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Water Stain on Kiwifruit
Water stain is a dark cosmetic defect normally affecting the side of kiwifruit. The severity of water stain can depend on weather conditions and the condition of foliage on the vines. If untreated, water stain can significantly reduce export pack-outs in New Zealand kiwifruit. Rejects can often run at around 5% and in severe conditions, badly affected blocks can exceed 25% which would prove very costly to the grower and the industry.
The main cause of water stain is from decaying necrotic leaf tissue dripping down on the fruit in wet conditions. Hence the reason for endeavoring to keep the leaf canopy in good condition, where possible, right up to harvest. The stain is normally due to the leaching of minerals and tannins from the decaying leaves depositing on the kiwifruit.
Liftoff is a liquid phosphorus and calcium formulation with excellent crop safety and performance. Phosyn, international specialists in crop nutrition, have undertaken research trials in Te Puke, Katikati, Pukekohe and Hastings and these trials showed Liftoff to be very effective in removing water stain at all the rates tested.
Liftoff has industry approval for use on export kiwifruit this season and is a very cost effective option for growers. It is available in 10 ltr, 200 ltr and 800 ltr containers.
Recommended application rate and timing for Liftoff is 500ml/100ltrs pre-harvest and apply alone to dry fruit. A water rate of 2000 to 4000 ltrs/ha is required to ensure good coverage and if there is severe staining and/or dense canopy the higher rate should be used. As Liftoff is a formulated quality product the use of surfactants, adjuvants etc. are not necessary and therefore not recommended.
Always read the label before using a PHOSYN product.
Author: Michael Waites, New Zealand
Published: April 2001