No. 5/May 23, 2016

What is That Yellow-Flowered Plant?
The springtime color scheme provided by winter annual weed species in many no-till fields has shifted from the hearty purple of flowering henbit and purple deadnettle to the bright yellow flowers of two species. Yellow rocket and cressleaf groundsel (a.k.a. butterweed) both produce bright yellow flowers and are common across much of the southern half of Illinois. Although flower color is similar, the plants are distinct species. Most of the yellow-flowered plants currently in fields is butterweed.

Sycamore Anthracnose
Sycamore Anthracnose occurs in three phases: canker, shoot blight, and leaf blight. The canker phase occurs in April and early May while the tree is dormant. This phase kills either individual buds or the tips of year-old shoots. Girdling cankers form just below the buds often killing them before the end of dormancy. Cankers can continue to enlarge, encircle and kill small shoots. The canker phase can be quite damaging, especially during springs with prolonged, cold temperatures that extend dormancy and allow the pathogen additional time to colonize bark and bud tissues.

Peony Problems
So far, it's been a beautiful year for peonies. The tree peonies bloomed earlier, and the herbaceous peonies are starting to open. While it's easy to enjoy these lovely plants while they're flowering, they're also easy to forget about later in the year when the colorful blossoms are gone, and all that's left are the leaves.

Some folks spend time and money mixing up concoctions to get moss to grow between bricks and stone pavers in sidewalks and patios. Others fills concrete or hypertufa troughs with all sorts of loose soil mediums to raise moss gardens on rocks and boulders, spraying them daily with moisture. Books have been written on developing your own moss garden.

Gnats in Your Face
Gnats have been bothersome recently. Numerous tiny flies hovering in one's face can result in reduced productivity and distraction can result in physical injury. Rove beetles are also numerous, appearing similar to gnats (small flies) while flying.

Emerald Ash Borer
Emerald ash borer adult emergence was reported in southern Illinois in early May. They are being found at this time, mid-May, in central Illinois. They should start emerging in northern Illinois around the end of May into early June. A major means of control relies on killing the newly emerged adults as they feed on ash leaves, reducing the number of eggs laid. Refer to the articles on emerald ash borer in Issue 3 of this newsletter for further information.

Modified Growing Degree Days (Base 50°F, March 1 through May 21)
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.