Russet Legend

Prepared by Susie Thompson, Ph.D., and Robert D. Davidson, Ph.D., Department of Horticulture & Landscape Architecture, San Luis Valley Research Center, Colorado State University

This profile was developed for production in the San Luis Valley. While some guidelines may be appropriate regardless of growing area, fine-tuning for specific production locales is recommended.

Russet Legend (COO83008-1) is an attractive, medium maturing potato cultivar with heavy russet skin. Officially release is pending by the Oregon Agricultural Experiment Station and Western Regional cooperators. Legend is a dual-purpose cultivar suitable for use in the fresh market and for processing into high quality French fries. It emerges rapidly and has a medium vine with white flowers. Legend has a determinate growth habit and a moderate root system. Tubers are oblong to long, with white flesh. Eyes are shallow and fairly well distributed. Specific gravity is medium to high (1.087+). Yield potential may exceed 450 cwt./acre, with US No. 1 production in excess of 90%.

GROWING SEASON MANAGEMENT

Pre-planting considerations: Tubers have medium dormancy. Single drop or cut seed is acceptable. When using cut seed, utilize practices which enhance suberization and prevent decay by pathogens. For seed, within-row spacing should be 6-8 inches. For commercial production space at about 12 inches. Plant seed about 4 inches deep with a good cover.

Fertility: Total fertilizer applied during the growing season should be in the following range, based upon soil analysis: N(160-180), P(100-200), K(0-60). Pre-plant incorporated N should be from 70 to 90#. Early season N applications do not seem to adversely affect the timing of tuberization. Sprinkler applied N should be in the 70 to 90# range, with applications ending within one month of harvest to promote adequate vine maturity and tuber skin set.

Irrigation: Interval at the maximum ET is about 3 days. Drought tolerance is moderate. Water usage will decline as vines mature, so monitor fields to prevent over watering late in the season and potential decay by pathogens such as Pythium or Phytophthora.

Pest control:

Weeds: Competition against weeds is good. Legend is resistant to metribuzin. Adverse reactions to other commonly utilized herbicides for potato production have not been noted in grower experiences.

Insects/Diseases: Standard insect control measures generally are effective. Control of foliar early blight usually requires 4-5 applications of fungicide.

Tuber development: Russet Legend consistently sets 7-9 tubers per plant. Tubers are set somewhat shallow in the hill, so greening may be a factor. Tuberization occurs early and tubers bulk at a very rapid rate. Legend will occasionally develop growth cracks and second growth. Internal quality is good. Tubers have a moderate response to shatter and blackspot bruise.

Vine kill: Average days from planting to vine kill are 105 to 110. Vine killing is usually required and is easy to accomplish. Adequate skin set occurs at about 21 days. Oversize tubers may be a problem, so carefully monitor the crop beginning in mid-August.

STORAGE MANAGEMENT

Legend is a long-term storage potato with few problems, and sprouting is minimal. Legend may be stored slightly cooler than Russet Burbank if intended for processing. Stem end discoloration has been noted in some production situations. Carefully monitor soil temperatures at harvest, maintain tuber hydration and avoid bruising. An application of Ridomil during early tuber bulking may also be beneficial.

DISEASE REACTION

Overall disease problems are minimal. Bacterial ring rot foliar symptom expression is adequate and occurs within 95 days after planting. Potato leafroll virus symptoms are also sufficient. Bacterial soft rot, caused by Erwinia, may be a problem in storage, and in the field as seed piece decay.

Field

Foliar early blight Moderately susceptible

Verticillium wilt Moderately resistant

Blackleg Susceptible

Seedpiece decay Moderately susceptible

Leafroll virus Moderately susceptible

Leafroll net necrosis Moderately resistant

PVY Susceptible

PVX Susceptible

Common scab

Bacterial ring rot Susceptible

Storage

Tuber early blight Moderately susceptible

Bacterial soft rot Moderately susceptible

Fusarium dry rot Moderately susceptible

Leak (Pythium)

Pink rot (Phytophthora)

Silver scurf

Rhizoctonia scurf Moderately resistant

Disease reaction ratings = susceptible, moderately susceptible, moderate, moderately resistant and resistant.

Spring 1998