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Drought Increases Pine Beetle Activity
MISSISSIPPI STATE -- Add pine trees to the list of Mississippi agricultural products hurt by drought conditions that triggered increased bark beetle attacks on the state's second most valuable crop.
Dr. Glenn Hughes, area forestry specialist in Ellisville with Mississippi State University's Extension Service, said the potential damage statewide to forest landowners' and homeowners' trees is significant. A mild winter could increase the threat in 2000.
"Whenever you have something that stresses a tree, whether it's weather or new construction, the tree will be more susceptible to insects and diseases," Hughes said. "Drought is a fairly common stress in the late summer and early fall, but this year was particularly dry."
Additional stresses could be part of the reason Hughes recently counted 85 spots along a 20 mile stretch of highway. The good news is the damage does not appear to be from the highly destructive southern pine beetles that can wipe out hundreds of acres at a time.
Instead, this year's infestations are primarily the Ips beetles, also known as the engraver beetles.
"Engraver beetles hit smaller clusters of trees and don't produce as many generations annually as the southern pine beetle," Hughes said. "Unlike the southern pine beetle that commonly attack healthy trees earlier in the year, Ips beetles are known for moving during late summer and fall drought periods."
Hughes said determining if the infestation is by an engraver beetle or the southern pine beetle is relatively easy.
"When you evaluate the galleries created underneath the bark, the southern pine beetle leave loopy S-curved chambers," Hughes said. "The engravers leave straighter, X- or Y-shaped chambers."
A third type of pine bark beetle, the black turpentine beetle, is the rarest of the pine bark beetles in Mississippi and mostly found in the lower third of the state. Regardless of the type of beetle, each one is lethal to pines.
"You can spot infested trees when their crowns go from dark green to yellow-green to red, and eventually to brown. Once the crown begins to change color, it's too late to save it," Hughes said. "For ideal control, remove the trees before the beetles leave the tree and attack others."
Dr. Evan Nebeker, professor of entomology and plant pathology at MSU, said the best response for the money could be doing nothing. . "About 80 percent of the infestations will go inactive on their own. Depending on the long-term goals, the cost of removal may not be worth the effort," Nebeker said.
Other options include:
* salvaging the area by removing infested trees,
* cutting and leaving during the hottest days of summer,
* cutting and spraying with a registered insecticide, or
* cutting, piling and burning infested trees.
Nebeker said spraying insecticides to prevent beetles is difficult because the tree must be sprayed from the ground to the first live branch, usually beyond reach of the sprayer. As a safeguard for pines in the home landscape, he recommended watering weekly during dry periods.
Contact your county forester or county agent for more information about the proper treatment or chemical to use.
Forestry usually runs neck-and-neck with the poultry industry for the top spot in Mississippi's agriculture picture. Last year, the state's timber industry was valued at $1.31 billion.