Tips for Northland avocado growers

Northland avocado growers could benefit from the pruning, irrigation, and phytophthora management strategies employed by growers in countries such as Australia, Chile and Mexico, according to a local horticultural advisor just returned from a World Avocado Congress.

Sarah Williamson, a technical advisor with Skeltons, the specialist horticulture crop protection arm of Farmlands, attended the Congress held in Cairns, Australia earlier this month, along with over 800 delegates from 24 countries.

The five-day conference was organised with speakers in four concurrent sessions on pests and diseases, cultural management, postharvest / processing, and marketing and supply chain. Speakers ranged from orchard managers talking about pruning practices on their orchards to molecular biologists talking about DNA manipulation in breeding programmes.

Mrs Williamson says one of the key points of benefit to local growers was the good results in trials being held in Chile applying a growth regulator foliar spray through irrigations lines rather than, as was the case locally, of being sprayed at flowering when shoot growth was just emerging.

"Applying through the irrigation is a lot simpler for the grower and residues on fruit are potentially minimised, so it could be something we should explore over here," she says.

A field trip was part of the conference and Mrs Williamson visited two avocado properties growing Hass and Shepard, on the Atherton tablelands near Mareeba.

"It gave us a chance to see the pruning systems the Australians are adopting on their orchards with the same aim to what we are trying to achieve, keeping tree height down and the canopy reasonably open.

"Both were using a monitoring system for managing their irrigation inputs that I hadn't seen before. It involves having a large probe, over a metre long, permanently installed under the trees with sensors along the length that record information such as soil moisture, pH and electrical conductivity.

"This information is relayed back to the grower's computer so they can make informed decisions on irrigation scheduling and fertiliser management."

Talking to these growers about phytophthora management was also interesting for Mrs Williamson.

"Even though they use the same products as us, they apply all of their treatments as foliar sprays rather than injecting trees as we do, and are achieving good control using this method."

The field trip also provided a more informal environment to talk to other delegates, including growers from Chile and Mexico where the scale of growing is so much bigger than in New Zealand.

"Some properties are up to 2000ha in size, which is nearly half of the whole avocado industry in New Zealand. They were very forthcoming with information and how they were fine tuning their systems."

The World Avocado Congress is held every four years and hosted by an avocado growing nation. Previous hosts include South Africa, California, Israel, Mexico, Spain and Chile.

Delegates included growers, exporters, suppliers, scientists, retailers and marketers. There was also trade displays from 33 companies that included agrichemical companies, nurseries, packaging suppliers, and various harvesting and packing equipment.

For more information contact:

Sarah Williamson, Skeltons Technical Advisor, 027 550 7016

www.skeltons.co.nz