Root-knot nematode populations can vary significantly across a cotton field. Thus a farmer might not need root-knot-nematode protection on every square foot of cotton he grows.
He does want all of the cotton to yield, however, and that’s what Monsanto plant breeders were trying to achieve when they began preparing Deltapine 1454 NR B2RF and other root-knot-nematode resistant cotton varieties for release.
“What distinguishes it from other root-knot-tolerant varieties, older root-knot varieties that are on the market, is a high level of resistance and a great agronomic fit, great yield performance in the full-season market it's targeted for,” said Dave Albers, product development manager for cotton germplasm for Monsanto.
“Largely, that’s the lower Southeast, that area of south Georgia, lower Alabama, South Carolina, as well as the lower part of the Southern High Plains and the Southern Rolling Plains – those areas that grow full season and have root-knot pressure.”
Albers said the concept behind the development of DP 1454 NR “and other root-knot-resistant varieties behind it” was to have varieties that would have strong performance in the presence of root-knot nematodes and in parts of fields were the root-knot populations were low.
“We didn’t want for a grower to have to give up yield in part of a field to get the protection from root-knot nematodes in the really high pressure or tough parts of the field,” said Albers, who was interviewed during a trip to visit farms in the Mid-South.
Nematode pests – primarily root-knot and reniform – can be found in soils in many parts of the South. Until recently, producers could prevent nematodes from reaching damaging population levels by applying aldicarb or Temik in-furrow. A few years ago, the registrant withdrew aldicarb from the market. Efforts to bring Temik back or find a suitable chemical replacement have not been successful. See Temik loss leaves growers scrambling.
“The DP 1454 data in those areas has shown great performance, certainly above average to very good performance in the non-nematode areas of the field and then top performance in the root-knot nematode areas,” Albers said. “We think it is a great combination, broadly adapted in those markets.”
Monsanto scientists tested DP 1454 NR in a number of locations with root-knot nematode populations ranging from threshold levels of 150 to 200 nematodes per 100 CCs of soil “up through 5X and 10X those levels,” said Albers. “So even with some extremely high populations in some of our tests, we’ve seen these varieties hold up very well.”
These are not the first root-knot or reniform-tolerant cotton varieties to be available for growers. Jack Jones, a cotton breeder with the LSU AgCenter, introduced several varieties with a level of nematode-resistance in the 1980s and early 90s.
One of the differences between those lines and DP 1454 is something called marker-assisted plant breeding.
“Our breeding group has developed our own set of genetic markers for these traits and other traits that are in the pipeline,” says Albers. “That is a real advantage in that when breeders take these lines to the field to test them, they know they are resistant to this particular pest. Then they’re selecting for agronomic fit, for fiber, to make sure we are bringing the entire package to growers that have this problem.”
Albers said Monsanto has other materials coming that will fit short-season cotton growing markets and reniform nematodes, something DP 1454 NR will not do. For now the nematode resistance is being included in Bollgard II, Roundup Ready Flex varieties. Monsanto plans to broaden those offerings to include Roundup Ready XTend and Bollgard III traits in the next two to three years.
For more on Roundup Ready XTend, visit Monsanto laying groundwork for Roundup Ready XTend.