The fall and early spring months are a good time to apply weed control, in the form of herbicides, to your lawn. Weeds invade lawns in areas where the grass is thin or weak and are not usually a problem in healthy turf.

Weeds do not overtake healthy turf. St. Augustine is a very aggressive and competitive grass allowing it to compete with weeds. If allowed to, St. Augustine could overtake and kill most shrubs in your yard.

Most weeds appear because of poor management of turf areas. Improper cultural practices can cause reduction in turf quality. Practices such as mowing too closely or infrequently, improper fertilization, too much or too little irrigation. In addition inadequate control of insects, diseases, and nematodes will also damage the turf and permit weed invasion.

Herbicides may temporarily remove the weeds, however, unless the basic cause of the weakened turf is corrected, weeds will continue to be a major problem. Weed control will only be successful if the turf is returned to a good, healthy, growing condition.

Pre emergence herbicides should be applied before germination of the weed seeds. A pre emergence herbicide provides several weeks of residual control in the soil and will kill the seedling weeds as they emerge. The timing of applications of this type of herbicide must coincide with the various germination times of weed species. If applied too late in the growing season, the weeds will have germinated and escaped control. Applying the pre emergence herbicide too early may also result in undesirable control.

Adequate soil moisture is important before and after application so timing for rainfall or irrigation is necessary. Most pre emergence herbicides will control germinating weed seeds over a six to twelve week period. Normally, the best time for application in South Florida is Feb. 1. However, our continuing cold has delayed some germination. This week is supposed to warm into the 70s and may be a good time to apply Atrizine on your St. Augustine lawns as a pre emergent and post emergent.

Once weeds have germinated and are actively growing they must be controlled with post emergence herbicides. Weeds are easier to control when in the seedling stage or healthy and actively growing. Applications made to weeds under stress may reduce the effectiveness. Post emergence herbicides are absorbed through the foliage, roots or both and then translocated throughout the plant. If conditions are cold the weeds will be dormant and not actively growing thus the herbicide will not be effective. If dry you should irrigate prior to application to ensure active growth of the weeds.

Do not water immediately following application or mow for several days to give the chemicals time to work.

Atrizine can be used in St. Augustine as a pre emergent to control most broadleaf weeds if applied before the weed seeds germinate. Apply every six months (spring and fall) for continued effective pre emergence weed control.

Post emergence control of broadleaf weeds can also be obtained with the use of Atrizine. It is important to apply herbicides to your lawn before it is too hot in the spring. If temperatures are too high more damage can occur to an already weakened turf.

Herbicides in general should not be applied to freshly mowed turf or to turf under stress. Use only herbicides labeled for use on St. Augustine grass as severe injury or death will usually result from applications of herbicides meant for other grass varieties.

In a recent column

I reported that using copper fungicide on the bud of palms after a freeze would help protect them from developing bud rot and dying. I got this information from an old publication dating back to the 1980s.

Actually, you need to apply this treatment before the freeze as this may help prevent bacteria populations that are already present from growing and becoming a problem. Another application would be needed after 10 days. First of all our palms on Marco Island did not suffer the freeze damage of palms in communities to the north and inland.

If you feel your palms suffered damage a more important action would be to insure the palms are well fed and that you leave any green fronds on the tree. Including fronds with some brown as these help with the tree’s photosynthesis and recovery if needed. The university recommends applying soluble or liquid fertilizer, S.T.E.M. (Peter’s Soluble Trace Element Mix) Spreader sticker, to the leaves monthly through the summer for young or newly planted palms.

All others should have the granular fertilizer in the spring and every four months as usual.

Eileen Ward and her husband Peter have owned and operated Greensward of Marco, Inc., a lawn maintenance and landscaping company since 1981. 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.