Potatoes

Crop Standards

Oregon Certified Seed Potato Crop Standards Handbook (pdf)

Post-Harvest Testing and Inspection Options (pdf)

Grower Directory

Seed Grower Contact List

Seed Report and Directory of Growers (pdf)

Field Readings

Oregon Certified Seed Potato Field Readings and Statistics (pdf)

Applications and Forms

Field Inspection Application Form

Seed Farm Requirement Form (pdf)

Inspection of Uncertified Potato Fields (pdf) (aka "Bacterial Ring Rot Inspection")

Latent Virus Testing Application (pdf)

Grower Tag Order Form (pdf)

Oregon Potato Information

Oregon Seed Production and Methods

Potato Handling, Cutting, and Sanitation

Selecting and Buying Seed

Variety Information

Potato Certification - National Level

Other Information

BRR Diagnostics Protocol (pdf)

Early Generation Seed Potato Production and Certification (pdf)

Field Planting Terminology Comparison Table (pdf)

OSCS Potato Certification Summary (pdf)

Directions to Potato Greenhouse (pdf)

 Winter Grow-out Process in Pictures

Varieties

Whoever can make two ears of corn or two blades of grass to grow where only one grew before, would deserve better of mankind and do more essential service to his country than the whole race of politicians combined.-- Jonathon Swift (1667-1745)

INTRODUCTION:

Selecting suitable varieties is an essential first step in any successful potato operation. Varieties must not only suit the intended market but also be well adapted to local growing conditions. Hundreds of varieties are potentially available to potato growers but as few as five probably account for 90% of the U.S. acreage. The leading variety, Russet Burbank, still provides about 40% of the U.S. production.

Varieties differ in a number of characteristics including: yield; skin and flesh color; tuber shape and eye depth; time of maturity; disease and pest resistance; carbohydrate composition; usage potential; dormancy and storability; and any number of additional particulars. Processors typically specify varieties in grower contracts, but not always. Fresh market growers, on the other hand, are free to choose.

Potato varieties have traditionally been categorized according to shape and color as Round Whites, Russets, or Reds. Recently, "Specialty" and "Gourmet" have entered the potato vocabulary to describe almost any variety not fitting into the three major divisions. Broadly speaking, round-white varieties are used for chipping and, to a lesser extent, as tablestock in central and eastern states. Reds and specialty gourmet varieties are used exclusively for the fresh market. Russets, which tend to produce oblong tubers, are used for both frozen processing and fresh market.

The carbohydrate (starch and sugar) composition of tubers plays an important role in determining variety usage. Processing varieties, for example, must have relatively high starch and low reducing (glucose/fructose) sugar levels. Starch content is directly related to specific gravity or dry matter in tubers. Typically, 60-80% of the dry matter is present as starch. Therefore, high-gravity or high-solids tubers contain high levels of starch.

Relationship Between Tuber Dry Matter and Optimum Use
Specific Gravity Dry Matter, % Texture Typical Uses
Below 1.060
(very low)
Below 16.2 Very soggy Pan frying, salads, canning
1.060-1.069
(low)
16.2-18.1 Soggy Pan frying, salads, boiling, canning
1.070-1.079
(medium)
18.2-20.2 Waxy Boiling, mashing; fair to good for chip processing and canning
1.080-1.089
(high)
20.3-22.3 Mealy, dry Baking, chip processing, frozen french fry processing; some cultivars tend to slough when boiled
Above 1.089
(very high)
Above 22.3 Very mealy or dry Baking, frozen french fry processing, chip processing; tendency to produce brittle chips and to slough when boiled

Adapted from: Mosley, A.R. and R.W. Chase. 1993. Selecting Cultivars and Obtaining Healthy Seed Lots. In: Potato Health Management, APS Press, 1993. Pp. 19-27.

 

Starch has profound effects on product texture and oil consumption during processing. Frying drives much of the water out of chips, for example, and replaces it with oil. Therefore, low dry matter/high water tubers tend to absorb more oil, which is typically the most expensive component of fries, and become more soggy and/or oily.

In contrast to starch, which primarily affects product texture and oil content, reducing sugars (primarily glucose and fructose) play a critical role in the processed color of potato chips and french fries. Even very low levels of sugar cause chips and fries to turn dark brown during frying. For that reason, varieties intended for processing either as chips or fries, especially during the winter and early spring, must have low levels of reducing sugars both in the field and storage. Sugar levels typically make up less than 3% of total tuber dry matter.