Slugs & Dahlias

Dahlias (Dahlia pinnata) are flowering plants from Mexico. They vary widely in size, color and form depending on the cultivar. Slugs attack dahlias during the early part of the growing season.

Identification

Slugs are mollusks, closely related to invertebrate organisms such as oysters and clams. They look like snails but they have no protective shell. Most slugs are gray or brown in color, and they range in size from 1/4 inch to over 2 inches in length. They have soft, elongated, worm-like bodies and eyes that protrude from narrow stalks.

Effects

Slugs chew irregular holes in dahlia leaves. They primarily prefer young foliage, according to the University of Minnesota. Slugs mainly cause cosmetic damage, but serious infestations can weaken or kill plants. They are more active during the evening, but they can be seen occasionally in cool, moist shady locations during the daytime.

Control

Dahlia growers hand-pick slugs from the plants or trap them by burying jars or containers in the ground so that the neck of the container is level with the soil surface. They pour beer, or a mixture of water and yeast, into the containers. Slugs are attracted to fermentation odors, so they crawl in and drown. Animals such as snakes and turtles also provide biological control by feeding on slugs.

References

• University of Minnesota Extension: Growing Dahlias
• Ohio State University Extension Fact Sheet: Growing Dahlias
• University of Minnesota Extension: Slugs in Home Gardens