Even if the current temperatures suggest a normal winter, the weather extremes from last year are still having an impact. Never before has climate change been so clearly felt.
Constant stress
At temperatures of around 25°C potatoes react with stress; at higher temperatures the plant stops its growth completely. According to the Deutscher Wetterdienst, there were 55 days of over 27°C during the vegetation period of the potato and even 30 days of more than 30°C.
This meant constant stress for the potatoes. In order to mitigate these factors and to stabilize the harvest, above-average levels of irrigation were required. Nevertheless, due to the high temperatures the cell 
pressure and water content of the tubers was low and the tubers felt softer than usual. Almost 80% of a potato is made up of water. Under normal conditions, the process of physiological ageing begins during the storage period.
During this time, the tuber loses some of the water through evaporation or aeration and slowly softens. This normal process is very slow under proper storage conditions, in modern cold stores. Many varieties then only develop their taste potential, even if they are not quite as firm as they were when harvested. Due to the prolonged heat of last year, these processes have started much earlier and are going much faster. But that does not change the taste or the nutritional value of the organic potatoes; the important ingredients are preserved. Thus, a slightly softer potato is just as good as those of other years.
Premature ageing
"So far, the organic potatoes have remained surprisingly stable in storage. Only occasionally were there problems with premature aging and incipient germination. Luckily, we did not record any spoiled batches," says Monika Tietke from the Bio Potato Producers Association after evaluating the results of the association's annual volume survey. She added with a wink: "If you want to be precise, consumers even get more for their money. You pay by weight, so you get more nutrients per kilogram, since only the water content diminished."
Overall, the effects of the weather extremes of recent years, cannot just be winked away. These softer tubers are only an indication of how climate change can be felt concretely. Besides that, changes in the optical condition occur more frequently. On many organic potatoes, surface scabs and small dark spots can be found: again stress reactions to the last year's drought. Furthermore, Silver scurf and Rhizoctonia are occurring more often. All these factors do not compromise the intrinsic quality of the potatoes and making this clear to customers will be the main challenge for the rest of the season.
For more information:
Bio Kartoffel Erzeuger e.V
GF: Monika Tietke
Gross Breese 3
29494 Trebel
Tel 05848-981076
Fax 05848 1269
m.tietke@bke-verein.de
www.bke-verein.de