Research and Innovation

“There are more ways of killing a cat than to choke it with butter”. This old proverb may well apply to controlling husk spot with fungicides in macadamias.  There may be more holistic ways to reduce the impact of husk spot than reaching for a drum of fungicide.

A trial using the natural plant bio-stimulant PandA provides good reasons to be optimistic. Over the last two seasons at Branson Park,  Whian Whian (near Lismore) Frank, Joy and Ryan Hathaway have been co-operating in evaluating PandA on the A16 variety and comparing it against the conventional treatment of Spin (Carbendazim) and Copper.

This trial clearly indicates that nuts with husk spot symptoms treated with PandA fell earlier than those treated with conventional fungicide (Figures 1 and 2).  In 2010, 30% of the nuts fell early in Rounds 1 and 2 as compared with only 11% in the conventional fungicide treatment. 

Figure 1 :                                

2010 HARVEST Rounds 1 & 2

NIS kg/ha - % of total harvest

Figure 2 :

2011 HARVEST Rounds 1 & 2

NIS kg/ha - % of total harvest

In 2011, 69% of the PandA treatment nuts fell early in Rounds 1 and 2 as compared with 37% in the conventional fungicide treatment.

But here is the new twist to the story – Excellent nut quality.

By visually accessing the early fall of nuts showing husk spot symptoms, the conclusion was drawn by some that PandA  failed to control husk spot.  However, contra-intuitive the nut quality was significantly better than expected or at least equal to the conventional fungicide treatment. PandA treated nuts were not immature or of inferior quality as shown in Figures 3 and 4 (2010) and Figures 5 and 6 (2011) as a result of being sprayed with PandA.

Ryan Hathaway harvesting the PandA trial

Figure 3 :

Harvest Round 1-2010 - MPC

Figure 4:

Harvest Round 2- 2010 - MPC

Figure 5:

Harvest Round 1-2011 - Pacific

Figure 6:

Harvest Round 2 – 2011 - Pacific

 The key message here is that this trial has now been running for two seasons of low and high levels of husk spot disease pressure without any fungicide being applied.  This is a good reason for optimism and illustrates our potential to adopt more holistic approaches to disease control in macadamias.

Our results are in line with Asian research that suggests the application of PandA in some way alters the metabolism and disease resistance in the plant, enabling it to cope with stresses without impacting on yield or quality.

At this stage the safe option is to use the ‘belt and braces’ approach and apply PandA along with normal fungicide treatment.

The trial will continue this year, but the number of applications of the PandA FBS will be reduced to fit in more with farm practice, while the conventional treatments will remain unchanged. 

Trial Summary 2010

The trial suggests that a relatively safe option is to add PandA Foliar BioStimulant  (FBS) to the conventional fungicide spray where the additional cost for two applications at 6 Litre/ha costs $56/ha. 

The 2010 trial showed an increased income of $3,374/ha for that investment.

The author acknowledges that the 2010 result was achieved in a low husk spot pressure year and no claim is made or implied that PandA Foliar BioStmulant (FBS) or PandA will control husk spot. 

O’Grady Rural will continue to fund the trial in co operation with the Hathaway Family at Whian Whian and we appreciate the testing provided by Kevin Quinlan from the Macadamia Processing Company, Bob Evans at Pacific Plantations and Dr Olufemi Akinsanmi (Femi), Senior Research Officer, University of Queensland, School of Biological Sciences.

Details: PandA on Macadamia Trial 2010 & 2011

Previous history of severe husk spot problems

Variety: A16
Age of trees: 12-15 years approx
Tree spacing: 8 x 4m
Plot size for each treatment: 3 rows x 39 trees

Middle row of each plot was mechanically harvested three times per harvest round to pick-up all nuts
All nut and husk were weighed and sub-sampled in the field and immediately dehusked on the farm. Post dehusking NIS kg were recorded.

In 2010 the NIS of each treatment were split into 3 x 1 kg samples for testing by MPC, and in 2011 the NIS of each treatment were split into 6 x 1 kg samples for testing by MPC and Pacific Plantations. The samples were randomised for testing and were accessed for quality and value. The mean of 3 tests/treatment/harvest were used to value the overall treatment yield.
Number of harvest rounds in 2010 was six: (12 March, 9 April, 30 April, 1 June, 30 June, 4 August 2010)
Number of harvest rounds in 2011 was five: (13 March, 11 April, 03 May, 6 June, 20 June, 2011)

Treatments:

Spin Flow (Carbendazim) + Copper + PandA in 2,500 L/ha = 8 L/tree

Sprayed twice 22.9.09 and 30.10.09

2010

Spin Flow (Carbendazim) + Copper in 2,500 L/ha = 8 L/tree

Sprayed twice 22.9.09 and 30.10.09

2010

PandA @ 6 L/ha in 2,500 L/ha = 8 L/tree

Sprayed six times. Commenced July 31 – then monthly to 2.1.2010

Sprayed 4 times

Spin Flow @ 50ml/100L : Coppox @ 160gm/100L PandA @ 6L/2000L