What is that weed that reminds us northerners of snow on our lawns? If I have had one person ask me, I have had a dozen. The weed is Florida pusley (Richardia scabra) and is a native to Florida. This weed is aggressive and will take over turf areas which are thin from irrigation, bug or fungus problems. The leaves and stems are hairy with opposite leaves. The flowers start white and turn to purple as they age. This weed grows into a large clump forming from a single stem. This makes the weed easy to remove physically when you have a small infestation and if you enjoy pulling weeds I highly recommend you get the upper hand on pusley with this environmentally friendly method.
If your lawn is adjacent to a vacant lot or to a lawn which is poorly maintained and is infested with Florida pusley, it will be a constant battle to control this weed in your lawn since it spreads by seed. Weeds can get a foothold in your lawn in areas where the grass is thin or weak. Weeds do not overtake healthy turf. St. Augustine is a very aggressive and competitive grass allowing it to compete with weeds. As I’ve said before, St. Augustine grass could overtake and kill most shrubs in your yard.
Most weeds appear because of improper cultural practices such as mowing too closely or infrequently, improper fertilization or irrigation. These are the primary causes for thin or weak turf. In addition, inadequate control of insects, diseases, and nematodes will also damage the turf and allow weeds to invade.
Herbicides may temporarily remove the weeds, however, unless the basic cause of the weakened turf is corrected, weeds like pusley will continue to be a major problem. Weed control will only be successful if the turf is returned to a good healthy growing condition. The healthy, thick blanket of grass will not allow weeds to germinate at the soil line.
Pre-emergence herbicides provide several weeks of residual control in the soil and will kill the seedling weeds as they emerge. Pre-emergence herbicides should be applied before germination of the weed seeds. The timing of applications of this type of herbicide must coincide with the various germination times of weed species. For pusley, if it above freezing this weed is germinating.
Once weeds have germinated and are actively growing they must be controlled with post-emergence herbicides. Atrizine can be used in St Augustine grass to control most broadleaf and annual grass weeds. Trimic can be used in bahia grass to control most broadleaf weeds. Both seem to be somewhat effective against pusley. A call to your lawn spray company for other herbicides should be helpful. Use only herbicides labeled for your type of grass as severe injury or death will usually result if the wrong type of herbicide is applied. Herbicides in general should not be applied to freshly mowed turf or to turf under stress.
Weeds are easier to control when in the seedling stage or when large and actively growing. Applications made to weeds under stress may reduce the effectiveness. It sounds strange but you want your weeds to be healthy and actively growing. Post-emergence herbicides are absorbed through the foliage, roots or both and then trans-located throughout the plant. If conditions are dry, you want to irrigate prior to application to ensure active growth. Fertilization prior to application is also a good idea. Do not water or mow for several days following herbicide application to give the chemicals time to absorb into the weeds. Always avoid applying any herbicide during extreme hot or cold temperatures to avoid damage to the grass.
Crabgrass is another major problem in local lawns and control will require a special herbicide. They have taken the best product, Azulox, off the market but there are some replacements appearing. Cinnamon and baking soda are two popular crab grass treatments. These are not as effective and so patience and a healthy turf will be necessary when trying to kill crab grass using these natural remedies. They are contact herbicides and you can gain a degree of control, on small crab grass patches, when sprinkled lightly on top of wet patches of crab grass. You will see results right away as it burns the leaves of the plant. Unfortunately, the stolens and roots survive so it is important to limit treatments to small areas so as not to stress the St. Augustine or Bahai grass allowing it to grow and take over these areas again.
While herbicides can help with the weed control in your lawn the best way to a weed free lawn is to practice good horticultural practices like proper watering, mowing, insect and disease control to prevent weak areas which will be susceptible to weed invasions from the likes of Florida pusley and crab grass. Or you can embrace the lovely look of Florida snow. Doug Caldwell says the bees like it and bees are in serious trouble and can use all the help we can give them.
Eileen Ward and her husband Peter have owned and operated Greensward of Marco, Inc., a lawn maintenance and landscaping company since 1981. Watch Eileen’s gardening videos on MarcoIsland-TV.com. Eileen is an FNGLA Certified Horticultural Professional, has a Commercial Pesticide license in Natural Areas Management and is a registered Dealer in Agricultural products in Florida.