No. 4/May 27, 2014

Flatheaded Appletree Borer
Flatheaded appletree borer attacks trees in the rose family, being common in older hawthorn, serviceberry, cotoneaster, rose, and crabapple branches and trunks where it primarily attacks declining trees and shrubs near the end of their lifespan. It also attacks dead and dying branches of many other tree species, including maple, oak, ash, hickory, sycamore, tuliptree, and willow. In these situations, it is normally not considered to be a pest.

Twolined Chestnut Borer
Two-lined chestnut borer attack primarily oak and chestnut, but occasionally attack beech. They prefer white, black, red, scarlet, bur, and chestnut oaks. Although they primarily attack oaks that have been damaged or are under stress, they can attack healthy trees. It is common for twolined chestnut borer to become numerous in areas with gypsy moth infestations, causing the trees to die from the top down over two to three years.

When It Comes to Yew, You Had Better Know This!
Yews are a common woody ornamental staple in the yards of homeowners across America. Yews are used as hedges, windbreaks, topiaries, barriers, and more as their moderate growth rate and easy maintenance make for a relatively maintenance free implement in landscaping designs. This very prominent figure in homes across America has a finicky nature, though.

Fire Blight on Callery Pear
Fire Blight symptoms were observed on several Callery Pears this past week. The symptoms were more severe than those observed during the 2013 growing season. Fire blight is a bacterial disease that affects rosaceous plants. Apples, pears, crabapples, and ornamental pears are the most seriously affected species. Other rosaceous hosts include: cotoneaster, hawthorn, quince, firethorn, and mountain-ash

Crabapple Scab
Crabapples are showing early symptoms of scab. The lengthy cool, wet conditions have resulted in an ideal environment for the disease. These conditions and high disease pressure will likely result in infections occurring to disease susceptible cultivars as well as resistant cultivars normally unaffected by scab. The highly scab resistant Prairifire crabapple is one example that I observed on the U of I campus.

Bush Honeysuckle – Loved and Hated
There are quite a few species of exotic bush honeysuckles. They are native to Eurasia and grow as upright, deciduous shrubs (generally 6 to 15 ft.) that flower in the spring.  Of course there are native species too which can be easily confused.  This is likely part of the problem.  Originally grown as ornamentals in the 1800s in the Eastern U.S., they have spread far beyond their original plantings.

Modified Growing Degree Days (Base 50°F,  March 1 through May 22)
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.