Modoc: A potato variety with bright red skin and early maturity for fresh market

American Journal of Potato Research, Jul/Aug 2003 by Rykbost, K A, James, S R, Mosley, A R, Charlton, B A, Et al

Modoc tubers seldom exhibit internal or external defects. In three years of evaluation in regional trials, much less hollow heart and brown center was observed in Modoc than in Red LaSoda and Dark Red Norland (Table 4). Modoc tubers are not susceptible to growth cracks or shape defects. Vascular discoloration has not been identified as a concern at any location where Modoc has been evaluated. Modoc consistently received high ratings for skin color and eye depth and tubers are less susceptible to skinning damage at harvest than Red LaSoda.

USAGE

Modoc is a fresh market cultivar. Preliminary non-replicated evaluations at Klamath Falls, designed to detect serious culinary quality deficiencies, failed to detect after-cooking darkening, sloughing, or off-flavors in boiled, baked, or micro-waved Modoc tubers. Sensory evaluations at Washington State University indicated Modoc was similar to Dark Red Norland and Red LaSoda in culinary quality when boiled or microwaved (Table 5). Early maturity, an attractive appearance, uniform tuber size distribution, bright red skin color that does not fade appreciably in storage, and no observed storage deficiencies favor acceptance of Modoc for marketing directly from the field or from storage.

MANAGEMENT

Observations from trials conducted at Klamath Falls, Oregon, and other locations provide some guidance for cultural management of the Modoc variety. Low numbers of eyes concentrated at the apical end results in the need to use relatively small tubers for seed to avoid stand loss due to blind seed-pieces. Plant spacing at approximately 15 cm in 91-cm rows provides optimum tuber size distribution to minimize production of undesirable oversize tubers. This spacing produces acceptable tuber size for seed or fresh market use. Vine desiccation may be required to avoid excessive tuber size. Fertility practices should be similar to management of standard red varieties of similar maturity. Nitrogen banded at planting at 180 kg/ha has produced excellent yields in low organic matter mineral soils in Klamath Falls. Higher rates or split applications may delay maturity and skin set. Modoc's reaction to post emergence application of metribuzin at Aberdeen, Idaho, was rated as moderately resistant compared with resistant for Dark Red Norland and moderately susceptible for Red LaSoda.

Soils infested with Columbia root-knot nematode or stubby-root (Trichodorous spp.) nematodes should be fumigated or avoided. Soils with known powdery scab history should also be avoided.

AVAILABILITY

Limited quantities of in vitro plantlets and prenuclear seed stocks are available by request from the Foundation Potato Seed Program at Oregon State University, Corvallis, Oregon. Application for plant variety protection has been made for Modoc.

ACKNOWLEDGMENTS

The authors thank Oscar Gutbrod for evaluation of bacterial ringrot response, Soloman Yilma for production of in vitro plantlets and prenuclear seed stocks and our collaborators in the regional variety trials. The Oregon Agricultural Experiment Station, the Oregon Potato Commission, the USDA Cooperative Research, Education, and Extension Service, and the USDA Agricultural Research Service provided partial financial support of this research.