|The University of Arizona, College of Agriculture
Competitive Agricultural Systems in a Global Economy
Weed Management Techniques for Vegetable Crops
Vegetable crops and newly introduced crops in Arizona have very limited means of reducing
weed infestations from the time of planting until harvest. Spinach is grown on about 2,000 acres
in Arizona and during the fall through spring seasons. Typical winter annual weeds such as
London rocket, cheeseweed, shepherdspurse, goosefoot, and grasses generally infest spinach
fields from the time the crop begins to emerge. The weeds compete with the crop for sunlight,
water, and nutrients. Mechanical cultivation with tractors may remove weeds in the furrow
between the rows of spinach but expensive hand-hoeing is still required to remove the weeds
growing in the rows with the spinach. Without any available herbicide, growers have spent more
than $1,500 per acre to have crews hand-hoe the weeds.
Garbanzo beans have been increasing in acreage in Central Arizona in the past few years as a
rotational crop that is beneficially grown as an alternative to small grains and offers new
marketing opportunities for Arizona growers. During the long winter through spring growing
season, weeds become a problem especially as the beans mature. No available herbicides provide
season-long weed control for garbanzo bean production.
What has been done?
The University of Arizona Cooperative Extension Maricopa County commercial vegetable
crops program has an on-going project to evaluate new techniques and herbicides for weed
control in vegetable crops. Initiated in 1994, the project continually evaluates the efficacy and
crop safety of newly introduced herbicides for potential use in lettuce, cole crops, melons, onions,
and other crops that may be grown in rotation with vegetables in the desert. Results from the
Cooperative Extension program's field experiments identified effective and safe herbicides for use
in spinach and garbanzo beans that are grown in Arizona. Spinach growers through the efforts of
Western Growers Association successfully secured an emergency exemption for the use of
metolachlor (Dual and Dual Magnum herbicides) in 1998 and 1999. At the end of 1999,
garbanzo bean growers successfully petitioned the manufacturer to request and obtain a special
local need registration for oxyfluorfen (Goal herbicide).
Spinach growers now have a more economical tool to assure crop stand establishment with
fewer weeds. The exemption for the use of Dual herbicide does not offer complete weed control
but hand-hoeing costs were reduced from $1,500 to $500 for one grower. Goal herbicide
compliments other herbicides that are used and provides expanded control of a wider range of
weed species that typically infest garbanzo beans. Data from the University of Arizona
Cooperative Extension Maricopa County commercial vegetable crops program supported the
growers in obtaining the use of the new tools for weed management.
Various sources of unsolicited gift funds
Kai Umeda, Area Extension Agent, Vegetable Crops
University of Arizona Cooperative Extension
4341 E. Broadway
Phoenix, AZ 85040
This report is one of 29 impact statements submitted by the University
of Arizona College of Agriculture to the USDA's 1999 CSREES Science and Education
database in Washington, D.C. An impact statement is a brief summary, in lay terms, of the
economic, environmental and/or social impact of a land-grant program. It states
accomplishments and their payoff to society.
Located at http://ag.arizona.edu/impacts/2000/vegweeds.html
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