Bee health crucial to pollination

Bee health imperative for crop success

Smart Farmer How To
LOADED UP: A honey bee pollen forager on almond blossoms with the golden almond pollen in baskets on her back legs.

LOADED UP: A honey bee pollen forager on almond blossoms with the golden almond pollen in baskets on her back legs.

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The largest migration of livestock in Australia is upon us as almond bloom finishes and over 220000 bee hives, some six trillion bees give or take a few billion, are transported to 'greener pastures'.

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The largest migration of livestock in Australia is upon us as almond bloom finishes and over 220000 bee hives, some six trillion bees give or take a few billion, are transported to 'greener pastures'.

In the case of the honey bee, however, greener pastures equates to the next mass flowering event of a crop like avocado, canola, citrus, lucerne, or native, nectar-producing trees like river red gum (Eucalyptus camaldulensis), yellow box (Eucalyptus melliodora) or another gum tree not burnt in the 2019-20 bushfires.

Australia's smallest livestock need us to communicate for their benefit on pest control activities given they fly to flowers upwards of two kilometres from their hive.

Even pest control agents such as fungicide which are generally not toxic to adult bees, may have potential harmful effects when brought back to the hive on pollen or nectar and fed to juvenile bees.

AgriFutures has published new factsheets on fungicides and bees in almonds, apple, canola and pear.

All factsheets can be accessed at www.agrifutures.com.au

While fungicides can play a vital role in protecting plants against diseases, they should only be used when necessary to prevent disease resistance to fungicides, and to lessen their impacts on environment, human and pollinator health, also lessening farmer cost when fungicides are unnecessary.

Ideally, when honey bees are contracted into pollination the grower will not spray any pesticide on the crop, especially not insecticides as bees are insects.

SPRAY WISELY: Honey bees and other insects pollinate two-thirds of the food Australians eat. They do this best in environments free of pest control activities during pollination contract.

SPRAY WISELY: Honey bees and other insects pollinate two-thirds of the food Australians eat. They do this best in environments free of pest control activities during pollination contract.

If a pesticide such as a fungicide must be sprayed, there are best practices to follow to minimise harm to honey bees.

AgriFutures' authors Drs Katja Hogendoorn and Jay Iwasaki from the University of Adelaide reviewed all the peer-reviewed research available on fungicide impacts on honey bees.

They recommend growers and spray applicators:

  • Discuss the pesticide program with your beekeeper and agronomist before the start of the season to select chemicals that are friendly to bees while still achieving effective results;
  • Always read the pesticide label and follow directions for use;
  • Avoid applying insecticides with extended residual toxicity or systemic insecticides (such as neonicotinoids) which may be expressed in pollen and nectar that may affect the brood if taken back to hives;
  • Avoid all insecticide use during flowering;
  • Only spray fungicides if essential and only at night, when the bees aren't active allowing time for the chemical application to dry;
  • Thoroughly clean spray tanks to avoid remnant insecticide contaminating subsequent fungicide sprays;
  • Ensure bees have access to clean water; and cover or remove water sources before spraying;
  • Do not spray hives directly with any pesticide;
  • Ensure that the spray-rig driver turns off nozzles when near hives;
  • Ensure bees are not foraging in the area to be sprayed and do not hit flying bees with spray applications as the weight of spray droplets on their wings will mean they can't fly;
  • Notify neighbours when bees will be in the orchard and provide your contact details so they can provide notice before intended sprays; and
  • During the year, notify beekeepers with hives on nearby properties before applying pesticides to the orchard using appropriate communication method such as beekeeper contact details on the hive, BeeConnected app (www.croplife.org.au)or via state government bee biosecurity officers.

Importantly, even if the pesticide label reads 'not toxic to bees', any spray application which hits a flying bee prevents the bee from flying because of the weight of spray droplets on their wings.

This is incredibly important in winter flowering crops such as almonds where temperatures are quite cold through the day and every low wind, high temperature day counts to ensure successful pollination.

If fungicides must be applied during bloom, the grower or spray applicator should wait until no bees are flying in the late afternoon as temperatures drop and bees have returned to their hives for the day.

This minimises fungicide spray onto bees actively flying, foraging on flowers and doing their job of pollination to ensure the grower has a viable harvest.

When fungicides on one crop mix with insecticides from another nearby crop and are combined inside a honey bee hive, the chemical combination increases the negative impact insecticides have on honey bees, known as a synergistic effect.

Ideally, no spray should be applied when bees are actively foraging on a flowering crop to ensure hives are healthy and productive for the next pollination or honey production event.

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