Fusarium dry rot

Fusarium dry rot is one of the most common potato diseases. It is caused by fungi in the genus fusarium. This fungi causes a variety of colored rots in potatoes. This pathogen, while having both a sexual and asexual form, stays in an asexual cycle due to the way it spreads. Preferring warmer climates, it is not uncommon to find this pathogen in the northern United States where it has been reported to affect yield as much as 60%.

Fusarium dry rot of potato is a devastating post-harvest losses (vegetables) disease affecting both seed potatoes and potatoes for human consumption. Dry rot causes the skin of the tuber to wrinkle. The rotted areas of the potato may be brown, grey, or black and the rot creates depressions in the surface of the tuber. Seed pieces may rot completely before they have the chance to be planted.

The genus that causes dry rot of potato, Fusarium, is a fungus. Signs of a pathogenic Fusarium species can be seen on an infected potato, and include white or pink mycelia (masses of vegetative fungal tissue) and very colorful spores that can be blue, black, purple, grey, white, yellow, or pink.

The most prevalent Fusarium species is Fusarium sambucinum. There are thirteen known dry rotting species of Fusarium but Fusarium sambucinum causes the most problems in the United States. Fusarium species are asexual but some do have a sexual stage. The sexual stage for Fusarium sambucinum is known as Gibberella pulicaris but little is known about it other than it is an ascomycete.

Potatoes are not your typical vegetation. Each tuber is capable of producing a brand new plant from various eye spots. This allows farmers to culture an identical plant from each tuber and in turn cuts costs as each tuber can sprout a dozen new plants. And dozens of new sources of dry rot.

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