Nondormant Alfalfa Varieties for Arizona 2003
Cooperative
Extension, College of Agriculture & Life Sciences, The University of Arizona
Written by
Mike Ottman, Specialist, Plant Science
HOW TO SELECT AN ALFALFA VARIETY:
Determine an appropriate fall dormancy class
Alfalfa varieties differ in fall dormancy defined as growth during the fall. Nondormant alfalfa varieties are usually planted in mild winter areas for their ability to grow in the late fall, winter, and early spring. However, cool season growth of nondor-mant alfalfa may be undesirable in areas subject to repeated frosts or freezes. Nondormant and very nondormant alfalfa varieties (fall dormancy class 8 and 9) are adapted to elevations below 4000 feet in Arizona while moderately nondormant varieties (fall dormancy class 7) may be grown from 3000 to 5000 feet. Semi-dormant and dormant varieties (fall dormancy 6 and below) are adapted to colder winter areas above 4000 feet.
Identify potential pest problems
Select alfalfa varieties that have resistance to potential pest problems. Variety resistance is not available or not characterized for many important pests. However, pest resistance ratings are provided in this publication for Verticillium wilt, Fusarium wilt, anthracnose, Phytophthora root rot, various aphids, and stem and root knot nematode. Verticillium wilt is not currently a problem in Arizona, but it has been identified in southern California and may eventually invade Arizona. Fusarium wilt is rarely a problem due to varietal resistance. Anthracnose occurs in the lower Colorado River area during hot, humid weather. Phytophthora root rot can be a problem on poorly drained soils during cool weather. Aphids occur in most production areas. Stem nematode has been reported in Maricopa, Pinal, Graham, and Yuma Counties. Root knot nematode has been identified in the lower Colorado River area, but usually is not important.
Identify several promising varieties
Alfalfa variety trials are conducted by universities, private industry, and farmers. A summary of University of Arizona yield trials is contained on the facing page. This information is useful to narrow your choice to several varieties.
Field-test several promising varieties
Plant several promising varieties in narrow strips and evaluate performance under your own conditions.
Choose a variety (or two) for large-scale planting
Plant new varieties on no more than 80 acres or 25% of the newly seeded acreage. Planting inexpensive seed of a poorly-adapted variety costs in the long-run. A difference in seed cost of $1.00 per pound is easily recovered by a more productive variety in the first year. Non-certified seed is also undesirable due to poor seed quality, introduction of weeds, and the possibility of planting an incorrectly identified variety with undesirable characteristics.
Summary
Nondormant alfalfa varieties are adapted to mild winter areas in Arizona. An alfalfa variety should be selected based on dormancy class, potential pest problems, university yield trials, and on-farm tests. Choosing a variety based solely on seed cost rarely pays in the long run. This publication contains pest resistance ratings and a summary of University of Arizona yield trials for nondormant alfalfa varieties.
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Document located http://cals.arizona.edu/pubs/crops/az1267/
Published July 2003
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