Vole population explodes
    Oregon’s Willamette Valley was overrun by voles last summer, and the small rodents caused extensive damage to vegetable crops, seed crops, vineyards and nurseries. Voles, also known as meadow mice or field mice, are 5-8 inches long, including the tail. They eat crops and can kill trees by gnawing on trunks. They multiply rapidly, with each female capable of producing a litter of 4 to 8 young every three weeks.
    According to the University of Caliornia IPM program, widespread population peaks are difficult to control. Trapping is minimally effective and repellents don’t work. The only thing that works is to remove their cover, the IPM program says.
    “You can reduce the base area from which voles can invade gardens or landscaped areas by regularly mowing, spraying with herbicides, grazing, or tilling grassy areas along ditch banks, right-of-ways, or field edges adjacent to gardens. If feasible, weed-free strips can also serve as buffers around areas to be protected. The wider the cleared strip, the less apt voles will be to cross and become established in gardens. A minimum width of 15 feet is recommended, but even that can be ineffective when vole numbers are high.”
http://www.ipm.ucdavis.edu/PMG/PESTNOTES/pn7439.html
    Some growers have reported success at controlling voles with a mouse bait called Rodetrol. The product looks like dog kibble and is made of corn cobs, corn syrup and molasses. Its manufacturer claims that it prevents water absorption in a rodent’s digestive tract, which causes the animal to become listless, go into a coma and die. Its label and MSDS state that it is harmless to birds, fish, pets and humans. A company spokesman said that voles are susceptible to the product, but moisture outdoors may break it down. A vole-specific formula will be developed this year. He also said the product would be submitted for review to the Organic Materials Review Institute; if approved, organic growers would be able to use it.  For more information about Rodetrol, visit www.rodetrol.com or phone 877-622-8765.