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Varroa mite and adverse weather during bloom heighten Australian crop yield concerns

September 7, 2022

Restrictions on beehive movement due to varroa mite combined with cold, wet weather during Australia’s bloom period in August are leading to crop yield concerns heading into the country’s almond growing season. 

The Australian government has taken aggressive action to limit varroa mite’s spread since beekeepers in New South Wales detected the pest in their hives in June. It’s the parasite’s first known incursion into Australia.

Adverse weather has added additional concerns for Australia’s almond industry. A cold front swept through Victoria the week of August 21 bringing heavy rain, winds, and hail. Some areas in Victoria, a key growing state, dropped close to freezing.

While the impact on Australia’s bud set won’t be known until late September or October, industry experts said production could be affected.

“We’ve pretty much cancelled any optimism around an increased yield this year,” said Tim Jackson, CEO of the Almond Board of Australia. “At best we will come out with a crop size same as last year or potentially a little bit down.”

Based on hive stocking rates there is an expectation that production could be 20-30% off but growers don’t know how the trees will respond, he added.

“It has been one of the most challenging pollination seasons for all regions,” Jackson said. 

The impact might not be evenly distributed among  Australia’s growers.

“On my farms, my managers are saying we’re good, but I’ve heard from other people that it’s very bad,” said one grower in the country.

Although the center of the outbreak is nearly 600 km away from Australia’s core almond production region, the mite’s presence has prompted Australian officials to severely reduce the mobility of hives.

This has left some growers in Victoria with less than half the number of hives they would have in a normal year. One silver lining for growers is that the problem may give them a better idea of exactly how many hives are necessary to pollinate the crop.

“There’s always been this underlying suspicion that perhaps we’re overstocking,” Jackson said.

According to Australia’s National Biosecurity Communication and Engagement Network (NBCEN), the mite poses an existential threat to the country’s agricultural industry.

If varroa mite were to establish in Australia, European honey bees and the pollination services they provide could be reduced by 90-100%, according to information on the NBCEN website.

Australia exported about 209 million lbs during its last crop year, roughly 7% of global almond supply.