Looking at one of my corn trials last week was a reminder that slugs may be a bigger issue than usual this year.
Cold damp weather coupled with slow seedling growth is a recipe for slug problems.
Below are some things to keep in mind when thinking about slugs.
• Slugs will feed on leaves and the stems of all major row crops, sometimes cutting the plants like a cutworm. Begin a wimpy seedling, cotton is pretty sensitive to slug feeding, but corn and soybeans are also at risk.
• Slugs feed mostly at night, but like I observed last week, they can also be found feeding during the day in cloudy and cool weather. Mysterious holes in the leaves are a sign of slugs. They will often be hidden under debris and clumps of soil during the day. Plants may be cut similar to cutworm injury.
• Slugs are almost exclusively a problem in reduced-tillage fields but could be a problem in conventional fields that had very heavy weed cover the previous fall.
• Because they tend to occur where there is a lot of residue, be especially alert following a previous crop of corn or sorghum. They also tend to be worse in low, wet areas of the field. And these areas are the same spots where seedlings tend to grow slowly.
• Planting in wet fields, where the seed trench does not close completely, creates a slug highway down the row. In my experience, this creates the worst problems because slugs will feed all day long in the seed furrow, even before the seedling has completely emerged.
• Insecticides seldom provide effective control of slug infestations. They slough off the nastiest of chemicals.
• The only reliable treatments are baits that contain metaldehyde. Deadline M-Ps is a bait from Amvac that contains 4 percent metaldehyde. The Deadline M-Ps label allows a use rate of up to 40 pounds per acre in field crops, but it is pretty expensive, so the standard rate is 10 pounds per acre.
Deadline M-Ps is a pellet and must be spread relatively evenly across the field, which requires some planning. Also, this product is not typically carried in stock by local retailers. Be sure to place you order as quickly as possible if you decide treatment is needed.
• Treatment is recommended when slugs threaten to reduce stands below acceptable levels. I know that is a “weak” threshold, but it is really the best I can do. You can tolerate more slugs as seedlings get larger and as the weather warms (and dries).