The fungal disease is called Pseudoperonospora cubensis, which is a parasitic fungus known to exhibit host specialization. It lives in a wide temperature scope ranging from 10 to 30 degrees, it prefers cold weather (15-23 degrees) and high humidity and finds hot weather inhospitable.
Symptoms begin to appear on the lower leaves in the form of angular yellow spots (not circular) between the veins on the upper surface of the leaf, offset by a soft, velvety gray growth on the lower surface. Moreover, the infection results in poor growth, dwarfing of plants, and failure of the nodes, and leads at a later stage to the withering of all the leaves and death of the plants.
Traditional resistance to the disease depends on a series of agricultural treatments that reduce conditions favoured by the disease, such as ventilation, regulation of irrigation (irrigation in the morning), the reduction of soil and air humidity, trimming plants to reduce proliferation, pruning of infected parts, and finally spraying specialized fungicides such as Infinito or Rival Duo.
But are there new ways to combat the disease??
Yes, we can use varieties that are more resistant to the disease, and it has been proven that there are many varieties that are considered stronger facing the disease, where the latter is witnessed through fewer symptoms of infection or absence of them compared to normal varieties when cultivated under the same conditions and using the same agricultural treatments.
The most important among these varieties is the JULIA F1 cucumber variety, produced by the Apollo International Company, which is characterized by a high tolerance to disease until the end of the season, when normal procedures are applied to handle the disease. This variety is less affected by the negative results of the disease, in addition to its tolerance to downy mildew. The Julia variety is characterized by other important factors, as it succeeds in spring and autumn planting, and is multi-bearing on the node 3-4 fruits. The fruits are homogeneous and dark with a distinctive shine and desirability in the market. Their length is about 18 cm with a width of 3 cm. The variety’s resistance to diseases gives it continuity of growth and nodes, and thus high productivity and better yield. The use of the disease-tolerant varieties harvest techniques results in less use of pesticides, to get a healthy product free of residual effects and in a larger quantities, and this surely reduces production costs and improves the profitability of the farmer.
