Variety Trial

Interest in variety selection, flavor and culinary attributes surfaced early on in the OSPUD project. The importance of variety was a recurring theme in discussions ranging from nitrogen demand to late blight resistance. OSPUD members initially became interested in variety trialing because the European Union BlightMOP Project concluded that resistant germplasm is the best alternative to copper fungicides for control of potato late blight.  OSPUD partnered with the OSU Potato Breeding Program (Isabel Vales and Solomon Yilma) to identify and obtain seed of available LB resistant germplasm.  In 2006, farmers informally trialed Jacqueline Lee, Island Sunshine, and Defender, three LB resistant commercially available clones (see the Late Blight section for more information).  Farmers liked the quality and yield of both Jacqueline Lee (a yellow fleshed potato similar to Yukon Gold with moderate foliar LB resistance) and Defender (a russet with strong foliar LB resistance).

The 2006 informal trials generated considerable farmer interest in conducting variety trials.  The purpose was not only to evaluate performance on each individual farm, but to understand whether there was value in planting the same trial on many farms.  What could be learned by a cooperative, multi-farm variety trial? Seven farms were involved in the evaluation of fourteen varieties, including currently grown favorites, as well as three unreleased varieties of interest (two with documented late blight resistance).The OSPUD farmers generated the cultivar list.

Cultivar List (click here to read about the cultivars)

Experimental Design

Ospud staff obtained and planted all seed. Variety trials were planted in the center of each farm's commercial potato field. Farmers prepared the field for potato planting exactly as they prepared for their commercial crop and then planted the rest of the field, leaving an area in the center of the field (unplanted) for the trial.  Each on-farm trial consisted of two 15 ft. reps per clone (except at the Mt Vernon locations, where there were three reps) in a randomized complete block design. Seed was cut at the OSU vegetable research farm and planted at 3 inch depth by hand by Ospud staff.


During the growing season, plots were evaluated for

    (1) emergence / stand count

    (2) PVY incidence (see photo to right)

    (3) general observations on general vigor and health


At harvest, plots were evaluated for

(1)   yield

(2)   size distribution {large (8 oz +), medium (3-8 oz), small (0-3 oz), culls}

(3)   a subset of tubers (30 tubers/plot) were rated formario_with_cracked_potato_in_lab.jpg

o   Disease incidence and severity (scab, black scurf, silver scurf)

o   Insect damage incidence and severity (flea beetle and wireworm)

o   Moisture-related damage (elephant hide and cracking)

(4)   a subset of tubers (50 tubers/plot) were stored and rated for storability

(5)   a subset of tubers were collected for informal farmer and consumer evaluations of flavor, texture and appearance


Seed quality problems, including Fusarium dry rot, Erwinia and PVY incidence, were significant seedborne problems observed in several varieties across the farms. These seed quality problems adversely affected yields and led to in-depth discussions with OSU potato specialists (Jeff McMorran, Al Mosley and Oscar Gutbrod) during farmer meetings. A new seed source was identified which may potentially alleviate these seed problems.  


Yields may have also been affected by planting date, with earlier plantings producing greater yields due to less heat and moisture stress at tuber set. Yield, insect damage and disease incidence across varieties were variable on individual farms indicating additional data is required before making conclusions.