By Alyssa Essman
In the past couple of weeks, Mark Loux and Mark Sulc gave us some good reminders about the value of fall applied herbicides. They can be read here: Our Annual Article to Nag about Fall Herbicides and Cressleaf Groundsel and AVOID A NIGHTMARE NEXT SPRING!!!!!!!!.
We are persistent about this because fall applications are the most effective treatment for overwintering species. Winter annuals like marestail, cressleaf groundsel, and purple deadnettle are at the beginning of their life cycle and are most susceptible to herbicides at this growth stage. Biennials like wild carrot and poison hemlock that are ending the first year of their life cycle are sending nutrients down to the roots in preparation for winter. Systemic herbicides (glyphosate, 2,4-D) applied now will translocate down to the roots along with these nutrients and achieve a better kill than waiting until spring. In the spring these plants resume growth, start sending nutrients back up to the leaves, and are less susceptible to control efforts. This also applies to simple perennials like dandelion and creeping perennials like Canada thistle.
The above articles and links within provide fall herbicide recommendations for forage systems and following harvest in corn and soybean. Another consideration this time of year is the management of overwintering weeds in wheat production. The weeds listed above interfere with the early development and growth of wheat and other small grains. Burndown products labeled for use prior to wheat emergence include glyphosate, Gramoxone and Sharpen. Recommendations for burndown applications in no-till wheat were covered in this article: Life In A Time of Glyphosate Scarcity – Part 1 - Burndown In No-Till Wheat. Fields that don’t receive a burndown before planting or crop emergence also have the option of postemergence herbicides. Efficacy ratings for postemergence herbicides in small grain production can be found here: Weed Response to Postemergence Herbicides in Small Grains. Some products of note are those that control wild garlic. Contamination of wild garlic aerial bulblets in harvested wheat and other small grains can cause substantial dockage.
Source : osu.edu