Funded by Hort Innovation with grower R&D levies and Commonwealth investment, the Macadamia IPM project (NSW DPI component (MC16004)) is supporting growers in reducing these crop losses by investigating options for macadamia seed weevil (MSW) control.

Integrated pest management (IPM) is about controlling pests to an acceptable economic level using cultural and biological practices as well as chemical control. Cultural practices are central to controlling MSW numbers to levels at which growers can still achieve a profitable income, however good orchard hygiene practices are essential.

Infested nuts where weevils have dropped to the ground must be mulched and destroyed to reduce the next weevil generation. Additionally, all canopies should be structured to allow maximum spray penetration. Mulching the fallen infested nuts should occur a few weeks after every weevil spray.

For growers, this is a time consuming and expensive process, however it is essential, following NSW DPI research showing that spraying without mulching is just as ineffective as mulching on its own. This highlights the importance of an integrated pest management system; rather than relying on only one approach to controlling MSW.

In November 2018 the APVMA issued a minor use permit for indoxacarb. In the 2018–19 season, most growers using indoxacarb under this minor use permit have seen a significant decrease in MSW egg laying. This has resulted in less nut drop from egg laying. 

Ideally indoxacarb should be applied at match head stage, in combination with a husk spot (Psuedocercospora) spray. To date, the product has remained effective for around 16 weeks following application. By including indoxacarb in their IPM program, growers can now spread their efforts on managing  fruit spotting bug and lace bug.

Having saved at least three rounds of mulching and possibly three extra sprays within the season, growers have also applied a different mode of action pesticide which results in a better resistance strategy.