This document discusses integrated cereal crop disease management in irrigated agriculture. It notes that cereal crops in irrigated areas suffer from many seed-borne, foliar, and other diseases. It outlines the disease triangle of pathogen, host, and environment factors that influence disease development. It also discusses plant disease identification and stages of disease. Further, it explores host-pathogen interactions and concepts of resistance and susceptibility. The document then examines methods for identifying resistance genes. Finally, it proposes an integrated cereal crop disease management approach involving agricultural practices, resistant varieties, biological control, and applied chemical control using appropriate fungicides.

1. INTEGRATED CEREAL CROPS DISEASE
MANGMENTS IN IRIGATED AGRICULTURAL
Prof. Mohamed Abdelkader Hasan
Cereal Pathology
PPI(ARC) Egypt
abdelkaderhasan@yahoo.com

2. 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

3. 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

4. The Disease Triangle
Environment
Pathogen Host
DISEASE
Properties of Pathogen
Level of virulence
Adaptability
Dispersal efficiency
Survival efficiency
Reproductive fitness
Properties of Host
Susceptibility
Growth stage & form
Population density &
structure
General health
Properties of Environment
Temperature
Rainfall / Dew
Leaf wetness period
Soil properties
Wind

5. 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

6. Stages in Disease Development
• 1) Inoculation
• 2) Penetration
• 3) Infection
• 4)Growth and Reproduction
• 5)Dissemination of Pathogen

7. 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 interactions
Concepts and terminology - host: pathogen
interactions

8. 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:

9. Not all resistance provides a level of protection that will prevent yield
losses:
- Stripe rust resistance gene Yr18:
- ffungicides protected plots - no
loss
- ssusceptible control - 75%
loss
- Yr18 line - 30%
loss
Breeders want resistance that is:
easy to select, minimies yield loss, is durable

10. Plant Resistance: the retardation of
infection and growth of a parasite on or
with in host tissues.
Monogenic
resistance
Race specific
Polygenic resistance
Race non specific
Fast last
Durable
More than one
gene (minor)
Cultivar
resistance
One major gene

11. Identification resistance genes
Should be done at
pre breeding
program
Promising
lines

12. 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

13. 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.

14. 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 .

15. Advantages:
• Detects variations directly at DNA level
• Not influenced by environment
• Numerous in number
• Automation is possible
Disadvantages:-
• Costs
• Trained peoples
Molecular techniques

16. 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 disease
management plan
• Misidentification results in lack of knowledge = ineffective
control of the real disease.

17. 1- Agricultural practices
• Planting timing (sowing date)
spots Rust
Wheat stem
rust

18. • Seed rate
• Crop rotation
• Preparation of suitable seed bed( soil born
diseases)
• Irrigation
• fertilization
• Trap crops
Powdery mildew Plant density will
be high

19. Virus disease
• We must control the victor

20. • Tolerant or resistant
varieties
2-Resistant varieties
susceptible
Resistant

22. 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

23. 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

24. 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

25. Thank you