Jan. 27, 2006

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DALLAS – Chinch bugs have long been the bane of homeowners with St. Augustine grass lawns.

Drought and limited watering have added stress to St. Augustine lawns throughout the state, as have recent mild winters. These are conditions under which chinch bugs thrive.

"While fire ants and white grubs pose the greatest problem for turf grasses across Texas, the Southern Chinch Bug comes in a close second because of the amount of St. Augustine throughout the state and the bug's ability to kill it," said Dr. James Reinert, an entomologist with the Texas Agricultural Experiment Station in Dallas.

Roughly 25 percent of the lawns in the Dallas/Fort Worth area are St. Augustine, according to Reinert. But that number increases in the southern areas of the state. St. Augustine is the predominant grass used in lawns in Houston, San Antonio and Austin.

As the number of St. Augustine lawns increases, the potential for damage by the Southern Chinch Bug also increases.

"Chinch bugs insert a toxin that kills the St. Augustine as they feed by sucking the plant juices," said Reinert. "They feed on the stems at the nodes, near the base of the leaves. The result is brown patches in a lawn that will continue to grow if left untreated."

Currently, the only treatment option is repeated chemical applications to the lawn throughout the summer. None of the current products on the market provide long-term or residual control.

It's a problem that's been battled for decades by turf grass researchers from coast to coast across the Southern USA, said Reinert.

Approximately 30 years ago, turf grass research in Texas and Florida developed 'Floratam' a cultivar of St. Augustine resistant to the Southern Chinch Bug. But after 12 years of use across the southern states, the Chinch Bug adapted and overcame the Floratam resistance in parts of Florida. Chinch bugs have continued to adapt and overcome new St. Augustine cultivars ever since, said Reinert.

Recently, Reinert has determined the Southern Chinch Bugs in Texas are no longer controlled by the Floratam resistance.

Efforts continue at the Dallas center to develop new, more resistant cultivars that will control the new virulent Texas Chinch Bugs. Several new breeding lines are exhibiting greater than 65 percent resistance and two of the hybrids appear to be significantly exceeding that level. But none of the potential new cultivars are close to being available in the marketplace, Reinert said.

"The average turf grass research project takes from five to 10 years to develop a new turf grass variety," said Reinert. "But if homeowners think that sounds like a long time, they need to know that these same types of research projects used to take 14 years or more."

On average, the Dallas area has two generations of chinch bugs per year because of its colder winters. The milder the winter, the more generations of chinch bugs there will be. The more generations, the longer the feeding cycle, and the greater the opportunity for the bugs to damage the grass. For many St. Augustine lovers, that means more chinch bugs and more chinch bug damage during a drought.

St. Augustine fans also may not know studies have shown that over-fertilizing with high rates of nitrogen carries a side effect of making the lawn more susceptible to chinch bugs said Reinert.

"The short-term answer to the problem is moderation on the front lines," Reinert said. "The long-term answer is the development and release of new, chinch bug-resistant St. Augustine cultivars. But the research must be done first to make sure the grass will hold up after it is planted in the landscape. These new cultivars will also have to be resource efficient and have resistance to other pests."