Government of New Brunswick

Pink Eye

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Pink eye is caused by the bacterium, Pseudomonas fluorescens. Symptoms include a pink or brown discoloration and death of the tuber skin, particularly around the tuber eyes. This disease is usually associated with Verticillium wilt, but can also be found on tubers from plants free from wilt. The bacterium is soil borne. It shows up towards the end of the growing season and is more common when soil moisture is high. Under severe conditions, soft rot may develop at the seed end of the tubers, appearing similar to the first stage of late blight tuber rot.

In storage, the bacteria spread from diseased to healthy tubers through wounds and natural openings. Tuber rot will occur more rapidly at storage temperatures above 7EC than at lower temperatures. Pink eye is a disease of harvest and storage; it does not affect the growing plant. Kennebec is highly susceptible but the disease has also been reported on Sebago, Irish Cobbler, Shepody, Katahdin, Russet Norkotah, Yukon Gold, and Russet Burbank.

Control

There is no known control measure to prevent pink eye but if it does occur, tuber rot in storage can be reduced if the temperature can be lowered immediately and the potatoes air-dried. When the pink eye organism is present, infection will be more severe in mechanically harvested potatoes. This is because barrel harvested potatoes which are dug and picked by hand are drier going into storage. More moist soil is retained and more wounds occur on the mechanically harvested ones. Do not store dirty, wet potatoes.