Lawn Care Tips

In poor lawns seeds can germinate throughout the summer. By the time fall arrives, the lawn may be a collection of dandelions, plantain, crabgrass and other weeds. Fall is one of the best times to kill the weeds with herbicides. It is not the time to kill crabgrass, goosegrass, and related summer annuals, but it is the time to kill perennial and winter annual weeds. They are easier to kill in September as they begin active growth during cooler and wetter weather. If crabgrass is in your lawn now, there is little point in wasting time and money to kill it. It will soon die after it has produced seeds and the days become shorter and cooler.

Crabgrass needs to be treated with a pre-emergence herbicide in late March or early April before it appears. On the other hand, some weeds we see mostly in spring such as duckweed and henbit, start to germinate in early September. Pre-emergence herbicides such as dacthal should be applied now to reduce their stand if these weeds were a problem last spring. If these weeds are not controlled in the fall, the seedlings will develop during the winter, and post-emergence herbicides must be applied in spring to eliminate them. If not, they will die out naturally by June. Broadleaf weeds, such as dandelions, that have already germinated can not be killed by pre-emergence materials. Additional common broadleaf lawn weeds include plantain, dock, bindweed, ground ivy, wood sorrel and purslane.

Herbicides that kill these weeds are sold under many different names, but those that contain 2,4-D are most commonly used. There are several advantages to using these herbicides in fall. They kill both weeds from the past season as well as any that have germinated during the summer. Perhaps the greatest advantage is that trees, shrubs, and garden flowers are bearing dormancy and are less sensitive to these materials than during spring. Consequently there is less chance of damage.

Care in application should be practiced, however. Hard-to-kill weeds such as ground ivy, white clover and sorrel are better treated with a material that contains several herbicide ingredients. A combination of 2,4-D, MCPP, and dicamba is most effective on these weeds. Do not apply materials containing dicamba on areas where roots of trees and shrubs may extend. Herbicides such as 2,4-D kill by absorbing through the leaves and into the plant root system.

All this takes time, 2,4-D may cause plants to twist and curl for several weeks before they finally die. Follow directions carefully when using any herbicides. Too much does not kill better or faster, but may be more likely to damage desirable plants. Too much of a material may not kill as effectively as the proper amount.

Mac Perry's Florida Lawn and Garden Care, by Mac Perry.