Rust

Symptoms

Orange-brown pustules develop on the undersides of leaves. These can often go unnoticed and the disease has taken quite a hold by the time the pustules appear on the upper leaf surface and are noticed.

Cause

A fungus which produces spores that need a moist environment to germinate, so most bad infections are in damper places.

Harm

Badly affected plants can be so weakened they are unable to withstand winter frosts.

Treatment

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