Pest Alert: Emerald Ash Borer Arrives in Texas
October 25, 2017
You may have heard about the incredibly troubling status of our nation’s Ash trees. They are under threat of being wiped out, much like American and Dutch Elms, all because of a shiny, green beetle called the Emerald Ash Borer.
The beetle (Agrilus planipennis), referred to in the industry as EAB, is native to Asia. It was imported into the United States, unknowingly, in 2002 on packaging materials from China. The insect—which is actually quite pretty—is metallic emerald green and about a 1/2” long. The adults are most often seen in late spring and early summer, but it is the larval stage that does the damage. They burrow into the trunk of Ash trees and feed under the bark, leaving trails called ‘galleries’ that inhibit the ability of the tree to carry water and nutrients.
Ash trees are one of the most abundant tree species in the U.S., numbering around 7-9 million, with tree populations most dense in northern regions. EAB has killed 40 million trees in Michigan alone, and the spreading of the beetle has not stopped. Currently, the beetle has been found in 31 states along with parts of Canada; with Texas being added to the list in 2016. While we don’t have infected trees, the beetles have been found in Harris County and near the Louisiana border.
“Its recent trapping in Northeast Texas indicates southern movement, generally following the interstate roads. Once a tree is identified as having EAB, its survival rate is .03% and should be removed. It is costly and limited once infested and then the tree becomes hazardous to climb after a few years.” Chad Simmons, PTS Certified Arborist
Out of the 16 different Ash species that are susceptible to EAB, seven species are found in Texas. Interestingly, EAB also attacks white fringe tree, Chionanthus virginicus. Even though there are not a significant amount of Ash in Texas’ forests, they have been planted as street trees in many cities. Therefore, it is important to know what to look for. Signs and symptoms of the pest being present include:
-thinning or dying of tree crowns
-suckers at the base of the tree
-D-shaped exit holes (where the adult beetles emerge)
-heavy woodpecker activity
Woodpeckers are probably the best natural control for EAB, so as always, it’s a good idea to create healthy wildlife habitat in our urban landscapes. But unfortunately, woodpeckers can’t prevent an infestation.
It doesn’t matter how healthy your Ash tree is - EAB will attack both healthy and stressed trees. Once a tree is infested with Emerald Ash borer, it typically takes 2-3 years for the tree to die. There are treatment plans, but they often prove futile once the tree is in serious decline from infestation. States in the north are giving their best efforts to control the spread by using insecticide tree injections and soil drenching. In addition, traps for EAB are being placed ahead of the insect to catch them before they move in and infest an area.
Removal of susceptible trees can help stop the spread of this destructive beetle, as well as planting new trees that are not susceptible. If you live in or close to Harris County, it’s especially good to keep a close eye on your Ash trees. If you suspect a tree is in trouble, it never hurts to call an expert.