Have you ever looked at your garden and wondered how so many giant holes magically appear on your zucchini plants overnight? Have you seen the slimy living boogers and wondered if maybe there are more of them this year? Turns out that slug populations have grown in the Willamette Valley over the past decade, and both farmers and researchers have taken notice.
In the not so distant past, slugs in the Willamette Valley weren’t an issue, but that has slowly changed. Some farmers believe that implementing the “burn ban” has something to do with their increasing numbers. Historically, farmers might opt to burn their fields after harvest, but after a 21-car pileup on I-5 in 1988 thanks to a large field fire, the rules changed.
Making things worse are the changes in soil conservation, including no till and conservation tillage practices in which residue from the previous year’s crops is left. This ready food source and habitat, along with not being burned to death, has helped grey slug populations grow around the country.
Some farms, such as Saddlebutte Ag in nearby Tangent, attest to spending as much as $60,000 per year trying to control the primordial plant predators. Other estimates suggest that farmers could be spending up to $40 per acre on controls, while Oregon’s agricultural industry is suffering anywhere between $45 million and $60 million in damages.
Metaldehyde and iron pellets have been used, but that usefulness is in question as they have little effect on slug eggs. Luckily, researchers at Oregon State University are working to find new solutions. Last year OSU picked up slug and snail expert Rory McDonnell, who studies interesting ways to kill the little goobers.
McDonnell is currently studying a native US nematode that may serve this purpose. While a similar nematode is doing the trick for European farmers, McDonnell is busy making sure the US variety will not parasitize other critters along the way. Also in the works are studies into plant extracts, oils, and attractants to lure unwary slugs into kill zones.
However, until more conclusive research is presented, the rest of us are encouraged to grab a salt shaker or magnifying glass and take matters into our own hands. If you drink a lot of coffee, try spreading the grounds around your favorite plants, just remember to replace them as it rains.
By Anthony Vitale