In pollination, the pollen grains are transferred from the stamen (male part) to the pistil (female part) of flowers. The central part of the raspberry flower consists of 100 to 125 pistils. These are surrounded by numerous stamens. Each pistil is able to produce a seed and a drupelet. Usually 75 to 85 drupelets develop.
Placement of honey bee colonies is important in order to ensure adequate pollination. At least two hives per acre are recommended. Research shows that bees are responsible for 90 to 95 percent of raspberry pollination. Honey bees are responsible for most of this pollination, although bumble bees and other wild bees may serve more effectively during windy or cold weather. Hives should be placed so that bee flight patterns are not against prevailing winds.
Many of the insecticides recommended for the pre-bloom or post-harvest periods are highly toxic to bees and should not be used during bloom. The insecticides methoxychlor and malathion may be used during bloom if they are applied in early morning (before 8 a.m.) or evening (after 6 p.m.) when bees are not present.
None of the recommended fungicides for plant disease control are toxic to bees.