OHIO DEPARTMENT OF AGRICULTURE
Division of Plant Industry-Apiculture
8995 East Main Street
Reynoldsburg, Ohio 43068-3399
VALUE OF BEE POLLINATION TO OHIO AGRICULTURE
The pollination mechanisms for some Ohio crops are poorly understood, particularly hybrids and new varieties A few crops have been investigated and the pollination requirements are well known. An example is the pickling cucumber. In this case, bees provide nearly 100% of the pollination. The amount bees contribute to the pollination of other crops is sometimes less. Strawberries vary in their need for bee pollination. The ‘average’ variely requires about 24% insect pollination for complete seed set. The remainder is due to self-pollination Strawberry growers usually have a crop of berries, but without bee pollination, the qualily is sometimes inferior to a crop produced with the aid of bee pollination. With apples, bees are essential for cross-pollination. New varieties and cultural planting methods add new questions as to how apples are pollinated.
UNMEASURED POLLINATION BENEFITS
There are areas where it is almost Hpossible to place a dollar value on bee pollination One is the contribution that pollination of plants makes to wildlife food production. Another is the natural beauty resulting from pollination of wildflowers. Many shrubs and countless annual plants reproduce by bee pollinated berries and seed, which provide food for birds and other animals. Ornithologists may suggest that humans “feed the birds in the winter,” but the birds also depend upon naturally grown seed and fruit resulting from bee pollination
The beekeeper with a small scale operation is very valuable in providing honey bees for this unmeasured contribution to pollination, because there are many Ohio hobbyist beekeepers spread through the state who increase food production for wildlife.
POLLINATION AND SOME AGRICULTURAL CROPS
Pumpkins and squash – Because the anthers are in one flower and the stigma is in another, transfer of pollen is essential to fruit set. Observations indcate that pollination is most effective in the early morning.
The value of bees has been shown in terms of fruit produced Wolfenbarger (1962) showed the correlation between colonies/acre and increased production in baskets of squash/acre
1/2 colony — 155 baskets Three colonies — 173 baskets
one colony — 161 baskets
Concrete data is scarce, however, evidence shows pumpkins and squash must be pollinated and honey bees are the chief pollinators. Recommendations are 1 to 3 colonies/acre. If yields are low, consider 3 colonies/acre. If yields are low, consider 3 colonies/acre. Colonies placed nearby are most effective.
Melons (cantaloupes. all cultivars of muskmelons) – The flowers open sometime after sunup, depending upon the sunlight, temperature and humidity. When the temperature is low, the humidity is high or the day cloudy, opening is delayed. Bee activity begins on the flower shortly after it opens, reaches a peak at about 11:00 a.m. and ceases about 5:00 p.m. (McGregor & Todd 1952) Collection of pollen by bees usually ends before noon, but nectar collection continues into the late afternoon.
A high correlation exists between the number of seeds in a muskmelon and its size. The more seeds, the larger the fruit. Increased bee visitation is associated with a greater number of seeds.
Honey bees visit muskmelon flowers as soon as the flowers open. They collect both nectar and pollen, move freely from flower to flower and plant to plant, and continue visiting the flowers until late afternoon. McGregor et al (1 965) showed that a honey bee visit to each flower about every 15 minutes is desirable for maximum fruit set. Whitaker and Bohn (1 952) showed that variations in visits by honey bees occur between plants sometimes only a few feet apart if there is a variation in the microclimate around the plants. This means that many flowers must receive more visits than necessary if all are to receive the optimum number.
When there is heavy bee activity, a heavy crown set results. (Rosa 1924, Whitner 1960) Such fruits are sweeter (McGregor & Todd 1952) and usually more oval. Taylor (1955) studied 37 muskmelon fields in relation to proximity to honey bee colonies. In 20 fields with an average of 1/2 colony per acre within a mile, production was 1.06 melons per plant and 242 crates per acre. In 17 fields with no hives of bees in visible vicinity, production was only .67 melon per plant and 161 crates per acre.
Recommendations by (McGregor & Todd 1952) suggest 1 colony/acre. Sims (1960) suggested 1 good strong colony/acre, the colony filling 2 deep hive bodies. Most research has been done on cantaloupes, however pollination requirements are the same for all muskmelon cultivars.
Cucumbers – The need for insect pollination of cukes has been known for years. Before the turn of the century honey bees were used to pollinate cukes grown under glass. More recent tests have verified the need for bees. The best time of the day for effective cucumber pollination was from 10:00 a.m. to 3:00 p.m. (Con nor-Michigan 1 969). A cucumber flower should be visited 8 to 10 times for satisfactory fruit set. Viability in pollen grains decreases with increased bee travel distances.
Depending on if you have monecious or gyneocious hybrids, the pollination requirements vary from 1 colony per acre to 2 to 3 colonies per acre (Hughes 1971). If you walk into the cuke field on a clear day and cannot count 30 to 40 bees within a 30 ft. diameter or cannot hear a noticeable hum, you probably need to bring in more bees.
Apples – The apple flower produces both nectar and pollen and is important to the colonies’ spring buildup.
Usually the more seeds that develop in the apple, the larger the fruit (Schowenget 1 935). About 6 or 7 seeds are necessary for good fruit set (Hartman & Howlett 1954). The average blossoming period for apples is about 9 days. However, cool weather lengthens and warm or dry windy weather shortens this period (Morris 1 921).
The pollination recommendations are that honey bees be placed near or distributed within the orchard. Colony numbers are from 1 to 3 per acre, being fairly strong and not weak. Removal of all colonies is important at the conclusion of pollination to avoid spray damage.
|Prepared by:||Gordon Rudloff
Ohio Department of Agriculture