Damage to tomatoes is not always caused by pathogens. We present environmental and physiological disturbances in tomato plants and give tips on how to avoid them.
Not only various tomato pests and diseases can cause damage to tomato plants and their fruits. In this article, we'll educate about common physiological damage and deformities that tend to occur throughout the summer and how to prevent them.
Tomato leaves curl up
When the leaves of the tomato plant curl up, it is often due to the care measures. If the leaves curl up in the summit area, the cause is usually a lack of water. The leaf curling of the tomato on the lowest leaves, on the other hand, occurs after severe pruning of side shoots and leaves. This creates a nutrient blockage in the lower shoots that are still present. As a result, the tomato curls up its leaves, but this does not affect the yield or the taste of the fruit.
Tip: If the leaves on young tomato plants curl up, this is in most cases due to a lack of water supply or an aphid infestation, which leads to deformation of young leaves and also to curling can. However, a viral disease such as the Curly Top Virus is also possible. Viruses are transmitted via sucking insects and cause irreversible growth disorders in the entire plant. Affected plants should be discarded entirely.
Tomatoes bursting
Cracking tomato fruit is a common damage, but why do tomatoes crack? The cause lies mainly in a fluctuating water supply and excessive pinching or pruning. The ring-shaped bursting occurs when there is an excessive supply of water and cool weather at the same time. By the way, the tendency of tomatoes to burst also depends on the variety. In particular, outdoor tomatoes with changing moisture levels due to rain and drought should be resistant to bursting. Most fruits scar after tearing andare safe to eat. It becomes problematic when fungal diseases penetrate the open wound and lead to mold and rot. Infected fruit should be disposed of immediately.
Green collars on tomatoes
The yellow or green collar on tomatoes is usually understood to mean tissue around the base of the stem that remains hard and does not change color when ripe. Excessive temperature of the fruit due to direct sunlight, as well as severe stinging, potassium deficiency and nitrogen over-fertilization can lead to this physiological disease. But here, too, the choice of variety is crucial. Beefsteak tomatoes and dark varieties in particular tend to be green, including well-known varieties such as 'Brandywine', 'Black Plum' or the 'Schwarze von der Krim'. If the tissue around the stem has hardened, it should be removed before consumption. However, the rest of the fruit is fully edible.
Blossom end rot on tomatoes
Fruit or blossom end rot is a dreaded physiological disorder in which the tissue at the bottom of the fruit turns black, sags and hardens. The cause is a severe lack of calcium, whereupon the tissue collapses due to a lack of stability. The spots can be prevented with sufficient calcium supply, adding lime to the planting and again as needed between June and August can prevent the often inedible fruits. Read our special article to learn more about tomato blossom end rot.
More Tomato Damage
In addition to the growth and development disorders mentioned, there are also rarer disorders:
- Sunburn: If the plants are not yet used to strong sunlight, sunburn can occur on the leaves and fruits. This is shown by the development of papery, transparent tissue changes, the fruit underneath is often watery and soft. Heavily burned leaves fall off early. Slowly acclimating young plants to the sun and shading the fruit effectively prevents sunburn on tomatoes.
- Oat and Barley Blossom: Oat and barley blossoms occur in poor lighting conditions, when the temperature is too cold and the humidity is high. In the case of the oat flower, the pale yellow sepals grow overlong and do not curlreturn. The barley flower, on the other hand, is short and thick, pollen and stigma are poorly formed. This results in fertilization problems with little yield and many flowers dropped.
- Internal tanning: As a result of excessive evaporation, brown, dried-up tissue forms inside the tomato fruit. Heat and dry air are problematic. Internal tanning occurs particularly after heavy watering and simultaneous potassium deficiency.
- Watersickness: If the fruit does not discolor in places when ripe and shows brown veins inside, it is called watersickness. Even watering and a good supply of potassium prevent this.
Tip: A balanced supply of nutrients can prevent many physiological disorders. An organic liquid fertilizer like our Plantura organic tomato & vegetable fertilizer can be easily dosed and spread over the irrigation water. The increased potassium content promotes fruit development in tomatoes and numerous other types of vegetables.
- Fertilization disorders: In addition to the oat and barley blossoms, suboptimal conditions can also lead to fertilization disorders. Extremely high or low humidity, temperatures above 30°C, lack of water and lack of pollinators (insects or wind movement) can lead to a lack of pollination and thus flower drop and poor yield.
- Fruit malformations: For genetic reasons, appendages, also known as "noses", can appear on fruits, which usually change color before the main fruit. Severely ribbed and overgrown fruits can also occur. You shouldn't get tomato seeds from these fruits, but they are perfectly edible and often a focal point in the garden.
In addition to environmental disturbances, numerous bacterial and viral pathogens and fungi can also damage tomatoes. We give tips on how to protect your tomatoes from diseases.