UMass Extension Landscape Message May 9, 2014

"Winter Moth caterpillars remain active but may still be in search of a suitable food source, in some areas. Oaks, which are a common host plant for this pest, are just now showing bud elongation and budbreak. At the time of Winter Moth egg hatch (7-10 days ago) oak buds were most likely still too tight for the tiny caterpillars to gain entrance. When this occurs, the caterpillars will then 'balloon' on the wind in search of another host plant that might be farther along in its' Spring growth. Caterpillars that are not successful at finding a food source eventually die of starvation. Recent monitoring in some areas of Southeastern MA that displayed moderate to large numbers of caterpillars one week ago now appear to be in low numbers. What this means at this time is not yet known. Many of the caterpillars could have ballooned to other hosts, died of starvation, or are just too small at this time to be readily observed. This invasive pest continues to present many challenges for monitoring and establishing population densities. From the standpoint of protecting trees and other host plants, we need to continue to monitor these plants frequently (every 2-3 days) and to make decisions for treatment when damage begins to first become apparent and/or when population size of the pest can be determined. When treatment is deemed necessary, a spray application of an insecticide that contains Spinosad can be very effective. Many pyrethroid insecticides are also labeled for this pest but tend to have a greater detrimental effect on beneficial organisms, such as parasitoids, predators, and pollinators. Do not apply Spinosad or pyrethroid insecticides to plants that are in bloom. For more detailed information about this pest, please see the Southeastern MA Regional Report above that has been submitted by Deborah Swanson in Plymouth County."

Southeast Region (Hanson):
"Rabbits continue to graze and have unfortunately discovered a new favorite, Epimedium sp. Deer also continue to browse their numerous favorite plants. Squirrels were observed biting the tips of branches and also eating the buds of various trees and shrubs, including rhododendron."

Claire