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

Production Update:

Alfalfa Nodulation: Alfalfa has the ability to interact with certain bacteria (rhizobia) to convert atmospheric nitrogen gas to a form useful to the plant. Inoculation is initiated by these bacteria, which invade the root hairs of the plant and cause the nodules to develop on the roots. The plants provide the bacteria with food (carbohydrate) and the bacteria provide the plants with nitrogen, and a symbiotic relationship is established. Nitrogen fertilizer is generally not required for healthy, effectively nodulated alfalfa.

Insect Management: Alfalfa looper (picture), Autographa californica (Speyer), is a minor pest of desert alfalfa. They are often present with alfalfa caterpillars or beet armyworms in sweep samples. Larvae move with a characteristic looping motion by bringing their hind prolegs forward to meet the true legs. Eggs are laid singly, larvae hatch within a few days, and feed for about two weeks devouring alfalfa leaves. The looper larvae spin a loose white cocoon among the leaves to pupate. In about ten days to two weeks moths emerge. The entire cycle is completed in about a month. Alfalfa loopers are rarely of economic importance in Arizona or California due to natural control. This insect is usually held in check by parasitic wasps, parasitic flies, and bacterial, fungal and viral diseases.

Weed Control: Alfalfa declines and nutsedge takes off at this time of year. The options for nutsedge control are fairly limited and include regular applications of EPTAM and ZORIAL. Both require more than one application to effectively suppress this weed.

10 Year Summary (June 30 - July 13, 1994-2003):

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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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