Out-of-crop weed control with glyphosate, such as stale seedbeds, has become an essential practise for most farmers wanting to reduce the weed burden before drilling. With in-crop weed control being fraught with problems such as weed resistance, seedbed conditions, increasing costs and very high weed pressures, it is important to minimise weed control out-of-crop.
But, as Alan East, Technical Manager for Interagro UK Ltd points out, glyphosate is one of those chemicals which are badly affected by hard water and pH and its activity is compromised. “Water hardness, a problem in most arable areas with samples commonly exceeding 300ppm of calcium carbonate equivalent, and high alkalinity (pH above 7) can both adversely affect glyphosate in the spray tank.”
What happens, explains Alan, is that calcium and magnesium cations in hard water lock up glyphosate molecules as irreversible complexes. “Once these ions are complexed, the active ingredient is unavailable in the spray tank. In effect a lower dose of glyphosate is applied. Growers need to unlock the herbicide’s activity so that it is able to work fully. The unique and advanced water conditioning agent Volta acts sacrificially by forming irreversible complexes with cations in water, in place of the glyphosate. This increases glyphosate availability and its effective dose, making every application count.”
“Using such an effective water conditioning agent, the performance of all formulations of glyphosate can be enhanced considerably. Recent independent trials with two types of glyphosate (a 720 g/l water soluble granule and a 360 g/l soluble concentrate) and three types of cultivations - ploughing, deep pass and straw rake on the surface - show that Volta works with any formulation under any cultivation regime. On average across all three cultivations the addition of Volta to Roundup Power Max resulted in 33% extra control of black-grass and for Rodeo 34.5% extra weed control – an amazing result and one well worth having for the small investment,” says Alan.
Alan explains that Volta consists of a unique blend of polybasic acids and sequestrants, which keep the glyphosate molecule fully optimised. The acid constituent reduces the pH of the spray solution giving a consistent pH of between 5.0 and 5.5, depending on the starting value of the water. This change in pH reduces alkaline hydrolysis, the main cause of pesticide breakdown in the spray tank.
“Volta also reduces the production of scum on the spray tank surface, by binding to metallic ions. This makes tank cleaning easier and reduces the risk of residues being left in the spray tank,” he says.
Alan says that there is an increasing requirement for Volta in hard water areas and when glyphosate is used in high water volumes and at low rates of use.
Volta must be added to the spray tank after the water is added and before the pesticide. It is recommended at a dose of 0.125% of the total spray volume for acidifying and in hard water greater or less than 200 mg/l Ca CO³. This means 125 mls/ha in 100 litres or 250 mls/ha in 200 litres of water. For maximum water conditioning with water with greater than 200 mg/l CaCO³, the dose rate is 0.25% of the spray volume - 250 mls/ha in 100 litres or 500 mls/ha in 200 litres of water. Volta is packed in a 5 litre pack.
