This document summarizes research on using tree shaker technology to manage husk spot disease in macadamia trees. Husk spot is a fungal disease that causes premature nut drop and severe yield losses. The researcher aims to test if tree shakers can effectively remove sticktight husks from tree canopies, which harbor the fungal spores. Preliminary results show tree shakers can remove up to 100% of sticktight husks. Tests on two macadamia cultivars also found lower husk spot severity after sticktight removal compared to untreated trees. While tree shakers show potential for husk spot control, challenges remain to optimize removal rates and reduce tree damage.

1. Pest and disease management
Dr Femi Akinsanmi
Cultural disease management with tree shakers
16thOctober, 2014

2. Application of tree shaker technology for husk spot control in macadamias

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 Husk spot disease.
 Disease management approach.
 Application of tree shaker technology for disease control.
 Potential additional benefits & challenges of using tree shakers in macadamia.
 Concluding remarks.
Outline

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Husk spot disease
 Fungal pathogen infects macadamia husks.
 Causes premature nut drop = severe yield loss (40%+).
 Potentially costs the Australian industry ~ $10m/year
 Increases annual production costs.
 Increases risk and reliance on pesticide applications.
 Accelerates nut drop.
Pseudocercospora macadamiae

5. Desirable nut drop
pattern
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Husk spot disease
0
5
10
15
20
25
30
35
40
Dec Jan Feb Mar Apr May Jun Jul
Percentage of total nut drop
Months
Desirable nut drop
pattern
Husk spot induced
nut drop pattern
Low grade kernel Premium kernel
Optimum
kernel
maturity
period

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1. Fungicide spray applications
 Prophylactic spray applications (Before infection and or symptom expression)
2. Disease resistance
 Select tolerant or less disease-conducive cultivars
3. Cultural control
 Harvest or after harvest period
 Pre-harvest period
4. Biological control
• Research currently underway (MC12008)
Husk spot management approach

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Husk spot management approach

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Fungal spores produced on
diseased husks from preceding
seasons infect developing nut.
Remove/reduce (sticktights) the source of Inoculum = Break disease cycle
Without
sticktights
22%
With
sticktights
78%
A38
Without
sticktights
17%
With
sticktights
83%
HAES246
Relative proportion of husk spot incidence
Husk spot management approach
 May stay in the tree canopy for several years
 Manual removal is labour-intensive
 Manual removal is not economical in commercial orchards

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Year 1 Year 2
Mechanical removal Untreated
Mechanical removal Mechanical removal
Untreated Untreated
Mechanical removal Untreated
Mechanical removal Mechanical removal
Untreated Untreated
No fungicide
Spray Fungicide
Research Questions:
1. Is tree shaker effective in reducing the prevalence of sticktights?
2. Should mechanical removal of sticktights be an annual farm operation?
3. Should sticktights removal operation be performed with fungicide spray applications?
Cultivars A38 & A16
Application of tree shaker technology to remove sticktights from tree canopy

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Husk spot management: Sticktights removal using tree shakers

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Removal efficiency:
almost 100%
Husk spot management: Cultural control (sticktights removal)

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• Tractor speed: 3.2 km/h
• Removal efficiency: 60%
Husk spot management: Cultural control (sticktights removal)

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Husk spot management
0%
20%
40%
60%
80%
100%
Mechanical sticktights
removal
Untreated control Mechanical sticktights
removal
Untreated control
Fungicide spray application No fungicide application
Husk spot severity
Treatment
Cultivar A38
Cultivar A16

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Additional advantages of using tree shaker technology in
macadamia
 Prompt & faster harvest period.
 Removal of dead leaves, twigs & branches (unwanted shading).
 Crop load thinning.

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0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
246 849 Daddow 816 842 814 A4 814 A16 781
Sticktights rating (0-5)
Macadamia cultivars (Bundaberg Research Station)
0
10
20
30
40
50
Non-irrigated-noethrel
Non-irrigated-ethrel
Irrigated-noethrel
Irrigated-ethrel
Average number of sticktights
Treatment
Application of tree shaker technology for harvesting in macadamia
• Optimise for macadamia
• Shaker with harvesting capability

17. Challenges for using tree shaker technology in macadamia
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• Reducing tree damage
• Increase removal percentage
• Optimise with abscission agent (for late varieties)
• Increase harvest speed and efficiency
• Canopy management

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Timing of application of tree shaker for disease control and harvesting in macadamia

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Application of tree shaker in macadamia will improve productivity
- Reduce husk spot
- Increase harvest tonnage
- Improve harvest efficiency
Efficient+ effective macadamia systems approach is the key

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Acknowledgements
UQ research team: Associate Professor Andre Drenth; Ms Cecilia O’Dwyer, Dr Andrew Miles
Macadamia growers & consultants:
 Dr Chris Searle (Suncoast Gold)
 Robbie Commens (AMS Productivity Development Officer)
 Matthew Burns (Hancock Farm Company)
 Ross Burling (CEO, Stahmann Farms)
 Scott Alcott and MFM team
HAL Project No. MC12007 - Disease management in Macadamia Industry