Main suspects: late blight and brown rot
If brown leaves appear on tomatoes during warm and humid weather, an outbreak of the dreaded herbaceous and Brown rot to fear. The spores of the pathogen, which multiplies explosively, already call for 10 hours of permanent moisture. Brown spots on foliage and stems are considered the first symptom of the Plant disease. Immediately remove all discolored parts of the plant and dispose of them in the household waste.
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Since there is currently a lack of effective control agents, prevention is becoming more relevant. Potatoes should never be planted in the immediate vicinity. Basically choose a sunny, air-bathed one Location. So that the leaves do not get unnecessarily damp, give that Irrigation water always right to the roots.
Trigger in dry weather
If brown leaves appear on tomatoes in consistently dry weather, this is no reason to give the all-clear. Various other causes come into question, with fatal consequences as well.
- Pests of all kinds, such as aphids, tomato rust mites or thrips
- Dry spots at temperatures above 25 degrees Celsius
- Tomato wilt caused by the bacterium Corynebacterium Michiganense
- Stem and root rot, a widespread fungal infection after Watering errors
- Leaf spot disease, also a fungal infection with additional curling leaves
Brown leaves indicate a lack of nutrients
If diseases and pests have been eliminated from culprits, take a critical look at them fertilization Of your tomato plants. A lack of certain nutrients can also cause brown leaves:
- A lack of nitrogen causes the leaves to turn brown from the top
- an undersupply of phosphorus causes the roots to wither and turns the leaves brown
- too little potassium causes brown leaves that spread out towards the center
- When there is a shortage of magnesium, the leaves initially turn a light yellow, later a brown color
Tips & Tricks
If you plant your tomatoes under a rain cover, you have the best chance of not being confronted with brown leaves. Your own greenhouse is not absolutely necessary for this. With a little manual skill you can build a rain canopy yourself and improve the mounting conditions many times over.
