Bumblebees can help in Kiwi pollination

When it comes to pollination and good fruit set, kiwi is a challenging crop. It is “dioecious”, a difficult word indicating that there are distinct male and female plants. Since fruits are harvested from female plants, growers tend to keep the proportion of male plants in the orchard as low as possible. Some even work without male plants and apply pollen spraying or dusting. When male plants are present, many growers rely on naturally occurring pollinators (e.g. solitary bees, syrphid flies) or honeybee hives to ensure pollination, even if nectar production and hence attractiveness to these pollinators of kiwi flowers is generally poor.

With a growing trend to produce kiwis under hail nets or plastic covers, pollination becomes even more challenging. In contrast to honeybees, bumblebees are happy to work in covered crops. The results of a 2016 trial in France clearly demonstrate that bumblebees do a great job. With sufficient males flowering synchronously (as was the case in a Biobest trial) excellent results were obtained with 12 hives per ha. Biobest’s most advanced pollination system, the Flying Doctors System, provided similar performance under these conditions, but is designed to deliver superior results in orchards with no or insufficient males or when males flower asynchronously. Whatever the growing conditions are, Biobest has a convenient bumblebee pollination solution for your kiwi crop.

Biobest and Zespri set up a trial together in May 2016 in the Adour region in Southwest France to demonstrate the pollination performance of bumblebees under hail nets. In this trial, a Gold3 orchard of 1ha was divided in 2 sections by means of a hail net. One section was pollinated by 2 Multi-Hives (= equivalent of 6 individual hives), another section by 6 Flying Doctors hives. Flying Doctors hives are equipped with a dispenser to be filled with pre-collected kiwi pollen. Upon leaving the hive, bumblebees get loaded with pollen and bring the pollen to the flowers.

In each section a certain number of flowers were bagged, which were carefully hand pollinated to serve as the “gold standard” for optimal pollination.

Biobest looked at two important yield and quality parameters, average fruit weight and number of seeds per plant. In terms of fruit weight, both the Multi-Hives and the Flying Doctors were a couple of percentage points better than the fruits obtained from hand pollination. The difference was not statistically significant.

When it comes to the number of seeds, an important quality parameter, again the Multi-Hives and the Flying Doctors exceeded the “gold standard” with respectively 5 and 4 %. This difference was statistically significant.

Number of seeds per fruit (indicative of the quality of the pollination) and individual fruit weight (indicative of fruit quality) per treatment. Different letters denote that the figures are statistically significant.

Conclusion for the kiwi grower: if you were to go out and carefully hand pollinate each flower, you could be almost but not quite as good as Biobest's bumblebees. It would bring you headaches and steep labor costs. Bumblebees will do an even better job at a very competitive cost. Use Multi-Hives if there are enough male plants flowering synchronously. If that’s not the case, make efficient use of pre-collected pollen in combination with Flying Doctors hives.

In both sections bumblebee pollination was compared to a manually pollinated treatment in the same compartments that is here provided as reference of optimal pollination.

For more information

Biobest Belgium NV

Ilse Velden 18

2260 Westerlo - Belgium

T +32 14 25 79 80

F +32 14 25 79 82