Bayer has made the first US delivery of Convintro, a new pre-emergent herbicide, sending it from its Kansas City plant to New Century FS in Ruthven, Iowa, so that corn and soybean growers can use it in the 2027 season.
Convintro is aimed at waterhemp and Palmer amaranth, two pigweeds whose populations now resist up to nine different herbicide sites of action. Its active ingredient, diflufenican, is a Group 12 PDS inhibitor that blocks carotenoid production in the weed. It is new to the United States, so it gives growers a different site of action to rotate into integrated weed management programmes.
The weeds are costly. Uncontrolled waterhemp has cut yields by 43% on average over three years, and Palmer amaranth at 2.5 plants per foot of row can reduce soybean yield potential by up to 79%, according to the figures Bayer cites. Each female plant can produce up to 1 million seeds, which spread with harvest and tillage machinery, wildlife, floods and manure, while wind can carry seed about 1,000 feet and pollen about 1,600 feet.
Both species can grow up to three inches a day and become hard to control once they pass 3 to 4 inches, which is why the product is designed to work before the weeds emerge. Bayer describes it as giving residual control in the critical early weeks, mixing with many other residual herbicides and easing pressure on later post-emergence sprays.
The product has federal approval from the US Environmental Protection Agency; approval state by state is still being completed, and growers are told to check the status in their region.
For farmers fighting resistance, a genuinely new site of action is rare news: most new herbicide products in recent years have combined old chemistry, and every extra mode of action helps slow the next round of resistance.
Photo: Yercaud-elango / Wikimedia Commons (CC BY-SA 4.0)
Source: AgriBusiness Global
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