With herbicides, they say it’s not what’s in the can, but what reaches the leaf that matters.

But it is because of what is in the can along with the active ingredient, glyphosate, that Roundup branded products are significantly quicker and better at reaching their target than any of the generics, claims Monsanto’s technical adviser, Manda Sansom.

“Not only do formulations under the umbrella name of Roundup generally contain more glyphosate per litre, but they include unique surfactants based on different chemistry to the tallow-amine ones of traditional glyphosate.

This gives all of the 12 products in our range a distinct advantage, particularly in adverse conditions.”

Recent Monsanto research highlights the comparative reliability of modern Roundup technology versus a generic, containing the same concentration of glyphosate, in both hot, dry conditions and unsettled weather.

Control of common couch was 15% better under extremes of hot and dry, and cool and dry.

And while there was little difference when rain didn’t follow application, Roundup had the edge when rain fell within two hours.

In practice, that means more spraying days, or more timely applications, resulting in less weed competition and less need to re-spray, says Mrs Sansom.

If you choose a generic and have to apply it in difficult conditions, you may well have to go in again, she warns.

Hard water

Another interesting finding was that Roundup brands are less affected by hard water than traditional ethoxylated tallow amine formulations.

Hard water, common in eastern and central England, can reduce efficacy by locking on to the glyphosate, thus reducing its effective dose, she says.

The latest two Monsanto glyphosates to hit the market are based on new salts.

Roundup Ace and Roundup Klik are more compatible with other herbicides used pre-emergence in following crops; for example, metazachlor in oilseed rape and chloridazon in sugar beet, Monsanto says.

Tank-mixing, which is approved in these products, can save on application costs.

With most formulations more concentrated than the 360g/litre typical of generic glyphosate, growers have to handle fewer cans, Mrs Sanson says.

“With the introduction last month of new agricultural waste regulations, banning the burning of plastics on farm, any saving on packaging waste is worth a lot.”

And Roundup Biactive is not classified as a hazardous substance under COSHH or the ADR transport scheme, unlike glyphosates formulated with an ethoxylated tallow amine wetter, she adds.

So what is the stumbling block?

Gram for gram, Monsanto’s top-of-the range products cost more, but product manager Stephen Beal is concerned many growers do not actually cost out the options.

“There is no doubt that, can for can, Roundup products cost more.

But if you work out what amount of active ingredient is within each, and do the sums based on the rate you are using, you might find the Roundup equivalent is no more expensive.”

He acknowledges there is still a market for generic glyphosate 360 and Monsanto has no plans to ditch its glyphosate 360 formulation while that remains.

Not everyone agrees, do you?

Is branded glyphosate worth the premium and how much extra would you pay?

Let us know at fwarable@rbi.co.uk