Adding Du-Wett Stainless to stain removal products in kiwifruit ensures tannin stains are removed and less water is used.
Du-Wett Stainless delivers superior results
No one likes having to deal with stubborn stains. Ask any kiwifruit grower. Caused by tannins leaching from the leaf canopy onto the fruit, stains result in fruit being rejected and can severely impact growers’ bottom lines. But, in kiwifruit at least, stains are not the end of the world; if you have the right solution.
A specialist, mildly acidic stain removal product, used while the fruit is still on the vine, will do the trick. But only if it gets in direct contact with the stain rather than being trapped in the hairy layer of the fruit’s surface. Pieter Van Der Westhuizen, UPL Northern Regional manager, says to get the best results it is essential to get maximum deposition and spreading of the stain removal product on to the kiwifruit skin surface.
High water rates does NOT equal effective spray deposition
“If you go back a few years, people thought you got better stain remover deposition and spreading with high water rates (around 3,000 litres per hectare). However, high water rates do not necessarily translate into effective deposition onto fruit surfaces. Especially in Hayward kiwifruit which is difficult to wet.
“Du-Wett Stainless added to the tank mix, reduces the need for high water rates because it reduces surface tension. Trials have proven that the best results are achieved at water volumes of 500 to 1,000 litres per hectare, meaning it’s possible to cover an area three to six times larger with a single tank. This vastly improves spray operator efficiency.”
Du-Wett Stainless, is a specialist super spreader, which tolerates the acidic environment of stain removal tank mixes. Most other superspreaders will break down in an acidic environment. Du-Wett Stainless can safely be tank-mixed with stain removal products such as KiwiLustre LF (phosphate buffered lactic acid). Pieter says lower water rates and improved coverage have the added advantage of faster drying fruit. That means picking can commence much sooner after spraying, resulting in less down time. “Picking crews can start their day a few hours earlier, and don’t have to wait for fruit to dry like they normally would.”
To get the best from Du-Wett Stainless the sprayer must be calibrated accurately. For heavily stained fruit, Pieter says a second pass can be made as a double pass application at 500 litres ha each way.
