Now that fall is here, it’s time to discuss management options for fall weed control.This can be a touchy subject, since most farmer’s priority is to get their crops harvested and into storage as soon as possible before snow falls.
Folks with pasture ground should also be considering fall management for weed control, especially if musk thistle is an issue on your property.
Now is as good a time as any to talk about fall management of musk thistle before it gets too cold.
Musk thistle is a biennial plant and considered a noxious weed in Nebraska. The most common life cycle for musk thistle growth is to germinate from seeds in the summer and develop into a rosette.
However, germination can be extended into late summer and early fall.
Bruce Anderson, Extension Specialist at UNL says, “many musk thistle rosettes also develop in the fall. Both spring and fall established rosettes will stay vegetative during that first year, but both will also bolt and form flowering stalks the next spring.”
Plants will usually start to bolt around May 1 of the year, start producing seeds and repeating the cycle over.
According to UNL’s Extension publication entitled “Noxious Weeds of Nebraska: Musk Thistle” (EC176), there are several ways to manage musk thistle depending on its level of infestation and control options the farmer, rancher, etc. wishes to implement.
Due to the nature of musk thistle, management can be tricky if spray applications are not made at the correct times.
Fall herbicide applications can be quite effective in managing first year plants that will overwinter in the rosette stage. Fall treatments will do a better job controlling fall-established rosettes compared to summer applications.
Fall applications are also less harmful to insects used as biological control and can minimize the risk of drift injury to susceptible plants like tomatoes, grapes, soybeans, and trees in the surrounding area as they are starting to die or preparing to overwinter.
One of the reasons why fall applications are so effective at managing musk thistle in the rosette stage is that as winter is approaching, these plants will start to translocate some of their nutrient reserves down to the roots.
These resources will be readily available next spring once temperatures warm up again. Herbicides applied during the fall will also be translocated down to the roots with the nutrient reserves.
Therefore, spraying in the fall will result in better management of musk thistle.
Spot herbicide applications can be quite effective if trying to manage individual plants or small patches of musk thistles. This method can be much cheaper than a broadcast application and may minimize the risk of herbicide drift to sensitive crops that haven’t died or started overwintering yet in fall.
Herbicides containing 2,4-D or dicamba based products can be quite effective in managing musk thistle in late fall. Several other herbicide products are recommended for fall application timing too.
If fall applications for managing musk thistle are needed on your operation or pasture ground, I would highly recommend taking a look at our publication on managing musk thistle at http://extensionpublications.unl.edu/assets/pdf/ec176.pdf.
This publication has a list of recommended herbicides to manage musk thistles and describes the best application time for each product.