SPONSORED CONTENT
Content provided by Barren County Cooperative Extension Service and sponsored by Southern States in Glasgow
The first step in determining weed control needs in the fall is to do a critical assessment or evaluation of
pasture fields and bordering fencerows. Not only take an inventory of the current weeds present, but scout
fields looking for any developing new weed problems in their seedling growth stages. Identify areas of the
field where potential cool-season weeds such as thistles, poison hemlock, and buttercup are emerging from
seed and starting to develop. These seedling plants are often present in areas where mature plants had been
observed earlier in the season when they were flowering during the spring and early summer months. They
are also often found in fields with open bare areas where the desirable forage species are thin due to
excessive grazing and other environmental conditions. University of Kentucky Extension Specialist, Dr. JD
Green discusses fall weed control
If you do see developing cool-season weed problems then you may want to take corrective action this fall and
early next spring to address these problems. In general, herbicide products that contain 2,4-D are usually
effective on young biennial thistles, poison hemlock rosettes, and germinating buttercups. As long as daytime
temperatures are near or above 60 F herbicide treatments can be applied when these weeds are in an active
growing period during October and November. In some cases, herbicide treatments may not be the best
solution or may not correct all weed problems observed.
Here are some additional points to consider as you make those decisions. When evaluating a pasture field
with developing weed problems, you must decide whether or not to either 1) drill or overseed more forages
into an existing pasture to improve the stand of desirable forage grasses to make them more competitive OR
2) spray herbicides to control emerged broadleaf weeds. You will not be able to do both practices at the
same time since most pasture herbicides have the potential to injure newly emerging forage grasses or
legumes. For pasture herbicides which contain only 2,4-D it is generally recommended to wait 3 to 4 weeks
after spraying before reseeding forage grasses and at least 6 to 8 weeks before seeding clovers or other
legumes. Other broadleaf herbicides may require a waiting period of 6 months or longer between time of
application and seeding forage legumes (consult the label of specific herbicide products used). Therefore, as a
general rule of thumb, if you decide to spray this fall you will need to wait until next spring before seeding
additional forages. If you reseed in the fall, then it is recommended that you wait until the new forage grass
seedlings have a well-established root systems with secondary roots before making a herbicide application. It
is important to note that anytime broadleaf pasture herbicides are applied clovers or other desirable legumes
are likely to be killed or severely injured within the areas treated.
If weeds are not prevalent and the existing stand of desirable forages appear to be competitive enough to
minimize emergence of winter annual weeds, another course of action this fall is a “wait and see” approach.
But, keep in mind that smaller weeds are easier to control than after they increase in size and become more
mature. You may need to revaluate these fields in late February and March to determine if corrective action is
needed in early spring.
For more information, contact the Barren County Cooperative Extension Service.
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