Specialty Potatoes
USDA Department of Agriculture
Cooperative State Research Service
Office for Small-Scale Agriculture
The potato. one of the most important food
crops, came under cultivation by South American "Indians" more than 2.000 years ago. Potatoes, of which there are hundreds
of varieties in every shape, size, and color, were carried to
Europe around 1500. From Europe they were introduced into the
British Colonies in North America.
In 1992, the potato is one of several food
crops featured in the Smithsonian Institution's National Museum
of Natural History's exhibition "Seeds of Change," commemorating
the 500th anniversary of Columbus' first voyage. For many years,
the potato had its own Potato Museum, in Washington, D.C. (Also
see The Incredible Potato, National Geographic Magazine,
May 1982.)
Interest is increasing in the yellow-fleshed
and other uncommon varieties-specialty potatoes. Yellow-fleshed
potatoes are the rule rather than the exception in most countries.
Some specialty potatoes available in the United States for many
years were long considered of little commercial value. Now, however,
with increased consumer demand, domestic potato breeders have
begun to release some excellent yellow-fleshed varieties.
In Washington State, nearly 200 specially
potato varieties and clones have been tested; some varieties appear
with pink or purple flesh and skin colors ranging from buff to
red. Many have given yields greater than 'Russet Burbank.' Erik
J. Sorensen, Washington State University Cooperative Extension,
Franklin County Courthouse, Pasco WA 99301, has results from test
trials.
With per capita fresh potato consumption
static or declining, the variety offered by specialty potatoes
can add to sales. Despite hurdles, they have a bright future but
will never completely replace the traditional white-fleshed, russet
type.
Climate, Soils, and Water
Although classified as a cool-season crop,
commercial acreage can be found in alt 50 States, with Idaho,
Washington, Oregon, Maine. Wisconsin, California, and North Dakota
leading. Soil temperatures should be between 45 and 70 degrees
F at planting time. Planting into cold soils delays emergence
and increases the risk of seed piece decay.
Although rainfall often suffices, irrigation
may produce highest yields. Potatoes need 18 to 30 inches of water
to mature. Potatoes are shallow rooted, with most roots being
in the upper foot of soil.
Potatoes are sensitive to water stress.
Well-drained, light textured soils, such as sandy loams or loamy
sands, generally produce the highest quality potatoes.
Good-Quality Seed
Potatoes are vulnerable to several diseases,
including blackleg, bacterial ring rot, and viruses, which can
be transmitted in infected seed. To avoid such problems, certified
potato seed is recommended. Not guaranteed to be disease free,
potatoes certified by State agencies have shown no more than an
allowable tolerance level for disease symptoms. For certain diseases,
such as ring rot, the tolerance level is zero. To be certified,
seed lots must be inspected in the field during the growing season
AND in storage or at shipment.
Addresses of State and Provincial certification
offices which list certified growers may be obtained from the
publisher of this factsheet.
A number of mail order companies also offer
limited quantities of specialty potato seed. Among these are some
run by innovative potato growers: Will Bonsall, Scatterseed Project,
Box 1167. Farmington, ME 04938:
David Ronninger, Ronninger's Seed Potatoes,
Star Route 1, Moyie Springs, ID 83845 (both curators for Seed
Savers).
Planting and Cultivation
In much of this country, potato seed pieces
are planted 3 to 4 inches deep. But where soil moisture may be
limited, seed pieces are planted an inch deeper. The amount of
seed required varies according to seed piece size and plant spacing.
A spacing of 9 to 12 inches between plants is common. Wider spacings
often result in oversized tubers.
Cut seed is widely used, but whole seed
is less sensitive to tuber decay. Cut seed pieces should be 2
to 2 1/2 ounces in weight, firm, and with at least one eye.
After planting, potatoes may be cultivated
to help control weeds and to reshape beds. It is common to hill
potato plants when they are 8 to 12 inches tall: Soil is mounded
to a height of 2 to 3 inches around the plant base Some varieties,
such as 'Yukon Gold,' set tubers high in the bed. Hilling helps
maintain suitable soil cover to prevent greening or sunburning
of tubers.
Pest Control
The potato is vulnerable to pests. In addition
to using certified seed, growers need many strategies to minimize
insect and disease problems. Strategies include proper soil fertility
and water management, crop rotation, sanitation, and the use of
resistant varieties.
Harvesting and Storage
Time of harvest varies according to variety
and intended market. Potatoes may be harvested with vines still
green and tubers comparatively immature. Such potatoes are generally
intended for immediate use as "new potatoes." Most potatoes,
however, are harvested at full maturity. Indicators of maturity
are tuber size, skin set, and death of the vine. Mature tubers
store better than immature tubers and resist bruising better.
Many varieties of specialty potatoes, such
as 'Michigold,' 'Donna,' and 'Yukon Gold,' produce a high percentage
of A-size tubers-generally the most desirable size.
'Yellow Finn,' however, is an exception.
The market prefers smaller sized tubers of this particular variety.
With red-skinned varieties, the small C size demands the highest
price. Many restaurants also prefer small potatoes.
Potatoes store best at 40 to 50 degrees
F, with adequate ventilation and relative humidity at 90 percent.
It is important to exclude light to prevent greening. Only sound
potatoes should be put into storage.
Varieties
The dark-yellow flesh of 'Yellow Finn' has
become something of a standard. By comparison. 'Yukon Gold' flesh
is relatively light-yellow. Many European varieties also have
light-yellow flesh.
'All Blue' is oblong with purple skin and
purple flesh. Sometimes called 'Purple Marker,' its striking appearance
led to its use as a marker for the ends of potato plots. It can
be baked or boiled and retains the purple flesh color even after
cooking. 'Purple Viking' has purple skin with red stripes.
Varieties with commercial potential:
Yellow-fleshed with buff or yellow skin:
'Delta Gold,' 'Donna,' 'Michigoid,' and 'Saginaw Gold.' Yellow-fleshed
with red or pink skin:
'Desiree,' 'Iditaried,' 'Red Gold,' and
'Rose Gold.' Yellow-fleshed with purple skin:
'Brigus.' And small sized or fingering potatoes:
'Banana' and 'Ruby Crescent.'
Good descriptions of potato varieties are
in two out-of-print books often found in university libraries:
"Description of and Key to American Potato Varieties,"
C.F. Clark and P.M. Lombard, USDA Circular No.741, Issued April
1946 (Revised November 1951) and "North American Potato Varieties," H.M. Darling. 1959 Potato Handbook, Potato Varieties Issue, Potato
Association of America (PAA).
Marketing
Marketing presents a challenge but the potato
is a familiar crop and most consumers are willing to try colorful
varieties. To successfully market specialty potatoes, farmers
need to work with those who sell and promote vegetables.
Specialty potatoes have received national
attention through articles in produce trade journals and the popular
press. Supermarket chains have featured yellow- fleshed potatoes.
At Larry's Supermarket in Seattle, a 4th of July promotion featured
red, white, and blue potatoes. Without such efforts it is difficult
to move specialty items beyond local markets and into the produce
mainstream.
Quality is of paramount importance to market
acceptance. For the fresh market, appearance strongly influences
sales. Color. size, shape, and defects shape consumers' first
impression of quality. Texture, flavor, and nutritive value are
less obvious. but still important quality components, affecting
first sales little but greatly influencing subsequent sales.
Many restaurants feature specialty potatoes.
Often customers who first tried them in a restaurant purchased
them later in supermarkets. Some brokers and others who pack and
ship fresh produce concentrate on specialty potatoes.
Marketing specialty potatoes is complicated
by the fact that most potatoes are not sold by variety name. Some
specialty potatoes have characteristics that lend themselves to
product differentiation. 'Yellow Finn' has a characteristic flattened
shape and deep eyes.' 'Yukon Gold' is distinguished by the pink
coloration around its eyes. Packaging can also be important to
market success. Bags that display the variety name along with
cooking or nutritional information are useful.
Yellow-fleshed varieties have already been
bred that can be used for either fresh market or processing. 'Saginaw
Gold' produces a chip with good color and taste. Purple or pink
potato chips and yellow french fries are among possibilities for
processed specialty potatoes. Looking beyond local markets, specialty
potatoes and potato products may also have potential for export.
The market for specialty potatoes is limited
and overproduction is a real danger. Growers are advised to develop
a market before trying new crops-and then only on a limited acreage.
Cooking Quality and Nutrition
Fresh potatoes contain about 80 percent
water. Solids, or dry matter. is highly correlated with texture.
A mealy texture is associated with high solids. a waxy texture
with low solids. Although individual tastes vary. varieties such
as 'Michigold' have a mealy texture usually considered best for
baking or french-frying. Varieties such as 'Red Gold.' with a
waxy texture. are more often used for boiling or in salads.
Potatoes are an excellent source of carbohydrates
and contain valuable amounts of protein, minerals, and vitamins.
Nutrient levels vary not only by variety but also according to
the maturity of the crop and storage time. Nutritive content can
be used to market specialty potatoes. It appears that the darker
the yellow flesh color, the higher the level of vitamin A.
For More Information
In addition to the U.S. Department of Agriculture,
State universities and county Cooperative Extension personnel
can provide useful information on local production methods and
marketing practices. PAA (Dr. David Curwen, Secretary, University
of Wisconsin, Hancock Ag Research Station, Hancock WI 54943) publishes
a Potato Extension Specialists Directory that lists University
faculty members in 46 States and the District of Columbia. PAA
also has an annual meeting and publishes "The American Potato
Journal," a monthly. (Contact Linda Best, Membership Secretary,
PAA, 8 Holmes Hall, University of Maine. Orono ME 04469-0163.)
Many potato production educational programs
are sponsored by the Cooperative Extension System. In Washington,
the Washington State Potato Conference and Trade Fair is held
each year. Similar programs exist in Idaho, Maine, Michigan, Nebraska,
and Oregon. Potatoes are included in numerous other conferences.
Other Information Sources
There are many excellent publications:
- Delta Golds... Consumer Response
to Yellow Fleshed Potatoes, Applied
Market Research Report #2." Agriculture and Resource Economics,
206 Winslow Hall, Univerisity of Maine, Orono, ME 04469.
- "Potato Handbook." Agricultural
Communications Center. 111 Ag Sciences Building, University of
Idaho. Moscow, ID 83843.
- "Potato Growers Handbook."
Washington State Potato Commission.
108 East Interlake Road, Moses Lake, WA 98823.
- "Potato Varieties - An introduction
to variety characteristics, management and performance in the
Klamath Basin." University
of California Tulelake Field Station. P.O. Box 447. Tulelake.
CA 96134.
- "North American Potato Varieties."
Potato Association of America.
8 Holmes Hall. University of Maine. Orono, ME 04469-0132.
- "Selecting Potato Varieties
for Michigan." Michigan
State University. Bulletin Office. P.O. Box 231, East Lansing,
Ml 48823-0231.
- "Integrated Pest Management
for Potatoes in the Western United States." Publication
3316. Agricultural Sciences Publications. Division of Agricultural
Sciences, University of California, Berkeley. CA 94720.
- "Compendium of Potato Diseases,"
American Phytopathological
Society. 3340 Pilot Knob Road. St. Paul, MN 55121.
- "A Guide to Monitoring Potato
Pests in New York State, 102 IPM 107." Cornell
Cooperative Extension, Research Center, 7 Business and Technology
Park, Ithaca, NY 14850.
- "Potato Diseases, Agriculture
Handbook No.474," Superintendent
of Documents, U.S. Government Printing Office. Washington, DC
20402.
A computer software program, Potato Crop
Management, is available from the University of Wisconsin,
WISPLAN Computing, 302 Hiram Smith Hall, 1545 Observatory Drive,
Madison, WI 53706.
Prepared by Erik J. Sorensen of the Washington
State University Cooperative Extension and George B. Holcomb of
the Office of Public Affairs, U.S. Department of Agriculture,
for USDA's Office for Small-Scale Agriculture (OSSA); Howard W. "Bud" Kerr, Jr., Program Director. OSSA's address:
Cooperative State Research Service, USDA,
Room 342-D, Aerospace Building.
Washington. DC 20250-2200.
Telephone: 202-401-4640
Fax: 202-401-5179
Mention of commercial enterprises or
brand names does not constitute endorsement or imply preference
by the U.S. Department of Agriculture.
January 1992
Back to "Archived Articles"
