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Pollination Three keys to SUCCESSFUL POLLINATION T he three major considerations in tree fruit pollination are: 1) compatibility, 2) pollination, and 3) bees as pollinators. To increase the likelihood of producing an acceptable commercial crop, you should consider each topic thoroughly, before advancing to the next topic. Compatibility. This refers to the ability of a viable pollen grain to grow a Pollination is a numbers game. There must be enough bees to pollen tube down the style and complete fertilization in the ovule. Many varieties of many species of fruits are self-incompatible; the style contains enzymes that destroy pollen tubes originating from the pollen from the same flowers or flowers of the same variety. The compatibility of fruit-tree pollination ranges from self- incompatible, progresses through various levels of partial compatibility, and ends with complete compatibility. Be sure to check with nursery per- sonnel or other credible sources, to be sure that compatible pollen will be moved around the orchard. Pollination. This is simply the transfer of viable pollen from the move the pollen throughout the orchards. by Eric C. Mussen University of California, Davis anthers to a receptive stigma of a flower. While in a few self-pollinating plants, pollen reaches the stigma before the flower opens, most flowers have various schemes to prevent being pollinated by their own pollen. Wind and water can move pollen around from a number of types of plants, but most fruit-tree pollen is heavy and relatively sticky, requiring vectors (pollinators) to move it. Bees. The most efficient pollinators tend to be bees. Bees generally rely on plant nectar as a carbohydrate source, and pollens for the rest of their nutritional requirements. Solitary bees, such as leafcutting bees, include single, mated females that find or build a nesting site, then collect nectar and pollen to provision their brood (larvae and pupae). The bee combines the nectar and pollen into a "dough ball" of paste-like consistency and lays an egg on the food. She seals the cell and repeats this process many times. After a larva consumes the food, it will pass through the stages of larva, pupa, or adult. Then, next spring the bees emerge, and mate, and the cycles are repeated. Social bees, like bumblebees and honeybees, live in colonies with specific individuals performing various duties, often depending upon age, to keep the colonies functional. Like other bees, bumblebees and honeybees are heavily covered with hairs so that, as they visit the flowers to obtain their food, they wipe the pollen over the reproductive parts of the flowers. Bumblebees are gener- alists that may visit many different species of plants on a foraging trip. Honeybees tend to be much more species- specific and confine their foraging trips to a single species. In both cases, the food is returned to the colonies and fed to all inhabitants. Growers rely primarily on honeybees for commercial crop pollination, due to their crop constancy and the ability to saturate a crop with huge numbers of bees. Many growers in the eastern states rely on mason bees for apple polli- nation, but honeybees usually are in high demand. Pollination is a numbers game. There 12 MARCH 15, 2012 GOOD FRUIT GROWER