Slide 2: Characters of desirable bio control agents Presented
K.Ragunath WHAT ARE BIO CONTROL AGENTS ? : WHAT ARE BIO CONTROL AGENTS ? A system of controlling plant pests, nematodes and diseases without the use of chemicals, by employing
parasites that feed upon them. Slide 4: A M fungi Trichoderma spp Pseudomonas spp Azetobacter spp Bio control
agents l k j m Slide 5: A M fungi Pseudomonas spp Bacillus spp Trichoderma spp Pasteuria penetrans Azetobacter spp B C A for nematode
Control l j m k h f FUNGI -Trichoderma spp : FUNGI -Trichoderma spp The fungal genus Trichoderma contains species that have the potential to be of economic importance
Species in this genus are useful in the biological control of soilborne diseases (19) and tree decays.
Some species produce useful bio chemicals and antibiotics and others are involved in plant disease . Evaluation of Trichoderma spp as biocontrol against nematode : Evaluation of Trichoderma spp as biocontrol against nematode The implementation of Trichoderma in IPM can be achieved using a soil treatment which reduced amounts of fungicides
Trichoderma harzianum & T. lignorum isolates were tested for their nematicidal activity against the root-knot nematode Meloidogyne javanica It is suggested that the main antinematode activity caused by
T. harzianum takes place in the soil and not within the roots. Slide 8: Mycoparasitism
chitinase Induced systemic
Trichodermin , dermadin,
trichoviidin Competition Solubilization & sequestration
plant nutrients Mechanism of action k l m j f Antagonistic fungus : Antagonistic fungus Many species of
Trichoderma hamatum Commercial form : Commercial form Bacteria –Pseudomonas fluorescens : Bacteria –Pseudomonas fluorescens Members of the genus display the following defining characteristics:
- Rod shaped
- One or more polar flagella, providing motility
- Aerobic, although some species have been found-to be facultative anaerobes
(e.g. P. aeruginosa)
- Non–spore forming
- Positive catalase test BIO FILM FORMATION : BIO FILM FORMATION Slime production also contributes to surface-colonising biofilms which are difficult to remove from food preparation surfaces MECHANISM OF ACTION : MECHANISM OF ACTION Antibiotic-mediated suppression
-phenazines, tropolone, pyrrolnitrin
Siderophore – mediated supression
-produce fluorescent siderophores which link with supression ability
Induced systemic resistance
-activates multiple defence mechanism Some keys : Some keys APPLICATION:
- Soil-borne pathogens are controlled with the use of seed treatments or hopper-box applications and foliar pathogens by spray applications
- Store in a cool, dry place in a sealed container
ENVIRONMENTAL IMPACT AND NON-TARGET TOXICITY:
- P. fluorescens. occurs widely in nature and is not expected to have any adverse effects on non-target organisms. P. fluorescence : P. fluorescence Pasteuria penetrans : Pasteuria penetrans Very effective against root knot nematodes in many crops.
The lifecycle has four stages
-sporogenesis characters : characters Pasteuria penetrans and related forms are considered as potential biological control agents of phytoparasitic nematodes.
Host adhesion is one of the most critical steps in the life-cycle of Pasteuria.
The endospores are released in soil by decaying hosts
The endospore represents the parasite durable stage as well as the infective propagule responsible for transmission. Endospore formation : Endospore formation Pasteuria endospore from Helicotylenchus lobus Pasteuria endospores
adhering to the cuticle
of Hoplolaimus galeatus AM Arbuscular Mycorrhizae : AM Arbuscular Mycorrhizae A symbiotic relationship with legumious plants.
The VAM fungi penetrate the living cells of plants without harming them, and form the typical organs, such as vesicles and arbuscles, in the root .
VAM fungi-infected plants have high potential of resistance to soil environmental stresses. ROLE : ROLE The known functions of VAM fungi on plants are that
1) the absorption of minerals, especially P, is promoted,
2) growth is stimulated,
3) high quality of fruits is produced every year,
4) resistance to environmental stresses is enhanced, and
5) resistance to soil disease is enhanced CONSIDERATIONS : CONSIDERATIONS While using care for
Cut down the amount of agrochemicals and chemical fertilizers applied.
Use fermented organic matter.
Use soil conditioners, such as charcoal and zeolite.
Consider the effectiveness of grasses
. Improve soil pH and aeration. Commercial form : Commercial form VAM fungi : VAM fungi Characters of desirable bio control agents : Characters of desirable bio control agents An desirable bio control agents should have following characteristics
It should not be pathogenic to plants, animals, human beings and microorganisms.
It should have broad spectrum of activity in controlling many types of diseases and must be genetically stable.
It should have fast growth and sporulation
It must be cultured under artificial media Contd ………. : Contd ………. The innoculam must be capable of abundant production using conventional methods such as liquid fermentation and withstanding term storage until application
It should be amenable for inexpensive mass multiplication and economically viable.
It should have long shelf life
It must be efficacious under different environmental conditions.
It should be compatable with bio fertilizers Contd…. : Contd…. It have host susceptibility to the action by the seed treating chemicals
It should not be toxic to beneficial organisms in or on the target area.
It should be easily formulated and method of application must be convenient and compatible with common cultural practices. Contd… : Contd… It should easily establish in the soil with high persistence and survival capacity
It should be biologically competitive with microorganisms REFERENCE : REFERENCE nematologists.org.au/Jan01/paecilomyces. htm
Biological control of crop diseases
- D. Dinakaran, G.Arjunan, G.Karthikeyan.