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Classification of Plant Disease

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PLANT PATHOLOGY CLASSIFICATION OF PLANT DISEASE ON THE BASIS OF SYMPTOMS ON THE BASIS OF ORGANS THEY ATTACK ON THE BASIS OF PARTS ON THE BASIS OF GEOGRAPHIC DISTRIBUTION ETC. – PowerPoint PPT presentation

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Title: Classification of Plant Disease


1
CLASSIFICATION OF PLANT DISEASE
  • SUBMITTED BY
  • SOMBIR KASHYAP
  • MSC FINAL
  • 5077
  • SUBMITTED TO
  • DR SUNDER SINGH ARYA
  • PROFESSOR DEPARTMENT OF BOTANY MDU ROHTAK

2
DEFINITION
  • Plant disease an impairment of the normal state
    of a plant that interrupts or modifies its vital
    functions.
  • Or
  • A malfunctioning process that is caused by
    continuous irritation and produce symptoms.
  • The organisms that cause disease are called
    pathogen.
  • E.g. bacteria, fungi, viruses and protozoa etc.
  • The study of disease condition is called
    pathology, also known as phytopathology

3
Difference between healthy and diseased plant
  • HEALTHY PLANT
  • Normal physiological functions including
  • Normal cell division, differentiation and
    development
  • Absorption of water and minerals from the soil
    and translocation
  • Photosynthesis
  • Reproduction
  • SICK /DISEASED PLANT
  • A plant would not have all of these functions

4
CLASSIFICATION ON THE BASIS OF CAUSE
  • Infectious disease a disease that is caused by
    a pathogen that can spread from a diseased plant
    to healthy plant.
  • Disease is caused by living organisms.
  • It is also known as parasitic and biotic disease
  • E.g. fungi, bacteria, virus, phytoplasma,
    nematodes, higher parasitic plants etc.
  • Such as Pectobacterium atrosepticum (a potato
    pathogen)

5
  • Non-infectious disease disease that is caused
    by non-living organisms.
  • Could not be spread to other healthy plant
  • Such as factors
  • Unfavourable environment e.g. frost injury,
    physiological wilt.
  • Too low/high temperature
  • Lack/excess of soil moisture
  • Air pollution
  • Nutrient deficiency- e.g. khaira disease in rice
    due deficiency of Zinc
  • Mineral toxicity
  • Soil acidity or alkalinity

6
ON THE BASIS OF OCCURRENCE AND GEOGRAPHIC
DISTRIBUTION
  • Endemic when a disease more or less constantly
    prevalent from year to year.
  • These diseases are natural to one country or part
    of the earth.
  • E.g. wart disease in potato in Darjeeling
  • Epidemic such a disease occurs periodically but
    in severe state involving major area of crop.
  • It may be constantly present in the locality.
  • This is because the environmental conditions
    favourable for rapid disease development occur
    only periodically.
  • E.g. rust, late blight, mildews.
  • Pandemic
  • E.g. late blight of potato
  • Sporadic these diseases occur at very irregular
    intervals and locations and in relatively few
    instances.
  • A given disease may be endemic in one region and
    epidemic in another.
  • E.g. leaf blight, wilt.

7
On the basis of natural perpetuation and mode of
infection
  • Soil borne pathogen survive in soil or on
    infested plant debris lying in soil either as
    their resting spores or as mycelial strands and
    rhizomorphs.
  • E.g. Root rot , wilt and seedling blight
  • Air borne the micro-organisms are spread
    through air and attack the plants causing disease
  • E.g. blight, rust, powdery mildew.
  • Seed borne the micro-organisms are carried
    along with seeds
  • E.g. damping off

8
On the basis of symptoms
  • Rust caused by Basidiomycetes of the order
    Uredinales
  • Mostly attack on leaves and stems
  • Appear as numerous rusty, orange, yellow, or even
    white-coloured spots that ruptured epidermis
  • Some form local spots, swelling and even galls
  • E.g. stem rust of wheat caused by Puccinia
    graminis, yellow or stripe rust of wheat , rye,
    and barley is caused P. striiformis, leaf rust of
    wheat and rye by P. triticina , leaf rust of
    barley , crown rust of oats , corn rust ,
    sugarcane rust , sorghum rust ,coffee leaf rust
    ( Hemileia vastatrix ) , cedar apple rust (
    Gymnosporangium juniperi ) etc

9
Rust on wheat leaf, stripe,stem
10
Rust on sugarcane leaf
11
Coffee leaf rust
12
  • Smuts caused by a fungus of the order
    Ustilaginales.
  • Many types of plant affected , but smuts are
    important in cereals and other grasses.
  • They produce a mass of black , powdery spores and
    no grains are formed.
  • The symptoms include the formation of masses of
    lack soot like spores and infected plant shows
    some degrees of distortions.
  • E.g. loose smut of wheat and barley caused by
    Ustilago nuda tritici
  • It is world wide in distribution
  • In India, occurs in all states where wheat is
    grown, losses may be up to 40 per cent in some
    area.

13
Smut in wheat and barley
14
  • Karnal bunt of wheat Mitra reported in 1930 and
    by 1985 also reported from W.B.,Gujrat, Bihar,
    M.P.
  • Pathogen- Tilletia indica
  • The disease is usually noticed only when the
    partly smutted and broken kernels are seen in
    threshold grain.
  • Although infected wheat is not toxic to humans or
    animals, wheat grain containing more than 3
    bunted kernels is generally considered unfit for
    human consumption.
  • Because the smut causes an unpleasant odour ,
    colour and taste in wheat product.
  • All the spikes on a plant are not infected , and
    within a spike only a few spikelets are attacked
    .
  • it becomes evident when the grains have
    developed.
  • Grains have been partially, rarely wholly ,
    converted into bunt balls enclosed by the
    pericarp.

15
Karnal bunt in wheat
16
  • Rots diseases that infect underground plant
    parts.
  • They can be caused by fungi, bacteria or
    soil-borne nematodes.
  • Infections lead to disintegration of underground
    tissues are difficult to manage because they are
    not visible.
  • E.g.
  • Rhizoctonia and Phytophthora are root rots.
  • These two fungi attack the root system of many
    different plants.
  • Bacteria can only enter the host tissue through
    wounds.
  • Crown and collar rots occur at the soil line
    where the plant emerges.

17
 crown rot infection on Beta vulgaris
18
  • Wilt a wilt disease is any number of disease
    that affect the vascular system of plants.
  • Bacterial wilt of Cucurbits is caused by the
    bacteria Erwinia tracheiphila.
  • Bacteria spread through the xylem vessels from
    the area of infection to the main stem and the
    entire plant wilts and dies.
  • E.g. wilt disease in potato, tomato.

19
bacterial wilt symptoms displayed by a muskmelon
plant
20
Wilt in tomato
21
  • Canker a canker is a dead area in bark or
    cortex of woody stems.
  • They are often large areas with definite margin.
  • Dead bark splits and falls away.
  • An example is citrus canker (bacterial)

22
Citrus canker
23
  • Powdery mildew it is a fungal disease of
    foliage , stems, flowers and fruit where a
    superficial fungal growth covers the surface of
    the plant.
  • E.g. grapes, cucumbers, grasses, soyabean etc.
  • Symptoms white, powdery spreading patches of
    fungus on upper or lower surfaces, flowers and
    fruit.
  • Sometimes tissue become stunted or distorted.
  • Disease seldom kill their hosts but utilize their
    nutrients, reduce photosynthesis , increase
    respiration and transpiration and reduce yields
    by as much as 20 to 40.

24
Powdery mildew of grape and soyabean leaves
25
Powdery mildew of cucurbits
26
  • Downy mildew it is caused by family
    Peronosporaceae.
  • Many ornamental and edible plants including peas,
    onions, lettuce, grapevines are affected.
  • Main symptoms are discoloured areas on upper leaf
    surfaces white, grey or purple mould below.
  • Timing is mainly summer and autumn, particularly
    in wet conditions.
  • E.g. rose and lettuce.

27
Downy mildew on rose and lettuce
28
On the basis of organ they attack
  • Root disease
  • Shoot disease
  • Fruit disease
  • Foliage disease

29
On the basis of host plant
  • Cereal disease
  • Vegetable disease
  • Fruit disease
  • Forest disease
  • Ornamental disease

30
On the basis of extent to which plant disease
associated with plant
  • Localised these disease are limited to a
    definite area of varying extents of an organ, or
    only to a particular part of the plant.
  • Systematic pathogen spreads throughout the
    entire plant to varying extents and is associated
    with almost every stage of plants life cycle.

31
Based on pathogen generations
  • Monocyclic disease those diseases which have
    only generation in one cropping season e.g. loose
    smut of wheat.
  • Polycyclic disease those diseases which have
    more than one generation in a cropping season
    e.g. late blight of potato

32




  • References
  • George N. Agrios , Plant pathology 5th edition
  • R.S. Mehrotra , Plant pathology 2nd edition
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