My runner beans have tiny spots on leaves. Last year the spots developed into a ‘rust’ like powder. Lots of beans on plants but what can I safely spray them with? Before it’s too late.

Some varieties can be more susceptible to rust or leaf spot than others. As the vines have beans on them, you will have to be very selective as to what fungicides are used, your local garden centre will be able to advise a suitable spray.

Copper oxychloride is a good protectant spray but once the rust appears it is hard to control. Remove affected foliage and any affected beans if it has spread to them, dispose of in the rubbish or burn, and not the compost to stop the spread of the disease.

Improving air circulation around the vines which helps reduce the environment rust thrives in (warm, humid). Avoid overhead watering and use a hose or watering can to minimise the amount of moisture around the vines.

Pick up any fallen leaves and plant material. Look for varieties that are rust resistant, spray with copper early in the season.