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Don't get caught out: pull forward post-em applications (press release)

Consider pulling forward black-grass herbicide programmes in preparation for uncertain weather later in February, two independent agronomists are warning farmers.

Met Office predictions show two possible weather scenarios for the UK in late February and protracted grass-weed growth will only add to the pressure.  Growers will need to take advantage of any windows of opportunity.

“If conditions remain the same, with reasonable day temperatures and the right weather, I’d crack on,” says Sean Sparling. “The current slow growth however, means that application variables will have much more of an impact on the final result, but close attention to detail will ensure a good application.

“A dry black-grass leaf and at least three hours of dry conditions following application will secure rainfastness.  Nozzles and water volumes are important factors too.  Getting good coverage is absolutely critical.”

Meanwhile, further north, Patrick Stephenson says conditions aren’t yet suitable for travel.  “We wouldn’t normally consider post-em herbicide applications now but if current conditions prevail then we think we might be on in only a fortnight.

“If temperatures remain high, above 8oC, then pulling applications forward is a good idea.  Weeds will be growing, getting bigger by the day and by March or April we’ll be dealing with a different animal altogether.”

Mr Sparling agrees. “Bigger grass-weeds produce more amino acids – the antidote to ALS inhibitors.  If the weather warms up then black-grass will get going and any comprising variables will have an even greater impact.”

Meanwhile, if the cold snap materialises then it’s best to wait until soil temperatures rise again. “Plant metabolism doesn’t stop but the plants do slow down a great deal - below 3-4oC soil temperatures growth is minimal.

“New products such as GF2070 (pyroxsulam, cloquintocet and flupyrsulfuron), like Broadway Sunrise (pyroxsulam, cloquintocet and pendimethalin), prefer warmer conditions and more active growth. I’m more comfortable with going on with Atlantis WG in colder conditions.”

Mr Stephenson wouldn’t apply any post-em herbicides below 4oC either.  “The problem is that we’ve a lot of black-grass out there.  I don’t want to have to wait but if it turns really cold I’ll have to.

“Taking out bigger plants now will give the crop a chance to become more robust and it will then be able to deal with any second flush itself, crowding out any germinating weed seeds.”

Mr Stephenson and Mr Sparling agree that active growth is more important than temperature.  “It has become evident as we’ve gained experience with sulfonylurea-based products that efficacy is more closely related to active growth of target weeds rather than temperature.  Weather has an influence through impacting growth," explains Mr Sparling.




26th January 2012


For further information:

Issued by:

Chris Cooksley

Natalie Reed

Bayer CropScience

+44 (0) 1223 226615

+44 (0)1608 637805