease from the bite of a tick nymph. It is important to protect yourself and workers from these giant mites.

Mimosa Webworm
Mimosa webworm heavily attacks silktree or mimosa, Albizia julibrissin, in southern Illinois. It is common for much of the foliage of silktrees to be brown and heavily webbed together in late summer. It also attacks honey locust throughout the state, but is only occasionally numerous enough to cause obvious aesthetic damage. When numerous, the foliage of a third or more of honey locusts will be brown in late summer.

Modified Growing Degree Days (Base 50°F, March 1 through June 1)
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 in this article with the degree day accumulations above to determine what insect pests could be active in their area.