Albuquerque, New Mexico
July 23, 2009
Weed control is an ongoing problem
for any agricultural operation. Since the first seed was
planted, farmers have battled unwanted plants manually with a
hoe, culturally with crop rotation and chemically with
herbicides and fumigants.
As the price of petroleum-based chemicals increases and
restrictions on chemical fumigants increase, researchers at
New Mexico State University’s
College of Agricultural, Consumer and Environmental Sciences are
studying alternatives to help the agricultural producer in the
ongoing battle with weeds.
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NMSU
College of Agricultural, Consumer and Environmental
Sciences assistant professor Mark Uchanski is studying
the biofumigation effect of Ida Gold mustard on weeds in
the onion fields of the Mesilla Valley. By growing the
mustard plant between onion crops, and then tilling it
back into the soil, a bioactive compound will permeate
the soil and inhibit the weeds’ growth.
(NMSU photo by Jane Moorman) |
Mark Uchanski (photo), assistant
professor in the Department of Plant and Environmental Sciences,
specializing in vegetable physiology, is studying biofumigation
as an alternative.
“Biofumigation is the natural process of intentionally using the
bioactive, or biologically active compounds that can affect the
growth and development of pests, properties of a plant and other
organic materials to aid in reducing populations of plant pests
in the soil,” Uchanski said. “Studies have shown that
biofumigation works in other parts of the country, now I want to
see if it will work in the desert Southwest.”
Uchanski’s current research is focused on managing agricultural
weeds using Ida Gold mustard, hairy vetch and winter wheat.
These crops are grown for several weeks, then tilled into the
soil to release their bioactive compounds during decomposition,
to help manage troublesome weeds such as morning glory and
yellow and purple nutsedge in New Mexico’s onion fields.
Determining the level of bioactive compounds, such as
glucosinolates, in a plant is the starting point for selecting a
good biofumigant crop.
“The mustard cultivar ‘Ida Gold’ has been bred for the specific
purpose of being as ‘hot’ as possible,” Uchanski said. “If you
chewed on the leaf of the plant you would have a very unpleasant
experience – similar to eating horseradish. Plants that have a
strong effect on the human taste system have an effect on soil
pests. We are good at tasting the glucosinolates, which cause
the strong flavors.”
When the glucosinolates combine with an enzyme, also in the
plant cell, a volatile plant compound is released. In humans,
when the plant is chewed up this very volatile aroma goes into
the nasal passages and causes discomfort. In the soil
environment the resulting compounds are what can inhibit the
unwanted plants.
“Two conditions need to be present for the chemical reaction to
occur – water and heat. The hot part we have. Water is the big
issue. When you incorporate the plant material into a dry soil
environment, all that will happen is that the material will dry
out. They will not be biological active because there is not
enough moisture,” Uchanski said of the challenges of making
biofumigation work in the dry conditions of the Southwest.
Spring onions were selected for the study, because the weeds in
the spring are very difficult to manage. The climate conditions
– temperature and moisture – are perfect for other plants, not
just the onions, to germinate and grow. The unwanted plants
compete with the onions for nutrients, light and moisture.
For the biofumigation to work, the cover crop will be planted in
the early fall, cut when the flowers come on about eight weeks
later and then tilled into the ground.
“The glucosinolates are at their highest when the plant is
blooming. Therefore, the residues are the most bioactive and we
hope to see the most weed control,” he said. “The biofumigated
field may lay fallow for a period of about six weeks over the
winter, then onions can be sown the following February.”
To further introduce this research and alternative soil pest
control technique, Uchanski has invited John Masiumas, associate
professor at the University of Illinois at Urbana-Champaign, to
visit NMSU this fall and participate in the Lowenstein Lecture
Series. He will be presenting talks and seminars about
biofumigation and its potential for the desert Southwest.
“Through our research, we hope to demonstrate that the cultural
practice of biofumigating, with carefully chosen crops planted
before onions, will give growers another weapon in the constant
battle against weeks,” Uchanski said. |
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