by We will tell you why white, yellow or brown spots appeared on cucumber leaves, with photos, a description of the problem and control measures.
The appearance of spots on cucumber leaves in a greenhouse or open ground is not always a reason to put an end to the harvest. Often, it is enough to simply adjust the watering and fertilizing regime. But sometimes this indicates more serious problems. What exactly?
Yellow spots on cucumber leaves
There may be several reasons why yellow spots appear on cucumber leaves. These include the vagaries of the weather, a lack of nutrients, and some kind of disease.
Nutrient Deficiency
Symptoms: As a rule, the lower leaves turn yellow and dry out first. Sometimes spots appear in the vein area.
Control measures: Feed the cucumbers with complex mineral fertilizer. If the yellowing of the leaves was the result of a missed scheduled feeding, replenish the deficiency of the necessary element.
Sunburn of leaves
Symptoms: A yellow, drying spot on the leaf, usually at the point of contact with the greenhouse glass.
Control measures: If cucumbers are grown in a greenhouse, they need to be tied up so that the leaves do not touch the glass.
Bacteriosis of cucumbers
Symptoms: First, watery formations appear on the back of the leaf, then angular yellow spots on the upper side. Externally, the signs of the disease are similar to those of angular spot, but when leaves are affected by bacteriosis, the edges of the spots are not limited by the veins of the leaf. Later, the spots turn brown, but a yellow rim remains around the perimeter.
Control measures: Cucumbers are sprayed with a 0,5% solution of Abiga-Peak, diluting 50 g of the substance in 10 liters of water. In total, during the growing season, the crop is sprayed three times with an interval of at least 20 days. To avoid cucumber diseases in the future, it is necessary to carry out preventive measures.
Common cucumber mosaic
Symptoms: In the phase of the third-fourth pair of leaves, yellow-green spots appear, later – mosaic. The leaves gradually begin to wrinkle.
Control measures: At the first signs, dig up and burn the affected plants. If the mosaic has affected greenhouse cucumbers, then after harvesting, the soil in the greenhouse should be replaced. Prevention of this disease consists of observing crop rotation, disinfecting the seed material and fighting cucumber pests that contribute to the occurrence of cucumber mosaic.
Blackleg
Symptoms: Yellow spots on the leaves of cucumber seedlings appear after the stem turns black.
Control measures: Reduce watering, loosen the soil under the cucumber bushes and sprinkle it with wood ash. Treat the soil with a weak solution of potassium permanganate.
White and light spots on cucumber leaves
White spots on cucumber leaves often appear in a greenhouse, but can also occur when grown in open ground. The reasons are an invasion of spider mites, damage by white mosaic or powdery mildew.
White mosaic
Symptoms: The mosaic pattern on cucumber leaves is white in color.
Control measures: At the first signs, dig up and burn the affected plants. Prevention is the same as for ordinary cucumber mosaic.
Mučnistaâ rosa
Symptoms: White or slightly reddish mealy spots on leaves, stems, and less often on cucumbers. As the disease progresses, the leaves begin to droop. The disease spreads in damp weather.
Control measures: To combat powdery mildew, the crop is sprayed with Alirin-B (10 tablets per 15-20 liters of water) from the beginning of flowering until the end of fruiting at intervals of 7-10 days. For prevention, seeds are soaked in Sporobacterin, and plants are sprayed with Baktofit during the growing season according to the instructions.
spider mite
Symptoms: Light spots in the form of dots appear on the outer side of the leaves, and a white web is visible on the back side.
Control measures: Spray the plants with insectoacaricides (Antikleshch, Bitoksibacillin, Fitoverm) according to the instructions. For preventive purposes, you can subsequently use the same preparations to treat plants during the growing season.
Brown, rusty and brown spots on cucumber leaves
Rusty and brownish-brown spots on cucumber leaves can also signal various cucumber problems. However, the most common cause is fungal infection.
Antraknoz
Symptoms: Brownish-red round spots from 0,3 to 3-4 cm in diameter, usually sunken, appear on leaves, stems and fruits. As the disease progresses, holes may form in the center of the spots.
Control measures: To treat anthracnose, plantings are treated with a 1% solution of Bordeaux mixture or a 0,4% solution of copper oxychloride. After two weeks, spraying is repeated. You can also use Abiga-Peak, OxyHOM and other fungicides.
Ascochytosis (black mycosphaerella stem rot) of cucumbers
Symptoms: Grayish watery spots form on the leaves, they soon turn brown and dry out. It also appears on the fruits. Brown ulcers appear on them, then the skin turns white, and a rusty slimy spot forms inside the fruit. Cucumbers grown in greenhouses are most often affected.
Control measures: Every 10 days, the plants are sprayed with a 1% solution of Bordeaux mixture. The procedure is carried out 3-4 times. Urea can also be added to the solution (10 g per 10 l of water) to nourish the bushes. The stems are dusted with a mixture of copper sulfate and chalk (1:1).
Downy mildew (perinospora)
Symptoms: At the beginning of the disease, light green spots, sometimes bordered by veins, form on the upper side of the leaf. Over time, the spots turn brown, and grayish-purple fungal spores form on the underside of the leaf. As a result, the leaves turn completely brown, but usually do not droop.
Control measures: It is necessary to spray the infected leaves of plants with chemical preparations Abiga-Peak or Consento. For preventive purposes, plants are subsequently sprayed during the growing season with biological pesticides – Gamair, Trichoderma Veride 471 or Fitosporin-M.
Dry spots on cucumber leaves
Large dry yellow spots on the leaves may appear due to insufficient watering. In this case, the problem is solved quite simply. Also, cucumber leaves can dry out from all sorts of diseases.
Alternaria (dry spot)
Symptoms: Develops in cucumbers grown in greenhouses. In plants planted near the entrance, dry brown, slightly convex spots with a diameter of 0,5-2 cm appear on the lower leaves. The disease quickly spreads to neighboring plants.
Control measures: When treating the disease, spraying with copper sulfate (20 g per 10 l of water) and chemical fungicides (for example, Abiga-Peak, Consento, Famox) is effective. Treatments are carried out every 10-14 days. Trichocin is used for prevention afterwards.
bacterial wilt
Symptoms: At first, an almost imperceptible viscous film appears on the leaves, then – spots of a paler color, subsequently they turn yellow and dry up. As a result, the plant completely wrinkles, dries up and dies.
Control measures: Affected plants are destroyed, the rest are treated with a 0,2% solution of copper sulfate or Fitolavin according to the instructions. Subsequently, for prevention, it is recommended to disinfect the seed material by soaking it in a dark pink solution of potassium permanganate for half an hour before sowing.
We hope that now you will be attentive to your plants, will be able to clearly and promptly respond to sudden symptoms, and in your garden diseases will not prevent cucumbers from bearing fruit well.
