Defend trees from beetles, disease in storm aftermath

RAYMOND, Miss. -- Landowners who had timber damage from the January ice storm should watch for bark beetles and disease.

Butch Bailey, forestry specialist with the Mississippi State University Extension Service, said people should be vigilant in looking for the symptoms that indicate beetles are active instead of the beetles themselves.

“All of these beetles are very tiny -- smaller than a grain of rice,” Bailey said. “That’s important because many people assume a critter than can kill an entire forest must be big. The beetles themselves are small, the holes they dig through the bark are small, and the galleries they dig right under the bark are small.”

The first sign of bark beetles is pitch tubes, or small balls of tree sap mixed with inner bark where the beetles bore into the tree bark. These look like popcorn stuck to the sides of trees. They can be as small as pea-sized on heavily stressed trees and up to dime- to nickel-sized on less stressed trees.

“The best diagnostic is to pull the bark off around the pitch tubes, and look at the galleries, which are the little tunnels the beetles dig right underneath the bark,” Bailey said.

“They’re very small, about as wide as a grain of rice. If the galleries run basically straight and vertically up and down the trunk, that indicates Ips beetles. If the galleries are curving and random, like cooked spaghetti thrown against a wall, that indicates southern pine beetles,” he said.

Red or fading treetops are a second sign of beetle activity and the one that landowners often notice first. However, brown spot needle blight is beginning to appear now and could be confused with beetle damage.

Brown spot needle blight starts near the bottom of the canopy and progress upward. With this disease, it’s common to see brown dieback of just the tips of the needles, with the rest being a yellow to light brown or tan color. With dieback from beetles, the entire needle turns yellow and then reddish brown.

Bailey said what landowners do about beetles depends on which beetle is present, the time of year and how many trees are infected.

For black turpentine beetles, no action is needed unless a majority of the stand is infested. In this case, consider thinning the infested trees or clearcutting.

If Ips beetles are detected in the spring and summer, watch for quickly growing spots of infected trees. For large spots of 25 trees or more that seem to be growing rapidly, consider salvage thinning if possible.

“In most years, Ips don’t do much damage, and a logging job will do more harm than good,” Bailey said. “In the fall, it is usually better to do nothing for most cases and monitor these trees next spring. Bark beetle activity will decrease rapidly in the late fall and winter even if you do nothing.”

For southern pine beetles, or SPB, mark each infested spot carefully. Carefully monitor areas with fewer than 20 infested trees for spread. When SPB infests more than 20 trees in one area, the beetles will likely spread throughout the season.

The best practice is to hire a logger to cut the infested trees along with a buffer of about a tree-lengths distance around the infested spot. Leave any dead trees in the center of the spot. These cannot host SPB but do host natural predators of SPB. The beneficial insects in the dead trees, or snags, can help control the SPB population. 

“Salvage will most likely not be possible,” Bailey said. “In that case, we recommend cutting down all infested trees and the buffer of uninfested trees and burning them or piling them in the center of the standing dead snags. The buffer is important because it disperses the beetles and helps prevent mass attacks on nearby trees.”

Kristy McAndrew, Extension forest health specialist, said trees are also at heightened risk of certain diseases because of the damage and stress they have endured.

“Each broken limb is not only stressful for the tree, but it’s a possible entry point for diseases,” she said. “Since much of the damage I’ve been seeing is in the canopy and upper stem, I’m most concerned about canker fungi.

“There are various species that cause cankers. The big concern with these is stem deformities, which can reduce value of the wood or cause weak stems,” she said.

Landowners should watch for wounds near breaks that seem to be getting worse or spreading. Also, note if there is an excessive amount of resin being produced by the wounds. Document any signs of disease with clear photos. This will help determine if the symptoms are getting worse over subsequent growing seasons.

Landowners who observe issues throughout a stand should call their local MSU Extension agent or a registered forester.

For more information, download MSU Extension Publications 2876, “Ips: The Other Pine Bark Beetles” and 2748, “Southern Pine Beetle in Mississippi: An Overview.”

For more about the threat from bark beetles, refer to the related article Bark beetles threaten ice-damaged timber.