Tomato cultivation is currently in full swing and the first tomatoes are already ripening. However, that doesn't mean that all problems with the plant are over. If the tomato suddenly turns yellow leaves, there can be various reasons. Read below about the most common causes and what you can do to avoid endangering your tomato harvest.
The most common causes at a glance
If the tomato leaves turn yellow, it can be due to various reasons. Both pests and diseases can be to blame. In many cases, however, it is a deficiency that can be remedied with the right care.
Why is my tomato getting yellow leaves?
As a rule, the yellowing of the leaves is due to a lack of the pigment chlorophyll. If it is not sufficiently developed, the leaves will turn yellow. One of the most common reasons for this is incorrect watering. Both too much and too little water can harm the plant, so it is crucial that you water your tomatoes properly.
Even with proper care, the leaves of the tomato plant can change color. Yellowing is a common symptomvarious diseasesas well as in the event of a pest infestation. In rare cases, a nutrient deficiency can also cause tomato leaves to turn yellow and fall off.
Important: You should always remove yellow leaves on tomatoes when they are below the first inflorescence.
Now let's take a closer look at the various causes of discoloration and give tips on how to solve the problem.
Tomato gets yellow leaves due to improper water supply
Tomatoes need regular watering to thrive. While the plants can forgive small watering errors, incorrect watering can cause major damage and even lead to crop failure. Regardless of whether you water too much or too little, the discoloration of the leaves is often a sign of incorrect water supply.
If the substrate is too dry, the leaves will turn brown and fall off, with overwatering resulting in yellow leaves. Because of the excessive moisture, waterlogging occurs and the roots begin to rot so that they can no longer transport nutrients to the plant.
There is no perfect recipe for this,how much water a tomato needs, but a good rule of thumb is to do a moisture test by sticking your thumb several inches into the soil to check the moisture near the roots. When the soil feels dry, it's time to water, and the closer the tomato plants get to full maturity, the more water they will need. Better yet, purchase a soil moisture meter and use it regularly as a watering guide.
Tomato diseases that cause yellow leaves
Often a tomato gets yellow leaves when the plant suffers from a disease. Both leaf spot and bacterial wilt can cause yellowing of tomato leaves. If this is the case, action must be taken as quickly as possible so that the plant does not die out and infect other plants.
Leaf spot causes the leaves to turn yellow and have gray spots and black spots. If the infestation is still small, remove the infected leaves, spray the plant with milk and thin it out. If more than half of the plant is infected, it can no longer be saved and you must remove it.
Bacterial wilt causes the tomato leaves to turn yellow from below and the shoots to develop brown-yellow streaks. If the tomato disease is discovered early, save the plant by removing the infected leaves, loosening the soil and the plantsupply with fertilizer. In the case of a larger infestation (more than 1/3 of the plant) it must be completely destroyed.
Important: Infected leaves do not belong in the compost!
Discoloration due to nutrient deficiency
The nutrient deficiency can also be a cause of yellow leaves on tomato plants. Tomatoes are heavy feeders, meaning the plant needs twice as much fertilizer as a cucumber and even four times as much as beans.
If the plant does not receive enough nitrogen, the older leaves begin to turn yellow and in many cases fall off because they make their nitrogen available to the younger leaves to survive.
The yellowing of the leaves can also be the result of an iron deficiency, although this is particularly noticeable in the youngest leaves. A magnesium deficiency, on the other hand, leads to yellowing that looks more like speckles or spots on the older leaves.
These three – nitrogen, iron and magnesium – are the most common nutrient deficiencies that hobby gardeners should pay attention to when it comes to yellow leaves and should fertilize regularly. It should be borne in mind that the plant also needs a lot of water if it is given a lot of fertilizer.
Which pest can cause yellow leaves on tomatoes?
If the tomato has been attacked by whiteflies or thrips (also known as thunderflies), it usually reacts with yellow leaves. To prevent whitefly infestation, you can protect the plants outdoors with an insect net and possibly place yellow boards near the plants. If the plant is infected with thrips, spray it with soft soap solution and spread primary rock powder on the soil.
Can you still eat the fruit if the tomato has yellow leaves?
If a lush growing tomato with lots of fruitsgets yellow leaves, in most cases this is not a reason not to be able to enjoy the fruit. Only in the event that the plant has been attacked by a disease such as bacterial wilt will the tomatoes become inedible and must not be consumed.
