Borage and Bees for Strawberry Pollination - An Informal Experiment

Many decades ago, we students at the Australian Forestry School were advised that the greatest leaps forward in forest management, AND the greatest failures, were brought about by experienced foresters acting on incomplete scientific data plus logical reasoning and intuition. However, the greatest progress long-term was due to diligent researchers conducting well designed and controlled experiments, using statistical analyses to draw valid conclusions. I’m sure the same applies to apiculture. What follows is clearly in the part-scientific, intuitive category.

As a follow-up to my previous ideas on bee nutrition and pollination of crops, I attach some photos taken on 17 July 2014 of a bed of borage (Borago officinalis) on the western edge of the middle part of a large strawberry farm owned by Ray Daniels, trading as Sunray Strawberries. Ray and I were guided by incomplete scientific data plus intuition to do what we believe to be best for the bees and the strawberries they are pollinating.

Border of Borage planted alongside a commercial strawberry crop

Border of Borage planted alongside a commercial strawberry crop

According to DPI online pages, “bumbly fruit” (tucked-in end, distorted shape) is most commonly caused by poor pollination due to lack of bees, or wet weather, or both: and boron or calcium deficiencies, frost damage and Rutherglen bug may also cause the same symptoms. Given the slim financial margins, production of too many deformed or otherwise unmarketable fruit can turn profit into loss. Progressive strawberry farmers such as Ray recognise the importance of pollination and bee-friendly practices. They practise integrated pest management (IPM) to minimise the use of insecticides, which are applied at night and washed off by sprinklers before daylight. Nutrient deficiencies are avoided by pre-plant liming and fertilising and by dispensing soluble fertilisers through the irrigation system during the life of the crop. So the strawberries’ needs are catered for, but how about the bees’ needs?

The Borage planting, shown in this photo on the left, extends the whole length of the strawberry planting

The Borage planting, shown in this photo on the left, extends the whole length of the strawberry planting

Strawberries in my experience produce only small quantities of nectar, but good quantities of pollen of unknown quality. The pollen is reputed to have low crude protein levels, but I have not been able to find a reference to confirm or deny this. Nor are there any readily available data on the amino acids and fatty acids comprising the protein fraction of strawberry pollens, of which there are many cultivars.

My gut instinct was to provide a companion crop to supplement the bees’ diet. Borage plants contain all of the ten amino acids and two fatty acids essential to honeybee nutrition plus the two fatty acids important in combating brood diseases, but whether these fourteen compounds are present in the pollen collected by the bees has yet to be confirmed by chemical analysis. Nevertheless, there is strong anecdotal belief that Borage is good for bees.

In a rare example of a positive “precautionary approach”, where action is taken despite the lack of scientific certainty, Ray Daniels willingly sacrificed half a kilometre of irrigated strawberry beds for me to sow Borage in. We anticipated that the Borage would keep the bees in good condition through the cool months of this strawberry season, just as a smaller sowing did last year. The Borage beds received the same treatment as the strawberry beds, which were formed up and covered with a plastic-sheet mulch to conserve soil moisture and to suppress weed growth. Simultaneously with laying the plastic, a line of pelletised fertiliser was applied, the beds were fumigated for nematode control and tee tape was laid under the plastic sheet to allow irrigation and periodic application of soluble fertiliser. In late February, two lines of holes were punched through the plastic mulch at spacings suitable for strawberry plants, but as later became evident, really too close for Borage. One or two Borage seeds per hole were sown into dry soil ahead of sprinkler irrigation for strawberry planting in early March.

Close up view of the Borage shrubs, showing the prolific flowers utilised by the bees as a source of pollen

Close up view of the Borage shrubs, showing the prolific flowers utilised by the bees as a source of pollen

While the Borage was germinating and growing, a sporadic flowering of native and exotic vegetation kept the bees in good condition, with some surplus. On 29 April the tea tree (Melaleuca quinquinervia) began flowering, and from 1st to 8th May under cool conditions that indicated an early winter (which did not eventuate), the supers of all my hives in the area were robbed of all capped honey, and the brood boxes were snugged with a sheet of plastic over most of each queen excluder. On 7 June, after an unusually warm, late, Autumn, another round of robbing (harvesting), commenced. The 42 hives near the Borage were robbed on 16 June, and the last of the outlying hives on 23 June. With little blossom apart from Borage and strawberries, and all hives in similar condition with plenty of uncapped honey, this is the point after which comparisons can be made.

The unusually mild winter continued through July. By early August, in weather too bleak for brood inspections, some hives clearly needed space for more honey. Sufficiently capped boxes and individual frames were robbed and replaced with stickies. The hives nearest the Borage produced noticeably more honey than those on other sites, three of which are on strawberry farms with similar access to native riparian vegetation and farm ground cover.

Hives closest to the Borage produced a greater crop of honey/hive

Hives closest to the Borage produced a greater crop of honey/hive

On suitable days from 27 August to 16 September the brood boxes were “Spring Managed”, by way of 100 percent inspection for brood diseases, removal of all available frames of honey, removal of at least one frame of capped brood for queenless nucs or self-queening new hives, and replacement with irradiated white stickies or foundation. Again, the hives nearest the Borage yielded more honey per hive, except for five hives that had been left on a mango farm, where about a hundred trees had reacted to a false Spring and flowered early.

Some people believe that an area should be kept clear of all flowering plants except the target crop to be pollinated. My observations are that some crops, notably Macadamiaspp, are only attractive to bees at specific and limited times of the day, so it is in everyone’s interests to have alternative sources for the bees to operate. Borage and strawberries have so many flowers in all stages of development that whatever time of day I looked, bees were working both. On 16 September I quizzed Ray’s Field Supervisor, Robert Marshall, who spends every picking day from daylight to late afternoon organising up to 150 strawberry pickers and overseeing their sorting of fruit into trays for the packing shed, and discards. Robert sees every part of every strawberry block on the farm, and attends to the occasional bee sting and rare cases of allergic reaction.

No one is better placed to observe the bees at work and the condition of the strawberries. Robert does not believe the Borage restricts the pollination work of the bees. He sees plenty of bees at all times of the day in all parts of the farm. As for deformed fruit, the only block with a slight problem at the time was Festival variety, several hundred metres to the south-east of the bees and the Borage, but Robert believed the cause was more likely Rutherglen Bug for two reasons. There were plenty of bees working the block, and the deformed fruit all had the pointy end deformed, whereas insufficient pollination can affect any part of the fruit.

Although the bees are in the strawberry crop at the same time as the strawberry-picking farm workers, few of the farm workers receive bee stings

Although the bees are in the strawberry crop at the same time as the strawberry-picking farm workers, few of the farm workers receive bee stings

Strawberries, depending on variety or cultivar, are to some extent self-pollinating. The clincher for the value of complete pollination was as reported in my previous letter about putting a hive in Ray’s greenhouse. Various lines of research were being conducted using several varieties of strawberries grown hydroponically (and therefore without any mineral deficiency) in an insect-proof greenhouse. Before the bees were introduced, Rudi the researcher could not find a single strawberry that was not deformed. Not long after the hive was placed, he could not find a single deformed fruit among thousands.

We must assume that there is an unknown number of feral European bee hives in the remnant and regrowth forests near the strawberry farms, but I expect the number is small compared with the number of managed hives. Neither Ray nor I could put a figure on the contribution my hives make to the complete pollination of his strawberry flowers, but the completion of the pollination task is what matters. As I did not weigh the boxes and/or frames of honey from each hive before and after extraction, I cannot put a figure on the contribution the Borage made to winter honey production, and it would certainly be dwarfed by a good summer honey flow from the local native species, but it is of strategic importance in the flowering calendar. I am impressed by the contribution of an irrigated crop during the dry conditions we have experienced, when the native trees are holding onto their buds, so it was much appreciated.

The placement of the bee hives in relation to the strawberry crop, with the border of Borage alongside the closest edge of the crop

The placement of the bee hives in relation to the strawberry crop, with the border of Borage alongside the closest edge of the crop

The strawberry season in this part of the world is approaching its end for 2014, and the strawberries and Borage will be hoed in after the plastic mulch has been lifted and removed.

Where a crop of little nutritional value to bees is to be pollinated, it makes sense for the farmer to grow a suitable supplementary bee fodder, as the farmer is best equipped to prepare the site and to irrigate as required. With the threat of Varroa mite hanging over us, and a consequent shift from honey production to crop pollination, it would be in everyone’s best interests – beekeepers, farmers and consumers alike – to have the data available to allow suitable plant species to be chosen as supplementary or complementary sources of pollen and nectar. This is where solid scientific research is needed.

If anyone can point me to pollen analyses similar to the excellent work on Australian native species by Rob Manning, Doug Somerville and others, but on crop species that benefit from pollination by bees, and plants (native and exotic) that are reputed to have all of the amino acids and fatty acids beneficial to bees, I would be most grateful.

Author: John Tadman