Slug sleuths: Ohioans take lead on slippery path


COLUMBUS – Something chewing on your just-planted beans? Ohio farmers, particularly no-tillers, are getting used to battling slugs.

And some of the best research on waging that battle is being done right here in the Buckeye State.

Team approach. The USDA’s Natural Resources Conservation Service, the Ohio Agricultural Research and Development Center , the Ohio Department of Natural Resources’ Division of Soil and Water Conservation, Ohio State University Extension, local Soil and Water Conservation District offices and some farmers are all working together on Ohio’s slug problem.

Field studies include the testing of slug baits, the use of rotary harrows that fluff crop residues and disturb slug eggs, and soil testing to determine if soil pH or soil nutrient levels effect slug populations.

Hard to get ahead. “The best strategy is to try to get your crops to outrun the slugs and we haven’t been able to do that this year,” said Natural Resources Conservation Service state agronomist Norm Widman.

“We thought the weather last year was as bad as it would get, but this year is worse than last.”

Widman said weather that’s good for the slugs is bad for the crops and vice versa.

“If we got some warm, sunny and dry weather, we could really cramp the slug’s style. We need all three of those things. It remains to be seen how these experimental slug treatments will work under conditions of normal weather.”

Let’s talk trash. The heaviest infestations of slugs have occurred on no-tilled fields. High levels of crop residues, or trash, from no-till farming can create a cool and moist environment that is favorable to slugs under certain weather conditions.

However, even some conventionally tilled crop fields in Ohio are suffering from unusually high slug infestations.

The probable cause is the unusually cool and moist weather that Ohio has experienced last year and this spring.

“There is even considerable damage in fields that were disked and harrowed,” Widman said.

“This spring, we were expecting good control by using the harrow. But right now we don’t know if the harrow hasn’t been effective enough or if it is just the extremely bad weather that has contributed to the slugs.”

Because of delayed planting, it is too early to evaluate the effectiveness of the other treatments being studied.

Good news. “We’re still better off than we were last year because some of the crops got planted early enough that they were able to outpace the slugs,” said OARDC entomologist Ron Hammond. “A year ago, that just didn’t happen.”

Researchers had hoped that light harrowing of crop residues in the fall might provide farmers with a weapon in the battle against slugs, but it showed little or no benefit this year, Hammond added.

Bait and wish. The most widely used technique for slug control to date has been the use of baits and, according to Widman, the use of slug baits has been the most successful treatment so far this year.

Widman said one of the baits that has tested successfully is Deadline MPs (mini pellets). Although some questioned the product’s efficacy in recent weeks, both Widman and Hammond said reports suggest that the material is working as expected.

“The bad news is that as the bad weather persists, the slugs go through new hatches and retreatment is sometimes needed,” Widman said.

For more information on techniques to control slug infestations, contact Widman at the NRCS state office, 614-255-2467, or contact Ron Hammond, OARDC, 330-263-3727.

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How do you know if slug treatment is working?

WOOSTER, Ohio – Concern with slugs persists, especially on crops planted the past few weeks and on those crops remaining to be planted.

Growers should continue to monitor their fields, recommends Ron Hammond, OARDC entomologist.

Is it working? Some growers are questioning the efficacy of Deadline MPs, but Hammond said most reports suggest that the material is working as expected.

When judging whether a treatment has worked, growers should examine the new corn leaves emerging from the corn whorl or on soybeans, the top-most leaves that are opening. If these newer leaves are free of slug feeding, one can usually assume that the majority of slugs have been controlled and the treatment worked.

If feeding continues to be heavy on these upper most leaves, re-treatment might be warranted.

Second treatment. Growers should only re-treat those areas of the field where slug feeding is continuing. Usually, the majority of the field will not need re-treatment.

Looking for dead slugs following treatment will not be worthwhile as none will be found, nor is looking for the continued presence of Deadline MP pellets, Hammond said. A heavy population of slugs will often consume most of the bait.

Take head count. Counting slugs at dusk will also indicate whether many slugs are left and the relative efficacy of the bait, but the slug counts should be random across the field, not just in areas where feeding is continuing.

These counts are only valid, Hammond reminded growers, if you knew how many slugs were present prior to treatment.

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