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.

Plants affected

• peppermint
• spearmint

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.

Common questions

How do I recognise mint rust on peppermint?

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

Do I have to report mint rust?

No. mint rust is not a notifiable organism, so there is nothing to report to an authority. Treat it as a normal garden problem.

How is mint rust treated?

Mainly with biological and cultural measures — removing affected material, changing the conditions that favour it, and treating with agents approved in your country. The exact steps and their timing depend on the plant, the season and where you live: Dr. Phyto works them out in a free diagnosis.