Dealing with slugs is about as much fun as it sounds. Last May I was called to southeastern Indiana where slugs were riddling a soybean field. Normally they hit earlier in the spring, when it's cool and wet, experts say, but they caught a window while it was wet and turned back cool with the crop up from Scottsburg to Clark County and riddled several fields.
Ken Scheeringa, assistant state climatologist, says to look for a warmer than normal, wetter than normal spring. Slugs like the moisture, but they prefer cooler temperatures. If a cool week develops and there is moisture with the crop up, they could be a problem, especially in fields with residue.
"They're an occasional pest at best in Indiana," says Andy Like, Daylight Farm Supply, Evansville. "When they do appear they are generally only a problem in early planted no-till or minimum till fields where plants are unable to outgrow the feeding.
"Damage to soybeans is usually worse than to corn. The growing point gets above the ground faster," he says.
Corn would have a chance to regrow because the growing point on corn plants doesn't emerge until the fifth to sixth leaf stage.
One problem is that while you may go your whole career and never encounter slugs, once is more than enough, and there are no good controls.
"Unfortunately, no economic threshold levels have been developed for slug infestations," Like says. "Only one active ingredient is labeled for slug control – dry granular baits containing metaldehyde. However, they can be cost prohibitive and can be difficult to apply."
Slugs can wipe out stands by feeding on seedlings. They may be worse in some areas than in others. Look to areas with the most residue first. They generally feed at night. However, they leave behind a trail of mucus that can be seen during the day. Look hard enough and you can likely find them hiding under residue.