Varroa is sweeping south and it is "only a matter of time before you won't get any bees on your farm," AsureQuality's Tony Roper warned conference delegates.
Without bees, clover won't seed and will become sparse or absent from swards. While lowland farmers can renew pasture and or apply nitrogen fertiliser instead, albeit at a cost, for those with steeper, less accessible country, such options become prohibitively pricey.
"There is a third option," Roper's colleague, Marco Gonzalez says. "Encourage managed hives on your property, either seasonally or permanently. We believe that's the sensible solution for the high country."
Roper says in fertiliser value alone, the nitrogen clover fixes is worth nearly $2 billion nationwide, not to mention the nutritional quality it adds to pasture.
But beekeepers face increased costs of $30 to $40/hive due to varroa, with more frequent checks needed.
That makes more distant sites less economic for them, meaning remote farms are less likely to attract beekeepers.
That's particularly the case if the farm has little or no vegetation with good pollen and/or nectar for bees, says Roper.
To help the beekeeper, farmers should protect hives from stock, particularly cattle, and offer sunny hive sites with shelter and nearby clean water.
They should also avoid spraying crops where bees are working, or where they are likely to be working before the spray dries.
Even herbicides and fungicides can be lethal to bees because the surfactants in the mix effectively suffocate a foraging bee, explains Roper.
Longer-term, when planting for shelter, amenity, erosion control, timber or riparian protection, look to plant species which have high quality pollen or nectar for bees and flower at times of year when other food sources are scarce, typically early spring and late autumn, he advises.
Many trees do just that, such as the Sydney blue Gum (Eucalyptus saligna) which has 28% protein pollen. However, some other widely-used species, such as Radiata pine, are useless from the bee's perspective because the pollen has just 9% protein.
"Ideally we want over 25% protein but over 20% is good."
Ironically, gorse, which features on many regional plant pest strategies, is an excellent source of pollen for bees, particularly in winter and early spring. "So maybe there is a place for gorse within the farm system," suggests Gonzalez.
A MAF Sustainable Farming Fund project, Trees for Bees, joint funded by Feds and now in its third year, is building an extensive list of such multi-purpose species. Preliminary advice, region by region, is already available on www.treesforbeesnz.org