Bollworm populations threaten Bt cotton again this year
EXCERPT: Last year, Texas A&M Extension entomologist David Kerns confirmed that some bollworm populations are resistant to Cry1Ac, the Bt protein found in both Monsanto's Bollgard II and Dow AgroSciences' WideStrike cotton varieties. Now Kerns has also confirmed that some populations… have resistance to Cry2Ab - the second protein found in Bollgard II. Nor can growers lean on the second protein in WideStrike cotton, Cry1F, which has only sublethal effects on the bollworm, [North Carolina State University Extension Entomologist Dominic] Reisig said.
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Worm rebellion continues
Emily Unglesbee
DTN The Progressive Farmer, 20 July 2017
https://www.dtnpf.com/agriculture/web/ag/news/crops/article/2017/07/20/bollworm-populations-threaten-bt?referrer=twitter#.WXbA8CUMHMo.twitter
* Bollworm populations threaten Bt cotton again this year
From the Carolinas to Texas, the cotton bollworm is leading an assault on Bt cotton again this year.
Growing resistance to the Bt traits found in the most common cotton varieties is proving problematic as southern states face another large population of the pest, said North Carolina State University Extension Entomologist Dominic Reisig.
"We're seeing earlier and higher bollworm populations than normal," he said. "As the season progresses, that means we'll see more generations of the insect."
For now, entomologists are trying to get growers reacquainted with how to scout for bollworm eggs and caterpillars in order to make timely insecticide applications.
MULTIPLE BT COTTON TRAITS FAILING
Last year, Texas A&M Extension entomologist David Kerns confirmed that some bollworm populations are resistant to Cry1Ac, the Bt protein found in both Monsanto's Bollgard II and Dow AgroSciences' WideStrike cotton varieties.
Now Kerns has also confirmed that some populations tested from Louisiana and Tennessee last year have resistance to Cry2Ab -- the second protein found in Bollgard II. Nor can growers lean on the second protein in WideStrike cotton, Cry1F, which has only sublethal effects on the bollworm, Reisig said.
Growers may also see problems with Bayer's TwinLink cotton, which expresses the proteins Cry1Ab and Cry2Ae, which act similarly to the proteins found in Bollgard II, Reisig said.