University of Arizona a dot Cooperative Extension

Alfalfa Report
Yuma County, Arizona
August 11, 2003

Yuma County Office
2200 W. 28th Street, Ste. 102
Yuma, AZ 85364
(928) 726-3904
(928) 726-8472 FAX

Production Update:
Reducing Costs: Various ways exist to reduce costs of hay production, which may or may not be advisable depending on the market. Insecticide costs may be reduced by relying on natural control mechanisms. If the difference in cost between the best hay and weedy hay is not great, weed control may not be warranted. Phosphorus fertilization could be delayed until the fall without significant loss of production unless soil test levels are very low. Fewer cuttings may be taken to reduce harvest costs. Reducing the number of irrigations may not affect yield dramatically in some cases. Completely eliminating irrigation and all other inputs for one or more cuttings is also an option where production costs exceed the value of the crop.

Insect Management: Western yellowstriped armyworm (adult) (Detour signlarva) is a common pest in low desert alfalfa from June through September. Egg masses, covered with gray cottony scales, are deposited on the upper side of leaves. Eggs hatch in a few days and larvae reach full size in 2 to 3 weeks. Larvae pupate on or under the soil surface. Larvae appear smooth and are usually black with two prominent orange yellow stripes and many narrow stripes on each side. An intense black spot on the lateral margin of the first legless segment is a distinguishing characteristic. First instar larvae web terminal leaves together and skeletonize the leaves, later dispersing through the crop. Spiders and predacious bugs prey on larvae and larvae may be parasitized by Hyposoter exigua wasps. Monitor fields weekly using a sweep net and check fields 2 to 3 times per week if heavy populations begin to develop. Make 5 sweep counts at each of 4 to 5 locations in the field. Treat when there are 15 non-parasitized armyworms of more than inch per sweep.

Weed Control: There are over 150 species of Dodder (Detour signpicture) throughout the world. Field Dodder (Cuscuta Campestris) is the one most commonly found on alfalfa. Dodder germinates at or very near the soil surface and is dependent on carbohydrates stored in the seed until it attaches to a host. If no host is found, it dies. Once attached, it is entirely dependent on the host for nutrients and water. It is spread by contaminated seed, equipment and soil movement. The best control is achieved with two applications of the highest labeled rated of Trifluralin applied in the spring and mid-summer.

Market Summary
Off grade
Past 2 Weeks (July 29 - Aug 11, 2003)
Last Year (July 29 - Aug 11, 2002)


10 Year Summary (July 29 - Aug 11, 1994-2003):

10 year summary July 29 - Aug 11, 1994-2003

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.

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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.

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