Production Update:

Dog days of summer: Summers in Arizona are tough for all of us including the alfalfa plant. Some people have a tendency to lose weight in the summer, and likewise, alfalfa plants literally lose weight during this time. Our weight loss comes from fat whereas the loss of weight in the alfalfa plant occurs to depletion of stored sugar in the root, the alfalfa plant's energy reserve. We lose weight during the summer due to a variety of reasons including loss of appetite and more energy expended to do a given amount of work in a hot climate. The alfalfa plant loses weight in the summer primarily due to an increase in basal metabolism with higher temperature. One way of helping alfalfa in the summer is to extend at least one cutting cycle to bloom to allow sugars to build up in the root.

Insect Management: Several fields have developed injurious levels of Empoasca (picture) leafhopper this summer. Adult are about 1/8" long, bright green, and have wedge-shaped bodies. Nymphs resemble adults but lack wings; both run rapidly forward, backward, or from side to side when disturbed. At the first sign of injury, Sample using a standard sweep net. Infestations often start on field margins, so include them in your sampling. Taking 10 sweeps in 4 to 6 areas over the entire field and count the adults and nymphs. When an alfalfa field is two or more weeks from harvest, treat if counts reach 5 leafhoppers per sweep. If alfalfa is to be harvested in 10 days to 2 weeks, treat if counts reach 10 per sweep. A leafhopper infestation of treatable magnitude may be confined to the first 50 to 100 feet of the field margin. In this case, treat only the field edges. Ambush®, Baythroid®, Furadan®, Guthion®, Lannate®, Lorsban®, Mustang®, and Warrior® are insecticides that may be used for leafhopper control in alfalfa.

Weed Control: When alfalfa is taken out to establish a different crop, herbicides used during the previous year or two can cause problems to some crops. The herbicides used in alfalfa that have the longest persistence in the soil are Pursuit and Zorial. Those with moderate soil persistence are Sencor, Raptor, Balan, Eptam, Trifluralin and Kerb. Those with slight persistence are Gramoxone, Buctril and 2,4-DB. Poast and Select are not likely to cause problems.

10 Year Summary (July 13, to July 26, 1995-2004):

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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