Winter Moth Could Damage Area Trees

Tree buds are a welcome sign of spring. Unfortunately, the winter moth is due to return within the next several weeks and attack those beloved buds. If not treated properly, emerging leaves could be riddled with holes, and complete defoliation may ultimately kill the tree in as little as four-years, according to Kristina MacPherson, Manager of .

MacPherson said that a variety of treatments are available that should be applied now to protect the foliage and the health of the trees.

“Winter moth is very destructive to a wide range of deciduous plants such as apple, cherry, blueberry, maple, oak, linden and ash,” MacPherson said. “In Massachusetts, the Eastern part of the state typically sees the most damage, making preventative measures important to saving our trees.” 

Many outbreaks popped-up last spring, MacPherson said, causing concern for this spring. Adding to the concern was the high amount of moths that were seen this winter. According to MacPherson, that is a warning sign that outbreaks may be high.

When temperatures begin to average 55 degrees, the winter moth eggs begin to hatch. The caterpillars then find their way under the scales of flower and leaf buds to feed on the unopened bud.

As the caterpillars grow, they continue to feed on unfolding leaves and are capable of defoliation on a large scale, MacPherson said. If spring flowering is delayed, the problem is further intensified as caterpillars continue to feed on closed buds. In fruit trees, such as apple or blueberry, this may lead to a loss of fruiting.

As a first level of defense, MacPherson recommends spraying trees now while they are dormant (no leaves out) with a horticultural oil, such as Bonide All Seasons Horticultural Oil, to smother the eggs. Spray should be applied when temperatures are above freezing for 48 hours, so as not damage the plants. Cover as much bark and stems as can safely be reached, she suggested.

As leaves unfold, caterpillars will appear to swing from the trees on silky strands spreading to neighboring trees.

“We recommend spraying trees with a product containing spinosad, such as Bonide’s Captain Jack’s Dead Bug Brew,” says MacPherson. “Spinosad is a natural bacterium that targets caterpillars and similar insects. Once ingested, the caterpillars will stop feeding immediately and die within two-to-three days.” 

If trees are sprayed as the leaves are unfolding, MacPherson advises additional applications to protect the untreated foliage.

Unfortunately for the typical homeowner, many trees are far too large to treat on their own. Many companies, such as Mahoney’s SafeLawns and Landscapes, have now emerged that offer spraying services capable of reaching the tops of large trees.

“Our service division, Mahoney’s SafeLawns and Landscapes offers a full line of organic lawn and plant healthcare services, including packages for Winter Moth, as well Hemlock Wooly Adelgid, another destructive invasive insect,” MacPherson said. “Our products are deemed safe for the environment, an aspect we pride ourselves on.”

Should a homeowner wish to treat trees on their own, all of Mahoney’s retail locations carry the above-mentioned products.

Treatment is best applied now to protect healthy plants from defoliation. For more information please visit www.MahoneysSafeLawns.com or call (781) 305-5555.