Here in the Northeast, spring is taking its time arriving. Mike had to postpone pruning because of cold temperatures and a snow storm on April 4th that brought us 5″ of snow. Now with temperatures a bit more in the normal range, our roses are starting to show a burst of new growth, but with warmer temperatures comes a new annual event — the arrival of winter moth larvae.
Winter moths are small, light brown moths that were first recorded around 1930 in Nova Scotia. They slowly migrated south along the east coast into New England, were detected in Massachusetts in the 1990s and arrived in Rhode Island in 2004. Our first encounter with them was several years ago. The moths mate in early December, hence the name, and lay their eggs in trees and shrubs. The eggs hatch sometime in April in our garden. It’s this larvae stage that does the damage by feeding on a wide variety of plants including our roses and blueberries.
Mike noticed chewed-up foliage and discovered moth larvae yesterday — small, green caterpillars that had rolled up in a silky cocoon inside our rose leaves. This is when they surreptitiously eat away on the foliage and young rose buds unless an intervention takes place.
While we very rarely apply insecticides in our garden, we do spray our roses, as well as our blueberry bush, for winter moths with a very low toxicity product called Spinosad. This is a naturally occurring soil dwelling bacterium that works on larvae by contact as well as by ingestion — IF applied at the right time. The best time to apply Spinosad is immediately after egg-hatch in early spring before the tiny worms tunnel into buds.
So today Mike applied his first dose of “Captain Jack’s Deadbug,” an organic pesticide containing Spinosad. (Another effective product is “Monterey Garden Spray.) Usually, spraying twice, seven days apart will solve the winter moth problem and as an added benefit, rose sawflies will be controlled at the same time.
Without the use of Spinosad, the foliage on our trees, roses and blueberry bushes wind up looking like Swiss cheese. Since Captain Jack’s toxicity is extremely low, we find that using this product gives us the best outcome.