Competitive Plants. Honey bees flying up to 2 1/2 miles in all directions from a single hive have access to 12,500 acres. Competing bloom such as dandelions or other cover crops may be more attractive than the fruit bloom to the bees. In addition, when bees are moved into an orchard from an area where a particular weed predominates, they usually resume collecting nectar and pollen from the same species at the new location. Such bloom should be removed by mowing, use of herbicides, or cultivation before the bees are taken in.

Each crop and often varieties of a crop have unique characteristics that may require different approaches. Growers and beekeepers must work together. Cooperation and understanding of each other's needs and problems are mutually advantageous.

Because most tree fruits are propagated by grafts, a solid block of one variety is genetically only one plant. Most varieties are self-sterile and therefore cannot be productive without pollen from a compatible variety. Growers have productive orchards by interplanting compatible varieties with coinciding blooming periods, providing bouquets of flowers from other varieties, or supplying the beekeepers with pollen to use in pollen inserts.

Apples, pears, and sweet cherries must receive pollen from another variety because their own pollen is not compatible. Because apples are quite attractive to bees, they often attract many wild bees from the surrounding area. When apples are insufficiently pollinated, they develop lopsided fruit; the apple is larger on the sides where the seeds have formed. For a full commercial crop, 5 to 10 percent of full bloom should set fruit.

Some pear varieties are capable of setting fruit without pollination (parthenocarpic fruit). However, large numbers of bees must be present to achieve adequate fruit set. Honey bees visit pears primarily for pollen. Since the nectar is very dilute and unattractive, pears pose more of a pollination problem than do apples. Move bees in at 25 to 50 percent bloom. Honey bees work pears best when colonies are first put into the orchard. Later, they tend to be attracted to competing flowers in the area. Use twice as many colonies as you would use for apples in the same locality.

Sweet cherries must be pollinated soon after the flower opens, as reproductive parts of the flower degenerate quickly. Therefore, colonies should be in the orchard at the start of bloom.

Leading commercial varieties of tart cherries are self-fruitful, so orchards may be planted in solid blocks of one variety. However, the pollen is heavy and sticky, so bee transfer is required. The blossoms are attractive and bees work them well.

Most commercial varieties of peaches and nectarines are self-fruitful and may be planted in solid blocks. Bloom is very attractive, so colonies of honey bees are not normally rented. In areas where wild bees are scarce and weather may reduce bee flights, it would be good insurance for growers to place colonies of honey bees in the orchard. The only major peach variety requiring cross-pollination is J.H. Hale.

Colonies should be present in plum orchards from first bloom until petal fall. Interplantings are considered a safeguard for all varieties. Prune types are partially self-fruitful, but the pollen from European plums often will improve set on the prune-plum. The blossoms are attractive to bees.

Honey bees are usually necessary for commercial production of highbush blueberries. Full pollination results in higher yields, larger berries, and earlier ripening. Blueberries yield nectar and pollen, but bees visit the flower predominantly for nectar. Current varieties are self-fruitful but vary in attractiveness to honey bees.

Most modern strawberry varieties are self-fruitful. The anthers that contain pollen circle the receptacle that contains the pistils. Some varieties have tall stamens, so the anthers are close to the stigmas and pollination can occur readily as leaves and flowers are moved by the wind. Additional movement of pollen by bees increases yield only slightly. Other varieties have tall receptacles and short stamens. Unless pollen movement in these varieties is aided by bees, pollination, yield, and size will be reduced, and many berries will be misshapen. Most growers would benefit from the consistent use of honey bees in their fields.

Commercial production of vine crops requires bee pollination since two types of flowers are found on the vines, and the pollen is dense and sticky. Cucumbers, squash, pumpkins, and watermelons have separate male and female flowers, whereas muskmelons have male and hermaphroditic (perfect or bisexual) flowers. The sticky pollen of the male flowers must be transferred to the female flowers to achieve fruit set. Even with hermaphroditic flowers, commercial yields of muskmelon are not possible when there are few insect pollinators.

Cucurbit flowers are usually open and attractive to bees for only one day or less. The opening of the flower, release of pollen, and commencement of nectar secretion normally precedes bee activity. Pumpkin and squash flowers usually open around daybreak and close by noon, whereas cucumbers, muskmelons, and watermelons open around 8:00 AM. and remain open the entire day.

Pollination must take place on the day when the flowers open, since pollen viability, stigmatic receptivity, and attractiveness to bees last only one day. Pumpkin and squash pollination is most effective in early morning, primarily before 9:00 A.M. In cantaloupes, cucumbers, and watermelons, pollination is most effective during late morning and early afternoon. Honey bees are normally most active in the field from 10:00 A.M. to 3:00 P.M., with peak flight occurring near noon. Honey bees are not as effective in pollinating squash and pumpkins as the other cucurbits, since the flowers close at noon.

Multiple bee visits of at least eight to twelve per flower are needed to produce marketable fruit. When large populations of hybrid cucumbers are grown for machine harvesting, flowers should receive fifteen to twenty visits for maximum fruit set. In general, as the number of visits increase, so does the fruit set, number of seeds per fruit, and fruit weight. Fruit shape also improves up to a point as the number of visits increase. Cucumbers may be misshapen in spite of adequate pollination.

With vine crops, a high level of bee activity in the field is effective only over a few days due to fruit inhibition. As the number of fruit on the vine increases, the probability of additional fruit developing and being well shaped decreases, even though optimum pollination conditions exist.

Pollination of lima beans normally occurs without the aid of an insect visitor. The anthers surround the stigma and shed their pollen upon it. Mechanical tripping is unnecessary to ensure adequate pollination. If the stigma is pollinated by an insect visitor before it is touched by its own pollen, cross-pollination will result. Most research to date has not conclusively shown significant increases in yield with bee visitation. However, some growers feel they benefit by having colonies of honey bees near their fields.

Bees work the crop well for nectar and obtain some pollen from it. Nectar is secreted at the base of the flower and is a source of fine-quality honey. Nectar secretion seems to be greatest when plants first come into bloom and remains intense for about a week.