Answer: You have a real challenge on your hands! Florida betony is a ?winter? perennial and, like most plants in the mint (Labiatae) family, has a square stem with opposite leaves. In turfgrass, products containing atrazine (Aatrex, Hi-Yield Atrazine, Scotts Bonus S, others), 2,4-D (various trade names), dicamba (Banvel, others), and 2,4-D + MCPP + dicamba (Ace Lawn Weed Killer, Wipe-Out, Weed-B-Gon Lawn Weed Killer, 33 Plus, others) may be used for control.
Centipedegrass and St. Augustinegrass are not as tolerant of 2,4-D and dicamba herbicides as are bermudagrass, zoysiagrass and tall fescue. Use 2,4-D or dicamba-containing herbicides only if the product is labeled for use on centipedegrass and St. Augustinegrass (some formulations containing these herbicides are specifically made for these grasses). Always apply herbicides that contain 2,4-D, dicamba or MCPP during the cool months of the year, when Florida betony is actively growing. Applications during the hot summer or cold winter months are not effective in controlling Florida betony.
Few herbicides are available to control Florida betony in ornamentals. Several cultural practices, however, can provide good control of Florida betony in landscape situations. Coarse textured mulches such as pine straw or pine bark applied to a depth of 2 to 4 inches, will smother the plant and help 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 non-chemical control options include hand-pulling and hoeing. Since this weed reproduces from underground tubers, you must completely remove all tubers when hand-weeding.
In ornamentals, dichlobenil (sold under the trade name Casoron?) provides excellent control of Florida betony in most established woody ornamentals. Dichlobenil is labeled for use in a wide variety of woody shrubs and trees, roses and English ivy, but it is not recommended for use in either annual or perennial flowers. Dichlobenil is a volatile herbicide that readily escapes as a gas under high air and soil temperatures. The ideal time to apply dichlobenil to control Florida betony is from early November through mid-February. Cool temperatures at this time of year will help prevent dichlobenil loss from the soil and will improve Florida betony control.
Hope this information is helpful!
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