Northwest Norkotah

NW 90 Growing Information

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Seed Storage and Size

Seed Spacing

NWN 90: 9 to 10 inches (about 27-30 cwt/acre)

Nitrogen Fertilizer Recommendations

Soil Test N1 (0-12 in)	NWN 90
ppm (NO3-N + NH4-N)	Yield Goal (cwt/acre)
	400	500	600
	lbs N/acre2
0	160	190	220
5	140	170	200
10	120	150	180
15	100	130	160
20	80	110	140
25	60	90	120

¹ Soil test N = Nitrate-N + Ammonium N

² Following grain or corn, add 15 lbs N/acre for each ton of straw or stalks up to a total of 60 lbs N/acre

If the field has not been fumigated or has not been out of potatoes for at least 4 years, apply an additional 40-50lbs N/acre

Nitrogen Timing

Apply 50-60% of total seasonal N preplant with 75% applied by row closure. The remaining N applications made during tuber bulking should be guided by petiole nitrate N tests and should be completed by early August.

Petiole Nitrate Concentrations

Tuber set: 18,000 to 20,000 ppm

Early tuber bulking: 16,000 to 18,000 ppm

Late tuber bulking: 14,000 to 16,000 ppm

Maturation: 8,000 to 10,000 ppm

Phosphorus, Potassium, and other Nutrients

Follow recommendations for Russet Burbank

Irrigation

The water use pattern for NWN 90 is similar to Russet Burbank. Maintain available soil moisture above 65-70% throughout tuber bulking but adjust water application amounts later in the season as the plants start to senesce.

Late season irrigation needs to be closely monitored to avoid overwatering that can produce enlarged lenticels and increased disease problems.

Diseases

As with other Norkotah line selections, NWN 90 is susceptible to PVY, early blight and late blight, so follow standard management practices for these diseases.

Vine Kill

NWN 90 tubers mature later in the season so kill vines 16-21 days before harvest for adequate maturity.

Note: It is important to use the recommended 9-10 inch seed piece spacing and the nitrogen fertilizer application rates listed above to produce the optimal tuber size profile and minimize the possibility of hollow heart development.