Dry Rot of Potato – Fusarium solani var. coeruleum

Fusarium solani var. coeruleum

Fusarium solani var. coeruleum

This disease can also affect field crops, however the damage is significant while the tubercles are stored.

Symptoms

This disease severely affects the plants as these suffer from a mass wilt or death. The plants also have a slow growing pace, that can be observed as the plants have different heights.

The tubercles that have been affected have a watery pulp, they rot, the leaves of the plant wilt, turn yellow and become dry. The stems also have brown conducting veins, just like the tubercles. The tubercles that have been infected through their existing wounds first become wrinkled, then the affected area turns brown. After that, the peel wrinkles looking like irregular circles on the brown and dry area, which will then sink.

Fusarium solani var. coeruleum - affected tubercle

In the environment is moist, fluffy swelling will emerge on the surface of the tubercles. These swellings can be white, gray or pink and deep inside the tubercle is completely rotten. If the environment is dry, the tubercles will harden and they will be hard to be cut. The affected pulp will be crumbly under the intact peel.

Pathogen:

The Fusarium solani fungus will survive for a long time inside the soil, or on the plants’ residues as resilient spores. The attack of the nematodes, followed by sudden temperature and moisture variations will make the plants more sensitive and it will aid the attack of the fungi which then spread through the spores helped by the wind (if the attack is on the stems and leaves), or by the ground water (if the tubercles are affected).

Fusarium solani var. coeruleum - affected tubercle 1

When harvesting the tubercles, the fungi are spread along the dust from the containers, baskets, or reused bags that haven’t been disinfected.

Prevention and control

We recommend applying a 5-6 year crop rotation, which excludes plants from the Solanaceae family. Another important prevention method is to use healthy tubercles when planting. Sorting the tubercles before storing is also very important, as well as making sure that while storing the tubercles the warehouse temperature is 1-3 degrees Celsius. It is also very important to have the warehouse well aired at all times and to make sure that it has been disinfected prior to bringing the tubercles in, using a mixture of 2% copper (Champ 77 WG, Funguran, Zeama Bordeleza).

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