Novel approaches to the management of soilborne diseases in vegetable crops
Novel approaches to the management of soilborne
diseases in vegetable crops
Presented on behalf of:
Horticulture Australia Limited
DPI VictoriaIan Porter
Plant volatilesCassie Scoble
Caroline DonaldDenise Wite
Oscar Villalta
Fungal volatilesRoss Mann
Scott Mattner
Systemic Acquired Resistance
Arati AgarwalCaroline Donald
Northern Territory Dept. of Resources
GraftingBarry Condè
Mark Traynor
With thanks to:
Disease control strategies
Inoculum load
Pathogen lifecycle
Host resistance
Direct effects on the pathogenI) Plant volatiles• Secondary metabolites
ie. essential oilsvolatile compounds
• Rich in bioactive chemicals terpenoids and phenolics
• Strong antimicrobial activity
Aim: Screen efficacy of essential oils against key soilborne pathogens
Contact bioassaysVapour phase
(volatile) bioassays
Pot trials Preliminary field trials
Essential oilsInhibited growth & biocidal
– Thyme, Clove bud, Origanum
Inhibited growth but not biocidal– Geranium, Peppermint, Pine,
Tea tree, Basil, Fennel Sweet
Did not inhibit growth– Eucalyptus, Rosemary,
Black pepper, Orange sweet, Cardamom
Pure compounds– Terpenoid (thymol, carvacrol & eugenol) and phenolic (geraniol) compounds - NO growth &
biocidal against all pathogens at lowest rate tested 500 ppm
Commercial blends– Effective only at the higher concentrations and only against some pathogens – eg. ECO-V (mustard oil & allyl isothiocyanates) and Vigor (mustard & chilli pepper extracts)
biocidal against R. solani and inhibitory to F. oxysporum at 2500ppm
Summary of in-vitro (contact bioassay) screening% growth compared to control
Essential OilRate ppm S.minor F.oxysporum R.solani T.hamatum
Origanum 1 118.49 49.93 51.9 80.6910 96.28 54.64 75.44 80.31100 61.47 24.22 0.00 38.03500 0.00 0.00 0.00 0
Thyme 1 96.76 26.81 101.15 85.0610 96.32 25.99 90.49 78.37100 68.96 5.12 0.00 32.91500 0.00 0.00 0.00 0
Clove bud 1 98.25 21.20 91.54 98.2210 87.42 21.40 76.78 112.41100 66.79 7.29 0.00 59.93500 0.00 0.00 0.00 0
Red= Biocidal activity (plugs did not regrow on umamended agar)
400 kg/ ha 200 kg/ ha
Basamid® 100% emergence
0 %
0 %
10% 5 % 1%
Origanum 32% emergence
Uninoc Inoc
Treatment Active ingredient
Disease incidence
(%)
Disease severity
(0-5)Perlka® calcium
cyanamide100 b 4.0 b
Fumafert® mustard meal & neem cake
99 b 3.9 b
Bioweed™ pine oil 100 b 3.8 b
Promax™ thyme oil 100 b 3.4 b
Vigor® mustard & chilli pepper extracts
100 b 3.3 a
ECO-V mustard oil & allyl isothiocyanates
98 b 3.3 a
Basamid® dazomet 80 a 2.9 a
Untreated 100 b 4.0 b
Root rot incidence and severity on green beans grown in soil treated with formulations of plant products
compared to Perlka® & Basamid® at Lindenow, Victoria.
56% emergenceThyme
5%10% 1%
Direct effects on the pathogenII) Fungal volatiles
• Fungi that live in native flora (endophytes)- volatile metabolites
• Mycofumigation- Incorporation of endophyte into soil where it
releases volatile biocidal compounds
Aim - Screen native flora for volatile producing endophytes and evaluate efficacy against key pathogens
Percent inhibition of three pathogens of vegetable crops (Pythium sulcatum, Fusarium oxysporum and Sclerotinia minor) following exposure (5 days) to volatile secondary metabolites produced by isolates of Genus 1 (blue – industry standard).
Pythium Fusarium Sclerotinia Isolate 1.1 100.0 % 46.4 % 100.0 % Isolate 1.2 100.0 % 6.9 % 100.0 % Isolate 1.3 100.0 % 29.4 % 100.0 % Isolate 1.4 89.0 % 21.6 % 95.0 % Isolate 1.5 100.0 % 20.6 % 100.0 % Isolate 1.6 100.0 % 10.2 % 95.2 % Isolate 1.7 100.0 % 36.1 % 100.0 % Isolate 1.8 100.0 % 28.9 % 100.0 % Isolate 1.9 54.5 % 2.9 % 44.7 % Isolate 1.10 100.0 % 27.2 % 100.0 % Isolate 1.11 100.0 % 29.2 % 100.0 % Isolate 1.12 100.0 % 25.9 % 100.0 % Isolate 1.13 100.0 % 29.0 % 100.0 % Isolate 1.14 100.0 % 0.4 % 69.5 % Isolate 1.15 100.0 % 29.4 % 98.4 % Isolate 1.16 54.2 % 0.0 % 62.5 % Isolate 1.17 68.8 % 5.9 % 64.4 % Isolate 1.18 100.0 % 9.8 % 96.3 %
Muscodor albus (CZ620) 100.0 % 32.3 % 100.0 % LSD (5 %) 12.6 7.4 13.5
P Value 0.001 0.001 0.001
Antimicrobial activity•18 endophytes (from one genus) demonstrating strong antimicrobial activity in vitro (septum plate bioassays)
GC/MS profile of volatile compounds produced by Isolate 1.1 over a 12 day period (peaks relate to individual compounds; y axis relates to concentration of those compounds).
Chromatogram Plots
5 10 15 20 25 30 35minutes
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10-2-A_Rep2.xms 10.0:250.0> 10.0:250.0>
10-2-A_Rep2.xms 10.0:250.0> 10.0:250.0>
10-2-A_Rep2.xms 10.0:250.0> 10.0:250.0>
10-2-A_Rep2.xms 10.0:250.0> 10.0:250.0>
10-2-A_Rep2.xms 10.0:250.0> 10.0:250.0>
10-2-A_Rep2.xms 10.0:250.0> 10.0:250.0>
10-2-A_Rep2.xms 10.0:250.0> 10.0:250.0>
2 days
3 days
4 days
5 days
10 days
11 days
12 days
Pinene (terpenes)
Eucalyptol
Cyclohexane
derivatives
Ethanol
Mycofumigation pot trial
Substrate Pythium spp. Rhizoctonia solani (AG 2.1) (pg DNA / g soil) (pg DNA / g soil)
Untreated 179 10,581 Bran : Sand (1:1) 271 11,986
Vermiculite 285 15,846 Wheat 65 4
Basamid® 4 0 P Value 0.004 <0.001
LSD (5 %) 131.5 5571.3
Effect of mycofumigation with isolate 1.1 (200g/L) on populations of Pythium spp. and Rhizoctonia solani (AG2.1) in field soil (ex. Cranbourne).
Host resistance
I) Grafting
Vegetable crops extensively grafted worldwide:
•Watermelon,cucumber, melon, bitter melon, tomato, eggplant, pepper
Countries where grafting is common:
•Japan, Korea, China, Taiwan, USA, Spain, Italy, France, Netherlands
•75% cucumber plants grown in Korea and Japan are grafted
•50% of commercial seedling growers in Korea produce grafted seedlings – the largest of these produced 9 million grafted seedlings in 2008
Australian experience
•Limited!
•Fusarium wilt of Snake bean (NT)
•Bacterial wilt of eggplant and tomato (QLD, NT)
•Improved vigour of tomatoes
Use of grafting to manage Fusarium wilt of snake beans - NT
Host resistanceII) Salicylic acid mediated Systemic Acquired Resistance
SYSTEMIN (wounding/insects)
OLIGOURONIDES(pathogen attack)
CHITOSAN
LINOLENIC ACID
JASMONIC ACID
GENE ACTIVATION
mRNA
PROTEINASE INHIBITORS
XPCMBS
XDIECASALICYLIC
ACID
X
OCTADECANOID SIGNALLING
PGPRPATHOGEN INVASION
PHENYLALANINEPHENYLALANINE
AMMONIUM LYASE (PAL)TRANS-CINNAMIC ACID
BENZOIC ACID
SALICYLIC ACID
GENE ACTIVATION
BTHINA
PATHOGENESIS RELATED PROTEINSSALICYLIC ACID SIGNALLING
BENZOIC ACID 2-HYDROXYLASE (BA2H)
SA CONJUGATESEG SA β-GLUCOSIDE(AND OTHER STORAGE OR TRANSPORT FORMS)
REDUCTION OF NPR1 FROM OLIGOMERIC TO MONOMERIC FORM
Plant defence responses mediated by jasmonic acid or Salicylic acid. (Based on Doares et al. 1995; Mauch-Mani and Métraux 1998; Ryals et al. 1996).
0.5mM salicylic acid dip applied for 1 minute.
Inoculated 4 hours later with 200µL of resting spore suspension (108 spores/mL).
Control plants
Disease index = 0
Infection rate = 0%
P. brassicae inoculated, not treated
Disease index = 81.5
Infection rate = 100%
P. brassicae inoculated
Salicylic acid pretreatment
Disease index = 20
Infection rate = 50%
- SA
+ SA
Cont 104 105 106 107
SAR in broccoli
0.1mM SA dip applied for 15 mins, 24hrs before inoculation
Gene Root Leaf
Actin 8 No change No change
PR-1 38 fold change 4 fold change
PR-2 Not induced 60 fold change
Chitinase Not induced 23 fold change
Actin 133 bp
PR-1105 bp
PR-2111 bp
Chitinase133 bp
ROOT
LEAF
Gene expression studies(plants treated with triple dip 0, 24 & 48 hrs before analysis at 72 hrs)
Where to now?Plant volatiles•Key issue: application - retention of volatiles in soil
Fungal volatiles•Work ongoing PhD Ross Mann.
Grafting•Commercial acceptance in NT snake bean industry•Seek to expand into other high value, multiple pick commodities (eg. cucumber, eggplant, capsicum)
Systemic Acquired Resistance•Work ongoing PhD David Lovelock.•Understand the biochemistry of the observed effects.•Issues - variability of response, application to older seedlings, wider use across a range of brassica hosts and pathogens.