Insect and Disease Survey

Forests can be devastated by insect infestations or tree diseases. Knowing how to recognize a problem and taking the correct action can possibly save millions of dollars worth of timber. We work closely with the State Forestry Agencies to survey and control a variety of forest pests. Immediate and decisive action by the forest landowner can have a significant effect on forest health.

Two of the most troublesome insects of southern forests include the Southern Pine Bark Beetle (Dendroctunus sp.) and the Hemlock Woolly Adelgid (Adeles tsugae).




Left: SPB pods on the outside of a pine tree. Right: The southern pine beetle.
Photo courtesy of Gerald J. Lenhard
Bugwood.org



The Southern Pine Beetle


The southern pine beetle (SPB) is the most destructive pine bark beetle in the south. Randomly flying females locate weakened trees which are called focus trees. Focus trees then become the source of an attracting pheromone called frontalin that attracts other flying beetles. As the focus trees become less attractive due to the male pheromone verbenone, incoming beetles begin to attack neighboring trees. This switching mechanism causes the infestation to grow.

The SPB attacks all species of Southern Yellow Pines including Eastern White Pine. It is particularly destructive in overmature and overcrowded timber stands. Beetle outbreaks are cyclic and usually follow drought, which weakens pine trees, making them susceptible to beetle attacks.

Trees are killed when thousands of adult beetles bore underneath the bark to feed and lay eggs. The female beetles construct winding S-shaped galleries in the cambium while feeding and laying eggs. Adult beetles carry blue stain fungi, which clogs water movement in the sapwood, drying the needles and killing the tree.

The usual signs of pine beetle attack will be pitch tubes (photo top left) on the outside of the bark, which look like small pieces of popcorn. The needles eventually turn pale to yellow-green (called faders), then red, then brown.

The removal of all infested trees by salvage is the best means of controlling Southern Pine Beetle spots. Another method of control is cut-and-leave. This method involves felling infested trees along with a buffer of uninfested trees and leaving them in the forest. Cut-and-leave should only be done when the trees can’t be salvaged, and only during the summer months.

Aerial detection of southern pine beetle spots is the most effective means of locating infested areas. State Forestry Agencies across the south conduct annual Southern Pine Beetle surveys in order to detect and record spot size and location. See this Map of Georgia that shows the highest at risk areas for Southern Pine Beetle infestations.


Aerial view of southern pine beetle infestation photo courtesy of Terry Price, Bugwood.org

How can early detection of an SPB infection help a land owner? Click here.