Spring and Winter Moth
With spring comes winter moth--what you can do
The Joys . . .and One Scourge of Spring
Horticulturist and Plant Records Coordinator
Warm sun and the return of green life—spring is a joy that never fades. Everyone gladdens at the sight of emerging flower beds. Now is a time to enjoy woodland ephemerals like celandine poppy (Stylophorum diphyllum) and Virginia bluebells (Mertensia virginica). Trilliums are in their glory as is swamp azalea (Rhododendron viscosum). Large yellow lady’s slipper (Cypripedium parviflorum var. pubescens) is just beginning to lure bumblebees while highbush blueberry (Vaccinium corymbosum) is finishing. Creeping phlox (Phlox stolonifera) is a flurry of blossom and scent.
While all this happens at our feet, don’t forget to look up! The forest that shelters these gems is also unfolding. You’ll find a canopy of hardwood and mixed forests at its most colorful. As the bright red flowers of swamp or red maple (Acer rubrum) fall, silver maple (Acer saccharinum) and sugar maple (Acer saccharum) leaf out in a range from garnet red to lime green. Just after maples, our many native oaks unfold and prepare to flower. Starting out in khaki tones, oaks slowly expand and thicken their leaves to an eventual range from deep green black oak (Quercus velutina) to the bluish white oak (Quercus alba) and swamp white oak (Q. bicolor). A few of the exquisite understory trees in flower include Sassafrass (S. albidum), flowering dogwood (Cornus florida), and redbud (Cercis canadensis).
Beware the winter moth
Everywhere among the trees are birds busily feasting on emerging insects. Now is also a time to look for early signs of infestation on trees. One pest that may have wintered over in your trees, recently arrived in Eastern Massachusetts, is winter moth (Operophtera brumata). This moth is a non-native agricultural pest in the Pacific Northwest, where the parasitic fly Cyzenis albicans has been used to control winter moth with some success.
Winter moth feeds on the buds and emerging leaves of oaks, maples, birches, and other trees. For apple and blueberry growers, winter moth can bring big losses. Confirmed in nine eastern Massachusetts counties, winter moth has also been detected in coastal Maine, southeastern Connecticut, and throughout Rhode Island.
Rolf Briggs of Tree Specialists, Inc. in Holliston, Massachusetts, has been monitoring winter moth in 22 Metrowest communities, tracking population density and targeting locations of highest infestation for treatment. Mr. Briggs has worked in conjunction with Dr. Robert Childs and Dr. Joseph Elkinton, entomologists from U. Mass. Amherst, on projects to release parasitic flies against winter moth in Massachusetts.
What you can do
And homeowners can help! Reporting damage helps track the pest (To find our more, visit massnrc.org/pests. ). Protect your trees during dry spells. Watering deeply and slowly can go a long way to helping trees naturally recover from pest damage., “People should water their trees,” Briggs advises “over the next four to five weeks during dry periods to encourage a second set of foliage after damage. In the absence of rain, an inch of water per week is needed.”
Trees can produce a new set of leaves and regain their lost energy quickly with your help. “In an urban environment, this should be two inches of water each week,” says Briggs,. “The added competition of turf, stress from road salt, and lower air quality means more care, and water, are needed.
“It is important not to treat trees that have no holes in their leaves. Do not spray trees pre-emptively,” Briggs emphasizes. Targeted use of chemical controls is a last resort. Our understanding of this pest and possible means of control are still developing. Indiscriminate spraying can cause more damage than the target pest, so restraint and basic tree care are the best courses of action.