No. 9/August 12, 2021

Dogwood sawfly
Dogwood sawflies (Macremphytus tarsatus) are native to much of the eastern US and Canada. They are a wasp species whose caterpillar-like larvae feed on the foliage of dogwoods in groups.

July 2021 Plant Clinic Sample Summary
The Plant Clinic remains open. We are currently operating with reduced staff and are only in the lab as needed for diagnostics and other lab work. We may not be able to answer or return phone calls in a timely manner though we are making every attempt to do so. You can also email us at

Southern Blight
Sorry, those aren’t mustard seeds sprinkled at the base of your coneflowers. They are sclerotia, fruiting bodies produced by the southern blight fungus, Athelia rolfsii (syn. Sclerotium rolfsii). The U of I Plant Clinic recently diagnosed an Echinacea sample with southern blight. This soilborne pathogen causes basal rot to stems and petioles of herbaceous plants. It is capable of infecting a wide variety of plant species, including many annuals, perennials, woody ornamentals, and turfgrass. I have mostly encountered this pathogen infecting hosta, where it is commonly referred to as hosta petiole blight.

Dogwood Powdery Mildew
Powdery mildew is a common fungal disease problem on many perennials, as well as annuals, shrubs, and even trees and turf. It is most noticeable in the hot, dry dog days of August. Unlike most fungal diseases, powdery mildew develops rapidly in extended periods of warm, dry weather when morning dews are heavy.

Considerations Before Consuming Produce Following a Pesticide Misapplication
Every summer Extension Pesticide Safety Education Specialists are asked the same type of question repeatedly by home vegetable gardeners. The details leading up the situation at hand vary, but in the end the basic question is the same. Their vegetable plants have accidentally or mistakenly come into contact with a pesticide being applied. They always want to know if their produce is safe to eat.