Comment submitted by J. Miller, University of Idaho

Research has shown that potato tubers that are rotting due to late blight and pink rot can contaminate healthy tubers during harvest. This leads to the rotting of potato tubers in storage. In 2000/2001, over 100,000,000 pounds of potatoes were discarded in eastern Idaho due to rot initiated by pink rot in eastern Idaho alone. Several disinfectants are currently labeled to be applied to potato tubers just after harvest and prior to storage for the purpose of stopping these and other rots. However, labeled disinfectants are fairly ineffective for controlling post-harvest late blight and pink rot. Disinfectants were used in eastern Idaho in 2000/2001 and substantial loss still occurred. Phosphorous acid has been the only class of fungicide that has been very effective in controlling post-harvest late blight and pink rot. Results from the University of Idaho showed that when phosphorous acid was applied at a rate of 12.8 fl oz/ton tubers to tubers that had been inoculated with the late blight pathogen, only 27% of tubers became infected compared to 100% in the untreated control and 100% with tubers treated with hydrogen peroxide/peroxyacetic acid. Similar results have been obtained with pink rot. The potato industry is in need of phosphorous acid based products to help mitigate tuber loss due to rot in storage.