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May
2002

 

 

 

By
B. Rosie Lerner

Extension Consumer Horticulturist
Purdue University

 

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Pollination Is Essential In Home Orchard

If growing your own fruit is in your landscape plan, you'll need to make sure you've provided an adequate opportunity for pollination to occur. In most cases, you will need to plant at least two of each type of fruit tree.

There are two types of fruit trees with respect to pollination -- self-fruitful and cross-pollinated. Self-fruitful means that pollen from the same cultivar (cultivated variety) will produce fruit. However, fruit set is enhanced even on self-fruitful trees if more than one tree is in the area.

Most fruit trees belong to the group that requires cross-pollination. These trees not only need pollen from another tree, but the tree must be of a different cultivar. Pollen from its own flowers or those of another tree of the same cultivar will not be able to successfully pollinate the female parts of the flowers, due to incompatible timing. You'll need to do a little homework to find the right mix of cultivars. Extension bulletins and gardening books are good places to find suggested combinations.

Even if you have compatible trees in place, other factors can interfere with pollination. One of the most frustrating foes of pollination is the weather, since we have so little control over such things as frost, rain and wind. Flower buds are formed in autumn for the following year's crop. Severe low temperatures in winter can kill or injure the buds before they even open. Those that do make it through winter can be injured by spring frosts. The more developed the bud, the more sensitive it is to cold injury. Fortunately, not every flower bud on the tree needs to survive to have a good crop. But each incident of frost further decreases the fruit potential.

When successful pollination does not take place, the flowers may drop immediately following the blooming period. In some cases, what appears to be a small fruit will form, but then drop off after a few weeks. In mild years when most of the flowers survive, a tree may set more fruit than it is capable of supporting on to maturity. The tree may then self-abort some of the fruit in a natural thinning process sometimes called "June drop." The tree will drop many small-sized fruit at about the same time, making for a dramatic, and often alarming, show. But the tree should have plenty more fruit staying on the tree that will be in better position to share the tree's resources.

Apples are one of the most popular home-grown fruits, and most are not self-fruitful. Generally, early-blooming cultivars should be used as pollinators for other early-blooming types and so on. Midseason bloomers can often act as pollinators for all others, since they will have some overlap with both early- and late-season cultivars.

Pears generally are not self-fruitful, either, so at least two cultivars are needed. Generally, any two cultivars will be compatible. The exception is that 'Seckel' pears will not pollinate 'Bartlett,' and vice versa. 'Kieffer,' 'Duchess,' and 'Bose' will set some fruit without benefit of cross-pollination, but will produce best among other cultivars.

Tart cherries are self-fruitful, but sweet cherries are more complicated. The sweet cherry 'Stella' is self-fruitful. Other sweet cherries need to be cross-pollinated, and some can only be pollinated by certain other cultivars.

Peaches, nectarines and apricots are generally self-fruitful, but fruit set may be enhanced by having more than one tree. Unfortunately, these trees are often quite susceptible to winter and spring frost injury in Indiana, resulting in poor or no fruit crop most years.

In order for adequate cross-pollination to take place, trees should be within 50 feet of one another. Pollen is too heavy and sticky for wind to carry it, so bees must do the job. Protect those bees by omitting the insecticide from your orchard pesticide spray while trees are in bloom.

 

5-01-2002

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Writer: B. Rosie Lerner

Editor: Oliva Maddox, (765) 496-3207

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Last updated: April 6, 2006
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