Date post: | 21-Jan-2018 |
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INTEGRATED CEREAL CROPS DISEASE MANGMENTS IN IRIGATED AGRICULTURAL
Prof. Mohamed Abdelkader Hasan
Cereal Pathology
PPI(ARC) [email protected]
INTEGRATED CEREAL CROPS DISEASE MANGMENTS IN IRIGATED AGRICULTURAL
Cereal crops in irrigated area are suffering from many
diseases
Seed born
diseases
Foliar
diseases
PLANT DISEASES
Plant disease is an impairment
of the normal state of a plant
that interrupts or modifies its
vital functions
Disease infection leads to
• Complete damage to the economic
part ( loose smut) • Partial damage to the economic part
(covered smut). • Damage to the other parts (down
mildew, powdery mildew, leaf spot and rusts)
Missing plants (damping –off, wilt)
A biotic factors
nutriments, pesticide exposure, environment pollution, température, moisture, & light.
Biotic factors fungi, bacteria, nematodes, parasitic plants & virus
The Disease Triangle
Environment
Pathogen HostDISEASE
Properties of PathogenLevel of virulence Adaptability Dispersal efficiency Survival efficiency Reproductive fitness
Properties of HostSusceptibility Growth stage & form Population density & structure
General healthProperties of Environment
Temperature Rainfall / Dew Leaf wetness period Soil properties Wind
Plant disease can be
• Sporadic the disease appear on few host plant
and distribute in a different places on the field
• Endemic the disease appear yearly on a
regular basis and in moderate severity
• Epidemic the disease appear with high severity
on most of the field and high
sensitivity to the environmental
conditions
Stages in Disease Development
• 1) Inoculation
• 2) Penetration
• 3) Infection
• 4)Growth and Reproduction
• 5)Dissemination of Pathogen
7
Host Resistant Susceptible Disease reaction
Pathogen Avirulent Virulent Pathogenicity
Host:Pathogen
Interaction
Incompatible
[Low]
Compatible
[High]
Infection type or
phenotype
Concepts and terminology - host: pathogen interactionsConcepts and terminology - host: pathogen
interactions
8
Resistant Susceptible
and terminology
Concepts and terminology -resistance and susceptibility
A B
0 1
- At what level is the cut-off between resistance and susceptiblity?
- Cultivar A is more resistant than cultivar B
Resistance and susceptibility are relative terms - they represent a continuum on a scale - e.g. stripe rust, scale from 0 to 1:
Not all resistance provides a level of protection that will prevent yield losses:
- Stripe rust resistance gene Yr18:
- ffungicides protected plots - noloss
- ssusceptible control - 75%loss
- Yr18 line - 30%loss
Breeders want resistance that is:easy to select, minimies yield loss, is durable
Plant Resistance: the retardation of infection and growth of a parasite on or with in host tissues.
Monogenic resistance
Race specific
Polygenic resistanceRace non specific
Fast lastDurable
More than one gene (minor)
Cultivarresistance
One major gene
Identification resistance genes
• 1- Gene postulation( probable)
• 2- Genetic analysis
• 3- Using DNA markers
Advantages:-
1- Analysis can be done in several weeks
2- Easy when only a few genes are present .
Gene postulation
Disadvantages:-
1- A collection of isolates differing in virulence is required.
2- The presence of a gene is indicated but not proven.
3- This method used only in identification of resistance
genes that express in seedling plants and not
appropriate for the identification of resistance genes that
are expressed in adult plants.
4-When more than one effective resistance gene is present in a
cultivar or breeding line, the characteristic infection types of
the individual genes are often altered due to interaction
between the resistance genes.
2- Genetic analysis
Advantages:-
1- Very accurate.
2-This method used for identification resistance
genes that express in seedling plants and also
appropriate for the identification of resistance
genes that are expressed in adult plants.
Disadvantages:-
1- This method needs at least 3 years for
identification any resistance genes .
Advantages:
• Detects variations directly at DNA level
• Not influenced by environment
• Numerous in number
• Automation is possible
Disadvantages:-
• Costs
• Trained peoples
Molecular techniques
INTEGRATED CEREAL CROPS DISEASE (ICM)
• Is the causal organism really causing the problem?
• 1st Step: Always identify causal organism before taking any action!
• Become familiar with its life cycle and habits
• Use the information to design a diseasemanagement plan
• Misidentification results in lack of knowledge = ineffective control of the real disease.
• Seed rate
• Crop rotation
• Preparation of suitable seed bed( soil born diseases)
• Irrigation
• fertilization
• Trap crops
Powdery mildew Plant density will be high
Biological control
In some cases we can use the natural enemies of the disease, fungi, bacteria and insect to reduce the disease severity
Bacillus thuringiensis
Applied Chemical Control
• fungicide: any material that is applied to kill, attract, repel, or regulate the disease
• Advantages: effective, fast, easy
• Fungicide should be:
*On the right time
*recommended dose
fungicides vary by…
• Mode of action: how they work to control the
the disease
– Systemic fungicides are absorbed through tissues and transported elsewhere where the disease encounters it
– Contact fungicides must come in direct contact with the disease