WERA_OLD027: Potato Variety Development
Statement of Issues and JustificationU.S. potato growers face many economic challenges including foreign competition, changes in consumer preferences, new environmental regulations, loss of crop-protection chemicals, increased input costs, new pest and disease pressures, as well as unpredictable growing conditions. Potato varieties need to be continuously improved to meet the changing conditions and demands of the industry and the consumer. Value of new varieties comes in the form of improved quality and marketability, increased yield, and reduced inputs due to disease and pest resistance and improved fertilizer- and water-use efficiency. The overall impact of new varieties will be profitable and sustainable production for the grower, improved competitiveness of the U.S. potato industry, a healthy, inexpensive food supply for American consumers, and an improved environment.
The states currently represented by WERA27 (California, Colorado, Idaho, Minnesota, Montana, New Mexico, Oregon, Washington, Texas) produce over two-thirds of all potatoes grown in the U.S. WERA27 is composed of a regionally-diverse interdisciplinary team of breeders, physiologists, pathologists, agronomists, biotechnologists, entomologists, virologists, extension specialists, economists, growers, and other industry representatives. This team is crucial to U.S. potato variety development and in turn, sustainability of the U.S. potato industry. Their combined participation allows for complete testing of improved germplasm that comes from federal and state breeding programs. Coordinated activities include seedling production, selection and evaluation, initial seed increase, complete in field and post harvest management research, advanced field and laboratory evaluations, evaluating processing quality and culinary attributes, developing agronomic recommendations for specific growing regions, and screening for resistance or susceptibility to diseases.
The predominant variety for many decades, both for processing and fresh markets, has been Russet Burbank, which accounted for 65% of the western U.S. potato acreage in the early 1980's but less than 50% in 2004. The steady decline in Russet Burbank production has come, in part, from the success of varieties developed and evaluated by participants of WERA27. Varieties replacing Russet Burbank production include Ranger Russet, Umatilla Russet, Shepody, Centennial Russet, Silverton Russet, Rio Grande Russet, Russet Nugget, and Russet Norkotah.
Examples of further success of WERA27 and other U.S. potato variety development programs are seen through changes in the production of chipping varieties, fresh market red-skinned and specialty varieties (e.g., pigmented flesh), and fresh market white-skinned varieties. Overall production of these specialty varieties has shifted away from one or two dominant varieties to that of numerous varieties, each with improved adaptation to different growing, storage or processing conditions, or market preferences. An increase has occurred in acreages of chipping varieties such as Ivory Crisp, Pike, Dakota Pearl, NorValley, and Frito Lay proprietary varieties resulting in a reduction of traditional chipping varieties, Norchip and Snowden. CalWhite has replaced White Rose as the dominant long white for fresh market in California. Dark Red Norland and Red LaSoda still dominate the red-skinned varieties, but new releases from the western and mid-western regions are bringing about additional changes. An increase in yellow-flesh acreage, primarily the Yukon Gold variety, has occurred in recent years in response to increased market demand; breeders in the western region have increased emphasis on yellow-flesh and other pigmented-flesh varieties. Private European seed companies have begun to export yellow-flesh varieties, which are common in Europe, to the U.S., facilitated by Plant Variety Protection (PVP) laws that protect their intellectual property rights.
Russet Burbank produces oblong to long, russet-skinned tubers with moderately high solids, has long-storage dormancy, and produces excellent baked and processed products. Despite these strengths, Russet Burbank has serious weaknesses. Russet Burbank is susceptible to Verticillium wilt, early blight, late blight, most potato viruses (including leafroll net necrosis), and some physiological disorders including hollow heart, brown center, internal brown spot, blackspot bruise, and dark-end fries caused by sugar accumulation in tuber stem ends when the crop is stressed. It is much more susceptible than most modern varieties to knobs, off-shapes, and internal and external defects associated with uneven growing conditions caused by fluctuating temperature and moisture. Serious quality reduction due to small tuber size and internal disorders aggravated by high temperatures is not uncommon for this variety.
Russet Burbank requires a high level of management, requiring more fertilizer, water, and pesticides than are required for varieties such as Bannock Russet, Alturas, and GemStar Russet - recent releases from the Northwest Tri-State Potato Variety Development Program. The recent movement toward more efficient use of fertilizers and irrigation, and less dependence on agricultural pesticides, adds urgency to the need for alternative varieties better adapted to low input production.
Russet Norkotah has become the predominant fresh market variety in many areas. It is early maturing with very smooth dark russet-skinned tubers that have good storage characteristics. The tubers are resistant to most physiological disorders, resulting in a high percentage of U.S. No.1 grades. The vines and tubers are susceptible to many viral and fungal diseases as well as environmental stresses. These susceptibilities frequently result in early dying and low yields. Growers have compensated by increasing nutrient and pesticide inputs (especially the use of fumigation), or by growing Russet Norkotah clonal selections with greater resistance to early dying. Several Russet Norkotah clonal selections have recently been released by the Colorado (CORN-3; CORN-8) and Texas (TXNS112, TXNS223, TXNS278, TXNS296) programs. The new clones produce higher tuber yields with fewer inputs than traditional Russet Norkotah. Because of these improvements, the clones have been rapidly adopted and are quickly replacing traditional Russet Norkotah. Collectively these clones comprise more than 50% of the Russet Norkotah certified seed acreage. The early success of these newly introduced clones has been somewhat overshadowed, however, by controversy within the industry regarding the long-term sustainability of all Russet Norkotah clones. Russet Norkotah tubers can be less palatable than many other varieties when consumed as a baked potato, especially after being held in cold storage for long periods. Along with the current low-carb diet fad, it is feared that Russet Norkotah's out-of-storage quality issues may be contributing to the slow decline in overall fresh potato consumption. New, early-maturing, fresh-market varieties would likely benefit this industry.
In order to identify varieties that may provide the U.S. industry benefit, they must be tested in key production areas and compared to the traditional varieties. Additionally, evaluation of germplasm from a range of sources under varying conditions offers the greatest probability of identifying superior varieties with improved pest resistance and reduced production inputs. Varietal materials from a wide range of sources are tested through the WERA27. Materials that are successful in the Northwest Tri-State (Washington, Oregon, Idaho) and the new Southwest Region (Texas, Colorado, California) variety evaluation programs, as well as material from other programs, are incorporated into the WERA27 evaluation scheme. Combining promising new genetic technologies and wild germplasm with traditional breeding efforts should result in superior new varieties.
Issues of increasing importance include late blight disease, ground-water contamination, water-use efficiency, transgenic and other biotechnology breeding tools, and plant variety protection. Western region breeders are active in addressing these issues. It is essential that they are discussed from many perspectives and that strategies be developed and implemented as a team. It is anticipated that new varieties will provide U.S. growers the ability to meet the challenges of constantly changing market and production conditions, thereby maintaining and potentially improving their economic well being. New varieties will help maintain a healthy, inexpensive food supply for American consumers and contribute to an improved environment.
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