Water or not to water

By MINDY POEHL | Central Texas Edition

Dry conditions spur landowners concerns for lawns burning up – when to water. Here, Extension turfgrass specialist, Dr. Jim McAfee, addresses the issue with participants attending a Lawn Care Workshop in Stephenville. -- Staff photo by Poehl

Sept. 15, 2005 - The phones at the Erath County Extension office have been ringing off the hook with people asking specific questions about their lawns. Since so many locals were interested in the same topic, the Erath County Extension Office held a Lawn Care Workshop at the Texas A&M Research and Extension Center in Stephenville, on Sept. 6. Dr. Jim McAfee, associate professor and Extension turfgrass specialist, was on hand to share his expertise on lawn management practices. 

"There is not a set period between one watering to the next, because the land across Texas is different," said McAfee. "The watering period will depend on the location, rainfall, time of year, the grass, and how well the soil holds water."

The key is to learn how your lawn shows signs of moisture stress. "Many turfgrasses can tolerate extensive stress and rebound when you water it at the right time," explained McAfee.

Signs of moisture stress, such as leaf rolling and an off-color appearance, are good indicators that the lawn needs to be watered. But, the whole lawn may not show symptoms.  

"Only water those spots that show signs of stress, rather than watering the entire lawn," McAfee stated. "This helps conserve water." 

Or, if rain is in the weather forecast, try to wait for the rain to fall before watering your lawn.

�Lawn grasses use the most water in summer and use less during late autumn, winter and early spring. When rain is absent, lawns can use between 1 to 1.5 inches of water per week during the summer, explained McAfee.

"You will conserve more water if you water your lawn early in the morning," McAfee said. 

McAfee also spoke about water runoff. Runoff happens when irrigation is applied at a rate that exceeds that amount of water that can penetrate into the soil. 

"Runoff occurs when you water the lawn too long and the soil can't hold any more water," McAfee said. "You can prevent runoff by determining the inches of water applied to the lawn."

He said to evenly space flat-bottom cans between sprinkler heads, water the lawn for 15 to 30 minutes, then measure the water caught in each can using a ruler. That measurement is the amount of water applied per unit of time in inches.

And, after clipping grass, McAfee suggested leaving the clippings behind to fertilize the lawn.

"Grass clippings are a great source of nutrients and help reduce the need for additional chemical fertilization," McAfee said. "They contribute organic matter to the soil over time."

After discussing how to maintain a beautiful lawn, different lawn challenges were verbalized.

Outbreaks of spider mites in hot, dry weather are evident, because those are the conditions in which they thrive. Spider mites can attack a host of plants in the landscape, including annuals, perennials, shrubs, trees and even turfgrass. 

Spider mites are tiny, red arthropods, closely related to ticks and spiders. 

"They feed on plant cells and produce small, yellowish marks," said McAfee. "Silk webs can be found on leaves and flowers and the plants will quickly turn brown and wither."

Spider mite infestations are easiest to control when they are detected early. First, make sure the plants are well watered. Then, try spraying the plants with a strong stream of water, which can dislodge many mites from leaf surfaces.

Elimination of moderate infestations of spider mites usually requires the use of specific pesticides known as miticides. However, some insecticides can control spider mites. Good spray coverage is essential when applying miticides. Thoroughly wet the foliage and try to contact as many mites as possible, paying particular attention to the undersides of leaves, where the mites live.

And what about those small spots on the leaf blades of St. Augustinegrass? It could be a sign that the gray leaf spot has infected your lawn.

Gray leaf spot is a fungus that attacks St. Augustinegrass, as well as several other turfgrass species, including perennial ryegrass, bermudagrass, fescue and centipedegrass. It develops rapidly with warm temperatures and abundant moisture, as well as causes severe damage to  lawns. 

Leaf spots first appear as tiny brown to ash-colored spots, or lesions, with purple margins that enlarge and become diamond-shaped. The St. Augustinegrass will have a yellowish color and appear drought stricken. High nitrogen fertilization, high humidity, 80 to 90 degree weather and above 70 degree nights, shaded areas, herbicide damaged areas, compacted soils, excessive thatch, and drainage problems are all promotants of the gray leaf spot.

Fall is also the prime time to treat for fire ants in order to reduce the numbers that will appear in the spring. 

One way to majorly reduce the number of fire ants is by ridding them in community-wide efforts. All residents on a block should apply fire ant  treatments at the same time on the same day, to maximize its effectiveness.

By using community-wide efforts,  fire ant mounds are reduced by 94 percent and the cost of pesticides is reduced by 84 percent. In fact, a  statewide study determined community-wide efforts throughout the state can reduce the impact of fire ants by $234 million. 

Communities should fight fire ants with the Texas Two Step Method. Step one is to spread a fire ant bait twice per year, in the fall and spring, when the yard has at least five fire ant mounds per quarter-acre. Step Two is to re-treat individual mounds in high traffic areas, such as along driveways and around mailboxes.

Fire ant bait is made of corn grit coated with soybean oil, which attracts the fire ants. The insecticide is dissolved in the soybean oil. Worker ants collect the bait and take it back to their colony to share with other  ants, including the queen. Some baits cause the queen to die while others make her unable to produce fertile eggs. 

Bait methods of fire ant control take longer than individual mound

treatments, but their effectiveness can reach a 90 percent suppression rate for six to 18 months.