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Spinach downy mildew (Peronospora spinaciae) – identify and control
Published on: February 13, 2022 Modified on: 26 April 2024
Spinach downy mildew, Peronospora spinaciae is an economically important disease in most areas where spinach is grown. It can be found in hotbeds, greenhouses, and crop fields.
Symptoms. The attacked leaves have green-yellow, diffuse spots, variable in size, in front of which, on the lower face, a gray-purple fuzz appears. In wet and cool weather, the spots enlarge, the tissues turn brown and become crumbly. In the attacked seed crops, the defoliation of the plants is signaled, the growth stops, and the inflorescences produce little seed, of poor quality.
The pathogen is Peronospora spinaciae. The fungus appears in conditions of high humidity and temperatures between 3-24 ° C, the optimum temperature being 9 ° C. The disease is severe in areas where there is heavy dew, fog, or frequent rains and temperatures between 8-18 ° C. During the growing season, the fungus spreads through spores, and from one year to the next it resists through resistance spores, but also through seeds or mycelium existing in infected plants in autumn.
Prevention and control. At planting of spinach, the drainage of the land and the location of the spring spinach soils must be taken into account, which must be found at great distances from those with autumn spinach. The crop rotation of at least 3 years, but also the sowing of healthy seeds limits the possible appearance of the disease. The treatment of the plants will start with the growth of leaves and until the appearance of large rosettes that cover the soil. Preventive treatments for spinach downy mildew are applied every 4-7 days. In seed crops, preventive treatments with specific fungicides will be applied.
Specialist's advice 
