1998 年在加利福尼亚州的一对杏仁园中首次报道，草甘膦抗性正在美国蔓延，而且杂草只会越来越聪明。根据一项广泛的新调查，随着越来越多的农场现在对多种杂草产生抗药性，这个问题变得更加严重。
研究公司 Stratus Agri-Marketing Inc. 的副总裁 Kent Fraser 在三年内对 31 个州的数千名美国种植者进行了调查，他告诉 农用化学品国际, “We were surprised to see how quickly the problem of glyphosate resistant weeds has spread, especially in the Midwest. It is also alarming that the number of farms with more than one of the confirmed resistant species has increased so fast.”
The crop input industry has responded with products of differing modes of action designed for resistance management. The products are to be used as part of an integrated approach with crop rotation representing a key component. “It will be interesting to see if growers choose to rotate chemistries from year-to-year, mix it up with multiple modes of action at different application times in one year, or use products with multiple modes of action built in,” Fraser said.
U.S. growers told Stratus that 61.2 million acres of cropland are infested with glyphosate resistant weeds — almost double the number recorded in 2010.
根据国际抗除草剂杂草调查，目前全球有 396 个独特的除草剂抗性案例，涉及 210 个品种。据报道，61 个国家的 63 种作物存在抗除草剂杂草。
The survey’s results were dramatic:
- 将近一半 (49%) 的美国种植者表示，2012 年他们的农场有抗草甘膦杂草，高于 2011 年的 34%。
- Resistance is still worst in the South. For example, 92% of growers in Georgia said they have glyphosate-resistant weeds.
- The mid-South and Midwest states are catching up. From 2011 to 2012 the acres with resistance almost doubled in Nebraska, Iowa and Indiana.
- It’s spreading at a faster pace each year: total resistant acres increased by 25% in 2011 and 51% in 2012.
- The problem is getting more complicated. More and more farms have at least two resistant species on their farm. In 2010 that was just 12% of farms, but two years later 27% had more than one.
- Marestail (horseweed) was the weed most often reported with glyphosate resistance, followed by Palmer amaranth (pigweed). Another half-dozen species were tracked in the study.