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Case Study

Biostart TripleX control of Sooty Mould
 An overview of trial work

 Dr Jerome Demmer, R & D Director, Biostart Ltd

5th March 2014

 


Overview

The following is a summary of experiments carried out by Biocult, an independent testing company, on behalf of BioStart, measuring the activity of Triplex in controlling the growth of sooty mould isolated from kiwifruit. 


Results

In vitro Biological Assays of Triplex

To establish whether Triplex has preventative activity against Sooty Mould a number of in vitro laboratory studies were conducted.

Zone of Inhibition Study – Bs1b Microbe

In this trial, bacterial cultures of the active ingredient of Triplex, Bacillus amyloliquefaciens or Bs1b, was added to agar dishes that had been inoculated with sooty mould spores.  The sooty mould used in these trials had been isolated from kiwifruit.   The Bs1b bacteria completely inhibited the growth and development of the sooty mould spores thereby  showing that  B. amyloliquefaciens BS1b has a very strong activity against sooty mould.

Zone of Inhibition Study – Triplex Product

In this trial, Triplex, either neat or diluted 1:200, was added to agar dishes that had been inoculated with sooty mould spores at either a high or low dose.  The sooty mould used in these trials had been isolated from kiwifruit.   The test of Triplex 1:200 allows the Bs1b microbe to be evaluated over the background activity of the other ingredients in the Triplex formulation.

Both the neat and diluted Triplex had activity against sooty mould with the activity in the diluted Triplex being due to Bs1b. The Bs1b activity took time to develop as the microbe grew and was directly correlated by the number of microbes present. 

These tests were conducted at both low and high spore dose rates of sooty mould.


High Sooty Mould Spore Levels 

ZOI (mm)Day 2Day 3Day 5
Triplex - neat0.800.500.30
Triplex - 1:2000.450.300.40
Control0.000.000.00

 

graph1.jpg

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Low Sooty Mould Spore Levels 

ZOI (mm)Day 2Day 3Day 5
Triplex - neat0.900.700.30
Triplex - 1:2000.450.500.65
Control0.000.000.00

 

graph2.jpg

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Sooty Mould Spore Germination Inhibition Study

In this trial, TripleX was tested for its ability to inhibit spore germination and the subsequent mycelial growth of sooty mould.  The sooty mould used in these trials had been isolated from kiwifruit.

Microscopy % spore germination Day 1Visual % Mycelium growth Day 2Visual % Mycelium growth Day 4
TripleX (1:200)850 (Slight BS-1b growth)25 (Good BS-1b growth)
Untreated Control100100100

TripleX was tested at a range of concentrations (1:50, 1:100 and 1:200) and all rates provided good reduction in spore germination when compared to controls.   The reduction for 1:200 dilution was best at 92 % reduction in spore germination.

Observations of mycelium growth on days 2 and 4 showed that Triplex at 1:200 reduced mycelium growth by 50 and 75 %, respectively.  This demonstrated that as Bs1b grew and became established it was able to exert its biocontrol activity on the sooty mould.

Sooty Mould Infected Fruit Study

Kiwifruit with clear symptoms of sooty mould infection were dipped in a diluted TripleX solution (1:200).  After 2 minutes in the solution the fruit were gently rubbed and assessed for the remaining sooty mould infection.  These trials showed that washing fruit in TripleX allowed the sooty mould to be easily removed from the fruit.  The sooty mould could not be easily removed from the fruit dipped in water.

kiwifruit_triplex.jpg

Summary

  • Biostart TripleX and its active ingredient, B. amyloliquefaciens BS-1b, showed good sooty mould inhibition in a range of in vitro test systems.   
  • TripleX is currently undergoing a range of field trials in commercial kiwifruit orchards.  
  • TripleX is commercially available and on the Zespri ‘Approved but Unproven” list.

Conclusion:

Experimental Kiwifruit Sooty Mould Program

Version 1.1

TimingApplication RateComments
Triple XIn response to monitoring of passionvine hopper or cicada apply 1st application at first sign of honey dew (early/mid Jan).Apply 3lt/ha in min 1500ltrs water every 18-21 days.Coverage is critical to get product to shoulder of fruit. Recommended to add non-ionic sticker/spreader to aid coverage. (Duwett, Hywett ,Nufilm, Filmstar,) at label rates.
  • Note: Recommended to add non-ionic sticker/spreader to aid coverage.(Duwett,Hywett,Nufilm,Filmstar ,Spreadwet 1000) at label rates with all applications.
  • Add TripleX to the tank first ,mix well, then add adjuvant.
TimingApplication rate
Prior to periods of high infestation of Passion Vine Hoppers3lt/ha TripleX. Water rate 1,500lt/ha. Add spreader sticker
7-10 days after infestation3lt/ha TripleX. Water rate 1,500lt/ha. Add spreader sticker
Continued applications throughout the season, at 3 to 4 weeks intervals.3lt/ha TripleX. Water rate 1,500lt/ha. Add spreader sticker

For further information contact

Stephen Wrigley
Sales Director
Ph 021 848 342
Email s.wrigley@biostart.co.nz

Geoff Warmouth
Horticulture Territory Manager
Ph 021 794 276
Email g.warmouth@biostart.co.nz


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