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.
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.
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.
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.
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 experience in managing our own hives, but it is something we are looking to expand in future as we also rely on bees to pollinate our avocado crop.
“We have permanent steel stands for the hives. Initially the stand were made for five hives, but we reduced the hives to three and found that the bees are now less aggressive.”
According to Francois Vorster, Director Sub-Tropical Fruit and Wildlife at the Mahela Group, their philosophy is to farm with nature. When negotiating with beekeepers they follow an approach of mutual cooperation rather than a business transaction.
“We try to use beekeepers who are willing to place and leave their hives on the farm for longer periods, even an entire year if possible.”
Mahela also keeps a couple of hives on one of the farms that is serviced by a professional beekeeper and they share the honey on a 50/50 basis. “This is something that I would like to expand as most of our crops need bees for pollination,” Vorster said.
They follow a couple of basic rules. Beehives are placed where they receive early morning sun so that the bees are active in the morning. The hives are placed on stands near water and some can also be locked to protect the bees and their hives.
Vorster says they do not trim weeds in the orchards just before macadamia and avocado flowering time. “We leave the weeds to make sure the bees have enough plants for foraging and an additional food source. After crop flowering, the indigenous bush as well as eucalyptus trees nearby also provide food for the bees.”
They use bee-friendly crop protection productions and if they have to spray, they preferred doing so at night or very early in the morning when bees were not foraging, he added.
The Whyte family’s Springfield Farm in the Levubu valley of Limpopo was one of the first in the area to plant macadamia nuts to their orchards. With years of experience in producing macadamia nuts and avocado, they appreciate the significant role bees play in their farming operation.
The Whyte family also owns Green Farms Nut Company, specialising in processing and marketing.
According to Graeme Whyte, they’ve made more than 100 of their own hives using old tyres. Apart from a good recycling exercise these tyre hives also provide a home to many swarms of bees. “The tyres have all filled with bees. We hang them in the surrounding indigenous bush along our macadamia orchards. I think they work quite well and cost very little to make. I have 100 hives at present and plan to expand.
“Recycling these old tyres, which would have been dumped or burned, has provided living spaces for hundreds of swarms which will multiply and create more swarms. I guess the long-term sustainability of the tyre hive must be determined, but at this stage it is ‘so far so good’ and I feel as if I am doing the bees a favour for a change.,” he said.
Whyte said he also collaborates with beekeepers. “A balance between own hives and the services of beekeepers is beneficial and adds to sustainable bee management in the long run. Beekeepers play a key role in looking after bees and providing a service to farmers, and should be supported for the sustainability of our industry,” he added.
There is more to pollinating macadamias than simply placing a few beehives near the orchards. Placement of the hives should be planned carefully.
When moving hives into an orchard, they should be placed in various locations. Research has shown that the trees closest to the hives will have better nut set, therefore hives should not be placed in one location or in a row.
Beehives should also not be placed or permanently established directly beneath trees. Too much shade will cause the temperature to fall, and bees will become inactive. Bee activity is limited below 13°C so consider placement in areas where the hives will receive early morning and late afternoon sun.
Hives should be placed within proximity of a water source, but not too close to irrigation systems, where the hives can get wet. Low-lying, damp and windy areas should also be avoided. Hives should also be placed on stilts away from ground-predators.
In agriculture, crop yields are threatened by weeds, insect pests and disease. Pesticides are one of the tools farmers use to protect their crops. The success of many crops also depends on sufficient pollination from insects like bees. Protecting crops and ensuring bee safety need to go hand in hand.
According to Barry Christie, the group agricultural technical manager at Green Farms Nut Company, there are a couple of principal factors farmers should consider when protecting their crops. “An integrated pest management strategy focusing on long-term prevention of pests and their damage through a combination of techniques such as chemical, cultural and biological control as well as targeted habitat management like increased plant diversity, should be implemented.”
Farmers can support bee and pollinator health with sustainable, pollinator-friendly farming practices, by planting wildflower strips on the farm, and providing nesting sites or hives for bees.
The following guidelines should be followed:
- Scout to determine the economical threshold of the insect damage before spraying.
- Implement biological control methods as part of an integrated pest management system.
- Before making an application, be aware of any honeybees and hives nearby.
- Communicate with neighbouring farmers and beekeepers. Many problems can be prevented with better communication and cooperation among growers, pesticide applicators and beekeepers.
- To reduce bee losses, farmers must adhere to the recommendations on the crop protection product labels. According to Dirk Uys, responsible for horticulture in Africa at Bayer, most problems occur when people apply products outside the registration recommendations. He also said that many of the new products on the market especially focus on the safety of bees.
- During the flowering phase of the macadamia trees, use products that are bee-safe. Select the least harmful insecticide for bees and spray in the late afternoon or at night.
- Do not spray in windy conditions when the spray may drift on to adjacent lands supporting foraging bees. Uys warns that the conditions for application must be right. “Once again this comes back to following the label instructions. In most cases when bees are killed by pesticides it is because the product was applied at the wrong time and drifted directly on to the bees or on to flowers on which the bees were feeding.”
- Avoid using dust products.
- Do not use herbicides on flowering weeds near the orchards. Weeds should be controlled before flowering or by mechanical methods such as slashing.
- Pesticide use should be kept to a minimum while there are hives on a property or when hive are installed permanently. Avoid using pesticides near the hives altogether. Most poisoning occurs when pesticides are applied to flowering crops, pastures and weeds. One of the greatest drawbacks to placing bees near agricultural crops is that they may be affected by pesticides.
- Educate field workers or applicators to ensure they make informed decisions regarding pesticide applications and that they follow the product labels.
Finding dead honeybees is not necessarily an indicator that they were killed by pesticides. It is important to monitor the symptoms of dying bees closely to narrow down the cause.
CroplifeSA compiled a guideline document, which can be of great value to all roleplayers in the industry and can be found at: https://croplife.co.za/wp-content/uploads/2020/11/Pollinator-Charter-Final.pdf
There is no singular approach to crop protection. Farmers are in a good position when they have a diverse toolbox at their disposal to safely control or manage pests and diseases. They can minimise damage from pests by using state-of-the-art chemical and biological products, advanced data analytics, and precision technologies.