The Ash Borer War
Mar 02, 2017 12:12PM
By Patrick McGee
Although native to East Asia, invasive emerald ash borers were first discovered within North America in Michigan during the summer of 2002. Douglas County suffered its first confirmed infestation last summer, when a sick ash tree at Pulaski Park in South Omaha revealed the bad news.
Ash trees have no natural defenses against the ash borer. So, Larson expects the epidemic to be substantial. He compares the potential damage to the epidemic of Dutch elm disease in the 1970s and 1980s. Larson expects increasing confirmation of ash borer infestation over the next two to three years.
“If we don't take the proper precautions, we will lose a lot of trees,” he says.
Precautions include yearly pesticide soil drenches for ash trees under 20 inches in diameter or biannual injections for trees over 20 inches in diameter. Larson says treatments range in price from $20 to $290; however, the cost of tree removal is also pricey. Larson believes that removal will be inevitable for untreated ash trees. He says ash borers are really good at finding trees, and they don't usually miss one.
Larson advises landowners to remove ash trees from their property if they don’t plan on applying treatments. “Spend it all at once on removal or over a period of time on treatment,” he says. He recommends annual inspection of healthy ash trees by an arborist to help decide whether to treat or cut.
Hal Freeman is one such certified arborist and the owner of Omaha Tree Care. He offers treatments to some clients but recommends cutting down most ash trees “rather than fighting it.”
He generally recommends removing the trees before infestation. He says that ash trees “could be seen as a liability” and “could affect the value of your home.” The dilemma bothers Freeman because, as an arborist, he prefers to save the trees.
Steve Torpy, another certified arborist and owner of Torpy Tree Service, recommends choosing good candidates and offering treatments. He says that a large-scale loss of ash trees “would be devastating to our urban forests.” He cites many benefits of having established ash trees, such as saving on electricity and gas, and slowing water run-off. “There's a lot of benefits people don't think about,” he says, arguing that “saving the trees can be cheaper than the cost of removal and replacement.” An arborist can help a tree owner make an educated decision, so long as a tree is not already infested.
Infestation begins when ash borer larvae chew serpentine tunnels into the ash tree, devouring the phloem and cambium layers underneath the bark, destroying the tree’s ability to circulate water and nutrients. Larson says that early in its infestation, the ash borer inhabits the very top of the ash tree. The top begins to wither first. Larson says that after four or five years, the beetle moves down into the lower portions of the tree. After six or seven years, the ash borer infests the trunk. Then, he says, “there is not much you can do.”
Larson says there are four key symptoms of infestation to look out for: dieback, brooking, exit holes, and woodpecker feeding. Larson says “dieback” occurs in the very top of trees when the borers eat the inside of branches and the tree can't grow leaves on those branches. “Brooking” refers to new chutes growing out of the lower portions of the tree. Larson says it is a common sign of infestation. “Exit holes” are visible in the bark of infested ash trees when the adult beetle emerges from the tree. He also says that an increase in woodpecker activity in an ash tree can be a telltale sign of infestation.
According to Larson, ash borer infestations have already been identified in more than 25 states. Larson says the insect has limited flight capabilities and has spread primarily through transportation of firewood and mulch. “People load up a truck with firewood and cross county lines.” It is unclear exactly how the beetle was brought over from China, but Larson says the prevailing opinion is that it arrived in some sort of wood product.
Larson says Nebraskans should be optimistic about saving their ash trees because the professionals have been working for nearly nine years in preparation for the epidemic. He has personally seen the devastation of the beetle in his home state of Indiana, one of the first states hit, and he says that experience is on our side now. Public awareness will help tree owners prepare. He encourages people to report green bugs that may be ash borers.
“I would rather look at 100 [insects] and find one that is [ash borer] than have someone get one and not call us,” he says. “They are beautiful insects but so destructive to trees.” OmahaHome
Visit emeraldashborer.info for more information.
This article was printed in the March/April 2017 edition of Omaha Home.