Once harvest is over, it’s time for farmers to consider how they’ll manage postharvest weeds. Although in some years weather may make this practice challenging, there are significant advantages to controlling post-harvest weeds.
Some of these benefits include effective control of difficult perennial weeds, such as dandelion, as well as winter annuals including narrow-leaved hawks-beard, stinkweed and shepherd’s purse. These types of weeds are very susceptible to glyphosate in the fall, and farmers will achieve best results by spraying these weeds with a glyphosate post-harvest.
Removing weeds also helps to preserve moisture and important soil nutrients and will give farmers a leg-up when it comes time to seed in the spring.
Here are five tips on how to effectively control weeds after harvest:
1. ALWAYS READ (AND FOLLOW) THE LABEL
Check the correct rate of glyphosate that should be applied for the weed stage and species being controlled. Unlike a pre-harvest application of glyphosate, applicators are not limited on the rate of glyphosate that can be applied.
2. WAIT FOR REGROWTH
Make sure weeds have some regrowth after the harvest operation before applying glyphosate. Lower and older leaves that remain after cutting are often poor at absorbing glyphosate and other herbicides. Waiting until two to three new leaves have emerged before spraying will optimize glyphosate uptake and maximizes weed control.
3. MANAGE STRAW AND CHAFF AT HARVEST
Weeds that are covered by crop refuse will have reduced spray contact, which may result in reduced weed control. Chopping and spreading straw to avoid windrows or baling off the straw before applying glyphosate will help to increase herbicide coverage and effectiveness.
4. WATCH THE WEATHER
Frosts, cold weather and short days will slow glyphosate activity, although following the label may help farmers achieve ultimate control. The biggest issue can be frost. Farmers should not apply glyphosate to perennial weeds within two to three days of frost or after a severe killing frost.
5. CONSIDER A TANK MIX
Tank mixing glyphosate can improve weed spectrum and provide residual protection, but read the label for any restrictions that could impact recropping and flexibility in spring.