Late blight and brown rot
The late blight is one of the most common diseases of tomato plants .
Causer and nature
Like late blight in potatoes , it is caused by an infestation with the pest fungus Phytophthora infestans . The pathogen is usually transmitted from the soil to the plant with rain or irrigation water. The late blight causes rapid browning and wilting of the foliage and tomato fruits just before they are ready for harvest.
- As a preventive measure, tomato plants should therefore be cultivated in such a way that irrigation water is poured onto the ground or - better - into dug pots so that nothing from the ground splashes up onto the plant. In addition, the plant should be kept under roofs to protect against rainwater. Another aid is a "tomato hat", which forms a tiny rain cover over the tomato plant.
- As a preventive measure, copper salt preparations can be injected.
- A preventive biological spray consists of chopped rhubarb leaves , which are poured with boiling water. After cooling, this is sifted and sprayed onto the tomatoes.
- Mulch (straw, wood chips, hay, etc.) prevents the water from spraying up soil particles, making it difficult for the pathogen to reach the plant.
- Living mulch (underplanting of beneficial interacting herbs or vegetables) also has this effect. See mixed culture .
Similar diseases caused by harmful fungi are Alternaria solani ( dry spot disease ), Stemphylium solani ( Stemphylium leaf spot disease), Cladosporium fulvum (velvet and brown spot disease), Fusarium oxysporum f. sp. lycopersici ( Fusarium wilt ), Verticillium albo-atrum ( Verticillium wilt ), Botrytis cinerea ( gray mold rot ), Phytophthora parasitica , Alternaria tomato , Septoria lycopersici , Sclerotium rolfsii , Colletotrichum -Arten-and Botrytenosporium .