Water warning for glyphosate

As growers prepare to spray off crops pre-harvest, a major glyphosate manufacturer has issued a reminder about the need for careful management of water quality in the spray tank.

Glyphosate is particularly vulnerable to ’lock-up’ – a problem caused when certain pesticide groups react with hard water.

"Little regard is taken of the water that growers put into the crop sprayer," says Bryan Pickles of Barclay Crop Protection. "But the dissolved minerals found in varying levels in all water – not just hard water – can have a deleterious effect on the performance of certain chemical groups.

"When glyphosate is mixed with water, it binds with cations in the water to form a strong complex which is not bio-available," he explains. "Only the remaining unbound glyphosate is fully available to act as a herbicide, effectively curtailing the efficacy of the applied product.

"Because it’s a characteristic of the molecule, this happens to all glyphosate formulations – even quality products, such as Gallup."

Growers can avoid the problem by using a water conditioner such as Velox Arbiter, he advises. "Added to the spray tank before the pesticide, a product like Velox Arbiter will ’bind-up’ the deactivating cations. Any subsequent addition of glyphosate will remain unbound and fully available to work as intended."

Compatible with all formulations of glyphosate, Velox Arbiter also prevents alkaline hydrolysis of pesticides – another characteristic of hard water – and offers two other benefits, humectancy and anti-foam control.

"As a humectant, Velox Arbiter stops pesticides from drying out and crystallising on the leaf surface, where they can’t be absorbed. It also contains an anti-foaming agent which saves the loss of time due to foaming during filling and mixing," explains Mr Pickles.

"There’s one additional point that’s worth making about water quality, and it’s something that no amount of additives and additional products can solve – it’s simply an issue of not cutting corners.

Use only clean, clear water in the spray tank. Both glyphosate and diquat are susceptible to inactivation by suspended silt and organic matter."