In February, we brought you news from the Georgia Forestry Commission concerning drought-related beetle outbreaks in Georgia. This is an update to that story from the Warnell School of Forestry and Natural Resources.
Rainfall levels were below normal in Georgia during most of 2016, and much of northern Georgia is still experiencing severe to extreme drought conditions. While these areas have received rainfall, drought conditions are still predicted through May 2017 in northern Georgia. Agriculture, wildlife, and water quality resources have been negatively affect by the drought.
Forests, especially in the Piedmont and mountain regions, are showing the drought effects, with over 200 Ips engraver infestations being reported in excess of five acres. Many infestations have been 25 to 50 acres in size. Pines are dying even in areas of the state that are not currently in official drought conditions, and the question is “Why is this happening?”
Drought stresses and weakens trees, making them more likely to be attacked by bark beetles. Under drought, trees do not receive enough water to perform their normal life processes, like converting sunlight to energy. Tree drought responses include leaf wilting, early leaf fall, dying tissue, shutting down roots, and changing chemical process within the tree. Many of these changes occur to conserve water and keep the tree from dying. Even as rainfall conditions return to normal, trees require time to fully recover from their drought response. So there can be a time-lag between increased rainfall and full tree health recovery. Unfortunately, this time-lag and milder winter temperatures gives bark beetles more time to attack pine trees.