A new grassweed sulfonylurea herbicide that Dow AgroSciences hopes to have available for this autumn, approval permitting, could provide growers with a viable alternative for blackgrass control to Atlantis.

Pyroxsulam, which Dow unveiled at Cereals 2007, would no longer be available as a straight option, the firm’s David Roberts confirmed at the ADAS Boxworth open day. “It didn’t quite cut it as a blackgrass product alone, and we didn’t want to exclude ourselves from the major grassweed market.”

Instead, the firm has developed GF 2070 containing pyroxsulam plus an, as yet, undisclosed residual partner. In demonstration trials at ADAS Boxworth it and Atlantis were giving comparable control of fop/dim (2R) resistant blackgrass when used following pre-emergence applications of Defy or Liberator.

GF 2070 looks like it could be a viable alternative to Atlantis in trials, Dow’s David Roberts says

The new product would be used in a similar way to Atlantis if approved, according to Mr Roberts. “We will only ever recommend it as part of a programme, and will strongly recommend the use of a pre- or peri-emergence application before following up with GF 2070 in the autumn.”

Where a pre- or peri-emergence residual herbicide has been applied beforehand there may be scope to apply GF 2070 alone, particularly if that application has been effective, he explained. “If you haven’t used one then you will definitely need to mix GF 2070 with a residual herbicide, such as Firebird or pendimethalin.”

The product could also be used in the spring, he said. “We won’t be recommending wholesale use in the spring, but if conditions dictated, then there isn’t any restriction.”

The determining factor for that decision would likely be the need for active growth at application timing, he explained.

Efficacy was similar to Atlantis in trials, according to Mr Roberts. “I hesitate to say it is better than Atlantis, but it is a viable alternative. We have comparable data from trials.”

An advantage for GF 2070 looked likely to be fewer restrictions on the choice of, and cultivations required for, following crops compared with Atlantis. “Cereals, beans, oilseed rape and even brassica transplants are all OK in the following autumn, and there are no restrictions on cultivations. It gives growers a greater degree of flexibility.”

GF 2070 will not be permitted to be used in mix or in sequence with Atlantis, because of the rules governing the use of sulfonylurea grassweed herbicides. Nor should it be used where Atlantis has failed to control blackgrass in the past, Mr Roberts stressed. “If you’ve had problems with Atlantis, don’t come knocking on our door.”

Dow had also developed GF 1364 containing pyroxsulam plus florasulam (as in Boxer) for use in the spring against ryegrass, bromes and wild oats, he said. “It has equal activity against those weeds as GF 2070. It should be useful for growers in the west where those weeds are an issue without blackgrass.”

Its development was behind GF 2070, he noted. “Approval for GF 2070 is being sought it is with PSD now. Our aim was to have a limited amount out this autumn, but it is in the hands of PSD.”

See: Cereals 2008 homepage

Dow herbicides

• Two new sulfonylurea based herbicides
  
• GF 2070 contains pyroxsulam + residual
  
• Aimed at blackgrass market
  
• GF1364 contains pyroxsulam + florasulam
  
• Aimed at other grassweeds