Delta and Pine Land Co. is releasing five new stacked-trait soybean varieties for 2007. The varieties contain both the Roundup Ready and STS traits, which offer Mid-South producers a tool for managing weed resistance, the company says.

The varieties “can contribute toward better weed control in fields where glyphosate-resistant weeds are a problem, while mitigating against the development of resistant weeds in fields where resistance isn't currently a problem,” said Rick Rice, D&PL marketing director. “And these varieties all come with top-end yield potential so a farmer doesn't have to sacrifice yield in order to gain the weed control benefits associated with the stacked-gene technology.”

Producers can apply Roundup in conjunction with DuPont Synchrony XP in an over-the-top application on RR/STS soybeans. Synchrony XP is labeled for over-the-top use in non-STS soybeans at the rate of 0.375 ounce-formulated per acre and for over-the-top of D&PL-brand RR/STS beans at a rate of up to 1.125 ounces of formulated product per acre.

The higher rate improves postemergence control of glyphosate-resistance weeds such as horseweed (marestail) and pigweed, while also providing potential residual activity.

“Synchrony's second mode of action delivers enhanced postemergence activity and potential residual control while helping in the long-term battle against herbicide resistance,” said Rice. “But, it requires the stacking of the Roundup Ready and STS traits together in the same plant to be able to use the high rate of Synchrony XP in an over-the-top tank mix with Roundup.”

D&PL has very good supplies of both DP 4919 RR/S and DP 5115 RR/S, two stacked-trait varieties with high yield performance in the Mid-South, especially in the north Delta regions of Missouri, Arkansas and Tennessee, the company says.

DP 4919 RR/S, a late-Group 4 variety, is a progeny of DP 4748 S, which has been a high-yielding line throughout much of the Mid-South. In trials in 2006, DP 4919 RR/S showed particularly good performance potential on light to sandy-loam fields with irrigation, said Kelly Whiting, soybean agronomist at D&PL.

“DP 5115 RR/S is an early Group 5 variety that demonstrated extremely high yields when planted on good-producing irrigated fields,” said Whiting. “Both of these varieties were bred for the Mid-South region and both have demonstrated outstanding performance potential.”

D&PL will also have a supply of seed for DP 4888 RR/S and DP 5335 RR/S, two new varieties with impressive testing results on clay-type soils. An introductory supply of DP 4112 RR/S, an early Group 4 variety, will also be available.