Timing the key when hedging macadamias

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Late November to early December is emerging as the ideal time to hedge macadamia trees, according to new research from Industry & Investment NSW.

"Timing is very important when hedging macadamias," said I&I NSW research horticulturist Lisa McFadyen.

"Most macadamia growers hedge their mature trees to keep the orchard manageable. But hedging can reduce yield in mature trees by 10 to 20 per cent."

New research by I&I NSW is showing that the time of year when the hedging takes place can have a major impact on the level of crop loss in the $80 million industry.

"The aim of our current project is to develop strategies to keep trees small and productive," Ms McFadyen said.

"We are investigating the macadamia trees physiological response to pruning and how it can be manipulated through timing to reduce the negative impact on yield."

Ms McFadyen said most growers hedge as soon as the harvest is finished and in most seasons this coincides with flowering and early nut development for the next seasons crop.

"We have found that trees pruned at this time develop regrowth that competes with developing nuts- and they suffer much greater nut drop and reduced final nut set.

Ms McFadyen said trials had focussed around two hedging times selected to avoid regrowth during the critical early nut drop period:

June - before flowering
November/December - at least 10 weeks after flowering and at the end of the premature nut drop period

"The trials confirm the concept that yield is most affected when regrowth competes with early nut growth," she said.

"Both hedging times resulted in greater yield than hedging at flowering."

Ms McFadyen pointed out that the later hedging time would be suitable under a regular light hedging regime. Severe hedging at the later time may remove too much crop.

Ms McFadyen said there is an advantage of the later hedging for subsequent seasons.

"The regrowth on trees pruned in the warmer months produces many short stems - as against few long stems from a cooler earlier pruning.

"More, shorter stems means more flowers in subsequent seasons, and potentially more nuts.

"Our results so far predict a greater yield by hedging lightly later in the year, around late November to early December."

Timing the key when hedging macadamias

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