Managing Bahiagrass in Lawns
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The best way of I know of to prevent bahiagrass and other weeds from infesting your lawn is to maintain a healthy lawn no matter what type of grass you have. Here are a few tips to maintaining the four common lawn grasses we grow here in eastern NC. Bermudagrass should be mowed to a height of 1 to 2 inches and fertilized at least two times (and up to four) between May and August applying 1 pound of nitrogen per 1000 square feet each time. I would recommend fertilizers with a 12-4-8 or 16-4-8 analysis for this fertilization. Use 8 pounds of 12-4-8 or 6 pounds of 16-4-8 per 1000 square feet. Centipedegrass should be mowed to 2 inches and fertilized once in late May or June with 15-0-15 fertilizer which is locally available (Do not apply more than 1/2 pound of actual nitrogen per 1000 square feet to centipede per year. This is equivalent to 3 pounds of 15-0-15 per 1000 square feet). St. Augustinegrass should be mowed to 3 to 4 inches and fertilized at two times between May and August with 1/2 pound of nitrogen per 1000 square feet each time. I would use 4 pounds of 12-4-8 or 3 pounds of 16-4-8 to achieve this. Zoysiagrass should be mowed to 2 inches and fertilized in April, June, and August with 1/2 pound of nitrogen per 1000 square feet each time. I would use 4 pounds of 12-4-8 or 3 pounds of 16-4-8 to supply that amount.
In order to maintain a healthy lawn, all lawns should be soil tested every two years to determine if additional nutrients need to be applied or pH needs to be adjusted. Leaving grass clippings on the lawn creates a better environment for grasses to grow in than bagging. When mowing, never remove more than 1/3 of the leaf blade at any one mowing. In other words, if you plan on mowing your lawn to 1 inch, then mowing should occur when the grass reaches 1.5 inches. Finally, keep a healthy lawn by making a late summer or early fall application of potassium. Apply 1 pound of potassium per 1000 square feet using 1.6 pounds of muriate of potash (0-0-60), 5 pounds of potassium-magnesium sulfate (0-0-22), or 2 pounds of potassium sulfate (0-0-50).
The above maintenance practices will go a long way to reducing weed pressure in the lawn. However, since some weeds are so competitive, like bahiagrass, you can do everything right and still have an infestation. If you have bahiagrass in your lawn there are several options for management. First if you have only a small clump of the weed, dig it out by hand or rent a sod cutter to remove it from the lawn. A second option may be to spot treat the bahiagrass with a non-selective herbicide (like Roundup) realizing that this will also kill the desired turfgrass in that area. The third option is to treat with a selective herbicide that is safe for the grass you are growing. The best time to treat bahiagrass is before seed head production begins but can be done anytime during the summer. Two applications about a week to 10 days apart will be needed. Treatment later in the growing season will require additional applications as bahiagrass matures. In bermudagrass, products containing MSMA, DSMA, or CMA can be used. In centipedegrass, products containing sethoxydim (like Vantage) are effective. Bahiagrass is sensitive to products containing imazaquin (like Image) and imazaquin can be applied to bermudagrass, centipedegrass, St. Augustinegrass, and zoysiagrass after spring greenup. Please remember to always read and follow label instructions before applying any pesticide to your lawn or landscape
If you have questions regarding your lawn, landscape, or garden give the Pitt County NC Master Gardener Extension Volunteers a call at 902-1705. Volunteers staff the office on Monday, Wednesday, and Friday from 10 am to noon. You may leave a message anytime for a return call or email questions to pittcomgv@hotmail.com.
Danny Lauderdale, Extension Agent
Agriculture - Horticulture