Field library

Common Scab

A germ in the soil that eats into the skin of the potato while it is still growing. It makes rough brown crusty patches, some raised and some sunken like pits, all over the tuber. It does not cut the weight much, but scabby potatoes fetch a poor price and are refused for seed.

How to scout

Lift a few potatoes from different corners of the field about a month before harvest and rub the soil off the skin to see whether rough brown crusts have formed.