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

Production Update:

Summer Irrigation Termination - Effect on Crop: Irrigations can be withheld from alfalfa during the summer without permanent damage to stands and yield. In some cases, however, the alfalfa may require one cutting for yields to fully recover from lack of summer irrigation. Summer irrigation termination must be practiced with caution since, in a study conducted on a sand soil on the Yuma-Mesa, stands were reduced from 4 to 1.5 plants per square foot by not irrigating during the summer. The ability of an alfalfa crown to survive without irrigation during the summer may be related to many factors such as soil type, presence of subsoil moisture or a shallow water table, age of stand, cultivar, previous cutting history, maximum and minimum daily temperature, rainfall, and amount of stubble.

Insect Management: Grasshoppers ( picture, 84KB) are normally of little concern in desert alfalfa. Damage is usually limited to a few weeks after weeds dry up in the foothills or deserts. When the natural vegetation begins to dry in the spring or early summer, migrations to irrigated crops usually occur. Monitor known grasshopper overwintering areas for potential problems. Eliminate weedy habitats by tillage of herbicides along field margins, roadsides, and along fence rows. Control can sometimes be achieved by spraying an insecticide around fields closest to the source of migration or by broadcasting insecticide bait over a vegetation free, 60-foot buffer strip, in advance of the migrating grasshoppers.

Weed Control: Some weeds have an allelopathic effect on crops by synthesizing and releasing toxic substances that retard the growth of other plants. This may be the case with bermudagrass ( picture) which inhibits the growth of alfalfa more than you would expect from competition alone. If left uncontrolled, bermudagrass can eventually take over an alfalfa field.

10 Year Summary (May 21 to June 3, 1993-2002):

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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