This document discusses the classification of plant diseases. It can be classified based on the cause, occurrence and dispersal, parts of the host affected, symptoms, and pathogenicity. The main types of classification are by infectious versus non-infectious cause, endemic versus epidemic occurrence, foliage versus stem versus root effects, and parasitic versus non-parasitic pathogenicity. Specific diseases discussed include blight, mildew, rust, smut, rot, and canker.

1. Classification of plant
diseases Group no 4

2. Classification on the basis
of occurrence and
dispersal of medium
Iqra hussain

3. What is plant disease??
 Definition of Plant disease
 An impairment of the normal state of the plant that modifies
its vital functions
 The organism that cause disease are called pathogens e.g.
bacteria ,viruses ,protozoa etc.
 The study of disease condition is called pathology

4. Healthy plant
Sick/ diseased plants
Difference between healthy and
disease plant
 Normal physiological
functions e.g.
 Normal cell division
,differentiation and
development
 Absorption of water and
minerals from
the soil and translocation
 Photosynthesis
 Reproduction
 A plant would not have all these
functions

5. Classification on the basis of
cause
 Infectious disease
A disease that is caused by pathogen which spread from
diseased plant to a healthy plant
 Non infectious disease
Disease which that is caused by non living organisms

6. On the basis of occurrence and
geographical distribution:
 Endemic
e.g. wart disease of potato
 Epidemic
e.g. rust, mildews
 Sporadic
e.g. leaf blight

7. Classification on the basis
of parts host and
symptoms
Maria jabeen

8. Classification based on the parts of
host affected:
 Foliage disease
 Stem disease
 Boot disease
 Vascular disease

9. Boot disease;
 Athlete foot disease
 Ring worm disease
 Yeast infection

10. Blight disease
 Blight is generally a plant infection caused by a pathogenic
organism. It caused browning, yellowing,
withering followed by the death of plant tissues. Plants
attacked by this disease also show discoloring of stems,
fruits and leaves. Plant blight is caused by a bacteria or
fungus. irregular dead areas on various parts of a plant which
is called the blight.

11. Mildew disease
 Mildew is a specific kind of mold, usually with a flat growth
habit. this is commonly produced by fungi.
 It is of two types:
 Powdery mildews
 Downy mildews

12. Downy mildew
 Foliage habitat
 produced in the severe conditions when the water film is
present , the relative humidity, and cool and hot environment.

13. Powdery Mildew disease
 Obligate parasite
 Produce patch and spots on plants in the form of powder in
plant tissue and leaves.
 Produce the conidiophores on plant surface.

14. Powdery mildew Downy mildew
Powdery and downy mildew:
 Origin
 Infection site
 Spores
 Growth conditions
 Transmission
 attack
 Origin
 Infection site
 Spores
 Growth conditions
 Transmission
 attack

15. Rust:
 Pathogen of puccinia
 It is spread by spores by the infected to healthy plant.
 Formation of pustules on each leaf blade.
 Two hosts

16. smut
 Mainly affeacted the wheat, sugarcane.
 Ustilogo is the genus of smut.
 Produced the black spores .
 Anthoceious life cycle.
 Spores dispersed by wind,insects or by water.

17. Rot
 caused by fungi, bacteria and fungus like organisms.
 causes the decay roots, stems, wood, flowers, and fruit.
 symptoms produced leaf spots and blights.

18. canker
 Destructive to wide range of trees and shrubs.
 Usually kill and branches and infected areas.
 Mostly occur in citrus family.
 Xanthomonas citrus

19. Classification on the basis
of host effected, casual
agents
Maryam wasim

20. On the basis of host effected:
 Disease Of
 vegetable
 EARLY BLIGHT
OF
 TOMATO

21. FRUIT DISEASE
 FRUIT ROT

22. TIMBER DISEASE
 WHITE ROT

23. First group:
Second group:
On the basis of casual agents:
 FUNGI
 BACTERIA
 SLIME MILDS
 VIRUSES
 PARASITIC ANGIOSPERM
 ALGAE
 INSECTS
 MITES
 NEMTODES
 SOIL MOISTURE
DISTURBANCE
 NUTRITIONAL DISORDER
 OPTIMAL TEMPERATURE
DISBALANCE
 LIGHT ITENSITY
DISBALANCE
 AIR POLLUTENTS
 CARELESS SPRAYING OF
CHEMICALS

24. Life cycle of apple scab:

25. Classification on the basis
of pathogenicity
Rida ajmal

26. Disease are classified as:
 Parasitic disease
 Non-parasitic disease

27. Parasitic disease:
Disease due to casual agencies( fungi, viruses Bacteria etc.)
 Some members which effect trees are:
 Viscum album ( semiparasites)
 Cuscutta spp (leguminous plants)
 Striga spp (root parasites)
 Cephaleorus spp (on angiosperm)
 Toxicogenic insects(insect damage plant by sucking,chewing
and show the same symptoms as fungi)

28. Non parasitic disease
 Disease due to non parasitic casual agencies.
 Agencies are as follows:
 Soil moisture disbalance
 Nutritional disorder
 High or low temperature effect
 Effect of light

29. Symptoms due to soil moisture
imbalance:
 Wilting: drooping of leaf or stem tips.
 Blast: sudden death of young bud inflorescence or young
fruit.
 Scorch: sudden death of leaves and fruits
 Firming: drying and dying of leaves specially in grass maize
and tobacco.
 Die back: dying backward from the twigs or tips of branches.

30. Wilting and die back: