Integrated cereal crops disease

INTEGRATED CEREAL CROPS DISEASE MANGMENTS IN IRIGATED AGRICULTURAL

Prof. Mohamed Abdelkader Hasan

Cereal Pathology

PPI(ARC) Egyptabdelkaderhasan@yahoo.com

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

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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

Should be done at pre breeding

program

Promising lines

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.

1- Agricultural practices

• Planting timing (sowing date)

spots Rust

Wheat stem rust

• Seed rate

• Crop rotation

• Preparation of suitable seed bed( soil born diseases)

• Irrigation

• fertilization

• Trap crops

Powdery mildew Plant density will be high

Virus disease

• We must control the victor

• Tolerant or resistant varieties

2-Resistant varieties

susceptible

Resistant

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

Thank you