San Antonio Express News
Sunday, May 9, 2004
By Lynn Rawe
People love their lawns, and millions of dollars each year are spent to keep them beautiful. The management of grass varieties will differ depending on the type of grass one has in their lawn.
Whether your turf is St. Augustine, Bermuda or Zoysia, there are a few tips to help all homeowners have a healthier lawn. Cultural practices are the key to managing your lawn.
Mowing height is important. Never remove more than 1/3 of the grass blade at one time. St. Augustine grass should be mowed between 2-4 inches in height; Bermuda should be mowed at 1-2 inches, for both common Bermuda and hybrid Bermuda, and Zoysia should be mowed at ½ to 1½ inch. Mow shaded lawns ½ to 1″ higher than lawns in full sun. Do not remove clippings after mowing. Clippings decompose and add nitrogen to your lawn, reducing the amount of nitrogen fertilizer needed. Always be sure that your mower blades are sharp to reduce disease problems. Mowing often will help reduce weed growth by eliminating the seed heads before they form.
With the cool, wet weather, fungi has become a major problem. Brown patch (Rhizoctonia) causes circular patches of light brown, thinned grass from a few inches to several feet in diameter. A musky odor may be present for 12-24 hours before symptoms appear, and may persist after symptoms show. Individual leaf blades and sheaths can be easily pulled from stolons because of rotting of the leaf sheath. Stolons often remain green. Grass will show a slight greening in the middle of the circular patches. Brown patch favors temperatures from 75-85o F., which occur in late spring and early fall. The disease stops when air temperature reaches 90o F. Homeowners can help prevent this disease by using minimum amounts of nitrogen when fertilizing. Water so that moisture is present on the grass for the shortest possible time. Increase aeration in poorly drained soils. If chemicals are needed, use (PCNB) known as Terraclor or (Myclobutinil), known as Immunox or F-Stop (a new product by Fertilome).
Herbicides for weeds, pesticides for insects, and fungicides for diseases can be selective to particular weeds, insects or diseases. Before using any chemical, be sure to identify the weed, disease or insect so that you will know the correct product to use. Whenever possible, use organic products or biological controls first. Know the square footage of your lawn. All products are applied according to area of the lawn, and knowing the square footage prevents over application. Always use caution when using herbicides. Herbicides for turf can cause damage to ornamental plants. Always read and follow label directions.
Not only can over-fertilization contribute to disease problems, but will increase the need for additional water due to rapid growth. As a general rule, St. Augustine and Bermuda should have 3 to 4 pounds of nitrogen per year. Never apply more than 1.5 pounds of nitrogen in a single application. For Bermuda, the recommended application is 1 pound of nitrogen every 6 weeks, and 1 pound every 8 weeks for St. Augustine. To determine the amount of fertilizer to apply to equal 1 pound of nitrogen per 1000 square feet, divide 100 by the first number of the fertilizer analysis. If you are applying 1.5 pounds of nitrogen per 1000 square feet, substitute 150 for 100. For example, if using a 15-5-10 fertilizer, at 1 pound per 1000 square feet, divide 100 by 15, which equals 6.6 (100¸15=6.6). If you have 5000 square feet, you take 5000 divided by 1000, and multiply by 6.6. This will give you 33 pounds of fertilizer needed for one application for 5000 square feet- (5000¸1000) X 6.6 = 33.
Knowing how much water to apply to lawns is a question many homeowners ask. Using data collected by local weather stations and information on evapo-transpiration of plants, calculations can be made to determine the amount of water needed for warm season grasses in our area. The San Antonio Water System (SAWS) and Texas Cooperative Extension provide such information through the Seasonal Irrigation Program (SIP). This information is available by dialing 210-281-1478 or contacting the Extension office with your name and email address for email notification. The telephone number of the Texas Cooperative Extension office is 210-467-6575.
Following proper cultural practices when caring for your lawn will result in a healthier, better looking yard – using fewer chemicals and fertilizer, and less water. As an added bonus, cutting back will result in saving you money.
This article was written by Lynn Rawe, County Extension Agent-Horticulture with Texas Cooperative Extension in Bexar County.