Controlling broadleaf weeds in broadleaf crops traditionally has not been easy or cheap
November 12, 2007 By Lorne McClinton
Controlling broadleaf weeds in broadleaf crops traditionally has not been easy
or cheap. Roundup Ready and Liberty Link varieties changed that for canola growers.
Still, the frequent application of glyphosate in many crop rotations causes
some concern for herbicide resistance management.
If Don Weeks, professor and head of the biochemistry department at the University
of Nebraska at Lincoln, has his way, dicamba-resistant canola may soon be an
option for canola growers as well. "Currently we have developed dicamba-resistant
tobacco, soybean and tomato varieties," Weeks says. "While I can't
give details, we are currently working on other crops as well and canola is
certainly one of the crops on our minds."
Ground zero gene provides resistance
Weeks' process is based on a soil bacteria gene found at a dicamba manufacturing
plant. The gene gives plants the ability to produce an enzyme that breaks the
herbicide down into an inactive compound. The level of crop safety is extremely
"We have tobacco plants that are resistant to 25 pounds of dicamba per
acre," Weeks says. "Since normal application rates are just one-quarter
to one-half pound in most fields, we have quite a good bit of crop safety insurance."
There are several advantages for growing dicamba-resistant crop varieties.
Weeks says that dicamba is environmentally friendly and breaks down readily
in the soil. The bottom line for farmers is that it does a good job controlling
many problem weeds. Plus, dicamba is one of the most effective and least expensive
"Dicamba-resistant varieties will also let you reduce your reliance on
glyphosate. This is another big factor. Inserting a dicamba-resistant crop into
a rotation with glyphosate-resistant crops will reduce selection pressure for
Since the technology is based on a bacterial enzyme that is very specific to
dicamba, it has no effect on other herbicides in the chemical group. MCPA and
2,4-D would still control a dicamba-resistant canola, and could be used to control
volunteers in the following year.
How soon the technology will be available to canola growers is still up in
the air. Canola will not be the first crop to hit the market with the gene.
"Dicamba-resistant soybeans are likely still a few years away from coming
to market," Weeks says. "Soybean varieties have been developed, but
it takes time to increase seed and move the trait into different maturity groups
and other varieties. I don't want to hazard a guess when dicamba-resistant canola
may be available."