Pre-emergent herbicides can control most weeds found this time of year

This time of year there are many weeds in lawns and around shrubs. Many of these weeds are annuals that come back from seeds each year.

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The weeds are easier to control because a pre-emergent herbicide can be applied to these areas to kill the plants as they sprout from the seed.

There are many more weeds that fall into the category of perennial weeds. These plants come back from an established root system each year. They will produce seeds to start new plants, or they can spread by vegetative means such as rhizomes.

When the seeds of perennial weeds germinate, they can be controlled by pre-emergent herbicides. Perennial weeds are some of the hardest weeds to control. Weeds such as wild onion and garlic, dallisgrass, dandelions and violets are perennials. But one of the worst perennial weeds is Florida betony.

Florida betony is a member of the mint family. Plants in the mint family have square stems. These plants are hard to control because they spread by underground rhizomes.

Florida betony produces an underground rhizome with 2- to 3-inch tubers growing off of the rhizomes. The tubers look like the rattles on a rattlesnake. This is how it gets its common name: rattlesnake weed.

These tubers are able to store a large amount of energy, which allows the plant to re-grow each year and after herbicide applications. The plant can regenerate from root pieces or portions of the tuber left in the ground. The easy in which this plant regenerates is one of the reasons that it is so hard to control. One of the ways that Florida betony is moved is when plant materials are moved from one landscape to another.

Florida betony is a winter perennial. It will emerge in late September to early October and go dormant when the weather gets hot in May. The leaves of Florida betony are opposite each other and are long stalked, lance-shaped, and with toothed margins. The plant will grow all winter and in early spring, then produce flowers. The flowers can be white or pink with purple spots. The flowers have two lips on them. The upper lip is hooded, and the lower lip has three lobes. These flowers produce viable seed that also can spread the plant.

Controlling Florida betony will depend on where it is growing. In turf grass, products containing atrazine, 2,4-D, dicamba, or mecoprop provide good selective control. Other herbicides have shown some control of Florida betony on turf grass.

University of Georgia research found that the following herbicides provided greater than 70 percent control two months after application: Monument (trifloxysulfuron), Manor (metsulfuron), Revolver, (foramsulfuron), and Speedzone (carfentrazone, 2,4-D ester, mecoprop, and dicamba).

These herbicides are labeled only for turf grass and are not available to homeowners.

In ornamentals, dichlobenil (sold under the trade name Casoron) provides excellent control of Florida betony in some established woody ornamentals. Dichlobenil cannot be applied over every ornamental plant. Check the label to see where it can be used and on what plants it can be used. Casoron is not used much in our area because it is not readily available in small homeowner-sized containers.

Products containing the active ingredient glyphosate (i.e. Roundup) can be used to control this plant in ornamental beds if applied as a spray directly to betony without contacting desirable plants.

If trying to establish a new bed that contains Florida betony, consider using glyphosate. Apply a 5 percent spray solution of glyphosate one week prior to cultivating the area. This will help reduce much of the betony population. Repeat applications will be needed to eliminate survivors. Maintaining a good 4- to 6-inch layer of pine bark or pine straw might eventually smother the betony.

In plant beds, betony can be hand-pulled. The tubers of betony can be found growing in mulch. Removing the mulch makes it possible to remove a large amount of tubers.

Florida Betony is a very hard weed to control, but controlling it when it first is discovered and staying on top of it can reduce the amount of this weed in the landscape.

Charles Phillips is a retired Columbia County Extension Service agent. He can be reached at cphillipshort@ comcast.net.