Snail Update: Impacts and Abamectin

Snail impacts on Southeast citrus production can be devastating. A big part of the problem is not the damage to citrus trees but the harm the pest inflicts on irrigation systems.

Lauren Diepenbrock, University of Florida Institute of Food and Agricultural Sciences associate professor and entomologist, conveyed this message to cold-hardy producers during the Citrus Grower’s Summer Update meeting on Aug. 14 in Valdosta, Georgia.

“Our trees already have starved roots from citrus greening, and now we’re adding these organisms (Bulimulus bonariensis) that are blocking the irrigation,” said Diepenbrock. “Trees are not getting the water and not getting the nutrients that they might be getting from fertigation systems. That’s a huge problem.”

B. bonariensis, commonly known as ghost snail or peanut snail, is known to be tree dwelling. The pest will climb trees, microjets and structures. Snails have an epiphragm, a membrane that protects them during periods of prolonged dryness and other unfavorable conditions.

Diepenbrock has been studying the pest over the past five years with the help of funding from the Citrus Research and Development Foundation.

“In 2020, when the growers were first telling me that they had these problems, I was kind of shocked. I really didn’t think the snails would be that big of a problem. That same year, I went out and saw how bad they were affecting the irrigation,” she said. “They’re not really feeding on the trees, necessarily. But if they get stuck in the individual protective cover, they will absolutely feed on the vegetation, and you will see defoliation. But for the most part, when we see them feed on mature citrus trees, it’s actually because they’re feeding on the canker or feeding on some other damage.”

Diepenbrock has been evaluating different chemical controls for snails. Chemistries with abamectin have shown the greatest contact mortality in her research. However, that knowledge comes with caveats.

“Abamectin is highly effective in killing this particular group of snails, if and only if it makes contact with their flesh,” she said. “It has to be done early in the morning or later in the evening when snails are active. There’s no residual on it. We don’t have all the proper documentation to make a recommendation on abamectin, and it’s not actually labeled for use on snails. But if you’re spraying already, you might get some bonus out of it.”