News

Scolytid beetle activity is on the rise this season, with instances of the beetle tunnelling into the terminal growing points of leaves on commercial macadamia farms at Knockrow, Fernleigh, Alstonville and Hogarth range NSW.

It is uncertain as to why and how this infestation has been triggered this year. If conditions are right, heavy leaf loss from Scolytid beetle activity is possible, as well as rapid dieback and tree death. 

Cryphalus subcompactus, (MBB macadamia bark beetle) will feed into most macadamia bark and stems. Their normal behaviour is to feed on the stems and branches present in orchards. If the female adult MBB can penetrate the cambium zone, she will lay a large numbers of eggs into the cambium layer under the bark, they will hatch and the larvae will ring bark the branch, killing all the terminal leaf above.  

Any form of stress to the tree over an extended period will potentially create a situation for infestation. Such examples could include: 

• Individual trees with indirect lightning strikes 
• Ethephon application on stressed trees 
• Irrigation program breaking down 
• Drought conditions 
• Flood.

We understand now that good management and husbandry will limit the opportunity for these pests to infest. Destroy all major limb prunings and dead trees through chipping or burning, immediately. 

More info

For more information, please see:

• NSW DPI Plant Protection Guide (p 20-25 and 37-40). View here. 
• the upcoming Winter 2024 News Bulletin article by Craig Maddox (NSW DPI Entomology) and Jay Anderson (SCU plant pathology).  

Acknowledgement This work is part of the Early Needs Recovery Program (ENRP) under the $150 million Primary Industries Support Package (PISP) that is co funded 50-50 by the Australian and NSW governments under the Disaster Recovery Funding Arrangements (DRFA).