Yuma County, Arizona
August 11, 2003
Yuma County Office
Insect Management: Western yellowstriped armyworm (adult) (larva) is a common pest in low desert alfalfa from June through September. Egg masses, covered with gray cottony scales, are deposited on the upper side of leaves. Eggs hatch in a few days and larvae reach full size in 2 to 3 weeks. Larvae pupate on or under the soil surface. Larvae appear smooth and are usually black with two prominent orange yellow stripes and many narrow stripes on each side. An intense black spot on the lateral margin of the first legless segment is a distinguishing characteristic. First instar larvae web terminal leaves together and skeletonize the leaves, later dispersing through the crop. Spiders and predacious bugs prey on larvae and larvae may be parasitized by Hyposoter exigua wasps. Monitor fields weekly using a sweep net and check fields 2 to 3 times per week if heavy populations begin to develop. Make 5 sweep counts at each of 4 to 5 locations in the field. Treat when there are 15 non-parasitized armyworms of more than ½ inch per sweep.
Weed Control: There are over 150 species of Dodder (picture)
throughout the world. Field Dodder (Cuscuta Campestris) is the one most
commonly found on alfalfa. Dodder germinates at or very near the soil
surface and is dependent on carbohydrates stored in the seed until it
attaches to a host. If no host is found, it dies. Once attached, it is
entirely dependent on the host for nutrients and water. It is spread by
contaminated seed, equipment and soil movement. The best control is achieved
with two applications of the highest labeled rated of Trifluralin applied
in the spring and mid-summer.
10 Year Summary (July 29 - Aug 11, 1994-2003):
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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