OAK WILT An Invasive Pathogen on Connecticut’s Doorstep!

P. Kurzeja, Forest Health Division, D. N. R.

What is it? Trees at risk: Where is it?

Oak wilt is a vascular disease of oak All oak species are susceptible and at risk. Oak wilt has spread throughout trees, caused by the Bretziella The red oak group (red, black, pin) is the the Eastern United States. Since (formerly Ceratocystic) fagacearum. The most susceptible, with mortality frequently first identification in NY State, fungus grows on the outer sapwood occurring within one growing season. oak wilt has been confirmed in of oak trees restricting the flow of in the white oak group (white, bur) are also numerous locations in Brooklyn and water and nutrients through the tree. affected but are more resistant. Long Island.

Signs and Symptoms: Impacts:

• turn dull green, brown or • Impacts property values and yellow neighborhood aesthetics • Discoloration of leaves • Increased costs with tree progressing from the edge of maintenance, removal and the to the middle replacement • Wilting and bronzing of foliage • Loss of a valued shade tree starting at top of the tree and • Negative impacts to the forestry moving downwards industry and production of high • Premature leaf drop (including value oak products green leaves) • Reduction in food source for • White, grey or black fungal mats forest animals provided by oak just under the that emit a trees fruity smell • Loss of habitat for some species • Vertical bark cracks in the trunk • Reduction of ecological services and large branches as a result of (air and water filtering) the fungal spore mats (also Invasive Species Centre D.W. French, • Safety and liability issues referred to as pressure pads) University of , exerting outward pressure on the Bugwood.org bark How is oak wilt spread?

Roots Insects Humans

The disease spreads from infected trees Insects such as sap-feeding nitidulid Movement of products, to uninfected trees of the same species beetles can move spores from infected (particularly those with bark), such as through -to-root contact. trees to healthy trees. firewood can spread the pathogen over long distances as they can harbor fungal mats.

James Solomon, USDA Forest Service, USDA Forest Service, Northeastern Joseph OBrien, USDA Forest Service, Bugwood.org Area State and Private Forestry Bugwood.org

What can you do? There is no cure for oak-wilt infected trees. The best approach is to avoid or reduce in areas where disease occurs by:

• Identifying and removing diseased trees; • Preventing the formation of, or severing, existing root connections between diseased and healthy trees; • DO NOT prune oak trees from April to • Minimizing wounds on healthy trees during the flight period of July. If must occur, or if a tree is injured, apply a thin layer of wound potential insect carriers. paint immediately.

• DO NOT move firewood. Oak wilt is spread by the movement of infected wood. If you see signs and symptoms of oak wilt, report the sightings to:

Dr. Robert Marra Department of & Ecology Connecticut Agricultural Experiment Station New Haven, CT [email protected] 203.974.8508

For more information on oak wilt, visit: https://www.fs.fed.us/research/invasive-species/plant-pathogens/oak-wilt.php