No. 3/May 20, 2019
Modified Growing Degree Days (Base 50⁰ F, March 1 through May 16)
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.
Eastern Tent Caterpillar
Eastern tent caterpillars (Maclacosoma americanum) are native North American pests that can be heavy defoliators. They feed predominately on members of the rose family including crabapple, apple, cherry species, hawthorn, peach, plum species and many others. When feeding, the caterpillars chew from the margin of the leaf inward, leaving the midvein of the leaf behind.
Scouting for Bagworms
When the Japanese Tree Lilacs are in bloom, it is time to scout for and control bagworms. This species flowers later than other lilacs, with large fluffy white blossoms on a 20 to 30-foot tree. Known for their fragrant flowers in early- to mid-June, Japanese tree lilac is a common urban tree. In Bloomington, Miller Park has impressive specimens by the entry to the zoo.
Fields of Yellow
The fields of central Illinois may not be full of corn or soybeans yet, but they are full of yellow. Butterweed is having a glorious year with the cool, wet weather conditions we have experienced. It is quite striking to see an entire field of yellow on an otherwise barren landscape. I’ve seen people stop to take pictures of it. My farmer brother recently watched two girls haul away buckets of the cut flowers from his field. He was fine with it but was puzzled just the same as to why they would want this weed of his. More power to them. Please, come take more.
Maple Leaf Blister
Maple leaf blister commonly infects silver and red maples as well as their hybrids. Outbreaks usually occur during springs with extended cool, wet weather. This disease is closely related to peach leaf curl, plum pockets, and oak leaf blister, all of which are caused by fungal pathogens belonging to the genus Taphrina. This group of pathogens infects leaves early in their development, often at the time of bud-break. As the leaves mature, they become resistant to the fungus, so there is effectively one infection cycle per year. The fungal pathogen causes abnormal cell division and enlargement, which can cause infected leaves to have a blistered, crinkled appearance. The blisters are initially green but quickly transition a brownish-black color. Anthracnose infections are also likely, given this spring’s predominately cool, wet weather. One way to distinguish a Taphrina infection from an anthracnose infection is that Taphrina usually does not cross leaf veins or infect the leaf petiole.
Red Thread
Red thread is a turf disease named for the thread-like structures produced on the tips infected grass blades. It is a foliar disease that usually occurs on tall mown turfgrasses during the spring and fall. This disease is particularly common on slow-growing, nitrogen-deficient, fine-leaf fescues and perennial ryegrass. Outbreaks are favored by cool (60 to 75 degrees F), wet periods coupled with extended overcast conditions.
What’s in a Rate?
If a little is great, and a lot is better, then way too much is just about right!- Mae West It might hold with some things, but when it comes to pesticides, rates are critical for control. Some labels have a range of pesticide application rates. These rates are based on timing and conditions. Applying the wrong amount of herbicide can result in problems that include, nonperformance in the control of weeds, and injury to off-target vegetation, turf, and non-target species. Most serious problems encountered with herbicide use often stem from improper application. Errors in application often occur with inaccurate calibration, mixing, improperly operating equipment, and failure to read the product label. A study conducted at the University of Nebraska looking at agriculture pesticide use found-"that the primary problem with ag chemicals is not the chemicals themselves but the people who apply them.” Misapplication wastes an estimated $1 billion annually. With these things in mind, applicators should take time to ensure the application is done accurately, with the correct amount applied at the right time.