Farmers relying on Roundup lose some of its benefit

[Guest guest]

My note - so why not go organic instead?

Farmers relying on Roundup lose some of its benefit

_http://news.uns.purdue.edu/x/2009a/090414JohnsonSurvey.html_

(http://news.uns.purdue.edu/x/2009a/090414JohnsonSurvey.html)

 

 

WEST LAFAYETTE, Ind. - Roundup Ready crops have made weed control much

easier for farmers, but a new study shows their reliance on the technology may

be weakening the herbicide's ability to control weeds.

 

Bill Johnson, a Purdue University associate professor of weed science,

said farmers who plant Roundup Ready crops and spray Roundup or

glyphosate-based herbicides almost exclusively are finding that weeds have

developed

resistance. It is only a matter of time, Johnson said, before there are so many

resistant weeds that the use of glyphosate products would become much less

effective in some places.

 

" We have weeds that have developed resistance, including giant ragweed,

which is one of the weeds that drove the adoption of Roundup, " Johnson said.

" It's a pretty major issue in the Eastern Corn Belt. That weed can cause up

to 100 percent yield loss. "

 

Johnson was part of a team, including Steve Weller, a Purdue professor of

horticulture and landscape architecture, that surveyed farmers in Indiana,

Illinois, Iowa, Mississippi, Nebraska and North Carolina about their views

on the ability of Roundup Ready crops to help control problematic weeds. A

paper on the survey was published in the most recent edition of the journal

Weed Technology. Researchers from Iowa State University, Mississippi State

University, North Carolina State University, the University of Nebraska and

Southern Illinois University Carbondale also contributed.

 

Roundup Ready crops are resistant to glyphosate, the active ingredient in

Roundup. So, if a farm uses Roundup Ready crops, the herbicide can be

sprayed on crops to kill weeds without damaging those crops.

 

Johnson said the problem has become farmers' overreliance on Roundup and

Roundup Ready crops. Those who saw the most benefit from using Roundup,

according to the survey, rotated between types of crops and those that were

Roundup Ready and conventional crop varieties.

 

Johnson said this shows that subjecting weeds to different herbicides is

important to keeping them from developing resistance to any particular

herbicide.

 

" Farmers do not think resistance is a problem until they actually have

it, " Johnson said. " And they think the chemical companies can turn on the

spigots and produce a new herbicide whenever they want. The problem is, since

Roundup is so effective, there's not been any money for new herbicide

discovery. "

 

Johnson said farmers should treat Roundup and Roundup Ready crops as an

investment and work to protect the technology. Rotating crops consistently

and using various herbicides will slow the development of

glyphosate-resistant weeds.

 

" Go after weeds with two different herbicides. That's the best short-term

solution, " Johnson said.

 

" We want to minimize the number of weeds resistant to Roundup. To do that,

you want to minimize the exposure that a weed population has to Roundup.

If you diversify a little bit, you'll extend the life of the technology. "

 

Monsanto, the maker of Roundup, funded the survey. Johnson said the next

step is studying the differences among management strategies in grower

fields to see which will slow the build-up of glyphosate resistance.

 

 

 

Writer: Brian Wallheimer, (765) 496-2050, _bwallhei_

(bwallhei)

Source: Bill Johnson, (765) 494-4656, _wgj_

(wgj)

 

 

Ag Communications: (765) 494-8415;

Steve Leer, _sleer_ (sleer)

Agriculture News Page

 

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ABSTRACT

U.S. Grower Views on Problematic Weeds

and Changes in Weed Pressure in Glyphosate-Resistant Corn, Cotton,

and Soybean Cropping Systems

 

Greg R. Kruger, William G. Johnson, Stephen C. Weller, Micheal D. K. Owen,

David R. Shaw, John W. Wilcut, David L. Jordan, Robert G. Wilson, Mark L.

Bernards,

and Bryan G. Young

 

Corn and soybean growers in Illinois, Indiana, Iowa, Mississippi,

Nebraska, and North Carolina, as well as cotton growers in Mississippi and

North

Carolina, were surveyed about their views on changes in problematic weeds and

weed pressure in cropping systems based on a glyphosate-resistant (GR)

crop. No growers using a GR cropping system for more than 5 yr reported heavy

weed pressure. Over all cropping systems investigated (continuous GR

soybean, continuous GR cotton, GR corn/GR soybean, GR soybean/non-GR crop, and

GR

corn/non-GR crop), 0 to 7% of survey respondents reported greater weed

pressure after implementing rotations using GR crops, whereas 31 to 57% felt

weed pressure was similar and 36 to 70% indicated that weed pressure was

less. Pigweed, morningglory, johnsongrass, ragweed, foxtail, and velvetleaf

were mentioned as their most problematic weeds, depending on the state and

cropping system. Systems using GR crops improved weed management compared

with the technologies used before the adoption of GR crops. However, the

long-term success of managing problematic weeds in GR cropping systems will

require the development of multifaceted integrated weed management programs that

include glyphosate as well as other weed management tactics.

 

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