Before all the heavy rain, certain area lawns and grass around farmsteads were looking pretty tough unless it was an irrigated area. In my own yard where some brown patch disease and heat stress thinned out some grass, there was ample space for dandelions to flourish. Along the rock lane I noticed an abundant new crop of winter annual henbit, which is the first weed to turn purple and flower in the spring. In other spots there was bindweed which is a deep rooted perennial broadleaf weed.
If you have troublesome perennial or biennial weeds in your lawn or in non-crop areas around your farm, now is a great time for controlling fall broadleaf weeds to eliminate perennials, such as dandelions, plantain, clover, and ground ivy. This time of year perennial weeds are transporting carbohydrates and energy to the crowns and roots for storage over the winter.
Herbicides applied to weeds now should be transported down to the roots where it will act to kill those roots. In the fall, weeds have less wax on the surface so absorption is greater into the plant. Even if weeds survive an application of herbicide in the fall, they are often weakened and killed by the cold temperatures of winter.
The application of growth regulator herbicides, most of which are 2,4-D based, will do an excellent job this time of year in reducing lawn weeds. I like to use 2,4-D amine regardless of the time of year and you don’t have to worry about off target damage from fumes or volatilization. 2,4-D amine does not fume. Most herbicides used around the yard for broadleaf weeds will contain both 2,4-D and Banvel (Dicamba) and MCPP. Some of several commercial herbicides used for broadleaf weed control include: 2,4-D, Banvel, Weed-B-Gone, Trimec Plus, and Trimec Classic.
A very difficult weed to kill is field bindweed. Bindweed should be treated now because we have vigorous fall growth after all the rain. The application at the thistle rate or 1.5 quarts per acre of 2,4-D four-pound active ingredient per gallon works well. That will start to reduce your infestation if you work on it in multiple years in the fall.
Based on what I am seeing in my low maintenance yard, pasture weeds will be bad this year with lots of opportunity for fall germination after these rains. Check for musk thistle rosettes in your pasture and other weeds that may have germinated including field pennycress, common mullein, and bull thistle. Good control of musk thistle can be obtained in October and even into November.
Research in Iowa indicated effective weed control was achieved using 2,4-D even with applications made after several nights when temperatures fell below 32 degrees. With the leaves of musk thistle close to the soil surface, the plant is protected from freezing temperatures. Daytime temperatures in the 50’s are satisfactory for control. The addition of ½ pint of Banvel to 2,4-D provides better weed control as temperatures get colder. If it gets really cold before you get a chance to spray, thistles may be dormant, then use Tordon 22K or Grazon herbicides, a restricted use product. It has residual activity even into spring.
The use of herbicides without good cultural practices and proper grazing management will usually give poor weed control. Be sure to read and follow label directions when using herbicides in your lawn or non-cropland or pastures. Finally, even the Santa Clause method works well for henbit and dandelion if there isn’t that much in your lawn. That method is call “Hoe”, “Hoe”, “Hoe!”