Productivity on avocado orchards has not lifted in the last 40 to 50 years while apple and kiwifruit industries have significantly increased crop yields, according to Plant & Food Research Ltd senior scientist Grant Thorp.

It's a real travesty for the avocado industry that yield hasn't risen –and if growers continue to do what they have always done they will get the same results, says Grant.

However, avocados are not alone in falling to increase yields. Macadamia and mango growers suffer the same problem and research from the mango industry may offer findings which could be applicable to avocados.
Grant says high crop loads on mango trees can regulate the metabolism of gibberellin (a natural plant growth regulator) and inhibit return bloom.
'In avocado, as in mango, we need to understand when this inhibition occurs so we can optimise the timing and intensity of flower and/or fruit thinning to ensure consistent yield.”
Preliminary trial work on avocados in New Zealand appears to show removing fruit from the trees in February may have a dramatic impact on flowering, Grant says.
'Two groups of trees were selected with moderate crop loads set from flowering in 2012 [all previous season's fruit had been harvested].
'All of the current season's fruit were removed from one group of trees in February 2013, and the remaining trees were left as controls.
'In spring 2013, the treatment trees [with fruit removed] have early and profuse flowering while the control trees with fruit retained, have delayed and sparse flowering.
Grant says repeating these treatments over time his fellow researchers will determine when fruit inhibit flower development, 'so we can use crop management techniques to achieve more consistent yields”.
'If we really want to start increasing bottom line tonnes per hectare for avocado we have got do something different. The new paradigm for avocado orchards is going from big trees to small trees.”
The apple industry took 50 years to go from a few big trees to a hectare to where it is now –and one of the factors has been the use of dwarfing root stocks. 'What we are trying to do is transfer the same principles to avocado trees. Progress has been made in New Zealand, California and Chile to develop small tree, high density orchards based on the slender pyramid training system.”
In Chile, production from orchards with 1111 trees per hectare was by year four 20.6 tonnes per hectare. 'In New Zealand, in years four and five, we are not getting there. The trees are great but we are not getting the flowers in young trees. This raises another question: How can we get more precocious flowering? We must be doing something wrong unless it is too marginal a growing environment to get consistent flowering.”
Dwarfing root stock and new cultivars may hold the answers; while other factors contributing to production levels include marginal growing conditions. 'You can't always have perfect growing conditions, and [you] need to know your regions and the impacts of climate and soil are crucial,” says Grant.