Potato wart eyed as risk to potato production

According to Gary Franc, plant pathologist with the College of Agriculture, Plant Sciences Department at the University of Wyoming, Laramie, WY, potato wart is a serious disease of cultivated potato that has been detected worldwide. Potato wart is caused by the fungus Synchytrium endobioticum, which is considered to be the most important worldwide quarantine plant pathogen of potato. While not harmful to humans, the disease causes unsightly growths that initially appear white, and then turn brown or black as they decay, rendering the potato tuber unrecognizable and inedible.

There is a zero tolerance for the fungus that causes potato wart. As a result, this disease has been placed on the USDA’s “Select Agent List” of plant pathogens deemed to pose a severe threat to plant health or to plant products.

Although direct losses from potato wart may be insignificant when first detected, indirect economic losses resulting from zero-tolerance regulations for potato wart can be devastating to growers. Indirect economic losses become especially evident in potato production areas that are subject to quarantine measures, as well as when the movement of commercial potatoes is restricted.

Spores released from infected plants can make soil unsuitable for potato production for decades. The long-term survival of fungal spores and the lack of suitable chemical controls for potato wart suppression make this disease especially problematic for any type of cultivated potato production, including small garden plots and subsistence farming to extensive land areas economically dependent on commercial production of potatoes for consumption or for potato seed production.

“Potato wart is much easier to prevent than it is to control,” Franc said. “It is highly critical that we prevent the introduction of the potato wart pathogen to production areas, and, where it is already introduced, to limit its spread,” he said.

“While regulatory action is important in potato wart management, it is essential that research efforts continue with the goal of developing and improving reliable and integrated disease suppression methods to directly deal with this disease,” said Franc.