by Meaghan English, TrueSouth Properties Wildlife Specialist
The drought of 2016 has taken a major toll on the hardwoods and pine trees throughout the Southeast. As the trees become weak due to the lack of moisture, they are also more susceptible to disease and parasites. Pine trees (loblolly, shortleaf, and Virginia) are most susceptible to the Southern Pine Beetle. The South has always been a hot spot for these pests, but the dry conditions have further increased the outbreak of the Southern Pine Beetle. I will describe a few characteristics/behavior of the beetle, signs of infestation, and management techniques to get rid of these pests.
The Southern Pine Beetle is a cylindrical shaped beetle with a rust colored body. There are four life stages for this beetle (egg, larva, pupa, and adult). It only takes one female to initiate an infestation of a pine tree. The female finds a host tree and release pheromones to attract the males. Once a male arrives, they also release pheromones attracting more beetles. The more beetles attracted, the more likely the tree will be completely colonized. The female then begins to drive her way into the cambium layer. She does this by finding bark crevices and boring her way through the splits in the outer layers of the bark. At the beginning of the infestation, the tree produces resin which flows out of the holes created by the beetle. As the infestation continues, male and female beetles work together to remove the resin and create clear “tunnels” into the bark. Once the female successfully enters the cambium layer, she begins to lay eggs and the male creates barriers and packs the holes. Once the eggs hatch, the larvae also begin chewing on the inside and outside layers of the bark. All life stages of the beetle begin to “girdle” the tree which ultimately causes the tree to die. To summarize in not so scientific wording, the Southern Pine Beetle eats the pine tree from the inside out. Once they are done with one tree, they glide to the next closest tree and start all over.
Signs of infestation
As previously mentioned, the beetle force resin out of the tree through the tunnels they created. These are called “pitch tubes” and depending on the species of pine, the resin is a white or yellow color. It appears as though popcorn is growing on the side of the tree (it is hard to miss). This is the first initial sign of infestation. Another telling sign is sawdust around the bottom of the tree. This is also from the beetles boring into the bark. Luckily, the drought this year has made all these signs much more visible because there is no rain to wash away the sawdust or anything like that. One important piece of information to keep in mind is that the top of the pine may appear to be healthy (the needles may still be green) so you cannot rely on the needles to be a sign of injury. You must look at the bark! Some trees may have a red top and you will swear they are infested with beetles, but that may just be a result of the drought. Go by pitch tubes and sawdust!
The most important technique for managing beetles is forest health. If you have a very dense stand and overcrowding is taking place, you have basically created a feeding frenzy for the beetles. It is very easy for them to glide from host to host since the trees are so tightly packed. Thinning is your best friend when it comes to the war against beetles. An open forest with an open canopy is the opposite of what the Southern Pine Beetle wants to see. So keep your forest healthy! Keep your forester close by and maybe talk to him or her about a routine management plan to keep your stand thin. Another important technique is early detection. Once you detect one dying pine with the qualifying characteristics of beetle damage, it’s important to take action quick. Most foresters would suggest removing the infected tree as well as the surrounding area that is within a certain distance (usually the length of the infected tree). This technique may cost you a few healthy trees, but in the big scheme of things it is the only way to protect your stand. To protect yourself from a beetle outbreak, keep an eye on your pine stands at all times and seek expert advice if you suspect beetle damage on your property. It is much easier to be proactive than reactive in this case.
October and November have been very dry for the state of Alabama and it is important to keep your trees protected from wildfires and beetles. If you have not taken a walk through your trees in a while, do so soon. You might be shocked at what you find. The drought has made it even easier for the beetles to invade, so act quickly!
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