Yuma County, Arizona
September 23, 2002
Yuma County Office
Insect Management: Three-cornered alfalfa hoppers (picture)are found in alfalfa from spring into the fall. They feed by inserting their needle-like mouth parts into stems and sucking out juices. Adult female hoppers girdle stems by depositing eggs causing the stem and leaves to turn red, purple or yellow above the girdle. Adults are light-green, thick-bodied, triangular insects about one-fourth inch long which move about the plants and fly when disturbed. Nymphs are grayish-white, soft-bodied, with saw-toothed spines on their backs and are confined to the lower portions of the plant. Nymphs may not be picked up in a sweep net. There are rarely enough three-cornered alfalfa hoppers in alfalfa fields to cause economic damage. An economic threshold has not been established, but if there are fewer than 15 three-cornered hoppers per sweep, it may not be economical to treat with insecticides.
Weed Control: Preplant incorporated treatments of eptam or balan can cause crop injury. At a seeding rate of 20-30 lbs./A, you start out with many more seedlings than are needed and some stand reduction will not normally result in yield reductions. These treatments are most useful when heavy weed infestations are expected to emerge with the crop.
10 Year Summary (March 26, to April 9, 1993-2002):
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, firstname.lastname@example.org Extension Agent, Yuma County
Michael Ottman, email@example.com Agronomy Specialist
College of Agriculture, The University of Arizona.
Eric Natwick, firstname.lastname@example.org UCCE Imperial County - Farm Advisor
University of California, Davis, CA.
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