Early spring lawn care tips for Central Oklahoma
Because we are at the beginning of the early spring lawn care season, we are receiving a lot of questions at the Extension Center about late-winter lawn weed control.
An effective way to control winter weeds that already are growing on dormant bermudagrass right now is to use a product containing glyphosate with or without an added broadleaf herbicide as a spot treatment. This application should be made while the bermudagrass is dormant in February and when temperatures are above 50 F.
Another common question we get is about using weed-and-feed products. The concept of combining an herbicide and a fertilizer may be good in theory, but may not work in every situation. Several potential problems exist when using this approach.
One problem is that the timing for herbicide application and fertilizer application are usually not in sync.
Some weed-and-feed products contain pre-emergence herbicides that control weeds as they germinate and are best applied by March 1 depending on weather conditions. Fertilizer applications for warm-season grasses such as bermudagrass should not go on until the first of May. The “unused” fertilizer from the weed-and-feed products actually would feed any winter weeds growing in the dormant bermudagrass.
The two really need to be applied at different times; so using a weed-and-feed blend on bermudagrass in later winter/early spring is not advised.
Another issue is that the selection of formulations for weed-and-feed blends is much more limiting than if one were choosing only a fertilizer. Fertilizer formulations are much more diverse because fertilizer companies make many more types. Most companies that produce weed-and-feed products only make one type, not allowing one to take into account special nutrient needs that may have shown up in a soil test. Also, types of weed killer used in weed and feed blends is limited compared to the many formulations available without fertilizer.
There is also more chance of over-application or misapplication of the weed killer when using weed-and-feed products. Because tree and shrub roots also can absorb many of the herbicide products, care in applying the herbicide is important. In fact, many of the herbicide products state that they should not be applied where roots of desirable trees or shrubs are growing. Research has shown that the roots of many tree species extend well beyond the drip line of a tree.
Another common problem is overthrow of the product into areas that have sensitive plants growing in them such as flower and shrub beds. This usually is a result of using the wrong equipment such as a broadcast spreader rather than a drop or gravity spreader. Once again, it makes good sense to apply products separately to allow for more accurate rates and distribution.
The real way to address weed problems is to start with improving turf management. A vigorous, healthy lawn is able to choke out most weeds. For information on recommended turfgrass management practices see the fact sheets HLA-6420 “Lawn Management in Oklahoma” and L-441 “Bermudagrass Lawn Management Calendar,” which can be found at osufacts.okstate.edu or by contacting your County Extension office.