Potato cancer
The potato cancer is caused by the fungus endobioticum Synchytrium caused fungal infection on the bulb and the stem base of the potato ( Solanum tuberosum ).
Symptoms and Biology
The disease is characterized by cauliflower-like cell growths called tumors. These are of very different sizes (up to the size of a fist) and attack lenticels , stolons and subterranean parts of the stems , but never the roots, as is the case with powder scab and nematode attacks . The tumors are light at first, darken over time, and eventually release a black powder. The disease can also develop during storage. The potato tubers may already be rotten when harvested. They are then easily overlooked. While the shrub growth appears healthy, the yield usually decreases sharply or remains completely absent. The pathogen occurs in different subspecies , against which there are resistant varieties . If potato cancer occurs, notification is required. The cultivation of potatoes is prohibited on the infested area. It may only be resumed once evidence of freedom from infestation is provided. Once the potato crayfish breed has been determined on the infested area, only varieties that are resistant to this type of pathogen may be grown on the neighboring properties . The epidemics are particularly bad in damp and cold climatic regions, such as northern and central Europe.
Combat
In addition to the drastic measure of isolating the disease on infested areas, there are only a few additional measures - namely the use of healthy and / or resistant seedlings . A longer crop rotation could also relieve the pressure of infestation (potatoes every 4–5 years). Chemical control is not possible. The fight against potato cancer is regulated by law in Germany.