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2003 Late Regional Trial Postharvest Evaluations

Regional trials are conducted throughout the western United States, including Washington. Entries in these trials are chosen by a coordinating committee and are grown for both early and full season harvests. This year’s full season trial contained two cultivars and fourteen clones. Russet Norkotah, Shepody, and PA95A11-14 were grown in the early trial but not in the late trial. The following is a summary of the Washington field results along with postharvest results from the Washington, Idaho and Oregon locations.

The postharvest evaluations are intended to identify those clones best suited for the French fry processing industry of the Pacific Northwest. The tuber samples are obtained from the Washington, Idaho and Oregon field trials for evaluations of storage and processing quality in Pullman.

Twelve numbered clones, along with Ranger Russet and Russet Burbank as check cultivars, were evaluated from each growing location. With the exception of CO93016-3Ru, all clones outperformed Russet Burbank. A91814-5, a new entry advanced from the 2002 Tri-State Trial, was the highest scoring clone, with a three state average of 32.1/35. This clone produced tubers with an average specific gravity of 1.090 and was rated relatively high in the taste panel evaluations.

A93157-6LS, TC1675-1Ru and A91186-2 were the next highest scoring clones in the 2003 Regional Trial. A93157-6LS and A91186-2 were advanced into the 2003 Regional Trial from the 2002 Tri-State Trial, where they were also rated among the top four clones, indicating consistency in performance.

CO93016-3Ru and ATX9202-1Ru were the lowest scoring clones this year, with three state averages of only 16.6 and 18.6 out of 35 possible points, respectively. CO93016-3Ru averaged only 2.9/5 on taste panel evaluations. ATX9202-1Ru had internal discoloration that was noted in samples from all states and a ‘woody-like’ texture in some tubers.

A91814-5, A93157-6LS and A91186-2 produced the lightest French fries after 64 days storage at 44 and 40°F, reflecting significant resistance to LTS. At the other extreme, CO93016-3Ru and ATX9202-1Ru produced darker colored fries after 64 days of storage at 48, 44 and 40°F, compared with the other numbered clones.

CO93001-11Ru had a higher than average susceptibility to bacterial soft rot. Tubers of this clone broke dormancy in late October, with sprout lengths of 2 and ¼ inch from 48 and 40°F storage, respectively. AC92009-4Ru, CO93016-3Ru and A9304-3 showed reduced wound-healing ability when compared with the other Regional Trial clones, but in general all clones wound-healed well.

When averaged over all clones, Idaho produced tubers with the highest length/width ratios, resulting in the highest yield (by number and weight) of m3-inch-long French fries per 8- to 10-oz tuber. This trend has been consistent for many years. Eight- to ten-ounce tubers of A91814-5 had length to width (L/W) ratios averaging 1.15, reflecting round tubers, and thus only 44% yield of French fries. This clone is being developed for the dehydration industry. Yields of fries from A91186-2, ATX9202-1Ru, A9304-3 and CO93016-3Ru were the highest, averaging 75%, and comparable to those from Russet Burbank. Compared with the other clones, A9305-10, TC1675-1Ru and A91814-5 showed more variation in tuber shape and thus fry yield across the tri-state production sites. In contrast, CO93016-3Ru, A91186-2 and A9304-3 produced tubers with length to width ratios and fry yields that were relatively constant across the three production sites.