M A Y J U N E 2 0 1 620 POTATO GROWER 2015 Fresh Market Potato Trial Crystal North Dakota by Dr. Asunta Susie Thompson NDSU Potato Breeder The northern plains potato produc- tion areas of Minnesota and North Dakota produce potatoes for all markets including tablestock seed and processing. About 17 of pro- duction is for the fresh tablestock market. Red Norland and Yukon Gold are two of the predominant cultivars one red skinned and one a yellow fleshed cultivar. While industry standards they have short- comings such as none uniform red skin color across fields for Red Norland and low tuber set often resulting in hollow heart for Yukon Gold. Both are susceptible to many pests and stresses including Colorado Potato Beetle late blight silver scurf PVY and soil moisture. Cultivars possessing excellent table- stock quality should have a uniform tuber size profile be attractive in terms of shape and skin finish pro- duce a high yield of marketable sized tubers be free of internal and external defects ideally be flavorful and for todays industry should combine environmental and eco- nomic sustainability. The North Dakota State University NDSU potato breeding program conducts crossing selection evalua- tion and cultivar development activities across North Dakota and western Minnesota in order to iden- tify superior genotypes for all mar- ket types. In 2015 field research tri- als were grown at eight sites. Five were irrigated Larimore Oakes Inkster Williston and Park Rapids and three were non-irrigated Hoople Crystal and Grand Forks sites. Trials are important in discov- ering selections with high yield potential disease and pest resist- ance stress tolerance and consumer quality attributes for tablestock and processing. This narrative summa- rizes the results from the Crystal Fresh Market Trial. Additional trials at this site included the non-irrigat- ed North Central Regional Fresh Market Trial and our Preliminary Fresh Market Trial. Thirty advancing fresh market selec- tions and commercially acceptable check cultivars were included in the trial planted on May 20 at Crystal North Dakota. The field plot design was a randomized complete block with four replicates cultural prac- tices typical of the growing area were used during the growing sea- son. Rows were spaced 36-inches apart with a 12-inch within-row spacing. Vines were desiccated on September 1 and the trial was har- vested on September 15. Days to days to vine kill were 102 while days to harvest totaled 117. Agronomic yield and grade and quality evaluations are summarized in Tables 1 2 and 3 respectively. Percentage stand was not statistical- ly different for clones and ranged from 49 to 100 Table 1. Vine sizes significantly differed as expected and ranged from medium- small for ND0102990B-3R to very large for Mondeo. Vine maturity ranged from 1.8 medium-early for ND102990B-3R to 4.5 for Mondeo. Stems per plant is indicative of seed quality physiological age and seed size tuber eye number genetic and dormancy genetic and envi- ronmental. Stem numbers ranged from 1.6 for Sangre to 2.9 for ND7982-1R. Seed quality was excel- lent in 2015 and this was reflected in the stem numbers. Most cultivars peak performance will be in the 1.5 to 3.0 stem range. Tuber shape is important for fresh marketing. Tuber shape ranged from round 1.0 for many selections to long for All Blue and Abby a KWS fingerling cultivar. Check cultivars such as Red Norland and Red LaSoda are more oblong while Dakota Ruby is very round. Richness of color and smoothness of skin finish are two important attributes for fresh mar- ket tubers. ATND99331-2PintoY is a buff colored clone with purple splashes and yellow flesh while All Blue is purple with purple flesh. Mondeo Vitabella and Yukon Gold are yellow with yellow flesh. Many NDSU selections and recent releases have outstanding bright red skin color. General rating is an overall assessment of appearance yield and quality attributes. General rating scores ranged from 2.8 to 4.0. Clones such as Red LaSoda Sangre and Viking which tend to have a larger tuber size profile slightly deeper eyes and lighter red skin color than new selections rated lower. Dakota Ruby and several advancing selections rated the high- est.