Potato Storage: Proper storage techniques can reduce disease pressure

Storage conditions can be ripe for diseases to develop and devastate potato crops, leading many universities to seek ways to control or prevent diseases before they become a problem. At the University of Maine (UM) a fungicide testing program looks at new chemicals and their potential for preventing potato diseases, as well as new uses for current chemicals.

"There are no postharvest diseases, so the problem begins in the field or delivery into storage,"said Steve Johnson, a potato specialist with the UM Cooperative Extension, Presque Isle.

"As you store potatoes longer, it certainly does get to be a problem. Whether it's fresh cut or processed, any amount (of disease) you can lower is a good thing,"Johnson said.

Multiple diseases such as late blight, pink rot, leak, black dot and silver scurf impact Maine's potato fields. Johnson is the leader of the UM testing program, looking at the effectiveness of new products and new uses for current chemicals. Two are scheduled for fall testing, but Johnson was hesitant to name them because they currently aren't labeled for potatoes. Those potential potato fungicides may soon receive labeling if they show success in battling disease.

Agraquest's Serenade and Syngenta's Mertect are two fungicides labeled for potatoes Johnson has studied, each showing positive reductions in silver scurf, but so far, Johnson has yet to see similar effects on black dot.

Even with the success of many fungicides, Johnson is seeking alternatives that can provide adequate disease reduction while limiting environmental impacts. Phosphorous acid is one such alternative that is already seeing use in Maine. Through phosphorous acid field trials, Johnson has seen reductions in late blight, pink rot and leak. Compounds with similar structures to bleach have shown mixed results.