Monsanto not worried about Roundup weed resistance
Tuesday January 14, 4:18 pm ET

ST. LOUIS, Mo., Jan 14 (Reuters) - Monsanto Co. (NYSE:MON - News) said Tuesday that increasing weed resistance to its popular Roundup herbicide is "not a major problem," and farmers should not reduce their use of the product because of fears over spreading resistance in parts of the United States.

"The instances of resistance are extremely low. We don't see it as a major problem for our business," said Monsanto spokeswoman Janice Armstrong.

The New York Times reported Tuesday that a weed known as mare's-tail, or horseweed, is showing resistance to Roundup herbicide, Monsanto's major product.

The report said the resistant weed has infested 20,000 acres in the peninsula area of Delaware, Maryland and eastern Virginia, as well as part of southern New Jersey. Overall, about half a million cotton and soybean acres in the U.S. have been overrun, the Times reported.

Scientists fear that spreading weed resistance can choke fields of key crops and require heavier use of different chemicals which could harm the environment.

Monsanto has a program to track reports of weed resistance to its glyphosate-based Roundup, which is one of the most widely used weed killers in the U.S.. It recommends that growers who do identify weed resistance in their fields use a different weed killer to knock out the resistant weeds.

The company acknowledged that reports of resistance increased last year, and has acted "proactively" to address farmers' problems, Armstrong said.

"We feel the situation is being taken care of," she said.

Armstrong said glyphosates have been used for nearly three decades but only four types of weeds have developed resistance to it, including the mare's-tail. The others are a goose grass in Malaysia, a rye grass in Australia, and a rye grass in California.

She said a different type of herbicide commonly used for corn fields with a triazine base has seen dozens of different weeds develop resistance.

Armstrong said the majority of the calls Monsanto receives from growers about weed problems ultimately relate to misapplication of its product.

There are concerns that the growing use of Monsanto Roundup Ready biotech soybean and corn seeds, which allow farmers to spray herbicide directly over whole fields without harming the crops, is increasing usage of the chemicals which increases the development of resistant weeds.

But Amstrong said that, with the exception of the mare's-tail, none of the weed resistance has been seen in biotech fields.

Monsanto's stock closed 39 cents lower, down 2 percent, at $18.61 Tuesday on the New York Stock Exchange.