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

Production Update:

Summer Slump:"Summer slump" is well-known by alfalfa growers as the decrease in yields that normally occurs each summer in Arizona. Yield decline with later harvests in the season occurs in most alfalfa-growing regions of the world. Factors responsible for summer decline may include temperature, day length, water stress, aging, and depletion of food reserves in the plant. The rate of maturation of the crop is probably a primary factor responsible for summer decline. In other words, the crop flowers so fast that time is not available to accumulate yields similar to the spring. Summer slump can not be avoided in Arizona, but maintaining adequate soil moisture levels can slow yield decline. Also, increasing the cutting interval for one harvest during the late summer is recommended to promote the health of the stand during this stressful time of year.

Insect Management: Beet armyworm and western yellowstriped armyworm moths are appearing in pheromone traps and larvae can be found in sweep net samples from alfalfa fields. It is not necessary to treat these worms until they reach the threshold of 15 non-parasitized worms per sweep.

Weed Control: The classification of weeds as summer or winter annuals is inappropriate in the low deserts where mild winters and frequent summer irrigations make it possible for weeds to grow out of season. For example, goosefoot and lambsquarters can be found now in some fields and sprangletop will often grow throughout the winter.

10 Year Summary (July 16, to July 29, 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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