Tomato leaves turning yellow: causes and what to do

Gardeners often notice yellowing on the leaves of greenhouse tomatoes, which is certainly not related to the changing seasons. So why do greenhouse tomatoes turn yellow, and how can you combat it? After all, if you don't detect the problem early, especially if it's not addressed, you could lose your harvest.

Causes of yellowing tomato leaves

There are several reasons why tomato leaves in a greenhouse have started to turn yellow:

1. Incorrect or inadequate watering. Lack of moisture and its deficiency are equally detrimental to tomatoes. If the soil dries out, provide moderate watering. By restoring the plant's watering schedule and loosening the soil, the leaves will quickly regain their healthy appearance.
2. Disease damage. Yellowing of tomato foliage can be a symptom of this diseases characteristic of these crops, like Fusarium wilt. It's important to recognize the disease early and take appropriate measures to treat tomatoes.
3. Micronutrient and mineral deficiencies. Most often, yellow foliage is a cry for help from the plant, indicating it lacks nutrients for development. When the fruit begins to ripen, it's important to remember to feed the tomatoes with nitrogen fertilizer.
4. Damage to the plant's root system. Root damage can be caused either by pests, which unfortunately aren't visible, or by root damage during transplanting of seedlings into open ground. If a plant has been mechanically damaged, it will focus all its energy on forming adventitious roots, leaving the leaves short on energy. Once these adventitious roots are fully restored, the leaf color will return to normal. If the damage is caused by pests, special pest control products will be essential.
5. High humidity in the greenhouse. Humidity in the greenhouse should not exceed 70%, otherwise the leaves will not only turn yellow but also rot.

How to eliminate yellowing of tomato leaves in a greenhouse

To understand how to combat yellowing tomato foliage in a greenhouse, it's crucial to correctly identify the cause. However, there are a number of general measures that can be taken not only to eliminate the problem but also as a preventative measure.

For example, even if the problem stems from a lack of fertilizer, damaged roots, or too little or too much moisture, first aid should be given to the roots. To do this, loosen the soil periodically. This procedure is recommended immediately after watering.

Next, you need to monitor the temperature in the greenhouse to ensure that the humidity level does not exceed the permissible limits under any circumstances (we remind you that the air humidity in the greenhouse should be between 60 and 70%).

If the weather outside is hot and dry, the structure needs to be ventilated, and the plants need to be watered using the sprinkler method.

Along with mechanical care and weed control, you can also feed your tomatoes with mineral fertilizers. If your tomatoes have only recently been planted in a greenhouse and are still establishing themselves, you should apply fertilizer through the foliar layer using a foliar spray. For this purpose, dilute mineral salts at a concentration of no more than 1% and spray the tomatoes in the morning if the weather is cool, or at night if the summer temperatures remain high.

Important! You cannot spray tomatoes in the summer during the daytime if the sun is shining, this can lead to leaf burns!

Preparations and folk methods for eliminating yellowing of leaves

You can also get rid of yellow leaves with specialized products. For example, use Epin, which is based on epibrassinolide, or Heteroauxin, which is based on indole-3-acetic acid. These products stimulate plant growth and also help develop the root system.

Instead of the above-mentioned medications, you can try a folk remedy. For example, make an infusion of comfrey leaves. You'll need a kilo of leaves per 10 liters of water. This homemade tomato remedy should be steeped for five days. Once the infusion is complete, mix it with a decoction of comfrey roots. Dilute the resulting solution with water in a 1:3 ratio. It can be used by spraying or watering the bushes. A bucket of this solution is needed for three meters of planting.

If you take timely and correct measures to stop the leaves from turning yellow and make them healthy again, you can save the plants and count on a good and full harvest.