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By MICHAEL PYLES
Trimble County Extension agent
Common chickweed, henbit, and purple deadnettle are cool-season weeds we usually see in crop fields during the fall and winter.
How-ever, other weeds, such as dandelions, have become more prevalent in recent years, according to J. D. Green, an Extension weed specialist at the University of Kentucky.
Dandelions are generally considered a major lawn or pasture weed, but increasingly have been found in grain-crop fields.
This expansion of dandelion populations likely is due to fewer applications of soil-residual herbicides, along with no-till crop production practices.
Dandelions are perennial plants with a taproot that helps it reproduce and survive. And, dandelion plants are prolific seed producers. During its peak flowering period in early spring, the flowers quickly transition from yellow blooms to mature seeds.
Like thistle seeds, dandelion seeds are spread by the wind to other sites. No-till crop fields are a prime seedbed. Dandelions germinate from seed in late summer and early fall, producing small rosettes. They begin an active growth period in early- to mid-fall, when temperatures start to moderate.
Therefore, initiating control during the late fall or early winter months likely will be most beneficial. Spring control options for dandelions often are less consistent or require higher herbicide rates to be effective. And, if you wait until spring, you risk that the plants will flower before you have a chance to apply an herbicide.
In corn and soybean fields, herbicide options in the fall consist of 2, 4-D; glyphosate; or a combination of both. Other weeds present at the time of application may favor the use of one treatment over another.
Apply herbicides anytime after crop harvest and after dandelions have initiated active growth. Generally, the best time is early- to mid-December, provided daytime temperatures reach 55-65 degrees Fahrenheit for a couple of days.
In some cases, only spots in the field that are moderately or heavily infested with dandelions will warrant herbicide treatment. If these areas are left untreated, they can result in dandelion populations that could interfere with crop emergence and reduce crop yields.
For more information, call me at (502) 255-7188.
Michael Pyles is Trimble County’s Cooperative Extension agent for agriculture.