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 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. Tubers are stored over winter and in the spring, they are cut up so that each piece yields a new plant. Fusarium takes advantage of this overwintering and spring cutting. The pathogen is unable to enter the tuber until it is either wounded through harvest, storage, or cutting and thus if there is any inoculum present in the soil, it has to wait until harvest occurs to infect the tuber. Once in, the fungus, along with other opportunistic pathogens like soft rot, begin to decompose the tubers and are able to kill off the plant before it emerges. Depending on the time of year, this pathogen moves and infects in different manners. As Fusarium is a soil borne pathogen, if there is sufficient wounding to the tubers, it may infiltrate that way. Because of the way this Fusarium species spreads, it does not need to produce any above ground fruiting bodies. It is only necessary to form microconidia late in the season or remain in the tubers to infect in the following season.