Circular 567

During the months of June and July, New Mexico supplies more than 50 percent of onions consumed in the United States (USDA 2000). Each year, New Mexico grows 7,000 to 8,000 acres of onions, producing 160,000 to 180,000 tons at a value of $40 million to $55 million. The per acre yield averages 920 50-pound sacks per acre.

Acreage, per acre yield, total production, and total value for the New Mexico onion crop have increased over the last 20 years. This increase can be attributed in part to improved varieties and improved cultural practices. The continued growth of the New Mexico onion industry requires well-adapted, high yielding, high quality varieties and the proper cultural practices to grow those varieties. The current cultural practices for growing onions in New Mexico have been presented by Corgan and his coworkers (2000). This guide will review the current onion varieties being grown in New Mexico. It will be revised as new varieties are evaluated.

Growers in New Mexico harvest onions from May 20 to September 15. Because a single onion variety has a harvest window of 7 to 10 days, multiple varieties with different maturity dates must be grown. New Mexico grows three separate onion crops: fall-seeded, transplanted, and spring-seeded. The fall-seeded crop is planted from September 15 to October 15 and harvested May 15 to June 20. Early-planted, fall-seeded varieties must possess high levels of bolting resistance to prevent yield losses to premature seedstalk formation.

The transplanted crop is seeded from October 1 to 20 in southern New Mexico and from November 15 to 30 in Arizona or south Texas. Transplants are placed from February 1 to March 1 and harvested from June 20 to July 10.

The spring-seeded crop is planted January 15 to March 1 and harvested from July 5 to August 15.

Growers in Deming, Columbus, Hatch, and Uvas areas plant their fall crop earlier and harvest each crop later than growers in the Las Cruces and Anthony areas.

Planting and harvest dates in this publication are for the Las Cruces area, so growers in other regions should adjust their planting and harvesting dates accordingly. Growers in eastern and northwestern New Mexico primarily plant a spring-seeded onion crop.

The desired characteristics of an onion variety grown in New Mexico vary depending upon the crop. However, all varieties must be well-adapted, be high yielding, possess moderate to high levels of pink root resistance, and possess high bulb quality.

Pink root resistance is necessary because most fields are infested with the organism causing pink root. Scale color for white varieties should be clear white, while scale color of red varieties should be dark red. Bulbs should possess multiple layers of scale that adhere to the bulb during grading. Early-planted, fall-seeded varieties must possess high levels of bolting resistance to prevent yield losses to premature seedstalk formation.

In the past, grano-shaped (top-shaped) onions were grown in New Mexico for the fall-planted crop, but round bulbs with less taper to the base currently are more desirable.

Short-day varieties grown for transplants must have a later maturity to produce large bulbs and also must possess some bolting resistance to prevent excessive bolting.

Fall-planted varieties grown as transplants mature one to two weeks later than when they are direct seeded. Spring-planted varieties grown as transplants mature one to two weeks earlier than when they are direct seeded.

In general, spring-planted varieties are more nearly round in shape, tend to have more scale, and tend to have a higher percentage of bulbs with single centers than fall-planted varieties.

FALL-PLANTED VARIETIES

References

Corgan, J. and M. Holland. 1990. Onion cultivars and planting dates for southern New Mexico. N. Mex. Agric. Ext. Guide H-229.

Corgan, J.N., M.M. Wall, C.S. Cramer, T. Sammis, B. Lewis, and J. Schroeder. 2000. Bulb onion culture and management. N.M. Coop. Exten. Serv. Circ. 563.

Cramer, C.S., J.L. Mendoza, and J.N. Corgan. 1998. Fall-planted onion variety trials at New Mexico State University, p. 299-312. In: R.E. Voss (ed.). Proc. 1998 Natl. Onion (and Other Allium) Res. Conf. Veg. Res. Info. Ctr., Univ. Calif., Davis, Calif.

Cramer, C.S., J.N. Corgan, J.L. Mendoza, and M.M. Wall. 2000. 1998-1999 Onion variety trials at New Mexico State University. N.M. Agric. Expt. Stn. Res. Rpt. 739.

U.S. Dept. Agr. 2000. Vegetables. 1999 Summary. Vg 1-2 (00). U.S. Govt. Printing Office, Washington, D.C.

New Mexico State University is an equal opportunity/affirmative action employer and educator. NMSU and the U.S. Department of Agriculture cooperating.