Tackling slugs in no-till fields

By Blake Jackson

In 2024, many no-till farmers faced significant challenges with slugs, leading to replanting soybeans multiple times to achieve acceptable stands.

Slugs are not insects but mollusks, a group that includes snails and clams, making them difficult to control with traditional insecticides.

No-till fields, particularly in regions with abundant rainfall, provide a stable environment for slugs, allowing their populations to thrive.

One common species causing damage is the grey garden slug, which has one generation per year, with eggs hatching in spring.

Juvenile slugs feed on crops during cool, wet conditions and burrow into the soil during the hot, dry summer. In the fall, they mate and lay eggs before most die from winter cold.

The mild winter of 2023-2024 contributed to higher slug populations. Warmer-than-usual temperatures and abundant rainfall allowed slugs to remain active longer.

Slugs can survive temperatures just above freezing and even endure cold spells as long as they are brief.

Long periods of extreme cold are necessary to significantly reduce their populations, which is becoming less common due to climate change. Another challenge was early planting.

Research has shown that early-planted soybeans have higher yield potential, encouraging farmers to plant soybeans before corn.

However, in regions with high slug populations, early planting can expose slow-growing soybeans to slug damage, particularly when cool, wet weather follows planting.

To reduce slug problems in the future, farmers should remain flexible with planting plans.

After a mild winter, it may be better to plant corn first, which is less susceptible to slug damage, and delay soybean planting until soil temperatures rise.

Farmers should also adopt integrated strategies to manage slugs.

Diverse crop rotations and practices like planting cover crops, using row cleaners, applying starter fertilizer, and ensuring good furrow closure can promote early crop growth, making it harder for slugs to cause damage.

Maintaining populations of natural predators, such as ground beetles, can help control slug populations, but this requires minimizing unnecessary insecticide use.

For farms affected by slugs, it’s important to develop a plan for the next season, considering all these strategies to manage slug pressure effectively.

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