Slugs – A Persistent Problem in Cool Years

I have gotten numerous calls about slugs this year in all crops but lately in cotton and soybean. Slug problems usually start on corn then soybeans then cotton in our area. This is only because we typically plant in this order. We have had isolated problems with slugs since 2004, some years worse than others. This has been exclusively a no-till problem, particularly no-till behind a grass crop like corn or grain sorghum. In 2005, Dr. Jeff Gore and I conducted several studies looking at control options with limited success. Insecticides simply do not work. The only viable option we found was products that contain metaldehyde as the active ingredient which is made for slug and snail control. Deadline MP’s by Amvac worked extremely well but is costly. Deadline MP’s is a pellet that must be broadcast at rates of 10-40 lbs per acre. The 10 lb rate is approximately $18.00-20.00/acre. The pellets attract the slugs where they feed and die. In a replicated test we conducted in 2005, we had a 96% percent reduction in slug numbers at the 10 lb rate compared to the untreated check. Option 2: If you have a persistent problem, tillage may be required. Also, dropping your residue removers down where they scratch the soil surface more than usual has been reported to provide enough of a clean band to get the plants up and going to get some size on them; however this does not always work under heavy pressure. This is a serious problem where they occur and often leads to replants. Keep in mind, if you have to replant, the slugs will still be there and you will be replanting back into the problem. In 2004, we had some fields that were replanted from slug damage and the replants were replanted from slug damage.

As long as the slugs are only feeding on the leaves and not the growing point, the plants will usually grow out of the problem with no yield loss, but it can delay the crop. The most severe damage caused by slugs is when they “run the drill”. This is when the press wheels do not close the seed furrow properly and slugs feed on the stems below the ground which causes them to break off and looks like cutworm damage. This can lead to extreme stand loss. With hot weather arriving most of these situations will correct themselves when plants simply outgrow the problem.

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