The leaf-eating Gypsy Moth caterpillar (Lymantria dispar) is one of the most invasive and destructive pests in the United States, and has killed or damaged millions of acres of trees. The past years’ of drought conditions in many regions of the country inhibited the fungus that is a natural predator of the Gypsy Moth larvae, causing several U.S. states to predict significant caterpillar infestation in 2017.
While conifers, and any weak trees, may die after a single season of gypsy moth defoliation, it usually takes more than one year of defoliation to kill deciduous trees. Most healthy deciduous shrubs and trees can lose up to 50 percent of their leaves without terrible effect, and will push out a secondary set of late-season leaves when the primary set of leaves has been destroyed.
However, even a partial defoliation can severely stress a tree, putting it at risk for secondary pests or diseases. While in this weakened state, the tree requires special care and attention to help it recover. Here’s what you can do to help:
Fertilization. Don’t fertilize the tree immediately after defoliation, since that may force excessive new leaf growth — growth that puts added demands on the tree’s food reserves. Rather, fertilize the stressed tree in the fall, or in the early spring after the ground thaws.
Watering. The tree needs one inch of water each week, so ensure it gets that through natural rainfall and/or by a deep watering once per week during dry periods (soaker hoses work well).
Pruning. We recommend not pruning the already ailing tree, since it could cause additional stress and slow recovery.
A strong and vigorous tree is better able to resist Gypsy Moth damage and recover from an infestation. Treatment with SavATree’s exclusive ArborKelp biostimulant will promote root growth and heighten stress tolerance.
