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Storage Quality

In season infection with tuber necrotic viruses, including PVY, TRV and PMTV, can affect harvested tubers and degrade postharvest processing quality.

For PVY, ongoing storage research at the University of Idaho indicates that fry processing potatoes with visible PVY symptoms, such as necrotic rings and sunken lesions, produce dark-colored, commercially unacceptable fried products. Tubers from PVY-infected plants that did not show visible symptoms, however, had processing quality that was comparable to that of tubers from PVY-free plants. These findings are similar to those obtained for Snowden and Russet Burbank grown in Wisconsin. Snowden chip color and stem-end chip defect scores were not different when symptomless tubers were harvested from PVY-infected and non-infected plants. Likewise for Russet Burbank, bud-end and stem-end fry color did not differ between tubers from PVY-infected and PVY-free plants. In-season PVY infection also had little effect on tuber shape and water loss in storage.

Top to bottom: Umatilla Russet with PVY-NTN, Ranger Russet with PVY-O, whole and cut in half

TRV and PMTV degrade fry processing quality and the effects of virus infection can become more severe during post harvest storage. TRV and PTMV-infected potatoes were grown by researchers in North Dakota and Washington (TRV only) and evaluated at harvest and multiple times post-harvest at the University of Idaho. Symptom expression was found to be highly variable at harvest, depending strongly on the production year and on the potato variety. Potatoes with visible symptoms produced unacceptable fried products. For PMTV and TRV, symptom expression was found to increase with time in storage (48F). In some cases, lots with good processing quality and few tubers expressing TRV symptoms shortly after harvest had a high percentage of symptomatic tubers and poor processing quality later in the storage period. Further research is needed to determine if symptoms develop at seed-storage temperatures.

Top to bottom: Ranger Russet infected with TRV, raw and fried

Photos courtesy of Lynn Woodell, University of Idaho

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