Colletotrichum wilt disease
The Colletotrichum -Welkekrankheit is caused by the fungus Colletotrichum coccodes , a Colletotrichum species such induced disease of potato .
Symptoms and Biology
The thermal optimum is between 25 and 30 ° C. For this reason, the disease appears more frequently in warm summers. The sources of contamination are the soil, compost heaps with potatoes and tomatoes, and the microsclerotia on the tubers.
On the plant: The symptoms appear only sporadically during the growing season and are expressed, especially in warm summers, by the fact that the plants turn yellow and the stems dry out. At the end of the vegetation period, the underground parts show typical features: destruction of the young roots, detachment of the covering of the roots and the formation of large black spots (microsclerotia).
On the tuber: White, matt spots form on the tuber, on which the microsclerotia develop. The points are larger than those of silver scab disease . Sometimes a growth depression with putrefaction of the deep plant layers can be observed.
Combat
The attack by Colletotrichum coccodes can be reduced by the following measures:
- Keeping a three-year crop rotation
- Use of healthy seedlings
- Avoid stress through appropriate fertilization and irrigation
- Spray seedlings adapted
- Avoid over-watering before harvest (promotes the spread of the fungus)
credentials
- ↑ Colletotrichum coccodes in the Fungorum index
literature
- Horst Börner: Plant diseases and plant protection. (= UTB 518). 8., newly revised. and act. Edition. Verlag Eugen Ulmer, Stuttgart 2009, ISBN 978-3-540-49067-8 .