Peppermint Plant Diseases

Verticillium Wilt

• Verticillium wilt is a fungus that lives in the soil and in mint plants. Initial symptoms may be curled or twisted upper leaves, followed by stunted plants that turn yellow, bronze or red as lower leaves die. Infected mint plants sometimes die before symptoms are observed.

Rust

• Rust symptoms on peppermint begin with round, brown pustules on the underside of the leaves, which then become discolored and fall off. Yellow blisters may appear on the plant in spring, while black spores appear on stems in the fall.

Powdery Mildew

• Mildew appears on mint leaves as a gray, powdery fungus, causing leaves to turn yellow and fall off.

Plowing and Flaming for Disease Control

• Plowing over stubble can help control plant mildew and rust; flaming works on rust and sometimes on verticillium wilt as well, if it is not too firmly established.

Crop Rotation

• Once verticillium wilt is established in a field, you should plant crops other than peppermint for six or more years before trying again.