SlideShare a Scribd company logo
1 of 35
RUFUS AKINRINLOLA
Graduate Student
Plant Pathology Department.
University of Nebraska-Lincoln
BIOLOGICAL CONTROL OF
PLANT PATHOGENS
BIOS/PLPT 369
Topics
1. Biological control
2. Importance of biological control
3. Mode of actions of biocontrol
4. Biocontrol application methods
5. Requirements for successful biocontrol agents
6. Limitations of biological control
7. Some commercial biological control agents
8. Summary
BIOLOGICAL CONTROL OF PLANT PATHOGENS
The term biological control :- as defined by Plant Pathologist;
 the use of microbial antagonists (including bacteria or fungi) to suppress
plant disease pathogens
BIOLOGICAL CONTROL
Inhibition of test organisms by biocontrol organism Sources: google image
 Alternative method of disease control
 Can be used in where other methods are not applicable.
 Biocontrol agents are nontoxic to man and the environment.
 Act on selective target organism.
 Biocontrol agents are self-sustaining-easy adaptation
 Diversify mode of actions
 Reduced possibility of inducing resistance in pathogens
 Cost effective
 Long term effects
Importance of biological control
Emmert, E. A., & Handelsman, J. (1999). Biocontrol of plant disease: a (Gram‐) positive perspective. FEMS Microbiology letters, 171(1), 1-9.
Mode of actions of biocontrol
1. Direct mechanism: Direct lysis or killing of pathogen by biocontrol agent
 Antibiosis
 Parasitism
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
2. Indirect mechanism: Exclusion of plant pathogen as a result of the presence, activity
or products of biocontrol agent.
 Competition
 Induced systemic resistance
Mode of actions of biocontrol
1. Direct mechanism: Direct lysis or killing of pathogen by biocontrol agent
 Antibiosis
 Parasitism
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
2. Indirect mechanism: Exclusion of plant pathogen as a result of the presence, activity
or products of biocontrol agent.
 Competition
 Induced systemic resistance
Mode of actions of biocontrol
1. Antibiotic mediated suppression
 Antibiotics are microbial toxins that can, at low concentrations, poison or kill other
microorganisms.
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Mode of actions of biocontrol
1. Antibiotic mediated suppression
 Antibiotics are microbial toxins that can, at low concentrations, poison or kill other
microorganisms.
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Inhibition of pathogens by biocontrol bacteria. Photo credit: Rufus Akinrinlola
Mode of actions of biocontrol
1. Antibiotic mediated suppression
 Antibiotics are microbial toxins that can, at low concentrations, poison or kill other
microorganisms.
 Volatile antibiotics
• Hydrogen cyanide,
• Aldehydes
• Alcohols
• Ketones
• Sulfides
 Nonvolatile antibiotics:
• Polyketides (diacetylphloroglucinol; DAPG and
mupirocin).
• Heterocyclic nitrogenous compounds.
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
2. Parasitism
 Direct utilization of pathogens as source nutrients.
 Mycoparasitism refers to association in which a parasitic fungus (hyperparasite) live as a
parasite to another fungus (hypoparasiste).
 Also known as Hyperparasitism, when hyperparasites (biocontrol fungi) utilize
hypoparasites (pathogenic fungi) as source of nutrients.
 Hyperparasites produce parasitizing hyphae to acquire host nutrients.
 May also requires cell wall degrading enzymes.
Source: The Microbial World.
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
A B
Source: The Microbial
World.
Example of Mycoparasitism: Pythium oligandrum Vs Fusarium culmorum
A. Single hypha of Pythium
oligandrum stopped the advancement
of Fusarium culmorum hyphae across
an agar plate.
B. At higher magnification F. culmorum
hyphae are seen disrupted - the contents
are highly vacuolated and coagulated.
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Steps involved in Mycoparasitism
1. Chemotropic growth: the biocontrol fungi grow toward the target fungi chemical
stimuli.
2. Recognition stage: interaction between biocontrol receptors and that of the host fungus
3. Attachment and cell wall degradation (chitinases and glucanases).
4. Penetration (appressoria-like structures).
Mode of actions of biocontrol
Ahanger et al., 2014; Dubey and Dwivedi, 1986.
Steps involved in Mycoparasitism
1. Chemotropic growth: the biocontrol fungi grow toward the target fungi chemical stimuli.
2. Recognition stage: interaction between biocontrol receptors and that of the host fungus
3. Attachment and cell wall degradation (chitinases and glucanases).
4. Penetration (appressoria-like structures).
Coiling Penetration
Barrier formation
by host hypha
Branching and
sporulation
Chlamydospores
formation
Lysis of
host hypha
Hyperparasite
(bicontrol)
Host fungus (pathogen)
hypha
Source: biocylopedia.com
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Source: Koutb and Ali, 2010
3. Competition
 Exclusion of pathogens by biological control agents via competition for space or
nutrients.
 Production of substances (such as siderophore) for nutrient (such as iron) acquisition.
 Deprive pathogens of nutrients.
 It’s an indirect mechanism
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Source: Koutb and Ali, 2010
3. Competition
 Exclusion of pathogens by biological control
agents via competition for space or
nutrients.
 Production of substances (such as siderophore)
for nutrient (such as iron) acquisition.
 Deprive pathogens of nutrients.
 It’s an indirect mechanism
Competition for space and nutrients between Pythium
irregulare pathogen (white restricted growth) and the
Epicoccum purpurascens (reddish wide growth) on
PDA medium after
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
4. Induced systemic resistance (ISR):
Also known as systemic acquired resistance (SAR), resistance in plants to
varieties of pathogens induced by the presence or products of biocontrol
agent.
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
ISR biocontrol agent may be;
 Necrogenic pathogen (applied on leaf).
 Non-pathogenic bacteria (PGPR) (applied to root or seed).
 Metabolites of pathogenic or saprophytic bacteria.
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Microbial metabolites able to induce ISR
 Polyacrylic acid
 Ethylene
 Salicylic acid
 Acetyl salicylic acid
 Amino acid derivatives
 Harpin ( Erwinia amylovora)
• Stress can induce defense mechanisms against pathogens
Mode of actions of biocontrol
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Physical thickening of cell walls by;
 Lignification.
 Deposition of callose.
 Accumulation of antimicrobial low-molecular-weight substances (e.g.,
phytoalexins).
 Synthesis of various proteins (e.g., chitinases, glucanases, peroxidases, and
other pathogenesis related (PR) proteins).
Induced systemic resistance- defense responses
Mode of actions of biocontrol
Ahanger et al., 2014; Lee et al., 2015
Induced systemic resistance- defense responses
C. Induced systemic
resistance by biocontrol
agent Bacillus
amyloliquefaciens HK34
B. Plant treated with
0.1mM benzothiadiazole
(positive control)
A. Plant treated
with distill
water
Biocontrol application methods
 There are five application methods
Biocontrol application methods
1. Seed treatment
Biocontrol application methods
2. Seedling dip method
Biocontrol application methods
3. Soil drench
Biocontrol application methods
4. Foliar spray
Biocontrol application methods
5. Irrigation drips
Biocontrol application methods
1. Seed treatment
2. Dipping
3. Drench
4. Foliar prays
5. Drips
Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
Requirements for successful biocontrol agents
1. Able to compete and persist
2. Able to colonize and proliferate
3. Must be non-pathogenic to host and environments
4. Must have excellent shelf life
5. Must be inexpensive
6. Must be able to produce in large quantities
7. Able to maintain viability
8. Delivery and application methods must support product establishment.
http://flax.nzdl.org/greenstone3/flax?c=BAWELS&a=d&rt=r&d=D2712&dt=simple&p.a=b&p.s=ClassifierBrowse&cls=
Limitations of biological control
1. Expensive/difficult to develop
2. Handling requires training
3. High Selectivity/Host Specificity
4. Variability in effectiveness
5. More susceptible to environmental conditions
6. Short shelf-life of formulations
7. Slow action
8. Storage Problem
http://flax.nzdl.org/greenstone3/flax?c=BAWELS&a=d&rt=r&d=D2712&dt=simple&p.a=b&p.s=ClassifierBrowse&cls=
Commercial biological control
 Active microbe: Bacillus subtilis strain GB03
 Mode of actions: Antibiosis
 Company : Gustafson, Inc, Plano, TX, USA
Junaid, J. M., Dar, N. A., Bhat, T. A., Bhat, A. H., & Bhat, M. A. (2013). Commercial biocontrol agents and their mechanism of action in the management of plant pathogens. International Journal of Modern Plant & Animal Sciences, 1(2), 39-57.
Commercial biological control
Some commercial biological control agents
Control of blue mold and gray mold on cherries,
apples, citrus.
Mode of action: Competition
Applicational methods:
• Dip or Drench
• Spray
Control of seed rot, root and stem rot and wilt caused
by Fusarium, Alternaria and Phomopsis on
ornamentals aand vegetables
Mode of actions:
Competition; Hyperparasitism; Antibiosis
Junaid, J. M., Dar, N. A., Bhat, T. A., Bhat, A. H., & Bhat, M. A. (2013). Commercial biocontrol agents and their mechanism of action in the management of plant pathogens. International Journal of Modern Plant & Animal Sciences, 1(2), 39-57.
Summary
 Biological control involves the use of microbial antagonists such as bacteria or fungi to
suppress plant disease pathogens.
 Biocontrol have several importance and advantages over other control methods
 Their mode of actions include antibiosis, competition, parasitism and induced systemic
resistance.
 There are however some limitations to the general use of biological control agents such
variability in effectiveness, low spectrum action, short shelf life of products etc.
 Some of the commercial available biocontrol agents include Biosave, Kodiak, Mycostop etc.
 A biological control agent can be applied as seed treatment, root dip, soil or furrow drench,
foliar sprays or through drip irrigation.
Thanks
Any question?
• Junaid, J. M., Dar, N. A., Bhat, T. A., Bhat, A. H., & Bhat, M. A. (2013). Commercial biocontrol agents and their
mechanism of action in the management of plant pathogens. International Journal of Modern Plant & Animal
Sciences, 1(2), 39-57.
• Jetiyanon, K., Fowler, W. D., & Kloepper, J. W. (2003). Broad-spectrum protection against several pathogens by
PGPR mixtures under field conditions in Thailand. Plant Disease, 87(11), 1390-1394.
• Lee, B. D., Dutta, S., Ryu, H., Yoo, S. J., Suh, D. S., & Park, K. (2015). Induction of systemic resistance in Panax
ginseng against Phytophthora cactorum by native Bacillus amyloliquefaciens HK34. Journal of ginseng
research, 39(3), 213-220.
• Koutb, M., & Ali, E. H. (2010). Potential of Epicoccum purpurascens Strain 5615 AUMC as a biocontrol agent of
Pythium irregulare root rot in three leguminous plants. Mycobiology, 38(4), 286-294.
• Kilic-Ekici, O., & Yuen, G. Y. (2003). Induced resistance as a mechanism of biological control by Lysobacter
enzymogenes strain C3. Phytopathology, 93(9), 1103-1110.
Sources

More Related Content

What's hot

Bacillus thurengiensis
Bacillus thurengiensisBacillus thurengiensis
Bacillus thurengiensis
Jazmin Caur
 

What's hot (20)

Trichoderma
TrichodermaTrichoderma
Trichoderma
 
Phosphate solubilizers
Phosphate solubilizersPhosphate solubilizers
Phosphate solubilizers
 
Mycorrhiza
MycorrhizaMycorrhiza
Mycorrhiza
 
Types of biofertilizers
Types of biofertilizersTypes of biofertilizers
Types of biofertilizers
 
Plant Pathogen Interaction
Plant Pathogen InteractionPlant Pathogen Interaction
Plant Pathogen Interaction
 
Rhizobium ppt
Rhizobium pptRhizobium ppt
Rhizobium ppt
 
Plant Growth Promoting microbes.pptx
Plant Growth Promoting microbes.pptxPlant Growth Promoting microbes.pptx
Plant Growth Promoting microbes.pptx
 
Biological Nitrogen fixation
Biological Nitrogen fixation Biological Nitrogen fixation
Biological Nitrogen fixation
 
Bacterial blight of paddy
Bacterial blight of paddyBacterial blight of paddy
Bacterial blight of paddy
 
Classification of plant disease
Classification of plant diseaseClassification of plant disease
Classification of plant disease
 
Rhizosphere & phyllosphere
Rhizosphere & phyllosphereRhizosphere & phyllosphere
Rhizosphere & phyllosphere
 
Principles of plant disease management
Principles of plant disease managementPrinciples of plant disease management
Principles of plant disease management
 
Rhizobium
RhizobiumRhizobium
Rhizobium
 
AZOSPIRILLUM
AZOSPIRILLUMAZOSPIRILLUM
AZOSPIRILLUM
 
Citrus canker ppt
Citrus canker pptCitrus canker ppt
Citrus canker ppt
 
Pr protein
Pr proteinPr protein
Pr protein
 
Chemical control of plant diseases
Chemical control of plant diseasesChemical control of plant diseases
Chemical control of plant diseases
 
Bacillus thurengiensis
Bacillus thurengiensisBacillus thurengiensis
Bacillus thurengiensis
 
Biofertilizers ppt
Biofertilizers pptBiofertilizers ppt
Biofertilizers ppt
 
Integrated Pest Management (IPM)
Integrated Pest Management (IPM)Integrated Pest Management (IPM)
Integrated Pest Management (IPM)
 

Similar to Biological control of plant pathogens

roleoffungiasbiocontrolagents-191117095847.pdf
roleoffungiasbiocontrolagents-191117095847.pdfroleoffungiasbiocontrolagents-191117095847.pdf
roleoffungiasbiocontrolagents-191117095847.pdf
dawitg2
 
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
wilhelm mendel
 
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
rachelsalk
 
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
rachelsalk
 
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
wilhelm mendel
 
Rouf ahmad (2)
Rouf ahmad (2)Rouf ahmad (2)
Rouf ahmad (2)
78686
 
Unit -3 -3.4.pptx forest insects, pest, disease
Unit -3 -3.4.pptx forest insects, pest, diseaseUnit -3 -3.4.pptx forest insects, pest, disease
Unit -3 -3.4.pptx forest insects, pest, disease
himkantipoudel
 
Bacterial contaminants of plant tissue culture
Bacterial contaminants of plant tissue cultureBacterial contaminants of plant tissue culture
Bacterial contaminants of plant tissue culture
Amer T. Wazwaz
 

Similar to Biological control of plant pathogens (20)

biological control of plantpathogens.pptx
biological control of plantpathogens.pptxbiological control of plantpathogens.pptx
biological control of plantpathogens.pptx
 
Invasive Alien Plants: Valuable Elixir with Pharmacological and Ethnomedicina...
Invasive Alien Plants: Valuable Elixir with Pharmacological and Ethnomedicina...Invasive Alien Plants: Valuable Elixir with Pharmacological and Ethnomedicina...
Invasive Alien Plants: Valuable Elixir with Pharmacological and Ethnomedicina...
 
Role of fungi as biocontrol agents
Role of fungi as biocontrol agentsRole of fungi as biocontrol agents
Role of fungi as biocontrol agents
 
roleoffungiasbiocontrolagents-191117095847.pdf
roleoffungiasbiocontrolagents-191117095847.pdfroleoffungiasbiocontrolagents-191117095847.pdf
roleoffungiasbiocontrolagents-191117095847.pdf
 
phage application in food safety
phage application in food safetyphage application in food safety
phage application in food safety
 
Bacteriophage and its Applications in Food
Bacteriophage and its Applications in FoodBacteriophage and its Applications in Food
Bacteriophage and its Applications in Food
 
Fungicides Tolerance in Trichoderma spp. and Pseudomonas fluorescens
Fungicides Tolerance in Trichoderma spp. and  Pseudomonas fluorescensFungicides Tolerance in Trichoderma spp. and  Pseudomonas fluorescens
Fungicides Tolerance in Trichoderma spp. and Pseudomonas fluorescens
 
Probiotics
ProbioticsProbiotics
Probiotics
 
Integrated disease management of vegetables
Integrated disease management of vegetablesIntegrated disease management of vegetables
Integrated disease management of vegetables
 
Role of Induced Systemic Resistance (ISR)In Plant Disease Management
Role of Induced Systemic Resistance (ISR)In Plant Disease ManagementRole of Induced Systemic Resistance (ISR)In Plant Disease Management
Role of Induced Systemic Resistance (ISR)In Plant Disease Management
 
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
 
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
Assessment of Antibiogram of Multidrug-Resistant Isolates of Enterobacter aer...
 
FUNGI AS BIOCONTROL AGENT.pptx
FUNGI AS BIOCONTROL AGENT.pptxFUNGI AS BIOCONTROL AGENT.pptx
FUNGI AS BIOCONTROL AGENT.pptx
 
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
 
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
Impact of Biofield Treatment on Yield, Quality and Control of Nematode in Car...
 
Comparative studies on phytochemical components and curd probiotics
Comparative studies on phytochemical components and curd probioticsComparative studies on phytochemical components and curd probiotics
Comparative studies on phytochemical components and curd probiotics
 
Rouf ahmad (2)
Rouf ahmad (2)Rouf ahmad (2)
Rouf ahmad (2)
 
Unit -3 -3.4.pptx forest insects, pest, disease
Unit -3 -3.4.pptx forest insects, pest, diseaseUnit -3 -3.4.pptx forest insects, pest, disease
Unit -3 -3.4.pptx forest insects, pest, disease
 
Biocontrol Agents
Biocontrol AgentsBiocontrol Agents
Biocontrol Agents
 
Bacterial contaminants of plant tissue culture
Bacterial contaminants of plant tissue cultureBacterial contaminants of plant tissue culture
Bacterial contaminants of plant tissue culture
 

More from Plant Disease Control Hub

More from Plant Disease Control Hub (16)

IPM strategies for plant-parasitic nematodes_R.Akinrinlola.pptx
IPM strategies for plant-parasitic nematodes_R.Akinrinlola.pptxIPM strategies for plant-parasitic nematodes_R.Akinrinlola.pptx
IPM strategies for plant-parasitic nematodes_R.Akinrinlola.pptx
 
Introduction to plant-parasitic nematodes_.pptx
Introduction to plant-parasitic nematodes_.pptxIntroduction to plant-parasitic nematodes_.pptx
Introduction to plant-parasitic nematodes_.pptx
 
Wayback: History of Entomopathogenic Nematodes.pptx
Wayback: History of Entomopathogenic Nematodes.pptxWayback: History of Entomopathogenic Nematodes.pptx
Wayback: History of Entomopathogenic Nematodes.pptx
 
Biological Control of Pierce Disease of Grape Vine
Biological Control of Pierce Disease of Grape VineBiological Control of Pierce Disease of Grape Vine
Biological Control of Pierce Disease of Grape Vine
 
Rufus plant microbe interactions
Rufus plant microbe interactionsRufus plant microbe interactions
Rufus plant microbe interactions
 
Rufus akinrinlola seminar_slides_for_southern_aps_meeting_2019_2_practice
Rufus akinrinlola seminar_slides_for_southern_aps_meeting_2019_2_practiceRufus akinrinlola seminar_slides_for_southern_aps_meeting_2019_2_practice
Rufus akinrinlola seminar_slides_for_southern_aps_meeting_2019_2_practice
 
Nigeria people places_foods
Nigeria people places_foodsNigeria people places_foods
Nigeria people places_foods
 
Rufus ms thesis_poster_03_22
Rufus ms thesis_poster_03_22Rufus ms thesis_poster_03_22
Rufus ms thesis_poster_03_22
 
Rufus thesis seminar_feb_2018
Rufus thesis seminar_feb_2018Rufus thesis seminar_feb_2018
Rufus thesis seminar_feb_2018
 
Rufus seminar 2017_mechanisms of biological control of plant diseases edite...
Rufus  seminar  2017_mechanisms of biological control of plant diseases edite...Rufus  seminar  2017_mechanisms of biological control of plant diseases edite...
Rufus seminar 2017_mechanisms of biological control of plant diseases edite...
 
Biological control of phytophthora sojae
Biological control of phytophthora sojaeBiological control of phytophthora sojae
Biological control of phytophthora sojae
 
Cultural practices for FHB
Cultural practices for FHBCultural practices for FHB
Cultural practices for FHB
 
Integrated management
Integrated managementIntegrated management
Integrated management
 
Chemical treatment for Fusarium head blight disease of wheat
Chemical treatment for Fusarium head blight disease of wheatChemical treatment for Fusarium head blight disease of wheat
Chemical treatment for Fusarium head blight disease of wheat
 
Bacillus species; the power points
Bacillus species; the power pointsBacillus species; the power points
Bacillus species; the power points
 
Black Pod disease of cocoa
Black Pod disease of cocoa Black Pod disease of cocoa
Black Pod disease of cocoa
 

Recently uploaded

Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...
Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...
Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...
EADTU
 
SURVEY I created for uni project research
SURVEY I created for uni project researchSURVEY I created for uni project research
SURVEY I created for uni project research
CaitlinCummins3
 
SPLICE Working Group: Reusable Code Examples
SPLICE Working Group:Reusable Code ExamplesSPLICE Working Group:Reusable Code Examples
SPLICE Working Group: Reusable Code Examples
Peter Brusilovsky
 

Recently uploaded (20)

Rich Dad Poor Dad ( PDFDrive.com )--.pdf
Rich Dad Poor Dad ( PDFDrive.com )--.pdfRich Dad Poor Dad ( PDFDrive.com )--.pdf
Rich Dad Poor Dad ( PDFDrive.com )--.pdf
 
Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...
Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...
Transparency, Recognition and the role of eSealing - Ildiko Mazar and Koen No...
 
UGC NET Paper 1 Unit 7 DATA INTERPRETATION.pdf
UGC NET Paper 1 Unit 7 DATA INTERPRETATION.pdfUGC NET Paper 1 Unit 7 DATA INTERPRETATION.pdf
UGC NET Paper 1 Unit 7 DATA INTERPRETATION.pdf
 
COMMUNICATING NEGATIVE NEWS - APPROACHES .pptx
COMMUNICATING NEGATIVE NEWS - APPROACHES .pptxCOMMUNICATING NEGATIVE NEWS - APPROACHES .pptx
COMMUNICATING NEGATIVE NEWS - APPROACHES .pptx
 
HMCS Vancouver Pre-Deployment Brief - May 2024 (Web Version).pptx
HMCS Vancouver Pre-Deployment Brief - May 2024 (Web Version).pptxHMCS Vancouver Pre-Deployment Brief - May 2024 (Web Version).pptx
HMCS Vancouver Pre-Deployment Brief - May 2024 (Web Version).pptx
 
PUBLIC FINANCE AND TAXATION COURSE-1-4.pdf
PUBLIC FINANCE AND TAXATION COURSE-1-4.pdfPUBLIC FINANCE AND TAXATION COURSE-1-4.pdf
PUBLIC FINANCE AND TAXATION COURSE-1-4.pdf
 
FSB Advising Checklist - Orientation 2024
FSB Advising Checklist - Orientation 2024FSB Advising Checklist - Orientation 2024
FSB Advising Checklist - Orientation 2024
 
REMIFENTANIL: An Ultra short acting opioid.pptx
REMIFENTANIL: An Ultra short acting opioid.pptxREMIFENTANIL: An Ultra short acting opioid.pptx
REMIFENTANIL: An Ultra short acting opioid.pptx
 
HMCS Max Bernays Pre-Deployment Brief (May 2024).pptx
HMCS Max Bernays Pre-Deployment Brief (May 2024).pptxHMCS Max Bernays Pre-Deployment Brief (May 2024).pptx
HMCS Max Bernays Pre-Deployment Brief (May 2024).pptx
 
SURVEY I created for uni project research
SURVEY I created for uni project researchSURVEY I created for uni project research
SURVEY I created for uni project research
 
SPLICE Working Group: Reusable Code Examples
SPLICE Working Group:Reusable Code ExamplesSPLICE Working Group:Reusable Code Examples
SPLICE Working Group: Reusable Code Examples
 
Pharmaceutical Biotechnology VI semester.pdf
Pharmaceutical Biotechnology VI semester.pdfPharmaceutical Biotechnology VI semester.pdf
Pharmaceutical Biotechnology VI semester.pdf
 
TỔNG HỢP HƠN 100 ĐỀ THI THỬ TỐT NGHIỆP THPT TOÁN 2024 - TỪ CÁC TRƯỜNG, TRƯỜNG...
TỔNG HỢP HƠN 100 ĐỀ THI THỬ TỐT NGHIỆP THPT TOÁN 2024 - TỪ CÁC TRƯỜNG, TRƯỜNG...TỔNG HỢP HƠN 100 ĐỀ THI THỬ TỐT NGHIỆP THPT TOÁN 2024 - TỪ CÁC TRƯỜNG, TRƯỜNG...
TỔNG HỢP HƠN 100 ĐỀ THI THỬ TỐT NGHIỆP THPT TOÁN 2024 - TỪ CÁC TRƯỜNG, TRƯỜNG...
 
Model Attribute _rec_name in the Odoo 17
Model Attribute _rec_name in the Odoo 17Model Attribute _rec_name in the Odoo 17
Model Attribute _rec_name in the Odoo 17
 
How to Send Pro Forma Invoice to Your Customers in Odoo 17
How to Send Pro Forma Invoice to Your Customers in Odoo 17How to Send Pro Forma Invoice to Your Customers in Odoo 17
How to Send Pro Forma Invoice to Your Customers in Odoo 17
 
When Quality Assurance Meets Innovation in Higher Education - Report launch w...
When Quality Assurance Meets Innovation in Higher Education - Report launch w...When Quality Assurance Meets Innovation in Higher Education - Report launch w...
When Quality Assurance Meets Innovation in Higher Education - Report launch w...
 
DEMONSTRATION LESSON IN ENGLISH 4 MATATAG CURRICULUM
DEMONSTRATION LESSON IN ENGLISH 4 MATATAG CURRICULUMDEMONSTRATION LESSON IN ENGLISH 4 MATATAG CURRICULUM
DEMONSTRATION LESSON IN ENGLISH 4 MATATAG CURRICULUM
 
dusjagr & nano talk on open tools for agriculture research and learning
dusjagr & nano talk on open tools for agriculture research and learningdusjagr & nano talk on open tools for agriculture research and learning
dusjagr & nano talk on open tools for agriculture research and learning
 
UChicago CMSC 23320 - The Best Commit Messages of 2024
UChicago CMSC 23320 - The Best Commit Messages of 2024UChicago CMSC 23320 - The Best Commit Messages of 2024
UChicago CMSC 23320 - The Best Commit Messages of 2024
 
OSCM Unit 2_Operations Processes & Systems
OSCM Unit 2_Operations Processes & SystemsOSCM Unit 2_Operations Processes & Systems
OSCM Unit 2_Operations Processes & Systems
 

Biological control of plant pathogens

  • 1. RUFUS AKINRINLOLA Graduate Student Plant Pathology Department. University of Nebraska-Lincoln BIOLOGICAL CONTROL OF PLANT PATHOGENS BIOS/PLPT 369
  • 2. Topics 1. Biological control 2. Importance of biological control 3. Mode of actions of biocontrol 4. Biocontrol application methods 5. Requirements for successful biocontrol agents 6. Limitations of biological control 7. Some commercial biological control agents 8. Summary BIOLOGICAL CONTROL OF PLANT PATHOGENS
  • 3. The term biological control :- as defined by Plant Pathologist;  the use of microbial antagonists (including bacteria or fungi) to suppress plant disease pathogens BIOLOGICAL CONTROL Inhibition of test organisms by biocontrol organism Sources: google image
  • 4.  Alternative method of disease control  Can be used in where other methods are not applicable.  Biocontrol agents are nontoxic to man and the environment.  Act on selective target organism.  Biocontrol agents are self-sustaining-easy adaptation  Diversify mode of actions  Reduced possibility of inducing resistance in pathogens  Cost effective  Long term effects Importance of biological control Emmert, E. A., & Handelsman, J. (1999). Biocontrol of plant disease: a (Gram‐) positive perspective. FEMS Microbiology letters, 171(1), 1-9.
  • 5. Mode of actions of biocontrol 1. Direct mechanism: Direct lysis or killing of pathogen by biocontrol agent  Antibiosis  Parasitism Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. 2. Indirect mechanism: Exclusion of plant pathogen as a result of the presence, activity or products of biocontrol agent.  Competition  Induced systemic resistance
  • 6. Mode of actions of biocontrol 1. Direct mechanism: Direct lysis or killing of pathogen by biocontrol agent  Antibiosis  Parasitism Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. 2. Indirect mechanism: Exclusion of plant pathogen as a result of the presence, activity or products of biocontrol agent.  Competition  Induced systemic resistance
  • 7. Mode of actions of biocontrol 1. Antibiotic mediated suppression  Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms. Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
  • 8. Mode of actions of biocontrol 1. Antibiotic mediated suppression  Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms. Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. Inhibition of pathogens by biocontrol bacteria. Photo credit: Rufus Akinrinlola
  • 9. Mode of actions of biocontrol 1. Antibiotic mediated suppression  Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms.  Volatile antibiotics • Hydrogen cyanide, • Aldehydes • Alcohols • Ketones • Sulfides  Nonvolatile antibiotics: • Polyketides (diacetylphloroglucinol; DAPG and mupirocin). • Heterocyclic nitrogenous compounds. Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
  • 10. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. 2. Parasitism  Direct utilization of pathogens as source nutrients.  Mycoparasitism refers to association in which a parasitic fungus (hyperparasite) live as a parasite to another fungus (hypoparasiste).  Also known as Hyperparasitism, when hyperparasites (biocontrol fungi) utilize hypoparasites (pathogenic fungi) as source of nutrients.  Hyperparasites produce parasitizing hyphae to acquire host nutrients.  May also requires cell wall degrading enzymes. Source: The Microbial World.
  • 11. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. A B Source: The Microbial World. Example of Mycoparasitism: Pythium oligandrum Vs Fusarium culmorum A. Single hypha of Pythium oligandrum stopped the advancement of Fusarium culmorum hyphae across an agar plate. B. At higher magnification F. culmorum hyphae are seen disrupted - the contents are highly vacuolated and coagulated.
  • 12. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. Steps involved in Mycoparasitism 1. Chemotropic growth: the biocontrol fungi grow toward the target fungi chemical stimuli. 2. Recognition stage: interaction between biocontrol receptors and that of the host fungus 3. Attachment and cell wall degradation (chitinases and glucanases). 4. Penetration (appressoria-like structures).
  • 13. Mode of actions of biocontrol Ahanger et al., 2014; Dubey and Dwivedi, 1986. Steps involved in Mycoparasitism 1. Chemotropic growth: the biocontrol fungi grow toward the target fungi chemical stimuli. 2. Recognition stage: interaction between biocontrol receptors and that of the host fungus 3. Attachment and cell wall degradation (chitinases and glucanases). 4. Penetration (appressoria-like structures). Coiling Penetration Barrier formation by host hypha Branching and sporulation Chlamydospores formation Lysis of host hypha Hyperparasite (bicontrol) Host fungus (pathogen) hypha Source: biocylopedia.com
  • 14. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. Source: Koutb and Ali, 2010 3. Competition  Exclusion of pathogens by biological control agents via competition for space or nutrients.  Production of substances (such as siderophore) for nutrient (such as iron) acquisition.  Deprive pathogens of nutrients.  It’s an indirect mechanism
  • 15. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. Source: Koutb and Ali, 2010 3. Competition  Exclusion of pathogens by biological control agents via competition for space or nutrients.  Production of substances (such as siderophore) for nutrient (such as iron) acquisition.  Deprive pathogens of nutrients.  It’s an indirect mechanism Competition for space and nutrients between Pythium irregulare pathogen (white restricted growth) and the Epicoccum purpurascens (reddish wide growth) on PDA medium after
  • 16. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. 4. Induced systemic resistance (ISR): Also known as systemic acquired resistance (SAR), resistance in plants to varieties of pathogens induced by the presence or products of biocontrol agent.
  • 17. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. ISR biocontrol agent may be;  Necrogenic pathogen (applied on leaf).  Non-pathogenic bacteria (PGPR) (applied to root or seed).  Metabolites of pathogenic or saprophytic bacteria.
  • 18. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. Microbial metabolites able to induce ISR  Polyacrylic acid  Ethylene  Salicylic acid  Acetyl salicylic acid  Amino acid derivatives  Harpin ( Erwinia amylovora) • Stress can induce defense mechanisms against pathogens
  • 19. Mode of actions of biocontrol Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58. Physical thickening of cell walls by;  Lignification.  Deposition of callose.  Accumulation of antimicrobial low-molecular-weight substances (e.g., phytoalexins).  Synthesis of various proteins (e.g., chitinases, glucanases, peroxidases, and other pathogenesis related (PR) proteins). Induced systemic resistance- defense responses
  • 20. Mode of actions of biocontrol Ahanger et al., 2014; Lee et al., 2015 Induced systemic resistance- defense responses C. Induced systemic resistance by biocontrol agent Bacillus amyloliquefaciens HK34 B. Plant treated with 0.1mM benzothiadiazole (positive control) A. Plant treated with distill water
  • 21. Biocontrol application methods  There are five application methods
  • 23. Biocontrol application methods 2. Seedling dip method
  • 27. Biocontrol application methods 1. Seed treatment 2. Dipping 3. Drench 4. Foliar prays 5. Drips Ahanger, R., Bhatand, H. A., & Dar, N. A. (2014). Biocontrol agents and their mechanism in plant disease management. Sci Acta Xaver, 5, 47-58.
  • 28. Requirements for successful biocontrol agents 1. Able to compete and persist 2. Able to colonize and proliferate 3. Must be non-pathogenic to host and environments 4. Must have excellent shelf life 5. Must be inexpensive 6. Must be able to produce in large quantities 7. Able to maintain viability 8. Delivery and application methods must support product establishment. http://flax.nzdl.org/greenstone3/flax?c=BAWELS&a=d&rt=r&d=D2712&dt=simple&p.a=b&p.s=ClassifierBrowse&cls=
  • 29. Limitations of biological control 1. Expensive/difficult to develop 2. Handling requires training 3. High Selectivity/Host Specificity 4. Variability in effectiveness 5. More susceptible to environmental conditions 6. Short shelf-life of formulations 7. Slow action 8. Storage Problem http://flax.nzdl.org/greenstone3/flax?c=BAWELS&a=d&rt=r&d=D2712&dt=simple&p.a=b&p.s=ClassifierBrowse&cls=
  • 30. Commercial biological control  Active microbe: Bacillus subtilis strain GB03  Mode of actions: Antibiosis  Company : Gustafson, Inc, Plano, TX, USA Junaid, J. M., Dar, N. A., Bhat, T. A., Bhat, A. H., & Bhat, M. A. (2013). Commercial biocontrol agents and their mechanism of action in the management of plant pathogens. International Journal of Modern Plant & Animal Sciences, 1(2), 39-57.
  • 32. Some commercial biological control agents Control of blue mold and gray mold on cherries, apples, citrus. Mode of action: Competition Applicational methods: • Dip or Drench • Spray Control of seed rot, root and stem rot and wilt caused by Fusarium, Alternaria and Phomopsis on ornamentals aand vegetables Mode of actions: Competition; Hyperparasitism; Antibiosis Junaid, J. M., Dar, N. A., Bhat, T. A., Bhat, A. H., & Bhat, M. A. (2013). Commercial biocontrol agents and their mechanism of action in the management of plant pathogens. International Journal of Modern Plant & Animal Sciences, 1(2), 39-57.
  • 33. Summary  Biological control involves the use of microbial antagonists such as bacteria or fungi to suppress plant disease pathogens.  Biocontrol have several importance and advantages over other control methods  Their mode of actions include antibiosis, competition, parasitism and induced systemic resistance.  There are however some limitations to the general use of biological control agents such variability in effectiveness, low spectrum action, short shelf life of products etc.  Some of the commercial available biocontrol agents include Biosave, Kodiak, Mycostop etc.  A biological control agent can be applied as seed treatment, root dip, soil or furrow drench, foliar sprays or through drip irrigation.
  • 35. • Junaid, J. M., Dar, N. A., Bhat, T. A., Bhat, A. H., & Bhat, M. A. (2013). Commercial biocontrol agents and their mechanism of action in the management of plant pathogens. International Journal of Modern Plant & Animal Sciences, 1(2), 39-57. • Jetiyanon, K., Fowler, W. D., & Kloepper, J. W. (2003). Broad-spectrum protection against several pathogens by PGPR mixtures under field conditions in Thailand. Plant Disease, 87(11), 1390-1394. • Lee, B. D., Dutta, S., Ryu, H., Yoo, S. J., Suh, D. S., & Park, K. (2015). Induction of systemic resistance in Panax ginseng against Phytophthora cactorum by native Bacillus amyloliquefaciens HK34. Journal of ginseng research, 39(3), 213-220. • Koutb, M., & Ali, E. H. (2010). Potential of Epicoccum purpurascens Strain 5615 AUMC as a biocontrol agent of Pythium irregulare root rot in three leguminous plants. Mycobiology, 38(4), 286-294. • Kilic-Ekici, O., & Yuen, G. Y. (2003). Induced resistance as a mechanism of biological control by Lysobacter enzymogenes strain C3. Phytopathology, 93(9), 1103-1110. Sources

Editor's Notes

  1. As an introduction, I suggest that define what is biological control and explain why biological control is important. As the topic, I suggest you explain the advantages and limitations of biological control.  
  2. Huffaker, C. B. (Ed.). (2012). Theory and practice of biological control. Elsevier.   Advantages of biological control Biological control has many advantages as a pest control method, particularly when compared with insecticides. One of the most important benefits is that biological control is an environmental friendly method and does not introduce pollutants into the environment. As Kok (1999) points out, biological control should be implemented whenever possible because it does not pollute the environment. We mentioned earlier several problems which are caused by insecticides and are related with environment pollution. The great advantage of this method is its selectivity. By this way, there is a restricted danger of damage to non target plant species. Weeden and Shelton (2005) underline that biological control does not create new problems, like conventional pesticides. According to van Emden (2004:149) "this does not mean that side effects can be totally excluded, although they have been very rare in the history of biological control". Selectivity is the most important factor regarding the balance of agricultural ecosystems because a great damage to non target species can lead to the restriction of natural enemies' populations. This can cause increased pest populations as mentioned earlier. How successfully a Biological control agent (BCA) can be deployed in an agricultural ecosystem, so as not to damage non target pests, depends on appropriate host specificity tests which determine the potential host range (Kok, 1999). The ability to self-perpetuate is an extremely interesting advantage of biological control method. According to Kok (1999), BCAs will increase in number and spread. Because BCAs are self-propagating and dispersing, pest control is self-perpetuating too. This is quite important regarding the economic feasibility of biological control (Reichelderfer, 1981). Another advantage of biological control method, which is a proof of environmental safety of BCAs, is that the pest is unable (or very slow) to develop resistance (Weeden and Shelton, 2005). It is probably possible a target pest to develop mechanisms of defence against attack by a natural enemy. For example, we could imagine that an effective control of a pest by a natural enemy could cause strong selection on the pest so as to develop mechanisms of escape or tolerance to attacks by the control agent, breaking down biocontrol system (Holt and Hochberg, 2005). Some examples of defence mechanisms that could develop by pests are escape behaviour and repellent chemicals. However, as Van Emden (2004) mentions, "we know of no cases where previously successful biological control has failed because of selection for resistance". Biological control can be cost effective. Its effectiveness is based on self-perpetuation and self-propagation as we mentioned earlier. Therefore, if we establish a control agent in a specific area, it will reduce the target pest in an acceptable threshold for quite long time (Kok, 1999). A small number of biocontrol agents can grow to very high densities and provide continuous control of a pest over a large area. When the cost of deployment of BCAs is considered in contrast to pesticide applications, biological control is generally less expensive than chemical control (Agriculture, Food and Rural Development of Canada, 2000). The financial benefit of biological control is greatest in cases when there is no other option. For example, biological control is very effective in inaccessible areas. Another interesting point regarding the cost efficiency of this method is that the yield benefit of biological control is probably less than yield achieved by agrochemicals, but the primary cost of BCA is generally lower than chemical pesticides (Reichelderfer
  3. 4. Antibiotic mediated suppression Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms.Antibiotics produced by bacteria include volatile antibiotics (hydrogen cyanide, aldehydes, alcohols, ketones, and sul?des) and nonvolatile antibiotics: polyketides (diacetylphloroglucinol; DAPG and mupirocin), heterocyclic nitrogenous compounds
  4. 4. Antibiotic mediated suppression Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms.Antibiotics produced by bacteria include volatile antibiotics (hydrogen cyanide, aldehydes, alcohols, ketones, and sul?des) and nonvolatile antibiotics: polyketides (diacetylphloroglucinol; DAPG and mupirocin), heterocyclic nitrogenous compounds
  5. 4. Antibiotic mediated suppression Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms.Antibiotics produced by bacteria include volatile antibiotics (hydrogen cyanide, aldehydes, alcohols, ketones, and sul?des) and nonvolatile antibiotics: polyketides (diacetylphloroglucinol; DAPG and mupirocin), heterocyclic nitrogenous compounds
  6. 4. Antibiotic mediated suppression Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms.Antibiotics produced by bacteria include volatile antibiotics (hydrogen cyanide, aldehydes, alcohols, ketones, and sul?des) and nonvolatile antibiotics: polyketides (diacetylphloroglucinol; DAPG and mupirocin), heterocyclic nitrogenous compounds
  7. 4. Antibiotic mediated suppression Antibiotics are microbial toxins that can, at low concentrations, poison or kill other microorganisms.Antibiotics produced by bacteria include volatile antibiotics (hydrogen cyanide, aldehydes, alcohols, ketones, and sul?des) and nonvolatile antibiotics: polyketides (diacetylphloroglucinol; DAPG and mupirocin), heterocyclic nitrogenous compounds 5. Competition This process is considered to be an indirect interaction whereby pathogens are excluded by Biocontrol agents and their mechanism in plant disease management 51 depletion of a food base or by physical occupation of site (Loritoet al., 1994). Biocontrol by nutrient competition can occur when the biocontrol agent decreases the availability of a particular substance thereby limiting the growth of the pathogen. Particularly, the biocontrol agents have a more efficient uptake or utilizing system for the substance than do the pathogens (Handelsman and Parke, 1989). For example, iron competition in alkaline soils may be a limiting factor for microbial growth in such soils (Leongand Expert 1989). Some bacteria, especially fluorescent pseudomonads produce siderophores that have very high affinities for iron and can sequester this limited resource from other microflora thereby preventing their growth (Loper and Buyer
  8. 6. Parasitism This process involves the direct utilization of one organism as food by another (Handelsman and Parke 1989). Fungi that are parasitic on other fungi are usually referred to as mycoparasites (Ba ker and Cook 1974.). Many mycoparasites occur on a wide range of fungi and some of them have been proposed to play an important role in disease control (Adams, 1990). For example, Darlucafilum( nowSphaerellopsisfilum) was described by Saccardo as a parasite of some rust fungi, especially Pucciniaand Uromyces(Sundheim and Tronsmo 1988). Trichodermalignorum(T. viride) parasitizing hyphae of Rhizoctoniasolaniand suggestion of RayeesA.Ahanger, Hilal A. Bhatand Nisar A. Dar 52 inoculating soil with Trichodermaspores to control damping-off of citrus seedling was reported by Weindling and Fawcett in 1936. This and other Trichodermaspecies were observed to parasitize Rhizoctoniabataticolaand Armillariamellea(Baker and Cook. 1974). Generally, mycoparasitism can be described as a four-step process (Chet, 1987): The first stage is chemotropic growth. The biocontrol fungi grow tropistically toward the target fungi that produce chemical stimuli. For example, a volatile or water- soluble substance produced by the host fungus serves as a chemo attractant for parasites. The next step is recognition. Lectins of hosts (pathogens) and carbohydrate receptors on the surface of the biocontrol fungus may be involved in this specific interaction (Inbar and Chet 1994). The third step is attachment and cell wall degradation. Mycoparasites can usually either coil around host hyphae or grow alongside it and produce cell wall degrading enzymes to attack the target fungus (Chet, 1987). These enzymes such as chitinases and b-1,3-glucanase may be involved in degradation of host cell walls and may be components of complex mixtures of synergistic proteins that act together against pathogenic fungi (Di Pietro, et al, 1992). The final step is penetration. The biocontrol agent produces appressoria-like structures to penetrate the target fungus cell wall (Chet, 1987). In hyperparasitism, the pathogen is directly attacked by a specific BCA that kills it or its propagules.
  9. 6. Parasitism This process involves the direct utilization of one organism as food by another (Handelsman and Parke 1989). Fungi that are parasitic on other fungi are usually referred to as mycoparasites (Ba ker and Cook 1974.). Many mycoparasites occur on a wide range of fungi and some of them have been proposed to play an important role in disease control (Adams, 1990). For example, Darlucafilum( nowSphaerellopsisfilum) was described by Saccardo as a parasite of some rust fungi, especially Pucciniaand Uromyces(Sundheim and Tronsmo 1988). Trichodermalignorum(T. viride) parasitizing hyphae of Rhizoctoniasolaniand suggestion of RayeesA.Ahanger, Hilal A. Bhatand Nisar A. Dar 52 inoculating soil with Trichodermaspores to control damping-off of citrus seedling was reported by Weindling and Fawcett in 1936. This and other Trichodermaspecies were observed to parasitize Rhizoctoniabataticolaand Armillariamellea(Baker and Cook. 1974). Generally, mycoparasitism can be described as a four-step process (Chet, 1987): The first stage is chemotropic growth. The biocontrol fungi grow tropistically toward the target fungi that produce chemical stimuli. For example, a volatile or water- soluble substance produced by the host fungus serves as a chemo attractant for parasites. The next step is recognition. Lectins of hosts (pathogens) and carbohydrate receptors on the surface of the biocontrol fungus may be involved in this specific interaction (Inbar and Chet 1994). The third step is attachment and cell wall degradation. Mycoparasites can usually either coil around host hyphae or grow alongside it and produce cell wall degrading enzymes to attack the target fungus (Chet, 1987). These enzymes such as chitinases and b-1,3-glucanase may be involved in degradation of host cell walls and may be components of complex mixtures of synergistic proteins that act together against pathogenic fungi (Di Pietro, et al, 1992). The final step is penetration. The biocontrol agent produces appressoria-like structures to penetrate the target fungus cell wall (Chet, 1987). In hyperparasitism, the pathogen is directly attacked by a specific BCA that kills it or its propagules.
  10. 5. Competition This process is considered to be an indirect interaction whereby pathogens are excluded by Biocontrol agents and their mechanism in plant disease management 51 depletion of a food base or by physical occupation of site (Loritoet al., 1994). Biocontrol by nutrient competition can occur when the biocontrol agent decreases the availability of a particular substance thereby limiting the growth of the pathogen. Particularly, the biocontrol agents have a more efficient uptake or utilizing system for the substance than do the pathogens (Handelsman and Parke, 1989). For example, iron competition in alkaline soils may be a limiting factor for microbial growth in such soils (Leongand Expert 1989). Some bacteria, especially fluorescent pseudomonads produce siderophores that have very high affinities for iron and can sequester this limited resource from other microflora thereby preventing their growth (Loper and Buyer
  11. 5. Competition This process is considered to be an indirect interaction whereby pathogens are excluded by Biocontrol agents and their mechanism in plant disease management 51 depletion of a food base or by physical occupation of site (Loritoet al., 1994). Biocontrol by nutrient competition can occur when the biocontrol agent decreases the availability of a particular substance thereby limiting the growth of the pathogen. Particularly, the biocontrol agents have a more efficient uptake or utilizing system for the substance than do the pathogens (Handelsman and Parke, 1989). For example, iron competition in alkaline soils may be a limiting factor for microbial growth in such soils (Leongand Expert 1989). Some bacteria, especially fluorescent pseudomonads produce siderophores that have very high affinities for iron and can sequester this limited resource from other microflora thereby preventing their growth (Loper and Buyer
  12. These defense responses physical thickening of cell walls by lignification, deposition of callose, accumulation of antimicrobial low-molecular-weight substances (e.g., phytoalexins), and synthesis of various proteins (e.g., chitinases, glucanases, peroxidases, and other pathogenesisrelated (PR) proteins) (Hammerschmidt, et al, 1984). This defense system is also triggered when plants are colonized by plant growth- promoting rhizobacteria (Sticher, et al., 1997) and a few binucleate Rhizoctonia(BNR) AG-K (Poromarto, et al., 1988). Recently, many strains of PGPR have been shown to be effective in controlling plant diseases by inducing plant systemic resistance (Liu, et al., 1995). Plants colonized by these strains are more resistant to foliar diseases, even though the PGPR is present only on roots (Wei, 1996). The chemical compounds that induce resistance of plants to pathogens may include polyacrylic acid, ethylene, salicylic acid and acetyl salicylic acid, various amino acid derivatives, the herbicide phosphinotricin, and harpin produced by Erwiniaamylovora(Sequeira, 1983). It is known that stress can induce defense mechanisms against pathogens (Maurhofer, et al., 1994). However, the hypothesis should be proved by genetic analysis such as heterologous expression, which shows that inducing ability may be transferred to other potent strains as an additional complementary mode of action, and gene mutation, which knocks out the ability and leads to less disease control. Induced resistance is an important mechanism of biological control by a number of strains of plant growth-promoting rhizobacteria (PGPR) applied to roots or seed (17,20,27,28). It also can be induced by foliar application of plant-pathogenic bacteria (24), their metabolites (25,30), and metabolites produced by saprophytic bacterial strains (23).
  13. These defense responses physical thickening of cell walls by lignification, deposition of callose, accumulation of antimicrobial low-molecular-weight substances (e.g., phytoalexins), and synthesis of various proteins (e.g., chitinases, glucanases, peroxidases, and other pathogenesisrelated (PR) proteins) (Hammerschmidt, et al, 1984). This defense system is also triggered when plants are colonized by plant growth- promoting rhizobacteria (Sticher, et al., 1997) and a few binucleate Rhizoctonia(BNR) AG-K (Poromarto, et al., 1988). Recently, many strains of PGPR have been shown to be effective in controlling plant diseases by inducing plant systemic resistance (Liu, et al., 1995). Plants colonized by these strains are more resistant to foliar diseases, even though the PGPR is present only on roots (Wei, 1996). The chemical compounds that induce resistance of plants to pathogens may include polyacrylic acid, ethylene, salicylic acid and acetyl salicylic acid, various amino acid derivatives, the herbicide phosphinotricin, and harpin produced by Erwiniaamylovora(Sequeira, 1983). It is known that stress can induce defense mechanisms against pathogens (Maurhofer, et al., 1994). However, the hypothesis should be proved by genetic analysis such as heterologous expression, which shows that inducing ability may be transferred to other potent strains as an additional complementary mode of action, and gene mutation, which knocks out the ability and leads to less disease control. Induced resistance is an important mechanism of biological control by a number of strains of plant growth-promoting rhizobacteria (PGPR) applied to roots or seed (17,20,27,28). It also can be induced by foliar application of plant-pathogenic bacteria (24), their metabolites (25,30), and metabolites produced by saprophytic bacterial strains (23).
  14. These defense responses physical thickening of cell walls by lignification, deposition of callose, accumulation of antimicrobial low-molecular-weight substances (e.g., phytoalexins), and synthesis of various proteins (e.g., chitinases, glucanases, peroxidases, and other pathogenesisrelated (PR) proteins) (Hammerschmidt, et al, 1984). This defense system is also triggered when plants are colonized by plant growth- promoting rhizobacteria (Sticher, et al., 1997) and a few binucleate Rhizoctonia(BNR) AG-K (Poromarto, et al., 1988). Recently, many strains of PGPR have been shown to be effective in controlling plant diseases by inducing plant systemic resistance (Liu, et al., 1995). Plants colonized by these strains are more resistant to foliar diseases, even though the PGPR is present only on roots (Wei, 1996). The chemical compounds that induce resistance of plants to pathogens may include polyacrylic acid, ethylene, salicylic acid and acetyl salicylic acid, various amino acid derivatives, the herbicide phosphinotricin, and harpin produced by Erwiniaamylovora(Sequeira, 1983). It is known that stress can induce defense mechanisms against pathogens (Maurhofer, et al., 1994). However, the hypothesis should be proved by genetic analysis such as heterologous expression, which shows that inducing ability may be transferred to other potent strains as an additional complementary mode of action, and gene mutation, which knocks out the ability and leads to less disease control. Induced resistance is an important mechanism of biological control by a number of strains of plant growth-promoting rhizobacteria (PGPR) applied to roots or seed (17,20,27,28). It also can be induced by foliar application of plant-pathogenic bacteria (24), their metabolites (25,30), and metabolites produced by saprophytic bacterial strains (23).
  15. Callose is a plant polysaccharide. It is composed of glucose residues linked together through β-1,3-linkages, and is termed a β-glucan. It is thought to be manufactured at the cell wall by callose synthases and is degraded by β-1,3-glucanases.
  16. Fig. 2. Effect of HK34 on the induction of systemic resistance against Phytophthora cactorum in leaves obtained from plants treated once under greenhouse conditions. Leaves are from plants treated with (A) sterile distilled water (negative control), (B) 0.1mM benzothiadiazole (positive control), and (C) HK34.
  17. METHODS OF APPLICATION Before application, BioSave T' 1 should be resuspended in water for at least 10 minutes for the frozen pellet formulation, and for 30 minutes for the dry formulation to allow for cell rehydration. The recommended rate is 250 g of frozen pellets or dry formulation per 150 liters, which results in a suspension containing 1.6 x 10 CFU/ml (a minimum guarantied by the manufacturer). BioSaveTM has been applied as a drench to bins with apples and pears, as a drip application with rotating brushes to apples, pears and citrus fruit on packing lines, or as a dip to apples and pears on packing lines. Application to potatoes has been mainly through a lowvolume spray during piling up of potatoes in storages, and to sweet potatoes as a dip. Since BioSavelM is exempt from residue tolerance, it can be applied to the commodities at any time prior, during and after storage, even immediately before packing.
  18. METHODS OF APPLICATION Before application, BioSave T' 1 should be resuspended in water for at least 10 minutes for the frozen pellet formulation, and for 30 minutes for the dry formulation to allow for cell rehydration. The recommended rate is 250 g of frozen pellets or dry formulation per 150 liters, which results in a suspension containing 1.6 x 10 CFU/ml (a minimum guarantied by the manufacturer). BioSaveTM has been applied as a drench to bins with apples and pears, as a drip application with rotating brushes to apples, pears and citrus fruit on packing lines, or as a dip to apples and pears on packing lines. Application to potatoes has been mainly through a lowvolume spray during piling up of potatoes in storages, and to sweet potatoes as a dip. Since BioSavelM is exempt from residue tolerance, it can be applied to the commodities at any time prior, during and after storage, even immediately before packing.
  19. METHODS OF APPLICATION Before application, BioSave T' 1 should be resuspended in water for at least 10 minutes for the frozen pellet formulation, and for 30 minutes for the dry formulation to allow for cell rehydration. The recommended rate is 250 g of frozen pellets or dry formulation per 150 liters, which results in a suspension containing 1.6 x 10 CFU/ml (a minimum guarantied by the manufacturer). BioSaveTM has been applied as a drench to bins with apples and pears, as a drip application with rotating brushes to apples, pears and citrus fruit on packing lines, or as a dip to apples and pears on packing lines. Application to potatoes has been mainly through a lowvolume spray during piling up of potatoes in storages, and to sweet potatoes as a dip. Since BioSavelM is exempt from residue tolerance, it can be applied to the commodities at any time prior, during and after storage, even immediately before packing.
  20. METHODS OF APPLICATION Before application, BioSave T' 1 should be resuspended in water for at least 10 minutes for the frozen pellet formulation, and for 30 minutes for the dry formulation to allow for cell rehydration. The recommended rate is 250 g of frozen pellets or dry formulation per 150 liters, which results in a suspension containing 1.6 x 10 CFU/ml (a minimum guarantied by the manufacturer). BioSaveTM has been applied as a drench to bins with apples and pears, as a drip application with rotating brushes to apples, pears and citrus fruit on packing lines, or as a dip to apples and pears on packing lines. Application to potatoes has been mainly through a lowvolume spray during piling up of potatoes in storages, and to sweet potatoes as a dip. Since BioSavelM is exempt from residue tolerance, it can be applied to the commodities at any time prior, during and after storage, even immediately before packing.
  21. METHODS OF APPLICATION Before application, BioSave T' 1 should be resuspended in water for at least 10 minutes for the frozen pellet formulation, and for 30 minutes for the dry formulation to allow for cell rehydration. The recommended rate is 250 g of frozen pellets or dry formulation per 150 liters, which results in a suspension containing 1.6 x 10 CFU/ml (a minimum guarantied by the manufacturer). BioSaveTM has been applied as a drench to bins with apples and pears, as a drip application with rotating brushes to apples, pears and citrus fruit on packing lines, or as a dip to apples and pears on packing lines. Application to potatoes has been mainly through a lowvolume spray during piling up of potatoes in storages, and to sweet potatoes as a dip. Since BioSavelM is exempt from residue tolerance, it can be applied to the commodities at any time prior, during and after storage, even immediately before packing.
  22. METHODS OF APPLICATION Before application, BioSave T' 1 should be resuspended in water for at least 10 minutes for the frozen pellet formulation, and for 30 minutes for the dry formulation to allow for cell rehydration. The recommended rate is 250 g of frozen pellets or dry formulation per 150 liters, which results in a suspension containing 1.6 x 10 CFU/ml (a minimum guarantied by the manufacturer). BioSaveTM has been applied as a drench to bins with apples and pears, as a drip application with rotating brushes to apples, pears and citrus fruit on packing lines, or as a dip to apples and pears on packing lines. Application to potatoes has been mainly through a lowvolume spray during piling up of potatoes in storages, and to sweet potatoes as a dip. Since BioSavelM is exempt from residue tolerance, it can be applied to the commodities at any time prior, during and after storage, even immediately before packing.
  23. METHODS OF APPLICATION Before application, BioSave T' 1 should be resuspended in water for at least 10 minutes for the frozen pellet formulation, and for 30 minutes for the dry formulation to allow for cell rehydration. The recommended rate is 250 g of frozen pellets or dry formulation per 150 liters, which results in a suspension containing 1.6 x 10 CFU/ml (a minimum guarantied by the manufacturer). BioSaveTM has been applied as a drench to bins with apples and pears, as a drip application with rotating brushes to apples, pears and citrus fruit on packing lines, or as a dip to apples and pears on packing lines. Application to potatoes has been mainly through a lowvolume spray during piling up of potatoes in storages, and to sweet potatoes as a dip. Since BioSavelM is exempt from residue tolerance, it can be applied to the commodities at any time prior, during and after storage, even immediately before packing.
  24. Limitations or Disadvantages of Microbial Control 1) High Selectivity/Host Specificity: Since the microbial agent is effective against only single pest species there is a very limited market potential. 2) Requirement of Additional Control Measures: An additional control measures are needed for non-target insect pest species. It present and not kept below ETL by natural control factor. 3) The Correct Time of Application: In this respect, the incubation period of disease, which is a critical factor and difficult to judge because of age specificity and stage specificity. The pathogens attack on certain stage (larval) and do not produce effect on eggs or adults. Susceptibility of larvae also decreases with increase in age. 4) Delayed Effect/Mortality: The pathogens require some time to produce response in their target host owing to its long disease incubation period. 5) The pathogens like viruses, bacteria must be ingested as early as possible to produce effects, while the fungi required entry through body integument for which good coverage of spray deposits is important. 6) Storage Problem: It is necessary to maintain the pathogen in viable condition. Even average temperature and sunlight degrade the microbial preparations. Exposure to sunlight causes UV radiation and losses its virulent immediately. The pathogens have very short self life. 7) Difficulty of Culturing in Large Quantities: Rearing host insect on artificial diet is more cumbersome and laborious works which requires constant supervision. The whole organisms techniques for in vivo prorogation of virus are fairly labourious and expensive. 8) Short Residual Effectiveness: This is the major limitation absent the effectiveness of pathogen under field conditions as sunlight causes UV radiation. 9) Not legally protected and data needed for registration is highly expensive.
  25. Limitations or Disadvantages of Microbial Control 1) High Selectivity/Host Specificity: Since the microbial agent is effective against only single pest species there is a very limited market potential. 2) Requirement of Additional Control Measures: An additional control measures are needed for non-target insect pest species. It present and not kept below ETL by natural control factor. 3) The Correct Time of Application: In this respect, the incubation period of disease, which is a critical factor and difficult to judge because of age specificity and stage specificity. The pathogens attack on certain stage (larval) and do not produce effect on eggs or adults. Susceptibility of larvae also decreases with increase in age. 4) Delayed Effect/Mortality: The pathogens require some time to produce response in their target host owing to its long disease incubation period. 5) The pathogens like viruses, bacteria must be ingested as early as possible to produce effects, while the fungi required entry through body integument for which good coverage of spray deposits is important. 6) Storage Problem: It is necessary to maintain the pathogen in viable condition. Even average temperature and sunlight degrade the microbial preparations. Exposure to sunlight causes UV radiation and losses its virulent immediately. The pathogens have very short self life. 7) Difficulty of Culturing in Large Quantities: Rearing host insect on artificial diet is more cumbersome and laborious works which requires constant supervision. The whole organisms techniques for in vivo prorogation of virus are fairly labourious and expensive. 8) Short Residual Effectiveness: This is the major limitation absent the effectiveness of pathogen under field conditions as sunlight causes UV radiation. 9) Not legally protected and data needed for registration is highly expensive.
  26. As an introduction, I suggest that define what is biological control and explain why biological control is important. As the topic, I suggest you explain the advantages and limitations of biological control.
  27. As an introduction, I suggest that define what is biological control and explain why biological control is important. As the topic, I suggest you explain the advantages and limitations of biological control.