A damaging condition of white oak trees has taken hold of extensive portions of forests in Wood County, says the West Virginia Department of Agriculture. A local forester, Jack Mathers, who has been tracking the problem for several years, brought the situation to the attention of the West Virginia Department of Agriculture and the USDA Forest Service. Mathers who works for Haessly Timber and Logs of Marietta, Ohio, recently spent a day with officials of WVDA and the USDA Forest Service, looking at areas where decline is occurring.
The Forest Service notes oak decline is a periodic occurrence of dieback or death of oaks. Reasons for oak weakening can be varied, including defoliating or sucking insects, drought, waterlogging or frost. Weakened trees are then killed by insects and diseases that normally cannot attack healthy trees. The conditions usually occurs over a period of years.
After studying the affected trees, the WVDA reported that there was considerable evidence of jumping oak gall wasp on the leaves.
"Surveys are underway now to document areas of jumping oak gall wasp and oak decline," says Agriculture Commissioner Gus R. Douglass. "At this time, we don't know how wide-spread the problem is."
The wasps lay eggs in the tissues on new oak leaves, which forms galls on the plant. Each gall contains a single immature wasp. When the galls mature they fall off the leaves but leave small pits. A number of galls can cause the leaf to turn brown and fall off. New generations of the wasps overwinter in the galls and emerge the next spring to start a new cycle of damage.
"This stress leaves the tree wide open for secondary agents such as Armillaria root rot and Hypoxylon canker to establish along with other decay fungi and secondary insects such as wood boring insects," says WVDA Forest Pathologist Jill Rose. "This causes further decline of the tree and, eventually, death."
The WVDA asks that if you detect outbreaks of oak decline to contact the Department's Plant Industries Division by phoning 304-558-2212.
Information about oak decline can be found at the USDA Forest Service web site at www.na.fs.fed.us/spfo/pubs/fidls/oakdecline/oakdecline.htm