The weed most brought into my office for identification the last two weeks has been Florida betony. This prolific weed also goes by the name rattlesnake weed because of the resemblance of the tubers (roots) to the rattles (buttons) found on a rattlesnake. It is one of the biggest problem weeds in our lawns and ornamentals during the cool months of the year.
This weed is found in habitats that range from full sun to partial shade. The plant can be found growing on various soil types in dry to wet soil moisture conditions.
Even though it is a winter weed, Florida betony can be seen in lawns or ornamentals throughout the year, but the primary periods of growth are during the cool temperatures of the fall and spring months. During the cold periods of winter the growth will slow. During the hot months it will die out or become dormant, but occasionally it hangs around in shady and moist areas of the landscape.
The first line of defense in turfgrass is to use cultural practices that promote vigorous turf growth and development. Florida betony does not readily infest a thick lawn that is properly fertilized and watered and that is mowed at the correct height and frequency.
The pre-emergence herbicides that most of you are familiar with such as benefin (Balan, Crabgrass Preventer), pendimethalin (Halts, others), and dithiopyr (Dimension), will not control Florida betony. Atrazine, used as a pre-emergent, does provide good control but for only 30-45 days.
The best postemergence control is with atrazine or products that contain 2,4-D + MCPP + dicamba mixtures (Weed-B-Gon, Spectracide Weed Stop, Ace Lawn Weed Killer, etc.). Spot treatments of glyphosate (Roundup, others) also can be used to control this weed, but the turfgrass will be severely injured or killed in the application if green turfgrass leaves or stems are present.
The preferred time to treat Florida betony with one of the herbicides is mid-late October during the fall growth flush. An additional herbicide application is always needed, normally during mid-late February to coincide with the spring growth flush. If you did not treat in October, do it now.
Few herbicides are available to control Florida betony in ornamentals, butyou can go a long way in controlling this weed without the use of herbicides. Mulches are useful for this purpose. Coarse textured mulches such as pinestraw, cypress or hardwood mulch applied to a depth of 2 to 4 inches, will limit the establishment of Florida betony. Landscape fabrics also may be used under various types of mulches and will help prevent Florida betony emergence. Other nonchemical control options include hand-pulling and hoeing. Since this weed reproduces from underground tubers, try to remove the tuber when hand-weeding.
If you have a severe Florida betony problem in turf or ornamentals, don’t think you will completely wipe it out in one year. It can take several years to eliminate problem perennial weeds.