Yellow spots on tomato leaves can appear for a variety of reasons. It can be fungal or viral diseases, adverse weather conditions, pests. If you have a similar problem, you need to take it very seriously. After all, without eliminating the root cause, you can lose the whole crop.
Single yellow spots on tomato leaves indicate that plants are undergoing stress. This can indeed be the case, provided that in general the tomatoes look healthy, without twisted leaves or any other external manifestations of the disease. Stress can be caused by transplantation, adverse conditions or a sharp change in temperature and humidity. As an aid to plants, the Riverm drug can be recommended. And, of course, it is necessary to get rid of stress factors.
Yellow spots on tomato leaves may appear from sunburn. They are very easy to recognize - they are light, yellowish-gray, dry. Affected and healthy plants should be slightly shaded on sunny days. If, in the presence of yellow spots, the lower leaves begin to curl, and in general the tomatoes look wilted, then they lack moisture. Abundant watering and, if possible, lowering the temperature will correct the situation.
One of the most common fungal diseases in tomatoes is cladosporiosis. Or, in simpler terms, brown spotting. At the initial stage of the disease, light spots appear on the lower leaves, which then turn yellow and darken even later. Small (up to 1 cm), irregular or oval brown spots on tomato leaves throughout the plant indicate that the disease has gone quite far. After this stage, the affected plant dies quickly enough, so you need to fight the disease at an early stage of the development of the disease. As an effective tool, you can recommend the drug "Hom". In order to reduce the risk of infection of healthy plants, it is necessary to adjust the temperature and humidity (if plants are grown in a greenhouse). The fungus does not develop when humidity is less than 70%.
Yellow spots on tomato leaves appear when plants are infected with a mosaic virus. With this disease, the leaves curl, and uneven coloring appears on the fruits. Affected plants need to be destroyed, since the virus is very easy to transfer to healthy tomatoes when watering or pinching. As a preventive measure, it is recommended to seed before planting in a one percent solution of potassium permanganate.
Still yellow spots on tomato leaves may occur due to a lack of certain trace elements. Yellowing of the lower leaves, the presence of bluish-red veins and the small size of the leaves indicate a lack of nitrogen. Yellow chlorosis between the veins, partial necrosis of the leaves and bending of their tips inward means a lack of magnesium. The uncharacteristic yellowing of the young upper leaves and the appearance of apical rot on the fruits is most likely caused by the absence of calcium, iron and copper in the plant nutrition. The appearance of yellow spots on young leaves, curvature of the apex, general fragility and brittleness of the plant indicate a lack of boron. You can correct the situation when feeding, using mixtures with the necessary set of trace elements.
The most important thing when yellow spots appear is to not miss the moment and eliminate the root cause of the problem. Then you can do without serious losses.