I have been getting a lot of calls this week about slugs in soybeans. They are a bigger problem this year in some areas because of the cooler, wetter spring/early summer. They are also typically worse in high-residue fields. Although we have had slug problems in both corn and soybean (even a few in cotton), we are not experts in management. We have been communicating with Dr. Ron Hammond at Ohio State University, who is an expert. I know Ron well. He and I have been serving on a soybean/insect regional project for many years and I have a lot of respect for him. Because of the more consistent pressure in his state, several years ago he took on the responsibility of doing slug management research.
Here are a few of the common questions that I have been getting, and some of Ron’s comments.
Question: I have lost my soybean stand and am considering replanting. Would tilling the field help get rid of the slugs?
Ron: “Tilling the field would probably help. However, if slug numbers are high, it might not get enough of them. But overall it should help. A good no-tiller will not do this however. As temps and soils warm and dry up, things will get better because seeds will germinate faster and plants will grow. Galen Dively (University of Maryland) normally suggests late plantings for this reason, as that is when the slug cycle tends to end. Just hope and pray for better weather. That’s what we do. Remember that the slugs are still there, just bigger and hungrier!”
Deadline (by AMVBAC) is the only registered product that will provide good, even excellent, control of slugs. It contains the active ingredient, metaldehyde. There are two mini-pellet formulations, M-Ps which are blue colored, and Bullets, which are tan colored. Most growers prefer the M-Ps as they are easier to see on the ground and make it easier to calibrate the applicator. If Deadline is applied when slugs are present, they will be attracted to it and will feed on it. But keep in mind the pellets do not stay active for more than a few days, and almost any amount of rain rinses out the active ingredient. A 10 lb/acre rate is sufficient, expensive, but effective. Consider treating the worst areas.
Question: What about Larvin? I have read that Larvin will kill slugs.
Ron: “Here is the scoop. Back in the 1980s, we had a grower-prepared bait for corn in Ohio that mixed cracked corn, beer, molasses, and mesurol for slug control. It was a state label. Never could get it for soybean. When soybean began being grown no-till, slugs then became a soybean problem. But we could not use the above bait. However, we found out that Larvin has molluscicidal properties, and got the exact same state label for soybean, but with Larvin rather than mesurol. Worked great. Remember that Larvin has a label on soybean as foliar, so has an EPA tolerance. Also remember that being a carbamate, Larvin has more impact on other things then does metaldehyde. Because of supposed bird kills, the company at the time pulled support of the label. So nobody has the ability to legally use it this way anymore. I checked into it for future use and was basically told, don’t bother…but yes, Larvin will kill slugs, is just NOT LEGAL.”
So what should you do? First consider delaying replanting until the weather straightens out. Delaying planting until it is warmer and drier could be the best approach. If you cannot delay planting, Deadline is the only legal and effective option.