Pollination and Fruit Thinning of Kiwifruit Vines
For fruit to be produced, male and female vines must be present in a block and must flower at the same time. Male flowers produce viable pollen for only the first 2 to 3 days after opening. However, female flowers are receptive to pollen for 7 to 9 days after opening, even when the petals have started falling.
Pollination is extremely important in kiwifruit production. Large fruit contain 1,000 to 1,400 seeds (research on Hayward). If pollination is poor, fruit will have indentations (narrow valleys) on one side or be non-uniform in shape. If you cut through these fruit, you’ll find there are no seeds in these areas.
Kiwifruit flowers are pollinated mainly by insects, although wind may play a minor role. Honey bees are the main pollinator used in kiwifruit vineyards.
Kiwifruit flowers do not produce nectar and are relatively unattractive to bees. About three to four hives per acre are needed to adequately pollinate kiwifruit. Place these in the vineyard no sooner than 10 percent bloom of the female vines.
In some years, you may have no male vines in flower as a result of winter injury to male plants (they are less hardy than the females). In this case, no naturally produced pollen will be available To get a crop, the females will have to be pollinated artificially. Call your county Extension agent for more information on sources of pollen and methods of artificial pollination.
Fruit thinning, or removing fruit after set, can be done to remove misshapen fruit that are unmarketable and to increase the size of the remaining fruit. However, it is doubtful whether thinning is economical in kiwifruit. Usually, proper dormant season pruning balances the crop load. Also, there’s evidence that in Hayward the yield loss due to fruit thinning is not compensated for by the increased size of remaining fruit.
Bernadine C. Strik, Extension Berry Crops Specialist, Oregon State University.
This fact sheet is adapted from Oregon State University Extension Publication, Growing Kiwifruit.