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bermuda grass

Overseeding Bermudagrass turf with perineal ryegrass is a common practice on athletic fields and golf courses in Alabama, as well as other southern states. In Alabama, bermudagrass turf will begin to go dormant during late fall after the turf has been exposed to cool temperatures accompanied with frost. The turf will remain dormant until warm temperatures return in mid-Spring. During this time of dormancy, bermudagrass turf will lose its green color and stop all vegetative growth. High traffic turf is also susceptible to damage due to prolonged periods of excess soil moisture that is common during Alabama winters. To help alleviate some of these issues, many turf managers choose to overseed with ryegrass during the dormant months.

Advantages

Overseeding improves the aesthetics of the turf, as well as the quality of the playing surface when managed correctly. Grown as an annual, perineal ryegrass is superior to annual ryegrass due to its fine texture, dark green color, and some disease tolerance. Perineal ryegrass can tolerate mowing heights less than ½-inch and creates attractive stripes when maintained with a reel mower or rotary mower with rollers.

Disadvantages

There are, however, a few downsides to overseeding during the dormant season. One negative is the fact that overseeding makes weed control much more difficult. Annual bluegrass, Poa annua, is a common annual weed found in turf. There are several chemical options available to remove this weed from bermudagrass, however, there are very few products labelled for use on overseeded bermudagrass due to ryegrass injury.

Another factor to consider when overseeding is spring transition. By late spring, perineal ryegrass has formed a dense turf that competes with the bermudagrass beginning to wake up from dormancy. Ideally, as the temperatures increase in late spring the perineal ryegrass will begin to die off as the bermudagrass takes over. Some turf managers will choose to vertical mow, aerify, or apply a selective herbicide to aid in the removal of the ryegrass.

Rates and Timing

Perineal ryegrass should be broadcast with a rotary spreader or drop spreader at a rate of 8 to 12 pounds per 1000 square feet. Timing varies widely according to activity on the turf. It is important to give the seed time to germinate and establish before putting an excessive amount of foot traffic or equipment on the turf. In Alabama, perineal ryegrass seed is typically spread in September and October.

Establishment

Applying a growth regulator to bermudagrass turf prior to overseeding can help slow the growth of the bermudagrass thus reducing the need for mowing while the ryegrass seed is establishing. It is important to maintain adequate soil moisture during the first few weeks after seeding to ensure good seed germination and prevent seedling desiccation. Areas with a dense bermudagrass canopy may benefit from vertical mowing prior to overseeding. This process will open the turf canopy and allow for increased seed to soil contact as well as increase light penetration for seed germination and establishment.

In addition to the initial application, turf managers may elect to periodically overseed thin areas throughout the fall on playing surfaces with lots of foot traffic and a short playing season, such as football fields. If possible, mowing should be avoided until seedlings are established and have developed a strong enough root system to tolerate abuse from mowing. Reel mowers should be well maintained with sharp reels to prevent the reels from pinching the leaf blade and pulling the seedling out of the ground.

Fertilization

During establishment, a balanced fertilizer (ex. 13-13-13) should be applied at a rate of ½ pound to 1 pound of Nitrogen per 1000 square feet. Additional nitrogen should be applied throughout the season according to desired growth and color.

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