Post Emergent Control of Chickweed
The beginning of winter may seem like a strange time to control weeds, but for tough winter annual weeds such as chickweed, this is the only time to get good control.
Annual weeds live only one year and disburse seeds during that year that germinate the next growing season to insure the perpetuation of problem annual weeds. To break things down one step farther, annual weeds are separated into winter annuals and summer annuals. Winter annuals germinate in the fall and grow throughout the winter, dying with the onset of hot weather. Summer annuals germinate in the spring and grow during the summer and die with frost.
One of the most pesky winter annual weeds is common chickweed. Homeowners tend to overlook its germination in the fall and only notice its presence in the spring when it begins to grow vigorously in thin and bare spots of the lawn. By June, chickweed is on the the down hill side of its life span and will die out when the days become hot. We are a very reactive society, however, and when we notice the chickweed, we have an overwhelming desire to do something right now. The homeowner should try to stifle this desire. The weed has already disbursed seeds for next year and will die out on its own without the use of herbicides. Seeds will then lie dormant until the cooler weather of fall arrives and then they will start to germinate and will grow throughout the winter.
Chickweed may be controlled in two ways. A pre-emergent herbicide can be applied in September which will keep the seeds from germinating. This works well but care should be taken to follow the directions very closely when applying to a newly seeded lawn or to a lawn that is about to be overseeded. Effective pre-emergent herbicides are benefin+trifluralin, bensulide and pendimethalin.
Post-emergent herbicides should be applied after the weed is up and actively growing. The target application time would be from November to early March. Effective post-emergent pesticides are 2,4D+MCPP and 2,4D+MCPP+dicamba. These herbicides may be applied anytime in the winter when temperatures are above 50 degrees. Chemical names are being used in this article rather than brand names because many brand names use the same chemicals. The consumer should look at the active ingredients located below the brand name to make sure it contains the chemicals needed for control of the target weed.
Timing, weed identification and the use of the right herbicide are all necessary for the control of nuisance weeds in the lawn.