Why water strain occurs in kiwi orchards?

Water-stained kiwi fruits fetch poor price in the market causing economic loss of produce.  It is characterized by distinct dark streaks or stains which occurs down the side of kiwi fruit due to deposition of tannins. This accumulation is a result of leaching of tannins from the dead fruit tissues due to rainfall. The malady can be controlled by removal of dead tissue from the plant canopy.  The blemishes can be rectified by treatment with weak solution of citric acid.