Teaching avocado trees how to grow
Tauranga, 2 September 2013:
Scientists and avocado growers are learning to teach avocado trees to grow in a more productive manner in a bid to
improve the yield and regularity of harvests, says Jerome Hardy, Technical Manager at the biggest avocado grower group,
AVOCO.
“Research to be presented at the Australia-New Zealand avocado conference in Tauranga 9-12 September will update
delegates on the latest thinking in a branch of science known as tree architecture, and most growers I know will be
closely following any new research related to tree pruning,” says Jerome.
“Historically, as an industry we have not been confident about pruning – the first obstacle is that fruit is lost in the
process and I have seen the enthusiasm of even the most resolute chainsaw-wielding characters fade quickly when fruit
starts to tumble.
“However, thanks to some determined growers and researchers, the idea that a programme of annual pruning has the
potential to improve productivity and efficiency is finally taking hold.
“The potential benefits are many. If we get this right we can simultaneously control tree height, improve access, lift
tree health and fruit quality and, most importantly, reduce the impact of alternate bearing.”
Dr Grant Thorp, a Senior Scientist with Plant & Food Research who is speaking at the conference, of which AVOCO is principal sponsor, says the research seeks to
understand the natural growth habits of the avocado tree in order to develop training and pruning systems.
He says the research has looked to the apple industry and its work on tree architecture, which typically involves
single-leader trees growing on dwarfing root stocks.
“We don’t have dwarfing root stock available in the avocado industry,” says Dr Thorp, “so we are looking at tree
training and pruning to develop a single-leader tree. Avocado tend to be big trees, with several large trunks, whereas
we are after a slender, pyramid growth habit – narrow trees, slightly wider at the base than at the top, with not too
much shading on the inside of the tree.”
He says there is also interest in developing these growing systems to create avocado trees that are suitable for
planting in higher density on hillsides. This would open up cheaper land options for orchardists, and possibly alleviate
some of the issues with frost protection.
Dr Thorp will also discuss irregular bearing, the tendency for avocado trees to produce a heavy crop in one season, and
be almost barren the next. “It’s a worldwide problem – in some years growers might get no crop at all.”
A research programme has been underway in New Zealand for several years studying the situation where avocado trees can
have flowers yet go on to produce no fruit. “We are considering the role of nutrition and pollination in this regard,
and Dr Peter Minchin will be presenting the results of this work at the conference,” says Dr Thorp.
“In new work to be discussed at the conference, we are investigating the scenario where we have fruit in one year but no
flowers in the next – we need to manage that effect so growers can achieve consistent cropping every year.”
Again with an eye on the apple industry, Dr Thorp says the research will include thinning out some of the flowers and
some of the maturing fruit to see if protocols can be developed to ensure regular cropping.
Dr Thorp is one of the guest speakers at the three-day conference, which starts 9 September. Further details about the
conference are available at www.avocadoconference.co.nz
ENDS