Zeneca's new and improved Touchdown herbicide, now pending EPA registration, can be used on Roundup Ready corn and cotton and won't cause yellow flash in soybeans.

That yellow flash has sometimes been seen in Roundup Ready soybean fields treated with the old Touchdown 5 or some other glyphosate products.

The new Touchdown now uses a glyphosate compound in combination with a balanced adjuvant delivery system that tackles the yellow flash problem, says Chuck Foresman, Zeneca's North American technical business lead for non-selective herbicides.

Spray delivery and retention are said to be improved, too.

Bill Beutke, North American market lead for Touchdown, says company studies show that when glyphosate - the active ingredient in Touchdown and Roundup - is applied alone, 15% of the herbicide is utilized by the plant 24 hours after application. When an adjuvant is added with the glyphosate, utilization goes up to 25%. Touchdown's new formulation with adjuvant delivery, however, provides nearly a 50% level within 24 hours after application.

Upon registration, Touchdown can be applied over Roundup Ready corn, cotton or soybeans and be used in all burndown applications. The new herbicide label is expected to include 170 weeds controlled over a broad range of crops.

The herbicide can be used at the same rates as Roundup Ultra. Its price will be comparable to Roundup Ultra, according to Foresman.

Registration is expected for the 2001 growing season.