The disease can be difficult to treat once established, but as soon as symptoms are noticed, apply a protective fungicide to prevent it from spreading. Destroy plants after harvest as the disease can spread to seeds.
Early blight often occurs during humid weather and is most likely to attack plants under stress. Remove dead or damaged leaves and make sure there’s good air movement around the plant. Fungal pathogens can persist on old material in the soil or on other ‘host’ plants, like nearby weeds, for up to a year. Remove diseased plants and bin or burn them.
Practice crop rotation and ensure potatoes and tomatoes plantings never follow. Choose a different spot each year (avoid planting in the same part of the garden for at least four years). If you don’t have enough space for this, consider growing tomatoes in pots and potatoes in grow bags. Look for disease-free seeds and only save seed from disease-free plants. Water the soil and feed plants regularly to keep them growing well – healthy plants can better resist pests and diseases.