Plan now for lawn weed control this spring season
Wednesday, January 15, 2014 12:00 AM
It will not be long before daffodils and other early spring flowers will signal time to apply preemergent herbicides for controlling spring and summer weeds in our lawns. Now is time to apply your preemergence herbicide. Keys for success with preemergence herbicides are: TIMING, RATE, UNIFORM COVERAGE, and ACTIVATION. Preemergence herbicides must be applied prior to weed seed germination to be effective. Crabgrass seed germinate when soil temperatures reach around 58 degrees so if crabgrass is a target weed you need to consider getting your preemergence herbicides on to your lawn by or shortly after Valentine Day in Southern Mississippi and a couple weeks later in the northern tier counties. The herbicide label will provide a list of the weed species the active ingredient will control and at what rate. If there are several weed species that you are targeting use a rate that controls the most difficult weed. Caution should also be taken to stay within rates labeled for your specific turf species. Preemergence herbicides create a thin weed control barrier on the soil surface. This barrier must provide complete coverage at a uniform rate to prevent any voids that would allow weed escapes. Liquid or granular application equipment should be accurately calibrated prior to making an application to ensure proper rates and coverage. Once the herbicide is applied it must be activated. This usually requires approximately one-half inch of rainfall or irrigation shortly after application to move the herbicide down through the leaf canopy to form the thin herbicide barrier at the soil surface.
Lawn burweed (Soliva pterosperma), more commonly called sticker weed is best described as a low-growing, freely branched winter annual having leaves that are twice divided into narrow segments or lobes similar to the appearance of carrot leaves but much smaller. The real identifier is once the plant reaches a reproductive stage the small fruit clusters, small rosette buttons, begin to form down in the leaf axils. At the tip of each seed within the cluster is a tiny spine that eventually dries at maturity and is what is left to cause you pain as they stick into tender flesh of bare feet, knees, hands, or whatever parts of the body that may come in contact with them.
If you had lawn burweed in your lawn last summer and did not apply a pre-emergent herbicide earlier this fall to control winter annual weeds then you most likely have them again and will have to endure their painful spines again this summer each time you walk barefoot on your lawn unless you take immediate action to control them now.
Once the fruiting clusters have formed and produced the tiny seeds and spines killing the plants will eliminate the weeds but the tiny spines and seed will remain to inflict pain for another summer. Extension publication #1532 provides a list of several good post- emergent herbicide choices (atrazine, 2,4-D, dicamba, metsulfuron, chlorsulfuron, etc.) that will control this weed along with most other winter annual weed species but timing is critical. This publication and others pertaining to weed control and home lawns can be downloaded from the extension web site at www.msucares.com.