Queensland Country Life
WHEN MacKay Estates decided to move into papaya production in 2007, the company was starting with a clean slate in new fields previously producing sugarcane.
From the beginning, the business adopted the integrated crop management strategies they had in place in its banana business, developed over many years in conjunction with Total Grower Services.
This involves maximising soil health to use the natural nitrogen and phosphorus supply to the crop by using Petrik Soil Technology products within the production system, and the use of beneficial predatory insects wherever possible to replace chemical control.
The management team has become known for thinking long term, and consistently running trials for new approaches to maximise the productivity and quality of its production system – all while minimising its environmental footprint.
When Anita Davina of Total Grower Services suggested the plantation become involved in a trial for a recently developed egg parasitoid for fruit-spotting bug, the MacKay family was immediately on board.
Fruit-spotting bug (FSB) is the major insect pest of papaya and a number of other tropical and subtropical crops.
Control is generally reliant upon chemicals. In many cases, these control measures also impact on predators of mites, resulting in a spray cycle and increased miticide use.
Richard Llewellyn of BioResources began work on FSB in 2010, starting with a Horticulture Australia Limited (HAL) voluntary contributor project to look at the options for the biocontrol of FSB.
This work then merged with the HAL FSB Multi-Industry project. Anastatus wasp, an egg parasitoid, was selected as the best option.
In fact, much work had been done by Harry Faye at DPI Mareeba in the 1990s that showed the potential of the wasp, but at the time, mass rearing was deemed too difficult.
The game-changer was when Mr Llewellyn found that the Chinese had been rearing Anastatus using silkworm eggs for many decades.
Mr Llewellyn established links with the Chinese producers, and was subsequently able to import silkworm eggs and mass rear Anastatus in large numbers for release on farms.
Mr Llewellyn said the Anastatus was not a quick fix – something the experience of the Reblo papaya production team has found.
Anastatus have been released in the surrounding scrub around the blocks for the past 18 months where the majority of the FSB breed.
Initially there was no difference in FSB activity, but over time it has declined.
To this point in the 2014-15 season, at this time of year when FSB activity is at its peak, the Mackays have still not treated for the pest in the majority of blocks – the only exception being one spot spray required in a young block.
The parasitoid wasps are often seen in the fields along with other beneficials such as the assassin bug – another predator previously rarely seen in crop – as sprays to control FSB impact on this predator.
Total Grower Services director of agronomy Shane Fitzgerald said the improved control happened gradually.
“The fields are monitored for plant health, productivity, and insect, mite and predator numbers weekly,” he said.
“The Mackay family already embrace a number of significant environmental initiatives using a Petrik soil inoculant, which solubilises phosphorus and allows them to significantly reduce nitrogen rates.
“Plant health is also maximised by optimising the soil nutrition. The combination of these has ensured the plantation is relatively free from phytophera root and fruit rot, which is another major production limitation across the industry.”
Mite control is achieved using P Californicus, another beneficial insect sourced from Paul Jones at Bugs for Bugs.
“All these environmental initiatives are achieved with the strictest quality control on packed fruit, ensuring only blemish-free fruit is marketed as the Reblo brand,” Mr Fitzgerald said.