NDSU Main Station * North Dakota Agricultural Experiment Station
315 Morrill, NDSU Fargo, ND 58105, Voice: (701) 231-7655 fax: (701) 231-8520


North Dakota Agricultural Experiment Station

D.W. Meyer, W.E. Norby, and R.O. Ashley

The 1998-99 winter was relatively mild with February, December, and March temperatures at 10.5, 5.7, and 5.3oF above normal, respectively. Twelve inches of snow in early November disappeared in late November and early December with temperatures 10 to 30oF above normal. Dormant-seeded alfalfa (seeded November 15) germinated by December 15. These warm conditions weakened the alfalfa dormancy, especially on 4-cut systems. Snow cover was adequate during late December and January when temperatures were very cold. Warm temperatures in February reduced snow cover, but adequate cover occurred when temperatures were cold.

Environmental conditions in 1998-99 resulted in the most differential winter injury/kill to alfalfa experienced in many years. The 4-cut system taken at mid-bud, late bud, 25% bloom, and after a killing frost had major winter injury in the 1997 seedings at Fargo and Carrington, in AM-95 (a management experiment), and in the 1996 seeding. The CV's in these experiments are very high making it difficult to detect varietal differences.

Forage yield data for alfalfa cultivars and experimental lines tested in North Dakota are presented in the next seven tables. Potato leafhopper caused more damage at Fargo than normal from an early arrival. All varietal trials were sprayed with Warrior at 4 oz/acre to control armyworms and the potato leafhopper. The alfalfa blotch leafminer was severe in the 1998 seeding during the fall of 1998 and again during the first harvest in 1999, the spraying with Warrior was apparently too late for control.

Forage yields on dryland at Fargo were exceptional for the fourth straight year even with the winter injury/kill! Forage yields averaged 7.16 tons/acre for the 3-cut system in the 1997 seeding and 6.33 tons/acre for the 4-cut system. Vernal forage yields were reduced in 1999 by Fusarium wilt in 1998, which resulted in higher relative yields. 5312 under the 4-cut system had a forage yield equal to the 3-cut mean. Forage yields of the 1996 seeding were equal between cutting systems. Relative yields were affected by Fusarium wilt in 1998 like the 1997 seeding. Forage yields of the 1998 seeding were reduced (an estimated 1-1.5 tons/acre) by winter injury from standing water and severe infestation of the alfalfa blotch leafminer in the first harvest. Forage yields in 2000 should not be affected since crown growth has given adequate stem density for maximum yield assuming no additional winter injury. Seeding-year forage yields averaged 3.15 tons/acre, the third consecutive year seeding-year forage yields have averaged greater than 3 tons/acre.

Irrigated forage yields at Carrington, ND, were above average for the 3-cut system, but substantially less than average for the 4-cut system due to winter kill. The winter kill occurred somewhat at random and seemed more associated with differences in soil texture than true varietal differences. This is the first time in 30 years that differential winter kill between the cutting systems occurred with about 15 years of observation. Three times before both the 3- and 4-cut systems were winter killed. Forage yields at Manning, ND, were less than 1.4 tons/acre due to a lack of precipitation after the first harvest.

The 1999 North Dakota alfalfa hay crop was estimated November 1 at 3.45 million tons, 40% greater than 1998 production, by the North Dakota Agricultural Statistical Service. The per acre yield at 2.3 tons is up 25% from the previous 5-year average due to above-average rainfall. Alfalfa acreage was estimated at 1.5 million, the same as 1998. Persistent cultivars that yield greater than Vernal are recommended for hay production in North Dakota.

These data are available on the web at http://www.ag.ndsu.nodak.edu/fargo/99data/alfalfa.htm or from Dr. Dwain Meyer, Plant Sciences Department, North Dakota State University, Fargo, ND 58105-5051.

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Email: mpeel@ndsuext.nodak.edu