Bean Rust: What is it and How to Manage It

by Corinne Mossati

Bean rust: You may have seen a rust-like coating or reddish-brown pustules on your bean pods and leaves and wondered if they can be saved. Read on to find out.

Bean Rust

Bean Rust – Photo © The Gourmantic Garden

My garden’s coastal location is coupled with high levels of humidity which reach 100% on some days. These climatic factors make it prone to a host of diseases including bean rust. Thankfully, in my case, the condition affects the plants after the second or third flush of beans when the plants are nearing the end of their life cycle.

What Causes Bean Rust

Bean rust is a fungal disease that affects a range of beans including bush beans and broad beans. The disease which favours wet conditions is caused by the pathogen Uromyces appendiculatus and spread by airborne spores.

How to Control Bean Rust

The good news is that the condition usually affects the plants towards the end of their life cycle. The not-so-good news is that there is little you can do aside from prevention.

Fungicides and wettable sulphur are often used to treat rust but they are more a preventative approach. As I’m not a fan of using fungicides on edibles, I prefer to take precautionary measures.

Here are some tips on controlling bean rust in your edible garden:

    1. When planting, don’t overcrowd the bean plants and allow enough spacing for better airflow.
    2. Water at soil level and avoid getting the leaves wet.
    3. Prune the lower leaves where possible, even if you’re growing bush beans.
    4. Thin out the plants if necessary to increase air circulation and reduce humidity.
    5. When growing bush beans, consider staking them to keep them upright and prevent them from touching and transmitting diseases.
    6. Remove the diseased parts, be it foliage or pods and dispose of them in the bin. Unless you have a hot compost which can kill the spores, it’s best not to compost the affected plants.

Can You Eat Beans with Rust

Bean Rust

Bean Rust – Photo © The Gourmantic Garden

The rust-like coating on beans makes them look less appetising but are they still edible? Some may advise that they are safe to consume but I prefer the safe approach. I avoid eating the pods. Instead, I shell them and I have consumed the bean seeds without any ill effects.

As a precautionary measure, do not save seeds from infected crops. If the condition affects your garden early in summer, and you’re in a temperate climate such as Sydney, it’s not too late to start another round of bush beans in the midsummer season.

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