How to treat yellow spots on tomato leaves
Yellow spots on tomato leaves are common in the grower's practice. If such a deviation is observed on plants, it is necessary to urgently deal with them. Spots reduce the yield, or even destroy it altogether.
Treating yellow spots on tomatoes
Various rashes, spotting are the most popular problems that arise, regardless of where the tomato is grown. Often it is caused by illness or growing conditions, but in order to start treatment, you need to understand and make the correct diagnosis.
Reasons for the appearance
Causes: temperature, humidity, disease, root damage, high fertilization or lack of nutrients.
All tomato diseases, do it into groups:
- viral - mosaic, curl (folding) foliage;
- fungal - gray rot, septulosis, late blight, powdery mildew, mold (cladosporium), fusaiors and others;
- bacterial - cancer.
Viral
Curly or folded leaves
A disease that takes its roots in the southeastern regions of the United States and northern Mexico.
Signs - tissues turn yellow, curling and curling of leaves, older ones are covered with a lilac color.
The viral disease is carried by small insects - whiteflies. A flying insect picks up the virus from the host plant (peppers, tomatoes, beans, weeds) and transfers it to healthy ones. A large infestation occurs when the whitefly population is high.
Insecticide treatment in order to reduce the whitefly population is not always effective, spraying the solution lacks the lower parts of the foliage, where a large number of insects live. It is recommended to remove infected plants and introduce fallowing. This will reduce the ability of whiteflies to develop resistance to the pesticide.
Mosaic
The virus enters plants with sap, with the help of aphids (insect) or through agricultural processing methods. The virus remains on inventory, seeds, tools, plant residues, or in the soil for 2 years.
The signs of the disease can vary depending on the age of the plant, the type of virus, the variety, and the growing conditions. Yellow spots or mosaic appear, deformation and necrosis of organs and leaves occurs.
Exposure of seeds in an incubator at a temperature of 70 degrees for 2-4 days. Cross protection method - grafting a light form of the virus to a plant, subsequently generates plant resistance to different types of virus.
Infected plants must be removed from the site.
With the help of bleach, tools are processed - they are disinfected. They monitor the site and remove infected plants in a timely manner, clean the ridge of plant debris - in order to prevent the spread of infection.
If the leaves are already covered with mosaics, it is necessary to spray with low-fat milk. A liter of milk is diluted in ten liters of water (room temperature), and one tablespoon of urea is added.Spraying is done once a week until the disease passes.
Fungal
Gray rot
It appears on plants, if you do not control watering and humidity in the greenhouse, plant tomatoes on non-sterile soil, sow untreated seeds.
Signs - at first, the disease spreads along the stem in the form of gray-brown spots. Gradually captures the entire stem. Then the shade brightens and streaks appear. Due to the defeat of the stem, the nutrition of the plant stops. The leaves are higher - turn yellow.
The main protective method is to control the humidity in the greenhouse, it is necessary to keep it low. Protect from mechanical damage when picking and caring for the tomato.
When spots appear, you need to coat them with a paste, which contains fungicides - copper sulfate, copper chloride (HOM), Bordeaux liquid and others.
Phytophthora
Signs - the bottom of the leaf is covered with yellow spots, the leaves are falling off. The fruits turn black.
There are many means of fighting late blight, they all work according to the same principle. It is recommended to alternate chemical preparations - this will give an effective result. Tomatoes are sprayed with solutions: kefir, saline, garlic, ash, tinder, milk-iodine and others.
Cladosporium
The disease is spread by spores. The plant dries up, wrinkles, turns brown and dies. Yellow spots on tomato leaves in a greenhouse are most commonly caused by this fungus.
Signs - first, the leaves of the lower tier turn yellow, then the whole plant. At the initial stage of the disease, the tomato becomes covered with yellow, and then reddish-brown shades.
A number of agrotechnical methods are being carried out to destroy the fungus in the soil. It is necessary to remove plant residues in a timely manner, steam and disinfect the soil, ventilate greenhouses and greenhouses, choose a stable type of tomato.
At the first signs of disease, plants need to be sprayed
Affected plants are sprayed with fungicides (every two weeks). It is recommended to spray during the growing season. Mechanical methods are supplemented with chemical preparations - HOM, Abiga-Peak, Poram. Processing is carried out in the evening or morning.
Fusarium
Signs - the plant acquires a pale green or yellow color, the tomato sprouts wither, the upper parts are deformed, twist and fall off, the roots die. High fever makes symptoms worse.
If you have a sign of fusarium, this is a doomed plant. The most you can do is clean the plant and disinfect the area.
Preventive methods will provide reliable protection for your crop:
- it is necessary to check the seedlings;
- use sterile instruments;
- when the fruits are formed, we apply only potash fertilizers;
- disinfect the roots of seedlings;
- sow in warm soil.
Bacterial
On the territory of the former Soviet Union, the bacterial disease appeared in 1936, in the form of contaminated seeds.
Tomato cancer is caused by bacteria. Signs of development - the greens begin to fade, a yellow line appears along the contour. Red and brown ulcers appear on young peduncles, sepals and petioles.
Treatment
The plant during the growing season is treated with preparations that include copper. Sprayed with Phytolavin antibiotic. Medicines with chitosan and humate will help.
Other reasons
A tomato may be covered with yellow leaves, not only due to diseases. Root damage is a common cause. Mechanical damage caused by careless loosening of the soil near the tomato. Leaves of the lower tier begin to turn yellow.
The root system of tomatoes has good recovery, so it goes away on its own. It is recommended to add organic fertilizer to the soil near the plant.
Another reason is poor-quality fertilizer or lack of it. Any plant, including tomatoes, changes its color if they lack copper, iron, manganese or sulfur.The yellowing of greens can speak of nitrogen starvation. As a result of a lack of magnesium - the tomato will cover with yellow pigments.
Conclusion
Tomato leaves can become covered with yellow spots for many reasons: various kinds of diseases, temperature, climate, humidity, lack of fertilizers. It is necessary to carry out preventive methods of processing the plant. Treat pests in a timely manner. It is important to regulate the humidity in the greenhouse and to ventilate. Vegetable growers recommend processing seeds, adhering to the rules of care, pest control of soil and tools, and you will get a rich harvest.