If you struggled with control of marestail this growing season, spraying this fall is an excellent option to avoid problems next spring. In fact, fall spraying is a great solution for homeowners, as well, if you have problems with dandelions, violets or ground ivy.
There are many reasons why fall spraying is a good management option. First off, fall applications target the most-vulnerable stage of growth for winter annuals and perennial plants, leading to better weed control. Winter annuals such as marestail and henbit are small in the fall and easier to kill compared to the spring when they are larger and hardened off from the winter. Perennial plants are moving carbohydrates to the roots to survive the winter, which results in herbicides being better able to kill the roots.
Secondly, temperatures are typically warmer in the fall compared to the spring, leading to better herbicide activity. Cooler temperatures slow weed growth and slow the movement of herbicides within the plant, leading to poor control.
Last, even if weeds are not completely killed by herbicides, they are more likely to die during the rest of the winter as they are less-tolerant of winter kill than healthy weeds.
Right now, next year's weed control doesn’t seem like a big priority. However, with the recent rains and cooler weather, winter annual weeds such as marestail and henbit have already started to emerge across the area. As you harvest or walk through your lawn, be sure to scout for weed issues and make applications if necessary.
We should still have plenty of time for herbicide applications, as good control is usually achieved as long as air temperatures remain above 50 degrees and weeds are actively growing.
There are numerous products labeled for fall application. Most commonly applications will contain 2,-4D ester and/or dicamba. Other products with longer residual control may give control into the spring, potentially reducing the need for spring herbicide applications. For a list of herbicide options, refer to EC130, Guide for Weed, Disease, and Insect Management in Nebraska or contact your local Extension office.
If you haven’t tried fall spraying and have struggled with winter annual or perennial weeds in the past, consider application this fall, even if you have to have it custom-applied. Given conversations with farmers across the area and my personal experience on our farm, you will be impressed by the level of control that can be achieved with fall spraying.