POLLINATION PROBLEMS IN FIELD CUCUMBER PRODUCTION: Summary Suggestions from Field Season 2000

by

Peter G. Kevan

Professor

Environmental Biology, University of Guelph

Guelph, Ontario N1G 2W1

The important findings in pollinator deployment are as follows:

1. There are not sufficient native or feral pollinators for field cucumber pollination.

2. The supply of honeybees for field cucumber pollination will be sufficient to meet growers' needs for the growing season 2001, but prices are likely to rise for various reasons.

3. The present application rate of about 1 hive per acre is sufficient for full pollination on both hand-picked and machine harvested fields.

4. Honeybee activity declines with distance from the hives over a range of about 300 to 400 m.

Over that distance, activity declines by about one third to one half. This represents about 0.05 to 0.02 honeybees per flower at any given instant during good pollination conditions.

5. All female flowers over that range appear to become fully pollinated.

6. Honeybee hives can be deployed in groups on production fields, provided the distance from the hives to the far distant areas of the fields are not more than about 300 m. Our studies do not allow conclusions about pollination over greater distances.

7. We suggest that groups of honeybee hives brought into large fields of cucumber for pollination be deployed so that the groups are not separated by more than about 500 m and that it is not more than 250 m from the hives to the field edges.

8. For hand-picked cucumbers, honeybee hives should be left on the fields for as long as is required.

9. For machine harvested cucumbers, the deployment of the hives depends on the field arrangements and planting sequences on adjacent fields or adjacent parts of the same large fields. Deployment will be dictated by the need for pollinators on fields, or parts of fields, within 250 m of the hives placed for pollination. Movement of hives between fields will be dictated by planting sequences (the growers' scheme) and the need for bees, when moved, to be moved more than 8 to 10 km (the beekeepers' management based on the fact that moving bees only short distances results in bees' becoming confused, attempting to return to their prior location and becoming lost).

10. Beekeepers are concerned that the management and moving of their colonies be the responsibility of the beekeepers, unless special arrangements with the growers are made.

Findings on the importance of pollinizer vines in field cucumber production need more consideration and the issue need further study to determine in pollinizers are truly needed, and if so, in what proportions.