Contents

Introduction Development of New Potato Varieties California Potato Variety Improvement Trials Summary Literature Cited Authors

California small-scale farmers and direct marketers are leaders in the production of "specialty potatoes", primarily yellow flesh. Varieties available to meet the requirements for direct marketing, organic production, and perceived high consumer quality parameters, such as flavor, however, have been limited. Small-scale producers and alternative marketers have had little research support in identification of most desirable and profitable varieties. During the 1990's, the University of California at Davis and Cooperative Extension, in cooperation with farmers throughout California, have conducted numerous trials to assess existing and potentially new specialty varieties. Breeding programs within the U. S. have begun to breed and select specialty varieties. In addition, European varieties, most of which are yellow-fleshed, have not been available to U.S. growers because of the US plant variety protection law. This changed in 1995, opening the door to many existing and new varieties and selections. Numerous of these have been evaluated for production, quality, and consumer acceptance. Specialty potato varieties with a range in yield potential, tuber size distribution, maturity, and flesh color intensity are available for conventional and alternative production and marketing systems. Consumer evaluations indicate a widely variable preference in color, taste, texture and other quality parameters; no conclusions can be made about general consumer preference.

Introduction

Potato consumption in the U. S. has slowly, but steadily, increased during the past two decades, primarily because of the increasing role of "fast food" restaurants and the prominent role of French fries in that system. Other reasons, however, are also responsible for this increase in popularity and consumption of, what was considered at one time to be, 'dirty', potato. These include the realization by the increasingly health conscious American consumers that potatoes have no fat or cholesterol, are high in easily digestible carbohydrate energy, and high in vitamins and minerals. Subsequently, numerous health organizations, and others, such as "Weight Watchers", have endorsed potatoes specifically, as well as vegetables in general. The increased use of microwave ovens in the 1980's for quick and easy dining, in turn, re-introduced the "baked" potato into home cooking, since potatoes could now be baked in 10-15 minutes instead of 45-60 minutes. Finally, the trends for up-scale restaurants to highlight new, whole red potatoes, then yellow flesh potatoes, and more recently, mashed potatoes, particularly yellow fleshed mashed potatoes, have helped to keep potatoes in the forefront of American diets.

Successful small-scale farmers depend on diversity in production and diversity in marketing to provide economic stability, to command higher prices, and to capture a higher percentage of consumer food expenditures. The most important production diversity components have been organic production systems and specialty crops. The most important marketing diversity components have been Farmers' Markets, direct sales to restaurants, specialty wholesalers, and more recently, CSA's (community supported agriculture) or subscription agriculture. Potatoes have been a staple crop for many small farmers in all of the above-mentioned production and marketing systems. To provide a product that is not available from larger scale and/or conventional marketing systems, however, small farmers have depended primarily upon organically grown or newly harvested, fresh potato tubers. In recent years, the demand for "specialty" potatoes has increased. Accurate statistics are unavailable from federal, state or county sources, but subjective evaluations by Farmers' Market managers and Cooperative Extension advisors indicate a steady increase during the past five years in the number of farmers and in acreage of production of "specialty" potatoes (verbal communications). Most of this increase has been in yellow flesh potatoes, while some increase has been in fingerlings and in "exotics" (e.g. purple skin and flesh, red flesh, multi-colored skin and/or flesh). The increased demand, thus increased production, has resulted partially from pro-active marketing by small farmers toward their established consumers and partially from consumers demanding yellow flesh potatoes. Interest in, and knowledge about, potatoes has increased among consumers, with the increasing perception that the white fleshed potatoes typically grown in the U.S. come from a very narrow range of the available germplasm in the world and have relatively less natural flavor. Varieties grown and consumed in much of South America (the native home of potatoes) and Europe have much more diversity, tend to be yellow fleshed, and generally considered to have more natural flavor.

California has been the leader and trendsetter for specialty crop production and marketing in the U.S. Most specialty crop marketing companies are located in California; most specialty crop imports enter through California. Consumption of specialty crops is highest in California. Specialty potatoes are no exception. The demand for yellow-fleshed, and other specialty potatoes, by California growers exceeds all other states.

Development of New Potato Varieties

The development of new potato varieties in the U.S. has always been, and still is, the primary responsibility of public institutions - USDA and land grant universities. Frito Lay, who develops varieties specifically for potato chips, and more recently Monsanto, with transgenic materials, are among the few private companies currently involved in potato variety development. Thus, nearly all varieties released in the U.S. during the 20th century have been publicly owned varieties. In Europe, by contrast, public potato variety breeding programs have been discontinued over the past two decades. Nearly all varieties grown in Europe have been developed and marketed by private breeding companies, with plant variety protection. Thus, the developer of a potato variety either controls the sales or receives a royalty fee for each unit of seed potatoes purchased, just as most vegetable seeds are marketed in the U.S. Since the U.S. plant variety protection laws specifically excluded potatoes, European potato seed companies have not allowed their varieties to be marketed in the U.S., because they could not control the seed production or collect any royalty fees; by law, all potato varieties were public varieties. In 1995, the U.S. law was changed to include potatoes, the only vegetable to be previously excluded. This change in law has attracted numerous European seed potato companies. Thus, a large number of yellow flesh potato varieties from The Netherlands and Germany, the principal seed potato countries in Europe, are becoming available to U.S. growers and consumers.

The demand for yellow flesh potatoes by U.S. consumers is indicated by the increasing demand for seed potatoes of yellow-fleshed tubers grown by larger-scale, conventional farms. The majority of acreage is planted to Yukon Gold variety, developed and released in Ontario, Canada in the 1980's. In 1990, Yukon Gold ranked 25th among most popular varieties in the U.S. In 1997, it ranked 12th. When combined with the fact that most small-scale producers in California, and other states, do not grow Yukon Gold, it is apparent that the demand for yellow-fleshed potato tubers has increased during the past decade, and appears to be continuing to increase. The most popular varieties grown by small-scale producers in California are Yellow Finn and Bintje, both very old European varieties that are no longer protected and thus not subject to royalties. Bintje can be compared with Russet Burbank, used for most of the frozen French fries in the U.S.; it has excellent quality, but is difficult to grow and has a low percent No. 1 tubers. Bintje is still a prominent variety in Europe, but commands a smaller percent of the market annually. The Yellow Finn has good culinary quality, but has relatively low yield potential and is susceptible to diseases and storage decay. It is rarely grown in Europe. Thus, the need exists for improved yellow-flesh potato varieties, both from a consumer and a producer perspective.

California Potato Variety Improvement Trials

In the late 1980's, the University of California began responding to the informal requests by small-scale producers and Farmers' Market consumers for new and improved "specialty" potatoes. The effort to grow yellow-fleshed, and other specialty, potatoes has increased annually since then. With the change in the U.S. Plant Variety Protection Act in 1995, private European breeding companies began entering new varieties into these trials. Currently, one German and four Holland companies have entries in UC trials. In 1996, the USDA western regional potato variety program added specialty potatoes as a category of varieties for multi-state evaluation, an indication of the growing interest in these varieties. Most of the evaluation has involved production parameters - yield, size, visual quality, storability, disease susceptibility. Numerous consumer and culinary evaluations have also been conducted.

The photos illustrate some of the varieties evaluated by UC and their differences in skin color and flesh color.

Table 1 summarizes the production performance of nine of the most commonly tested yellow flesh varieties. Locations of these trials included conventional, high input sites; organic, high input sites; and organic, low input sites. They were located in Kern, Siskiyou, Placer, Nevada, San Benito, Stanislaus, Fresno, Monterey and Santa Barbara Counties. Entries ranged from Yukon Gold, the standard yellow flesh in conventional production and marketing, in 23 trials; to Agria, a new, protected variety from The Netherlands, in 6 trials. Average total yields ranged from 440 cwt/A for Agria to 220 cwt/A for G742-4X, a new variety from Canada. Yellow Finn, one of the standards in alternative production and marketing systems, was among the lowest yielding. In conventional markets, the large tubers commonly command a higher price, while in alternative markets, the smaller tubers commonly cost more. The varieties with the highest percent of large tubers was Agria, Rose Gold, Red Gold and 6742-4X. The varieties with the highest percent of small tubers were Bintje, Granola, German Butter Ball and Yellow Finn. The varieties range in maturity from late (e.g. Agria and German Butter Ball) to early (e.g, Red Gold, G742-4X and Yukon Gold). Yellow flesh intensity ranged from dark yellow (e.g. German Butter Ball, Yellow Finn and Agria) to light yellow (e.g. Bintje, G742-4X and Rose Gold).

Table 2 lists consumer evaluation data collected from Master Gardeners in Santa Clara County in 1990 and 1991 on 17 varieties. These evaluations were based primarily on consumers' perception of "taste." Table 3 lists evaluation data collected from 100 consumers at a Placer County Farmers Market in 1997 on 13 varieties. These evaluations were based on consumers' perception of "taste, appearance, texture." Identical rating sheets were used in both trials; consumers were asked to evaluate each variety on a scale of 1-10, with 1 being "terrible" and 10 being "wonderful or heavenly."

These consumer evaluation data illustrate a common finding - perceived quality varies according to individual consumer preference, and thus is not only subjective but highly variable, more so than production variability among locations. Most varieties received both 1 and 10 scores. The average evaluation ranged from 5.8 to 6.8 at Santa Clara, and from 5.2 to 7.5 at Placer. At Santa Clara, the standard deviations for each variety ranged from 1.9 to 2.4, that is, approximately half of the evaluations were between + or - one standard deviation; at Placer, the standard deviations ranged from1.9 to 2.3. At Santa Clara, the yellow fleshed varieties averaged 6.4 while the white fleshed varieties averaged 6.5 rating. At Placer, the respective ratings were 6.2 and 6.3. At Santa Clara, the yellow skinned varieties averaged 6.5, the red skinned varieties 6.5, and the purple skinned varieties 6.2. At Placer, the respective ratings were 6.2, 6.5 and 5.5. Thus, from a strictly statistical perspective, no significant differences existed among the consumer preferences of these potato varieties, at either of the locations. However, to individual consumers, big differences obviously existed; no consensus preferences exist, with the possible exception of the lower preference for purple skinned varieties. Thus, while the preference and demand for yellow flesh varieties may be increasing, the attractiveness of red skinned varieties still is strong, at least among these consumer groups - farmers markets and home gardeners.

The characteristics of numerous other available specialty varieties are reported in annual summaries published jointly by the University of California, Davis and the California Potato Research Advisory Board. Many of the trials included observational data, thus, no yield or grade data may be available.

Summary

Interest in specialty potatoes, especially yellow fleshed varieties, has increased in California. They provide an opportunity for small farmers to diversify their production and marketing by supplying the alternative markets with varieties not generally available in conventional markets. Many new yellow fleshed varieties are available as a result of increased emphasis on specialty variety development within the U.S. and the change in plant variety protection law, which now allows privately owned European varieties to be marketed in the U.S. Consumer evaluations indicate a strong preference among individual varieties as to taste, appearance and texture, but no consensus opinions as to general preferences exists.

Literature Cited

Middaugh, A. R. 1999. 1998 Potato Statistical Yearbook. National Potato Council. Englewood, CO. 80 pp.

Gunther, Joseph. _________________

Thoman, Derek, Ed. 1998. The Packer -1998 Produce Availability & Merchandising Guide. Vol CIV, No. 54. Vance Publishing Corp., Lenexa, KS. 520 pp.

Voss, R. E., H. Phillips, H. Carlson, M. Dascomb, D. Douches, M. Gaskell, K. Haynes, S. Holm, M. Jimenez, D. Kirby, F. Laemmlen, R. Molinar, R. Mullen, R. Novy, J. Nunez, J. Pavek, K. Rykbost, R. Smith and J. Valencia. 1999. Potato Variety Selection and Development, 1998 Annual Report. Vegetable Crops Department Special Publication. Univ. of California, Davis. 60pp.

Authors

Ron-Voss is Extension Vegetable Specialist, UC Davis; Herb Phillips is Staff Research Associate, UC Davis; Kent Brittan is Farm Advisor, Sacramento; Harry Carlson is Farm Advisor, Siskiyou and Modoc Counties and Superintendent, Intermountain Research and Extension Center; Nancy Garrison is Horticultural Advisor, Santa Clara County; Mark Gaskell is Farm Advisor, Santa Barbara and San Luis Obispo Counties; Manuel Jimenez is Farm Advisor, Tulare County; Don Kirby is Staff Research Associate, Intermountain Research and Extension Center; Richard Molinar is Farm Advisor, Fresno County; Joe Nunez is Farm Advisor, Kern County; Richard Smith is Farm Advisor, Monterey County; Jesus Valencia is Farm Advisor, Stanislaus County; Garth Veerkamp is Farm Advisor, Placer-Nevada Counties.

Table 1. Performance of Yellow Flesh Potatoes in Locations Throughout California
Variety	No. of Trials	Total Yield cwt/A	Yield % of Total			Vine Vigor1	Vine Maturity2	Visual Appear3	Skin Color	Flesh Intensity4
			Marketable	Large	Small
Agria	6	440	86	44	42	4.6	4.6	3.7	Yellow	3.4
Bintje	4	405	86	10	77	-	-	2.7	Yellow	2.3
G742-4X	15	220	89	39	52	2.6	1.8	3.5	Yellow	2.3
German Butter Ball	11	405	91	22	69	4.5	4.4	3.0	Yellow	3.6
Granola	13	360	92	24	68	4.2	3.8	3.5	Yellow	2.7
Red Gold	7	405	96	62	42	3.0	1.7	2.8	Red	2.4
Rose Gold	18	350	90	56	34	3.7	2.9	2.9	Pink	2.3
Yellow Finn	17	255	82	25	57	3.8	3.6	3.0	Yellow	3.5
Yukon Gold	23	305	93	61	30	3.4	2.0	3.6	Yellow	3.3
Average	-	325	91	42	49	3.6	2.8	3.2	-	2.8

¹5 = Largest, 1 = Smallest
²5 = Latest; -1 = Earliest
³5 = Excellent, 1 = Poor
⁴5 = Darkest Yellow, 1 = White

Table 2. Tasting Evaluation - Santa Clara County Master Gardeners, 1990-1991
Variety	Skin Color	Flesh Color	Range in Scores1	Average Score1	Standard Deviation	Frequent Comments
All Blue	Purple	Blue	1-9	5.8	2.1	Mealy, Unusual, Mild
Augsburg Gold	Yellow	Yellow	2-10	6.6	2.2	Waxy, Smooth
Bintje	Yellow	Yellow	2-10	6.1	2.1	Mealy, Mild
Bison	Red	White	2-10	6.6	1.9	Moist, Good Flavor, Creamy
Caribe	Red	White	3-10	6.8	2.3	Moist, Sweet, Firm
Desiree	Pink	Yellow	2-10	6.4	1.9	Bland, Dry, Moist, Firm
German Yellow	Yellow	Yellow	1-10	6.4	2.0	Smooth, Sweet
Green Mountain	White	White	3-10	6.7	1.9	Dry, Good Texture, Bland
Katahdin	White	White	1-10	6.2	2.0	Waxy, Bland
Norgold Russet	Rust	White	1-10	6.5	2.4	Mealy, Moist, Smooth
Pink Pearl	Pink	White	1-10	6.7	2.1	Moist, Soft, Bland
Purple Chief	Purple	White	2-10	6.5	2.0	Mealy, Bland
Red Dale	Red	White	1-10	6.0	2.1	Moist, Creamy, Bland
Rose Finn Apple	Pink	Yellow	3-10	6.4	2.0	Waxy, Mellow
Sangre	Red	White	2-10	6.3	2.0	Moist, Mild
Yellow Finn	Yellow	Yellow	3-10	6.7	2.3	Moist, Creamy, Mild
Yukon Gold	Yellow	Yellow	2-10	6.5	2.0	Mealy, Mild

Average of 7 Yellow Flesh	6.4
Average of 9 White Flesh	6.5
Average of 5 Yellow Skin	6.5
Average of 7 Red or Pink Skin	6.5
Average of 2 Purple Skin	6.2

¹75 Evaluations; 10 = "Heavenly", 1 = "Terrible" based on taste

Table 3. Tasting Evaluation - Placer County Farmer's Market, 1997
Variety	Skin Color	Flesh Color	Range in Scores1	Average Score1	Standard Deviation	Frequent Comments
A83359-5R	Red	White	1-10	6.7	2.3	Bitter, Good Flavor, Moist
AD82706-2R	Red	White	1-10	7.5	2.0	Good Flavor, Sweet, Moist
All Blue	Purple	Blue	1-10	6.0	2.2	Ugly Color, Good Color
B 141	White/Purple	White	1-10	5.4	2.3	Dry
Delta Gold	Yellow	Yellow	2-10	5.8	2.1	Good Color, Dry
Desiree	Pink	Yellow	1-10	5.8	2.1	Good Flavor, Firm
Fontenot	Red	White	1-10	5.6	2.2	Dry, Good Flavor
G742-4X	Yellow	Yellow	1-10	6.3	2.0	Good Flavor, Moist
Longlac	Purple	White	1-10	5.2	2.0	Dry, Firm, Strange Texture
Red LaSoda	Red	White	2-10	6.6	1.9	Dry, Moist, Good Flavor, Poor Taste
Rose Gold	Pink	Yellow	1-10	6.3	2.2	Good Flavor, Smooth/Creamy
Ruby Red	Red	White	1-10	6.8	2.5	Good Flavor, Moist
Yellow Finn	Yellow	Yellow	2-10	6.4	1.9	Good Flavor, Sweet
Yukon Gold	Yellow	Yellow	1-10	6.4	2.0	Firm

Average of 6 Yellow Flesh	6.2
Average of 7 White Flesh	6.3
Average of 4 Yellow Skin	6.2
Average of 7 Red or Pink Skin	6.5
Average of 3 Purple Skin	5.5

¹100 evaluations; 10 = "Wonderful", 1 = "Terrible" based on taste, appearance, texture

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