Cereal Rye and Slugs

It’s a typical Ohio spring. Sporadic rains, followed by a few days of sunshine, then more drizzle. Farmers are trying to get crops planted, but progress varies. Under these conditions, cereal rye is growing fast which can help dry out soils but tends to shade newly planted crops. Second, with a warm winter and fairly warm spring with rain, slugs and voles (field mice) are flourishing. Weeds are also growing because it is too wet to spray all the fields. Here are some tips to deal with these problems. 

Cover crops, especially cereal rye, outcompete many troublesome weeds but the cover crop needs to be terminated. Most farmers will kill the cover crop with herbicides but crimper crop rollers can terminate naturally and if the crop is tall, get it on the ground. Once it is on the ground, it will hold moisture and keep soil temperatures cooler going into summer. Cereal rye is a natural fit for soybeans but is more difficult to manage with corn. Soybeans thrive on the nutrients released in late summer. Corn can suffer from the allelopathic effect or weed suppressing effect of the chemicals in the stems and leaves. 

If it is dry, farmers often terminate their cover crops early. In wet years, let them grow to help dry out the soil. Planting green is the best option, but you need a no-till planter or drill. Remove or lift up residue managers since they tend to clog up with residue. Second, remove front coulters and rely on sharp disc blades to make a furrow for seed. Farmers have the capability to put a large down force on their planters, but excess downforce causes seed placement issues. Conventional farmers do not like to plant their crops too deep due to crusting. 

On no-till fields, planting 2+ inches deep on soybeans and up to 3 inches on corn can be beneficial. The crops take a little longer to emerge, but they emerge often within 24 hours of each other and they have a deeper and more extensive root system. This helps them grow faster if slugs and voles are an issue. 

On corn, you can crimp it from V3 to V4 or three and four true leaves. On soybeans, after the first 1 or 2 trifoliate leaves emerge up to 4-6 inches tall. Soybeans benefit from late crimping, causing a hormonal change which makes them bush out and put on a few more pods, resulting in up to 5-7 bushels more soybeans. If planting cover crops before corn, try to get a variety that has a low allelopathic effect like Elbon, a certified cereal rye variety from Michigan. Better yet, plant legumes or clovers like Balansa, crimson, hairy vetch, or peas to add nitrogen. On soybeans, the variety is not as important because it is not affected by allelopathy. 

Both slugs and voles like this damp weather. They both like crops that have a low carbon: nitrogen ratio which means they like crops that are high in N or protein. Slugs love red clover, alfalfa, and soybeans. They generally only consume corn if there is nothing else to eat. While the no-till and cover crops is a great habitat for both species, they are also a problem in conventional tilled fields too. There are several things farmers can do to minimize slug and vole damage. 

First, plant both crops deep because the plant is stronger and then they can outgrow the feeding. Second, make sure the planting slot is closed. Sprouting seed that is not covered is like a feeding highway for both slugs and voles. Slugs prefer cereal rye over corn, so the cereal rye may reduce corn slug damage if the plants grow fast. To check for slugs, put a board or shingle in several places in the field. If you find more than 5 slugs per board, expect some problems. Over 10 slugs, expect a lot of problems. Getting the cover on the ground can help predators like birds (owls, starlings, hawks, etc.) and other predators get access to both slugs and voles. 

Farmers may apply pelleted baits on slugs and voles but they are about 50% effective. Baits tend to get expensive. On voles, the material often has to be applied in furrow. Small dogs, owls, hawks, and fox are the best natural predators. Rain and humidity cause pellets to mold, so they are effective for about 48 hours. If a slug eats the bait but does not die, they will not eat it again. Lime and gypsum spread over growing plants can help deter slugs. Sunny weather and fast-growing crops are the best cure!