mint rust

Symptoms

Distorted pale spring shoots (systemic infection), bright orange rust pustules on the underside of leaves in summer, brown spore patches in autumn, reduced harvest.

Easily confused with

• olive Verticillium wilt

  How to tell them apart: Puccinia menthae (mint rust) and Verticillium dahliae (Verticillium wilt) both yellow mint foliage, but the diagnostic signs are clear once you look closely. Turn leaves over: mint rust shows raised, powdery orange-to-rust-brown pustules (and earlier, pale yellow swollen spots with distorted, thickened young shoots) scattered on the LOWER leaf surface, all on healthy soil. Verticillium wilt shows NO pustules — instead yellowing and brown marginal scorch appear one-sided or on a single shoot/branch, the plant wilts in heat, is stunted, and a cut through a lower stem reveals brown streaking of the internal vascular tissue. In short: orange dust under the leaf = rust; one-sided wilt plus brown stem-vessel streaks = Verticillium.