Pictured Above: When looking at pollination in orchards, the construction of the macadamia flower should not be ignored. Macadamia flower clusters are born on long narrow racemes. The raceme cluster comprises up to 500 small flowers.  Photo provided Magda du Toit

While the removal of eucalyptus trees makes environmental and water-saving sense, the alien forests provide food for bees on a scale that cannot be matched by the growing number of macadamia trees, resulting in farmers having to up their game on pollination methodologies.

Honeybees play a vital role in human lives and have been kept for thousands of years for the harvesting of honey and to assist with pollination of certain crops. Without honeybees, farmers would not realise the yields to which they have grown accustomed in many agricultural crops.

Without the pollination service provided by honeybees, some pollinator-dependent crops may even fail altogether and the agricultural industry will most likely struggle to exist.

On Springfield Farms in the Levubu area, about 100 recycled tyre hives hang in indigenous trees near the macadamia orchards. Photo provided Springfield Farms

In many areas eucalyptus trees are being removed and replaced with macadamia trees. Although this may be beneficial with a view to water-use and soil management, this practice may also contribute to the reduction in bee numbers. Eucalyptus trees bear strong, fragrant blossoms that attract bees and as these trees’ numbers decrease, so do the bee numbers.

With the dwindling honeybee numbers, farmers cannot rely only on nature for the pollination of crops, yet on the other hand, many are struggling to procure enough hives for pollination.

When looking at pollination in macadamia production in particular, the following aspects should be considered:

  • Macadamia flowers are born on long narrow racemes arising from the axils of leaves or from the scars of shed leaves. The flowers develop on the inside of the tree on mature wood.
  • Flower distribution follows the canopy outward. The raceme cluster comprises up to 500 small flowers spaced along an axis. Each little flower has its own pedicel. The proximal flowers bloom first. These flowers are approximately 1cm to 2cm long and although they are incomplete in the sense that they do not have real petals but four petaloid sepals, they do contain male and female parts.
  • Pollen is shed inside the flower one to two days before it opens and then again one to two hours before opening. When the flowers open, the sepals curl back, exposing the anthers closed over the tip of the style. When the anthers separate, the style breaks free and straightens. The stigma only becomes receptive some time later and because the pollen of a specific flower is generally removed by insects before the stigma is receptive, pollen must come from another flower. Individual flowers remain attractive to insects for about three days.
  • Macadamia flowers open over a six to 12-day period. When contracting bees, it is important to place hives in the orchards during this time. A bee visits each raceme approximately 50 times per day.

While the flowers can self-pollinate, pollinators are essential for good yields. According to literature, bees and leaf roller moths are the major pollinators in macadamias.

Apart from a good recycling exercise, the tyre hives cost very little to make and provide a home to many swarms of bees. Photo provided Springfield Farms

When planting macadamias, farmers should also plan for cross-pollination between cultivars. Insufficient cross-pollination may reduce potential yields by 10%. Only 0,0004% of the flowers eventually set fruit.

Good pollination improves nut yield, nut size, kernel recovery and quality. Trees that do not yield fruit grow vigorously and shade out flowers and light, resulting in a negative cycle.

Farmers have three pollination options:

  • The free option

Farmers can opt to rely on feral colonies or on beekeepers who do not charge for bringing their hives to the fields or orchards. This option, however, offers no guarantee that there will be enough bees and that the crop will be pollinated sufficiently.

  • The paid-for commercial beekeeper option

The contractor option might mean higher costs that will add to the input costs of the crop, but the chances of better pollination are much higher. Better pollination means that yields will be higher and in the end, more money in the pocket. Growers should only use bee farmers registered with the Department of Agriculture. Farmers can also contact The South African Bee Industry Organisation (SABIO) to confirm the registration of a beekeeper. It is also advisable to draw up a contract with a beekeeper to avoid any misunderstandings or conflict. It is also wise to book a contractor a year in advance to ensure availability.

  • The do-it-yourself option

Grower-owned beehives give you control. But farmers will incur high start-up costs and it will require learning or obtaining specialised skills and knowledge. Although this is not impossible and even though it should ensure availability, is not easy to achieve at the stocking levels required for optimal pollination.

Some of the hives on one of the Mahela farms. Bees play an important role in the pollination of much of the fruit produced by the Mahela Group. Photo provided Magda du Toit

When keeping their own bees, farmers have different goals from those of beekeepers. Bees are brought into the environment primarily for pollination, and not for extracting honey. Although honey can be a by-product and sold, for most farmers this is not the main purpose of having bees on the farm.

From the macadamia farmers’ view:

Agristar Holdings Group

The Agristar Holdings Groups’ macadamia nut farms in White River implemented their own bee management programme.

“Bees are important for the pollination of macadamia flowers and precisely for that reason, we have our own bee management programme and manufacture our own beehives,” said Adriaan Heydenrych, the entomologist employed by Agristar.

About 400 hives and 120 swarms have been installed on all Agristar farms. Heydenrych, added that well-managed pollination can increase macadamia yield. They use at least two bee colonies to pollinate one hectare. “This makes hive management in the orchard crucial. We therefore employed a dedicated beekeeper,” he added.

Honeybees forage on nectar (carbohydrates) and pollen (protein) of flowering plants, and they require a large diversity of pollen and nectar from different plant sources to be healthy. While some beekeepers may supplement a colony’s food with sugary water, this is not a long-term or healthy option, according to Heydenrych.

Bee health is especially important to them and to support the bees, they plant bee gardens containing a variety of plant species, including basil as well as indigenous plants and weeds, as a forage resource for their bees. In the orchards, they plant bee-friendly cover crops ensuring the bees have food all year round. When bees are pollinating they are not creating honey stores. They also make sure that there is enough water available nearby.

“Just before the macadamia flowering season starts, we cut the flowers and plants in the bee gardens and the bees move to the orchards to forage for food and in return also pollinate the macadamia flowers. Movement of the hives creates stress, so we move the hives as little as possible,” Heydenrych said.

Allesbeste Boerdery

According to Zander Ernst of Allesbeste Boerdery in Tzaneen, they work on the minimum of one hive per ha. “Although some farmers place at least five hives per hectare, we are happy with the pollination we receive,”  he said, adding that when hives are contracted in or moved, it is important to not only look at the number of hives but also the placement.

Allesbeste contracts about 240 hives during the macadamia pollination season, but also has its own. At present Allebeste has 40 swarms and is looking to increase these. “We need more