Rust disease is commonly associated with roses but a wide range of trees, shrubs, perennials, bedding plants, bulbs, fruit and vegetables can be affected. Rust is characterized by leaf spots, most commonly on the underside of leaves, which develop into pustules, eventually releasing thousands of spores. These are then spread to other plants by rain splash or air movement. If left untreated they soon reduce the vigour of plants and in severe cases can kill the plant off altogether.
There are various rust disease, many of which appear orangey-brown, leading to the common name, but white, black, brown and yellow rusts are also to be found.
Rusts thrive in wet and warm conditions and are more of a problem during prolonged wet summer weather. If caught early enough, individual affected leaves can be removed, but it is best to prune out affected parts of the plant where possible. This will improve air circulation around the plants and reduce the risk of spread. Do not add affected material to compost heaps.
Once the affected parts are removed, treat plants with Plant Rescue Fungus Killer, available in concentrate or ready to use formulas. Repeat the application 2 weeks later to ensure total control of this unsightly plant disease.
When buying particularly susceptible plants such as roses and hollyhocks, look for cultivars with increased resistance to the disease. Other commonly affected plants include alliums, antirrhinum, bluebell, box, chrysanthemum, fuchsia, heuchera, hypericum, mahonia, pear, poplar and vinca.