Rust

Infected leaves
Typical rust spores on upper and lower surfaces
Infected crop
Rust-affected crop
Cause

Puccinia arachidis

Damage

Widespread in most peanut areas north of Kingaroy. The Sutherland variety has good tolerance to rust.

Can cause major crop losses if it starts early and is uncontrolled. Once rust starts in a crop, dews and fogs are sufficient to create a serious epidemic.

Symptoms

Small, yellow spots quickly produce typical 'rusty' pustules containing spores. Pustules are not visible for 7-10 days after infection. They are usually found underneath the lower leaves and spread very rapidly. Infections are often first found as a 'hot spot' with a few plants covered in rust.

Spread

The spores can blow long distances between crops.

Management options

Chemical
Protect with a fungicide until the crop is within two weeks of harvest. A spray program similar to that for leaf spot may be needed. Consider other diseases which may be in the crop (refer to Infopest or check with local extension officers).

Cultural
Rust spores cannot survive for very long without living plants, so destroy volunteer peanut plants between crops, especially on headlands, contour banks and around buildings. There are no known alternative hosts for peanut rust.

Chemical registrations and permits
Check the Australian Pesticides and Veterinary Medicines Authority chemical database and permit database for chemicals registered or approved under permit to treat this disease on the target crop in your state or location. Always read the label and observe withholding periods.