YUKON GOLD: MANAGEMENT PROFILE

Characteristics | Management Profile | Tables

Market Characteristics

Yukon Gold matures in 80 to 95 days after planting, so may be harvested as an early season crop. Tubers are set early and bulk quickly. Summer yields under good conditions range between 300 and 400 cwt/acre and, in the autumn (full season), yields may get over 500 cwt/acre. Specific gravity is usually between 1.080 to 1.085 (about 20-21% dry matter). Sugars are in the medium range and the variety can fry like a russet frier. Tuber shape is 'cylindrical' and reported as slightly oval and flattened. Highest market recommendation is for the 'count-carton' baking market. One of its drawbacks is a strong tendency for tubers to oversize due to setting few tubers and to green due to a high set close to the surface. Because of these set characteristics, some more unusual management strategies are needed for high marketable yield.

Seed (KEY practices)

For best stand, small whole seed ("single-drops") should be used due to uneven distribution of eyes which are mostly at the bud end. For cutting to seed pieces, small to medium size tubers need to be use to avoid "blind" pieces. Cutting and then planting immediately is very strongly discouraged, clearly not a recommended practice which results in poor stands, uneven emergence and seed decay by bacterial soft rot (Erwinia carotovora). Cut pieces need to be warmed, treated with a fungicide dust and allowed to heal; 7-10 days at 65F or two weeks at 60F before planting are recommended.

Planting (KEY practices)

Yukon Gold sprouts slowly, therefore, sprouts are susceptible to Rhizoctonia stem canker and planting in cool soils needs to be avoided. Because few tubers are set and they grow rapidly, whole or cut seed tubers must be planted close; 8-10 inches apart in the row are recommended for fresh market production. Else, tubers will oversize out of the market range and many may develop hollow heart. Seed pieces or tubers need to be planted deep, about 6 inches below row top. If not, due to the high set, many tubers will jut out of the ground near harvest and greening will be a grade-out problem. Avoid alkaline soils. The vine grows fast and tubers set quickly; therefore, late planting has little effect on yield potential.

Fertilization

Recommendations run 150 lb. N/acre, 100-150 lb. P2O5/acre, and 100-150 lb. K2O/acre for fresh market. [Recommendations from the San Luis Valley, Colo., are 120-180 lb N, 100-200 lb P and 0-60 lb K/acre with a 70-120 lb N/acre applied pre-plant and 60-70 lb N/acre applied through sprinklers at 20 lb N per application.] All N may be applied pre-plant or N may be split with half as starter and half at emergence. Recommendations for seed production are not available. No petiole nitrate-N levels have been reported.

Irrigation

Sprinkler irrigation at maximum ET (evapotranspiration) should be every 2½ to 3 days. Yukon Gold has a low to moderate tolerance to drought stress. In the middle of the season, it may wilt easily. But, water use drops off quickly when vines begin to senescence. Late season monitoring is essential to avoid over-watering and the development of black leg and soft rot, pink rot and leak.

Vine Desiccation (KEY practice)

Yukon Gold is a determinate variety and senescence occurs 70-90 days after emergence (about 100 days after planting); natural die-off is mid to late August with an early May planting.

Since tuber set is light, 5-8/plant, and tubers grow rapidly, there is a strong tendency to oversize and, therefore, tuber size needs to be closely monitored 9-10 weeks after emergence, beginning of August. Vine desiccation is recommended and Yukon Gold is quite responsive in August. Because tuber set is high and tubers may be close to the surface, chemical desiccation is preferred over mechanical. Skin set takes 2 to 3 weeks.

Storage

Tubers are resistant to bruising and store very well when cured well. Sprouting is minimal due to dormancy. When properly stored, tubers lose less moisture than many varieties. Humidity of 90-95% is desirable. If lenticels are swollen or skin is bruised, tubers are susceptible to storage wet rots -- soft rot, leak and pink rot. With rough handling, dry rot may occur. Silver scurf and early blight on tubers can be problems.

Pest and Defect Reactions

Vines are sensitive to air pollution (ozone) injury. Yukon Gold competes well against weeds. There is a low aphid preference for Yukon Gold, so spread of viral problems are not common. Seed is susceptible to Fusarium decay and a fungicidal dust treatment is recommended. Yukon Gold is susceptible to PVY and tolerant of leaf roll (PLRV); symptoms are easily discerned. The vine is very susceptible to both early and late blights. The tuber is prone to common scab; so/so to dry rot at harvest, and tolerant to net necrosis. Soft rot problems in storage have been associated with high field incidence of black leg. Leak has been associated with high late-season watering. Tubers are prone to hollow heart and heat necrosis when oversized. They are slow to green but set high in the hill.

A disease reaction summary is:

• Very Susceptible to: seed decay, black leg, early blight (foliar & tuber), late blight, early dying (V. wilt), PVY, soft rot, dry rot, leak, pink rot, silver scurf, black scurf.
• Susceptible to: common scab.
• Moderately Tolerant to: leaf roll and leaf roll net necrosis.
• Tolerant to: PVX.