SPECIALTY CHEMICALS: The Good Side of Grubs

Insects invade trees as well as turf, creating additional problems for some lawn care operators. The worst part is many of these pests are new to the North American ecosystem, making them difficult, if not nearly impossible, to control. “We are a global economy now,” says Nate Dodds, president of J.J. Mauget, Acadia, Calif. “This opens up the opportunity to bring in hitchhikers in the form of new foreign pests that have never been here before. It’s almost impossible to stop it.”

Many of these hitchhikers are wood-boring insects that feed on a trees cambium layer, disrupting its vascular flow. “Wood-boring insects live and breed inside of the tree,” says Roger Webb, owner of Tree Tech, Morriston, Fla. “The boring and tunneling action disrupts vascular water flow, damaging and eventually killing the tree.”

Dodds and Webb discuss five insects that, if left unchecked, will cause permanent damage to the nation’s indigenous tree population.

Emerald Ash Borer – The wood-boring insect’s larvae feed on the cambium layer of a tree, cutting off its water supply until it dies. To date, the insect has killed more than 20 million ash trees throughout Michigan, Ohio, Indiana, Maryland, Wisconsin and lower parts of Canada, calling for desperate action. For example, a Michigan county has declared a clear-cut policy of all ash trees to halt the insect’s spread. “It’s a favorite species among many people and is great loss for ornamental landscapes,” Webb says.

Asian Longhorn Beetle – Outbreaks of this wood-boring insect have been detected in the Long Island, N.Y., New Jersey and metropolitan Chicago areas. It has no known natural enemies in the U.S., Webb says, and it’s very difficult to detect and treat. Quarantines around infested areas should prevent accidental spreading, and all infested trees are being destroyed. “This insect is not as much of an economic threat because it’s under quarantine,” Dodds says. “Hot spots are being taken care of as they emerge.”

Mountain Pine Beetle – This insect invades conifers in the country's western region. The trees are particularly vulnerable during droughts. There is no chemical control for the beetle. However, governmental agencies control breakouts by clear cutting hot spots and thinning the tree population. “They’re basically trying to take away the insect’s habitat,” Webb says. The southern pine beetle is an insect that causes similar problems in the south.

Hemlock Woolly Adelgid – This insect sucks plant juice/sap from the needles of Hemlock trees from New England to the Carolinas. The end result is needle death and ultimately the tree's demise. “The insect is one of the leading natural causes of Hemlock death,” Webb says. “If the problem remains unchecked, Hemlocks will be depleted from the ecosystem and the woolly adelgid will either adapt to another tree or die off.” The insects produce a white, waxy covering to shield themselves from the environment, making chemical control very difficult.

Bark Beetle – Currently a forest problem, there is potential for bark beetles to overlap into landscape settings. Warmer winter temperatures are causing these insects to migrate from the Rockies into northern climates. “Northern areas are seeing heavier infestations than ever before,” Dobbs says. No systemic chemicals effectively kill the larva, and the best way to treat it is to spray the trees with a protectant that kills adult insects as they chew through the tree bark to lay eggs.