Tomato leaf curl under grow LED light – causes, prevention, treatment
Tomato leaf curl is a common problem in the cultivation of these popular vegetables, both in the ground and under cover. Leaf curl may be a result of a very serious disease, bacterial cancer, but more often they result from improper plant care and fertilization errors.
Tomato leaf curl is most often a symptom of water deficiency, poor sunlight, too rapid changes in temperature and air humidity, or fertilization errors.
In order to identify the causes of tomato leaf curl in your crop, it is helpful to learn to distinguish between the symptoms associated with each cause.
First of all, when you notice the first symptoms of tomato leaf curl, make sure that the plants are provided with the right growing conditions.
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For proper growth and fruiting, tomatoes need warmth and a well-sunny position.
Tomato leaf curl under grow LED light
Tomatoes grown under artificial LED lighting should be 12-30 inches from the light source. As the plant is growing, you need to adjust the height on a regular basis to keep the distance between the light source and the tomatoes. The distance may depend on the type of lighting, power and tomato species.
The optimal temperature is 27 ° C during the day and 17 ° C at night. The tomato likes it when the temperature difference between day and night is just around 10 ° C. Larger temperature fluctuations can cause tomato leaves to curl.
You should also remember about proper irrigation of the crop, but not over-irrigation. A very common cause of tomato leaf curl is a long-term water shortage.
That is why it is important to look after the plants every day and to check the soil and air humidity. If you forget about your plants for a few days, the effect can be disastrous.
The sight of curled leaves on the plants and the browning of their edges is the last phase before irreversible wilting of the entire plant.
Water the tomatoes directly on the ground so as not to sprinkle their stems and leaves, as wetting the aerial parts promotes the development of fungal diseases.
The best soil for tomato cultivation is light, deeply cultivated, well-drained and slightly acidic soil (pH 5.5 – 6.5 is ideal for tomatoes) and rich in organic ingredients. If the pH of the soil is too low, it should be limeed.
Before you start growing tomatoes, you should also mix well-composted manure or compost with the soil to enrich it with organic matter. For fertilizing tomatoes during the growing season, you can water with diluted nettle manure (mix with water in the ratio of 1 liter of liquid manure per 10 liters of water).
Nettle – properties, application in fertilization and plant protection
The upward curl of tomato leaves occurs when there is too much sunlight and a water shortage at the same time. It also happen when topping is performed in very sunny and hot weather.
Unfavorable climatic conditions, such as sudden temperature fluctuations during the day and night, lower than optimal air humidity, and at the same time excessive substrate humidity, disturbs the intake and nutrition of plants with calcium.
With a high calcium deficit, tomato leaves curl and discolor (especially older leaves). Other symptoms are: the tops of the plants turn dark green and the leaves on the underside are slightly purple.
The tops and edges of the leaves, including the petiole, twist and gradually die. In such a situation, it is necessary to improve the growing conditions. Make sure that the tomatoes are not over-fertilized with nitrogen or phosphorus. Also apply calcium fertilizers, e.g. calcium nitrate.
Tomato apical leaf curl may be due to copper deficiency. Older apical leaves curl “tubular”, while the youngest ones become smaller.
The petioles are short and the leaves are stiff. The occurrence of these symptoms may be related to the deficiency of copper in the soil or the occurrence of factors that make it difficult for tomatoes to uptake copper from the soil.
These factors are too high soil pH (above 6.5) and excessive nitrogen or phosphorus fertilization. In order to eliminate this cause you should check the soil pH using any pH-meter. Limit nitrogen fertilization and use soil or foliar copper fertilizers.
The curl of the youngest leaves and their deformation may result from manganese deficiency. The leaves turn gray-brown and necrotic at the same time.
Difficulties in manganese uptake may result from the insufficient amount of this element in the soil, too high pH of the soil, lack of light, excessive soil moisture or over-fertilization with other ingredients (e.g. potassium, phosphorus, calcium or copper).
In the first stage, it is necessary to check whether the pH of the substrate is appropriate. Then you must check if you can use foliar or soil fertilizers containing manganese chelate.
In amateur crops, in the event of symptoms of deficiency in the fertilization of tomatoes, it is worth reaching for liquid fertilizers enriched with microelements.
Thanks to the use of this type of fertilizer, we will be sure that the plants are provided with all the necessary nutrients, and the obtained fruit will be full of the taste and aroma expected from tomatoes.
Tomato leaf curl – bacterial cancer
Tomato bacterial cancer is an extremely dangerous disease for tomato crops. The most common source of bacterial infections are seeds infected with them or the soil in which they are sown. The cause of infection can also be a person who transfers bacteria on the surfaces of their hands or used garden tools from one plant to another during plant care.
Symptoms of infection with tomato bacterial cancer usually appear a few weeks after planting the seedlings or during the fruit setting phase. Characteristic symptoms are tomato leaf curl, which precede irreversible wilting of the plant.
Wilting begins at the bottom of the plant and usually progresses rapidly upwards. It is also common to wilt single leaf lobes folded on only one side of the petiole and on one side of the stem, while the other side of the leaf or plant appears to be healthy.
Cracks, cancerous wounds and mucilaginous discharge can be present on plants. The fruit may develop small dark spots surrounded by a light border approximately 2 mm in diameter. However, fruit symptoms are very rare.
So far, it has not been possible to breed tomatoes resistant to bacterial cancer. Experience shows only that determinate varieties get sick much less frequently.
There is no preparation that would be effective in combating tomato bacterial cancer. Therefore, the only solution is to remove the infected plants and burn them.
Under no circumstances you should put them into compost. All tools that have been in contact with infected plants should be disinfected (e.g. with hot vinegar). Prophylactic, still healthy plants you should spray with copper preparations or agents containing grapefruit extract.
These preparations may inhibit the further multiplication of bacteria and the development of the disease, but do not eliminate it. Therefore, after the end of cultivation, all other plants should also be removed and burned. The interior of the greenhouse and various equipment should be decontaminated with one of the disinfectants with a bactericidal effect.
Tomato leaf curl as a result of an aphid attack
Another cause of tomato leaf curl, fortunately fairly easy to recognize, may be the presence of pests such as aphids. Of the aphids on tomatoes, the peach aphid or potato aphid most often appears.
As a result of feeding these pests. The leaves are deforming in the form of a spoon-shaped bend of the leaf blade. These symptoms are usually accompanied by the sticky honey dew secreted by aphids on the leaves. As well as the abundant presence of these pests on the plant.
In the event of the appearance of these pests. It is necessary to use aphicidal preparations approved for use on vegetables. Remember about the precautionary measures and the waiting period.
In amateur crops on allotments and in home gardens. It is best practice to avoid the use of chemical plant protection products. It is better to use natural preparations or home remedies for aphids, such as onion decoction or garlic extract.
