Weed Update

Weeds don't take holidays.

While we are thinking about a holiday trip to the mountains or the coast -- weeds are going to keep doing what they do best -- reproducing. Summer annual weeds are going to seed with wild abandon. Although you cannot stop seed production you can sure reduce the amount of seeds produced by controlling summer annuals now. While herbicides like glyphosate work on mature weeds, the time it takes to die from glyphosate treatments will allow a lot of seeds to mature before plants succumb to the inevitable.

Fall applications work better you say?
I had a salesman once try to explain to me how bentazon (Basagran TO) worked really well on Yellow Nutsedge in early Fall. My response was -- "well, so does frost". Seriously, nutsedge has been making tubers for months but it is still a good idea to kill what you still have to prevent even more tubers from forming. Nutsedge can be controlled by glyphosate or glufosinate or bentazon But please, next year resolve to get serious about nutsedge earlier in the season.

Fall applications of glyphosate do work better on many perennial weeds. In particular, deciduous woody weeds are generally well controlled with late summer or early fall applications of glyphosate. But, you often don't see the results until next spring when plants begin to grow -- ahh, then the fun begins. New growth, if it occurs, will be stunted, malformed, and yellowed. Plants usually die back but often will start new growth after a time. When this occurs, treat again with an appropriate herbicide such as glyphosate or triclopyr for the one--two punch that knocks your weeds flat.

But don't forget to plan ahead --
Winter weeds have already started to emerge in some areas, so get your preemergence herbicide applications out soon to prevent winter annuals like henbit, chickweed and annual bluegrass from turning your Thanksgiving celebration into another gardening labor day.

Joseph C. Neal
Professor and Extension Specialist -- Weed Science
Department of Horticultural Science