No. 4/June 8, 2022

Modified Growing Degree Days June 6
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.

Bagworms (Family: Psychidae) are an insect that everyone has probably seen, even if they weren’t sure exactly what they were looking at. Bagworms are caterpillars that spin a small protective silk bag over their body. They decorate the bag with bits of leaves or other debris and drag the bag behind them as they walk, a behavior similar to that of hermit crabs. As the caterpillars grow, you may see bags up to 1.5 inches long.

Oak Apple Galls
Numerous galls are found on oak trees, and almost all of them are caused by cynipid wasps. Adult cynipid wasps are smaller than pinheads and do not sting people. The largest cynipid galls are the oak apple galls, being spherical, hollow galls that mature to sizes up to 2 inches in diameter, depending on the species of cynipid and the oak host. The legless, white larva typical of cynipid wasps lives in a small, seedlike structure in the center of radiating fibers that extend to the inside edge of the gall. Although they are initially green, oak apple galls mature to tan galls with a hard, papery exterior. Although the galls are common and easy to see, they are seldom important enough to need to be controlled.

A Few More Weed Seedlings Recently Found in Central Illinois
In the last issue of the Home, Yard, and Garden Newsletter, I wrote about 12 weed species that have recently germinated and can be widely found right now in central Illinois. Two weeks have passed and we have experienced some warmer temperatures and rainfall – both of which are needed for germination of you guessed it, MORE and DIFFERENT weeds! Here I present to you 5 more species that can be found making their way above ground if they aren’t there already.

Cryptocline Needle Blight of Yew
The Plant Clinic has seen an increase in the number of yew samples diagnosed with Cryptocline needle blight in the past few years. This fungal needle disease does not appear to be one of great concern given the lack of information about it in the literature. It has been reported in New England and eastern Canada on a few different species of yew. In the past few years, it has been confirmed on samples from Champaign, Cook, Lake, and Tazewell counties in Illinois.

Gymnosporangium Rusts on Apples, Crabapples, and Hawthorns
Rust symptoms were evident on downy hawthorn this past week in central Illinois. Three cedar rust diseases commonly occur in Illinois.

ALLELOPATHY: A Plant’s Chemical Warfare
When I think of plants that can defend themselves from pests, I think of thorns on roses or a venus fly trap, but not necessarily a black walnut tree? Besides the potential nut falling onto my head, they can pack a powerful punch on other plants. Some plants can inhibit the growth of another. This biological process is called allelopathy. Allelopathy refers to one plant's beneficial or harmful effects on another from the release of biochemicals called Allelochemicals. These allelochemicals can be used as growth regulators, herbicides, insecticides, and antimicrobial crop protection products.

Illinois Monarch Project
The Wings of Dreams BioBlitz is a competitive species count between individuals, families, and organizations across Illinois. Observations gathered during the BioBlitz will provide valuable data, including populations, rare species, and species diversity in Illinois! In addition to competing in a fun tournament, you are benefiting biologists around the world with your scientific data!