Macadamia plant protection guide
Summary
This 12th edition of the NSW Macadamia plant protection guide aims to provide commercial macadamia growers with up-to-date information on all aspects of protecting their orchard from pests and diseases.
Feature article
This year’s feature article (page 9) is on effective weed management in macadamia orchards. The focus is on using integrated, early-season strategies to maintain a clean harvest surface while reducing herbicide residue risk. It explains that non-chemical options such as double-ground mulch, mowing, living ground cover and targeted mechanical or organic tools should be prioritised, especially as harvest approaches, while herbicides remain useful when selected and applied correctly. The article outlines the roles of contact, systemic, pre-emergent, selective and non-selective herbicides, and emphasises the importance of accurately identifying weeds, correctly calculating rates based on treated area, appropriate droplet size, good coverage, preventing drift and strictly adhering to label, permit and record-keeping requirements.
As macadamia nuts are harvested from the orchard floor, herbicides should not be applied when nuts (nut in shell, nut in husk) are on the orchard floor, regardless of withholding period. Any spray contact with nuts can create residue, compliance and market access risks.
Most herbicide problems are avoidable because they result from poor timing, spraying too close to nut drop, using incorrect rates, spraying in unsuitable weather, spray drift, incomplete records or operator fatigue. Therefore, the safest approach is to plan weed control outside of the harvest period and minimise late-season herbicide use.
Diseases in nursery scion
Dr Femi Akinsanmi describes the main nursery diseases in macadamia (page 40), highlighting how fungal and bacterial pathogens can move from propagation material into young orchards and affect long-term productivity. Femi explains how phomopsis graft dieback, caused mainly by Diaporthe spp., is the most economically important nursery disease, being linked to much higher plant mortality than rootstock infection. The main inoculum source for the disease is orchard-sourced scion wood. He also shows that grafting greatly increases fungal diversity in nursery plants, that some native Trichoderma spp. might help suppress the main pathogens, and that HAES 695 (Beaumont) is generally more tolerant of major stem diseases than H2. Femi's work shows that disease management needs to start in the nursery, requiring cleaner scion sources, better pre-grafting screening, stronger nursery biosecurity, careful rootstock selection and potentially a certified scion repository system to reduce tree losses and improve orchard establishment.
Bark beetle case study
This year we have included a bark beetle case study (page 57), highlighting the importance of monitoring stressed trees and maintaining good orchard hygiene to minimise pest establishment and spread.
Permits expired
The permit to use methomyl (PER90593) for banana fruit caterpillar has expired.
With the expiry of the indoxacarb permit (PER86827) for macadamia seed weevil control, growers should transition to registered products. Avatar® Evo (contains indoxacarb) and Vayego® (contains tetraniliprole) are currently registered for the control of macadamia seed weevil and provide effective management options within an integrated pest management program.
New product
A new product (Teppan 50SL) with cyclaniliprole as the active ingredient is now available to control fruit spotting bug (page 66), macadamia nut borer (page 83) and macadamia seed weevil (page 86).
Citrus blossom bug
Due to concerns we are hearing from Queensland, citrus blossom bug (page 61) has been added to this year's guide. Special thanks to Dalton Baker, QDPI Research Scientist, who is the expert on this pest, for reviewing the section.
Distribution
The guide is available free to macadamia growers and is distributed to all macadamia processors in Australia. Copies can be collected from the NSW Department of Primary Industries and Regional Development (DPIRD) office at Wollongbar, processors, the Australian Macadamia Society, and selected rural retail stores. Every effort is made to have all macadamia growers obtain a copy of this publication.
For a hard copy of this guide, please contact Jeremy Bright on jeremy.bright@dpird.nsw.gov.au
