A severe frost back on October has seriously jeopardised the amount of fruit that will be available this season.

On the night of Thursday, October 7, 2022, Waikato orchards were subjected to a severe frost which caused extensive damage to orchard crops such as blueberries.

That night, Heli A1 team of David Mudford, Alex Mudford and Warrick Wright, were on standby as the first call for Monavale Blueberries (near Cambridge) to perform frost protection.

“They had been watching the weather constantly and we could also see it would be getting very cold heading into that weekend,” says Warrick.

“We were booked by the owners at the beginning of the week and the forecast was predicting a hard frost was likely around midnight. We moved two helicopters to Monavale and went home to relax until we were called out.”

The company had left their own weather station onsite and Warrick could see the temperatures were quite low by 8.30pm, so it wasn’t a surprise when Monavale called around 10.30pm.

“We took a 1600 litre fuel tanker to the site with us, fuelled the helicopters and were up in the air just after midnight.”

Frost protection involves using onboard thermometers to locate the inversion layer, where it is usually five or six degrees warmer than the zero or below ground temperatures.

This is often around 50 to 60 feet above the ground. The helicopters hover above the crop, moving at a speed of 10 to 15 knots pushing warm air towards the ground to keep it above zero degrees.

“Alex and I worked on half of the 110-acre orchard each and were up there for seven hours that night, adjusting height a few times to find warm air and refuelling two and a half times.”

The flying crew and those on the ground noticed a real plummet in temperature just before dawn and the pilots found it harder to locate warm air.

“We stayed up there until 7.30am, doing the best we could. Keeping the air moving is better than giving up.”

Despite all the monitoring and forward planning, and efforts in the air, daylight revealed that the frost damage was widespread.

Warrick explains how the conditions leading up to the night played a role in the severity of the weather event.

“Orchards mow their grass strips low in frost season so that sun during the day can warm the soils around the crops which gives off heat overnight, lessening the chances of a frost.

“That Thursday was a chilly, overcast, wet day, so as the skies cleared at night, the ground temperature dropped really fast, reaching as low of minus five on the orchard.”

Monavale Blueberries are truly devastated by the loss.

“This was the worst frost in the three-generation history of our orchard. Blueberries only flower and fruit once per year, so we won’t get another chance to produce a crop for another 12 months. Despite flying two helicopters as frost protection, the weather event was so severe that they couldn’t save the crop,” says Monavale Blueberries director Marije Banks.

“We estimate that we’ve had a 90 per cent loss - over 300 tonnes of blueberries. This loss could be greater if the plants are unable to bounce back and need replanting which is a huge investment as blueberry plants take five years to produce,” says Orchard manager Oliver de Groot.

Many orchards throughout the Waikato suffered losses that night and are concerned about the flow on effect it may have on their workers, suppliers, transporters, and customers.

Monavale usually export 90 per cent of their crop but now predict they will only supply locally this year.

​​​​​​​Source - https://www.sunlive.co.nz