Using Hawk in mix with Atlantis could help iron out any little inconsistencies in Atlantis performance, trials suggest.

Hawk – or perhaps more specifically clodinafop – tank mixes appear to reduce inconsistencies in Atlantis performance, according to Agrovista trials.

The firm’s Atlantis timing trial, where the product was applied on 14 different dates across last autumn and spring (see FW, Herbicide Supplement, 10 Aug 2007), showed there could be variability in performance according to application date, says the firm’s Craig Morgan.

In the trial Atlantis performance was excellent through the latter part of October and into November, he explains. “But then there was a peak of variable performance with applications on 21 and 29 November.”

Weather data didn’t show anything unusual. “There wasn’t any massive rain either directly before or after those dates, and it wasn’t unusually cold. My own feeling is that it could have been down to leaf moisture, or water around the roots, affecting uptake.”

But mixing Hawk with Atlantis, rather than the residual Firebird, did reduce some of that poorer performance, along with using higher doses of pre-emergence (see table). On average using Hawk rather than Firebird increased control by 8%. “It looks like it could help remove some of that seasonal variability.”

It wasn’t the first time Agrovista trials had showed good performance from Hawk at the Maidwell site, he says. “Our interest in Hawk was triggered through our nozzle work.”

That showed blackgrass control using Hawk following a good pre-emergence treatment could be improved from 67% when applied through standard 200-litre flat fan nozzles to 87% using the new Hawk nozzle. The trials illustrated how important using the nozzle was in getting best performance from the product, Mr Morgan stresses. “It is an integral part of our advice.”

The other critical factor is to know the fop-resistance status of your blackgrass, he says. The Maidwell site has no target-site resistance to fops or dims, such as clodinafop. “You are missing a trick if you don’t get it tested.”

Agrovista has previously offered the test for around about £30. Around 49% of their 180 samples showed no target-site fop resistance, and only 14% were triple-R resistant. “There’s a lot of hope there,” says Mr Morgan.

“I also think there’s less target-site resistance in our more traditional heartland of the central midlands than when you go further east. Our rotation of wheat, oilseed rape and winter beans allows some good residual chemistry to be used, whereas where more spring cropping is used there aren’t too many alternatives to the fops and dims,” he explains.

He wouldn’t use Hawk everywhere this season however, even if fields don’t have fop target-site resistance. “If it is a nice open autumn, and it is the first or second week of November I’d still use a residual partner with Atlantis. But once we get into days when it is a bit wetter, you’ve got dewy leaves, and you know you haven’t got fop-resistance, then I think you would be foolish not to use some of this clodinafop activity.

“And at a grower level the new Hawk (£15/ha) pricing probably makes it cheaper than Stomp (£18/ha).”

Using the new Hawk nozzle has to be an integral part of using the product, says Agrovista’s Craig Morgan.