Rejuvenating an orchard
A radical pruning approach is working.
The best fertiliser for your orchard is your footprints, is a saying Omokoroa-based avocado growers, Maria and Andrew Watchorn live by.
Their newest orchard on Walker Road East, Katikati was bought three years ago when it was the worse for wear and needed extensive input from them, physically and mentally. Maria told visiting New Zealand Avocado International Industry Conference delegates of walking through the trees with consultant, Colin Partridge, and asking if there was any hope.
“As an insurance policy we ordered a few hundred trees, knowing there was a two-year wait, so that gave us time to see how things went.”
Rejuvenating the orchard didn’t focus solely on canopy management. The whole orchard was injected under a fertilisation programme and full frost protection was put in place. Temperatures were monitored, and in certain areas where they found readings of 1 – 2 degrees C and lower, overhead sprinklers were installed.
The entire irrigation system was overhauled, with the introduction of 400 metres of three-phase power to run an updated high-tech frost protection and water system.
Self-confessed fusspot, Maria, pointed out the different coloured ribbons tied to various trees. Green ribbons denote the sickest specimens, deliberately held back from fruiting to ensure they recover to good condition before they face the extra pressure of producing fruit. Last year, some of these trees had replacements planted nearby but now they’re showing good signs of getting healthier.
Maria said close working relationships are one of the pillars of their success. Colin has been with them for over 10 years and is invaluable.
“We discuss most things and debate the odd thing,” she said.
“Colin has guided us throughout this whole pruning journey.”
The Watchorns were some of the first growers to make big cuts and many saw this as radical, however, they stuck to their guns and continued to believe that sunlight for generating growth and encouraging new budwood is vital to keep consistent crops and achieve yields every year. Their orchards have a variety of spacings with some 7metres x 7m, while others are 9m x 9m plantings. She encourages other orchardists to spend time with their pruners to make sure they understand what’s being aimed for.
“Our pruning philosophies have never really changed but we love learning new techniques,” she said.
“I enjoy attending pruning talks and know others have smart strategies. We’re not perfect but what we do has worked for us. It’s rare for us not to get fruit around whole of the cylinder because sunlight hits the trees everywhere.”
They prune to balance, making sure the trees stay healthy and highly productive as a balance of vegetative and flowering growth saves them from over-fruiting. “We’re not scared of flower pruning,” she said.
This will happen after or during the main spring prune, but a fruit prune will follow if required, especially if there are any worries about tree health or fruit volumes of individual trees.
“We used to prune once in the spring, but now we prune twice a year, both in spring and autumn,” she said.
“We need to meet export market requirements to get the best returns we can, so now we pick over a period of time, and this limits the pruning we can do as fruit is still hanging.
“In autumn, our decisions are based on assessing the trees and marking what needs to be reduced either in width or height as well as any limbs with dead wood.”
After trying many methods, they stick to the formula of any vertical growth being cut out, anything horizontal being thinned and only the healthiest most promising-looking spring growth being kept.
Maria said it’s almost like pruning grapes. The autumn prune removes much of the spring growth which ensures sunlight penetrates through the trees during winter, and generates
new budwood for the following spring. The latent buds start to push through in late September, and she said it’s rare not to have fruit form on those buds in the following season.
Creating windows or layers within the canopy utilises the inside space and achieves beautiful floral growth. The aim is to get sunlight penetrating, not just over the top but also streaming in through the sides. This helps light all angles of the tree, particularly in close plantings, as well as neighbouring trees.
“We don’t prune trees,” Maria said.
“We prune the canopy within our tree rows.”
Pruning to improve cost efficiencies is another important philosophy. Because picking is the orchards’ largest cost, pickers need quick and safe access so better visibility helps them see fruit more easily.
Spray penetration is also improved with the right pruning, Maria said.
“It’s not only beneficial that we’re hitting the surfaces where needed but it takes less time.”
Canopies are opened up to avoid a cylinder-shaped tree as maximising that canopy surface helps to produce fruit.
“If you can get that surface area rolling through the canopy, there’s so much more potential for fruit and your trees will be better balanced,” she said.
Opening up the canopy allows vegetative growth to reach down the limbs, which provides the option to cut the width or height of a limb back and not lose too much production.
“We prune to harvest as much sunlight as possible and always look to achieve dappled light throughout the canopy,” she said.
“No matter where we walk in the orchard, we want it to be warm. Spots of sunlight should move right across the ground, around and under your trees.Then you’re getting sunlight into the canopy and that will produce new growth.”