No. 4/June 20, 2023

Modified Growing Degree Days
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.

Aphids (Family: Aphidae) are one of the most common insect pests in the home landscape. They have small, pear-shaped bodies that can be many colors, including green, brown and yellow. Aphids can be identified by small structures called cornicles, which look like tailpipes on the rear ends of the insects. Aphids can be winged or wingless, with winged individuals appearing later in the season. Aphids can have many generations in a single year, so it is a good insect to scout for throughout the growing season.

Weeds That Do Well in Drought
Given the drought conditions that much of the state has been experiencing, it’s fitting to discuss weeds that may be thriving now or at least faring better than our cool-season turfgrasses are. Here are a few.

Optimizing the Activity of Tenacity Herbicide
Tenacity (active ingredient mesotrione) is a herbicide that can control a variety of weeds in cool-season turfgrasses. Most herbicides used in turf fall into two categories, either postemergence (which means the herbicide is applied to emerged, actively growing weeds) broadleaf herbicides, (e.g. Trimec), or preemergence (which means the herbicide must be applied prior to weed germination and emergence) grass herbicides, (e.g. Dimension or Barricade). Tenacity doesn’t neatly fit into either of those two categories, which makes a valuable herbicide for some difficult to control turf weeds. The label states that Tenacity has both preemergence and postemergence activity. And while this is technically true, the preemergence activity in turf is relatively short-lived and not economically or agronomically valuable. I believe this is in part because a turf environment is conducive to more rapid breakdown of herbicides as compared to when the herbicide is applied to bare soil as when used in corn.

Mower Blight
We’ve all likely experienced the following scenario. While mowing, you notice some tall grass growing near the base of a tree. You move the mower slightly closer to trim the overgrown grass despite knowing better. While you successfully cut the grass, your mower deck also managed to gouge through the tree’s bark causing permanent mechanical injury. While completely avoidable, this type of tree injury is all too common. So much so that many refer to it as mower blight.