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Novel desiccant targeted for stale seed-bed clean up

Mike Abram 01 July 2008
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A potentially quicker total weed-killer was among the new solutions demonstrated by Agrovista at their open day last week.


Pesticide manufacturer Nichino is seeking approval for a new desiccant that Agrovista intends to target at the stale seed-bed herbicide market.


A co-formulation of glyphosate and a new desiccant, pyraflufen-ethyl, its advantages in trials had been a much faster speed of kill and better control of difficult weeds, Agrovista technical manager Mark Hemmant told Farmers Weekly at the firm’s open day at Stoughton, Leicestershire.


Knockdown with the new product was much faster, as demonstrated in the firm’s trial plots, compared with 2 litres/ha of Roundup Ultimate (glyphosate). “It is significantly quicker – you can see it working after just one day,” Mr Hemmant said.


Initial symptoms were white spotting, which then coalesced into necrosis and leaf death, he explained.


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The quicker activity would be important for growers looking to kill volunteer oilseed rape before drilling. “I’m expecting a lot of volunteer oilseed rape this season, too, because of the uneven crops.”


The product had also helped against other difficult weeds – for example, volunteer peas and beans, and nettles – compared with glyphosate alone in trials, he suggested.


Previously, growers had to use higher doses of glyphosate or tank-mix in a product like Shark (carfentrazone-ethyl) to add activity for such weeds, Mr Hemmant said. The latter mix was good, but had a one-month planting interval after application. “That’s no good for stale seed-beds.”


The “joy” of pyraflufen-ethyl was that it had no residual life, which meant growers would be able to apply it and drill quickly afterwards, he suggested.


Agrovista trials this season were evaluating the product to clarify what doses were required for different weeds.


Approval for the product was being sought from the Pesticides Safety Directorate. “We hope it will be approved in time for the autumn, but it is in the hands of PSD,” Mr Hemmant said.


Pyraflufen-ethyl is already approved alone as a potato desiccant.









Adjuvant improves efficacy


The development desiccant’s efficacy is improved by adding Agrovista’s adjuvant Companion Gold, Mr Hemmant says.
The adjuvant had been developed with use primarily with glyphosate products, including Roundup Ultimate, to reduce drift, he said.
“Paul Miller of TAG has found that adding Companion Gold gives the same magnitude of drift reduction as a 3-star rated nozzle.”
Adding the product modifies the spray solution to produce a more consistent droplet size, which helps reduce drift.
“But using this product is not about then being able to spray when it is too windy,” Mr Hemmant stressed. “It is about spraying in the right conditions and reducing drift.”
As well as reducing drift Companion Gold also increases rainfastness – Monsanto backs reduced rainfastness times and cultivation intervals for Roundup Ultimate when mixed with Companion Gold – and increases efficacy.
“It has added up to 15% in oilseed rape yields when used in mix with either diquat or glyphosate as a desiccant,” Mr Hemmant noted. “We think because it reduces droplet bounce and increases spray retention it improves the evenness of desiccation, and indirectly reduces pod shatter.”
The firm had also carried out residue research to confirm all samples were below maximum residue levels, he said. “The latest timing cut-off for adjuvants is normally as soon as the crop starts producing the edible part unless the pesticide specifically states to use one, so we thought it was important to do the residue work to get rape desiccants onto the Companion Gold label.”
Similar work was ongoing with glyphosate plus Companion Gold sprays in wheat, he added.

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