Yellow-green spots on cucumbers are almost a disaster for gardeners, as they risk killing the plants. Cucumber blight is easily transmitted and threatens tomatoes as well as cucumbers. It is easy to spot – square yellow-green spots appear on the upper side of the leaves, bordered by leaf veins. These spots quickly spread and a grey-purple mycelium starts to form on the underside of the leaves. So how do you deal with this cucumber disaster?
Mold spreads best in a moist environment and at a temperature of 20-25℃. If you are growing cucumbers in a greenhouse or hothouse, be sure to provide plenty of ventilation. For beds, try to place cucumbers in the most sunny spot. If you want to minimise the risk of mould infestation, grow cucumbers on netting. The climbing stems will cling to the support and the leaves and fruit will dry out better. This method of growing can be used not only outdoors but also in greenhouses. Remember to check the cucumbers every day. If they grow next to tomatoes or courgettes, check them regularly too.
Grow a hardy variety
Some varieties of cucumbers have good tolerance to fungus and other pests, look for and grow such varieties. These varieties include Altai F1, Charlotte F1, Partner F1 and Bohemia F1. These varieties can tolerate poor climatic conditions, high and low temperatures, lack of moisture or certain types of bacteria, among other things
Try our grandmothers’ tricks
In the days when the supply of chemical sprays was very limited, our grandmothers relied on the power of nature. Tried-and-true tricks include spraying plants with one part milk and two to three parts water. Keep in mind that ideally the milk should be fresh. Another effective fighter is horseradish spray. Leave 60g of grated horseradish in 5 litres to infuse for a day.
What chemistry to use?
Effective preventative sprays include Previcur, Ortiva, Acrobat, Curzate or Dithane. These chemicals can be used not only for fungi, but also as prevention when planting them.