This document discusses different ways of classifying plant diseases. It can be classified based on the plant part affected (localized or systemic), perpetuation and spread (soil-borne, seed-borne, or air-borne), signs and symptoms (rusts, smuts, powdery mildews, etc.), host plants affected (cereal crops, forage crops, etc.), causal organism (fungal, bacterial, viral, etc.), occurrence (endemic, epidemic, sporadic, or pandemic), and pathogen generation (monocyclic, polycyclic, or polyetic). The classification systems provide ways of categorizing diseases based on factors like anatomy, life cycle, transmission, symptoms and epidemiology.

1. Dr. Sujit Ghosh
Dr. Sujit Ghosh

2. Classification
of plant
Based on
plant part
affected
Based on
perpetuation
and spread
Based on
pathogen
generation
Classification
of plant
diseases Based on the
signs and
symptoms
produced by
the pathogens
Based on the
host plants
affected
Based on
major Causes
(causal
organism)
Classification
of Diseases in
Relation to
Their
Occurrence

3. Based on plant part
affected
Localized: if they
affect only specific
organs or parts of
the plants.
Systemic, if entire
plant is affected.

4. Based on perpetuation
and spread
Soil borne -when the
pathogen perpetuates
through the agency of
soil.
Seed borne -when the
pathogen perpetuates
through seed (or any
propagation material).
Air borne -when they
are disseminated by
wind e.g. rusts and
powdery mildews.

5. Based on the signs and
symptoms produced by the
RUSTS
SMUTS
POWDERY MILDEWS
DOWNY MILDEWS
LEAF SPOTS
symptoms produced by the
pathogens ROOT ROTS
FRUIT ROTS
WILTS
BLIGHTS
CANKERS

6. Based on the host
plants affected
CEREAL CROP DISEASES
FORAGE CROP DISEASES
FLAX DISEASES
MILLET DISEASES
plants affected
PLANTATION CROP DISEASES
FRUIT CROP DISEASES
VEGETABLE CROP DISEASES
FLOWERING PLANT DISEASES

7. Based on major
Causes (causal
organism)
FUNGAL
DISEASES
BACTERIAL
DISEASES
VIRAL DISEASES
MYCOPLASMAL
DISEASES,

8. CLASSIFICATION OF DISEASES IN RELATION TO THEIR
OCCURRENCE
•ENDEMIC DISEASES –
•CONSTANTLY PRESENT FROM YEAR TO YEAR IN MODERATE
TO SEVERE FORM
•CONFINED TO A PARTICULAR AREA I.E. COUNTRY, DISTRICT
OR LOCATION.
•EPIDEMIC OR EPIPHYTOTIC DISEASES
• DISEASE OCCUR PERIODICALLY IN SEVERE FORM
•OVER A WIDESPREAD AREA OVER A SHORT TIME PERIOD,
SEVERE FORM DUE TO ENVIRONMENTAL SUPPORT
•SPORADIC DISEASES
•DISEASE OCCUR PERIODICALLY AND IRREGULARLY I.E.
APPEARS OFTEN, BUT NOT CONSTANTLY OR REGULARLY IN
MODERATE TO SEVERE FORM
•LIMITED GEOGRAPHIC AREA
•PANDEMIC DISEASES:
•WORDWIDE SPREAD, RAPID SPREAD IN MODERATE TO
SEVERE FORM
•SUDDEN OCCURRENCE AND RATE AND DISTANCE OF THE
SPREAD OF THE DISEASE IS HIGH

9. BASED ON PATHOGEN
GENERATION
MONOCYCLIC
DISEASE
THOSE DISEASE WHICH
COMPLETE ONLY ONE LIFE
CYCLE IN ONE CROPPING
SEASON. E.G. LOOSE SMUT OF
WHEAT, WILT OF TOMATO.
POLYCYCLIC
DISEASE
WHICH HAVE MORE THAN
ONE GENERATION IN ONE
CROPPING SEASON. E.G. LATE
BASED ON PATHOGEN
GENERATION DISEASE
DISEASES
CROPPING SEASON. E.G. LATE
BLIGHT OF POTATO
POLYETIC
DISEASE
THESE ARE ALSO POLYCYCLIC
DISEASES BUT THEY
COMPLETE THEIR DISEASE
CYCLE IN MORE THAN ONE
YEAR OVER YEARS E.G. CEDAR
RUST OF APPLE

10. Thank you