University of Arizona a dot Cooperative Extension

Alfalfa Report
Yuma County, Arizona
December 4, 2000

Yuma County Office
2200 W. 28th Street, Ste. 102
Yuma, AZ 85364
(520) 726-3904
(520) 726-8472 FAX

Production Update:
PDF version, 14KB

Seedling Cold Damage: Alfalfa seedlings are thought to be the most sensitive to cold damage at the cotyledon stage before any true leaves have formed. While this may be the case under artificial conditions, in reality, the opposite seems to be true: alfalfa in the cotyledon stage is rarely damaged by cold. The temperature of the plant leaf during a cold night may be warmer than air temperature a few feet above the soil surface. A broad leaf near the soil surface may intercept heat from the soil and maintain a temperature above air temperature. We have observed seedling soybean, which is very frost sensitive, survive when air temperatures in the low 20s were reported.

Insect Management: Cowpea aphid (Detour signpicture) is a black aphid that has become a serious pest of new and established stands of alfalfa. Western Arizona and southern California alfalfa stands became heavily infested in November and this problem is expected to continue into the spring months. When stands of alfalfa become heavily infested with cowpea aphid, treatment with an insecticide may be warranted to prevent yield loss due to stunting and leaf drop, and to prevent honeydew and sooty mold contamination. Treatment thresholds have not been established for cowpea aphid on alfalfa. Seedling alfalfa may be more susceptible to damage from cowpea aphid.

Weed Control: Pursuit can be applied to seedling alfalfa and will control a broad spectrum of broadleaf weeds. It will suppress but not kill many grasses. Weeds that are not controlled include prickly lettuce, sowthistle and lambsquarter. Stunting of seedling alfalfa will occur for one cutting.

Market Summary
Off grade
Past 2 Weeks (Nov. 21 to Dec. 4, 2000)
Last Year (Nov. 21 to Dec. 4, 1999)


10 Year Summary (November 21, to December 4, 1991-2000):

Graph of dollars per ton from November 21, to December 4, 1991-2000

Full Disclaimers

Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, James A. Christenson, Director Cooperative Extension, College of Agriculture and Life Sciences, The University of Arizona.

The University of Arizona is an equal opportunity, affirmative action institution. The University does not discriminate on the basis of race, color, religion, sex, national origin, age, disability, veteran status, or sexual orientation in its programs and activities.

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Information provided by:
Barry Tickes, Extension Agent, Yuma County
Michael Ottman, Agronomy Specialist
College of Agriculture, The University of Arizona.
Eric Natwick, UCCE Imperial County - Farm Advisor
University of California, Davis, CA.

Material written December 4, 2000.

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