Ludwig noted a few products are labeled for use as a preventative trunk spray, but most are either marginally effective or require multiple sprayings throughout the growing season, a practice that is both expensive and labor consuming.

More effective controls were once available, but as their labels expired, they were not re-licensed by the U.S. Environmental Protection Agency. This was because either the chemicals were considered hazardous or the chemicals' manufacturers lost interest because of the cost of re-licensing.

The product Ludwig is testing is less hazardous more environmentally friendly and allegedly lasts for as long as two months, he said. Having a dependable control is vital to the industry. The tiny beetle is known to attack more than 100 species of trees, but seems to favor and do more damage to juvenile trees such as those found in tree nurseries. Less than an eight-inch long, the beetle can kill a tree in a few weeks. It burrows into the trunks of susceptible tree species, pushing out a mixture of sawdust, tree sap and its own feces as it goes. This mixture, called frass, hardens into a thin stick about the size of toothpick that juts out horizontally from the tree trunk Once a tree is infested, no chemical controls will save it. A tree may be infested by a single beetle or by hundreds. For juvenile trees, 1 to 3 years old, the infestation most often proves fatal. Mature trees are more likely to survive the infestation but may serve as staging base for the beetle to attack nearby younger trees.

For this reason, the general control strategy is to cut down and destroy any infested trees immediately. If local ordinances permit, burning the tree is the best way to ensure the beetles are destroyed as well. If open burning isn't permitted, and the tree is small enough, it can be ground up and composted, Ludwig said. "The quandary com
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Contact: Robert Burns
rd-burns@tamu.edu
903-834-6191
Texas A&M University - Agricultural Communications
6-May-2004