Garden Tip #34

Verticillium wilt is making an appearance now as trees and shrubs begin to leaf out. Maple trees are especially susceptible. The sudden wilting and death of one or two branches in an otherwise healthy looking tree is the one obvious symptom. If this soil- borne disease attacked early in spring, tree branches may not have leafed out at all. Cutting into an affected branch typically reveals dark streaks. Control is difficult, but sometimes a tree can be preserved for a few years by cutting out the diseased wood and eliminating environmental stress such as drought. Make sure to disinfect pruning tools between cuts to avoid spreading the fungus. No fungicides for verticillium are registered for homeowners in Washington. For more information read Washington State University Cooperative Extension online article.

Garden Tip #33

Don’t despair if verticillium wilt lives in your garden’s soil because there are many resistant plants. A few verticillium-resistant trees include Apple and Crabapple, Mountain Ash, Ginkgo, Sweet Gum, Katsura, Douglas Fir, Arborvitae and White Oak. A long list of susceptible and resistant trees, shrubs, perennials and vegetables.

There is some evidence that broccoli (chopped up new shoots worked into the soil) can act as a soil fumigant, if added to the soil before planting. Studies were done by Krishna Subbarao at University of California, Davis, and showed reduced incidence of wilt in cauliflower crops where broccoli had been planted and its residue added to the soil.