Precision pollination in kiwi with the Flying Doctors®

When it comes to achieving optimal pollination and fruitset, a kiwi plant is a “strange animal”. Biobest’s Flying Doctors® bumblebees will leave the hive loaded with pollen and get the job done.

There’s something special about kiwi. It’s “dioecious”, a difficult word indicating that plants are either male or female and hence can’t self-pollinate. Cross-pollination is absolutely required, which implies transfer of pollen from male to female plants. There’s something special about kiwi flowers too. A female flower contains more than 40 stigma’s and 1.500 ovules. Good fruit quality requires transfer of a large number of pollen grains (generally more than 3.000 grains per flower). And it doesn’t stop there. Kiwi flowers produce only small amounts of nectar, so honeybees will rather visit other flowers in the surroundings than kiwi flowers.

Think further about “dioecious” for a second. Only female plants produce fruits, males won’t. So even if the grower needs the males badly as a pollen source, he’ll tend to limit the proportion of these “unproductive” plants. A typical ratio in the orchard is one male for five to eight females, with limited pollen availability as a result. All this explains why “artificial” pollination with pre-collected pollen is used by a number of growers. One technique consists in blowing approximately 1 kg of pollen per ha. Growers may collect pollen from male plants in their orchard or will sometimes purchase it. Pollen does not come cheap though (e.g. 2.000 €/kg or more).

What is the interest of bumblebees in all this? They don’t mind the relative absence of nectar and will happily visit kiwi flowers for pollen. Even the female flowers produce “dysfunctional” pollen that is still of interest to bumblebees. So, deploying bumblebees in a kiwi orchard is a big step forward.

Biobest’s latest technology, the Flying Doctors® (FD), is even more powerful. It enables targeted dissemination of pre-collected pollen in the crop. Every FD hive has a dispenser that can be filled with pre-collected or purchased kiwi pollen. Upon leaving the hive, bumblebees get loaded with pollen. The result: optimal pollination throughout the orchard.

Julien Mourrut-Salesse, Manager of the Sustainable Crop Management Specialists at Biobest: “I recommend nine Flying Doctors® hives for every hectare of kiwi orchard. The dispenser should be filled with 6 grams of pollen every 3 days. This technique allows a big saving of labour and an optimal result using less of the precious kiwi pollen.”
Julien mentions that some growers like to start by combining artificial pollination with the FD system. But he is confident that they will soon realize that FD in itself is sufficient. He also points out that he expects to see a further gradual reduction in the number of males/ha as growers build experience with the technology.

“The blooming seasons differs a little bit between the green and golden kiwi varieties,” says Julien. ”This allows us to move the FD hives around between varieties. Just consider that the hive should be kept closed for two days after moving.”

Julien concludes: “Kiwi growers in Italy and France are already most familiar with our bumblebees today. But we are now working actively in several other kiwi producing countries, like Greece, Korea, China and Chile.”

For more information, please contact Julien Mourrut (julien.mourrut@biobest.be).

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