Yuma County, Arizona
December 15, 2003
Yuma County Office
Insect Management: Pea aphid (PA) (picture) is a pest of alfalfa during the spring. PA first appears in December or January but may persist into early summer if the weather remains cool. Heavy infestations of PA (picture) are distributed over most of the plant. They can deposit large quantities of honeydew, fouling harvesting equipment, supporting sooty molds growth, and lowering hay quality. Regrowth may be stunted from a moderate to heavy PA population. Several species of predacious bugs and parasitic wasps attack these PA. Sample alfalfa fields by taking 5 to 6 stem samples in at least 5 locations per field weekly when aphids appear, then every 2 to 3 days as numbers approach the treatment threshold of 40 to 50 aphids per stem for plants under 10 inches, 70 to 80 per stem for plants 10 to 20 inches tall and more than 100 aphids per stem for plants over 20 inches tall.
Weed Control: All of the broadleaf herbicides used on non-dormant
alfalfa can cause crop injury. This injury ranges from slight and temporary
to severe and long term. Injury from 2,4-DB, Eptam, Buctril, and Gamoxone,
is temporary while Pursuit, Raptor and Zorial injury can be longer term.
Sencor and Velpar are good broad spectrum herbicides but can cause long
term and severe injury.
10 Year Summary (Dec 2 - Dec 15, 1994-2003):
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Information provided by:
Barry Tickes, email@example.com Extension Agent, Yuma County
Michael Ottman, firstname.lastname@example.org Agronomy Specialist
College of Agriculture, The University of Arizona.
Eric Natwick, email@example.com UCCE Imperial County - Farm Advisor
University of California, Davis, CA.
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