Frozen

Tony Koski
Extension Turf Specialist

No, Elsa, this isn’t about you..

A very frozen dandelion...still alive

Some have asked, on the heels of the recent “polar vortex” (not really…it was just a sign that winter is coming...read about that here) and temperatures hovering near zero, about how the early and abrupt cold snap might affect turf pests – weeds, fungi, and insects? The short answer (in case you want to leave now and hear Elsa sing…again) is that it likely had little effect on any turf pests – and is unlikely to affect turf pests in 2015.

There were plenty of signals (fewer hours of daylight, cooler temperatures, frost) this fall to encourage our lawn grasses (the good ones…and the perennial weedy ones as well) to ready themselves for winter. Insects that overwinter as adults, larvae, or pupae likewise were readying themselves for diapause (insect “hibernation”). Perennial weeds like dandelion, thistle and beloved bindweed were preparing themselves for winter dormancy well before last week’s chill arrived. The spores and mycelium of fungi (it was a good fall for powdery

Knotweed (Polygonum aviculare), a summer annual,
still alive after subzero temperatures!

mildew and rust on turf) are so resistant to temperature extremes that the arrival of 0 F went unnoticed by them – so they will be back next year, without question.

Seedling downy bromegrass (aka cheatgrass) thriving in
our chilly pre-winter cold snap

Even the seedlings of our winter annual weeds - species that germinated this past late summer/fall and will complete their life cycle in the spring – appear to have been completely unaffected by the week of extreme cold. The henbit, annual bluegrass, chickweed and cheatgrass I’ve looked at in the past few days appear perfectly healthy. So, I'm sorry to dash any hopes you had about any potential benefits that the recently departed cold front might have had on the pests in your lawn. They really didn’t notice. If you had any hopes of the misnamed polar vortex eliminating some of next year's turf pests, all I can say is … let it go…let it go……..