Causal Organisms for Plant diseases and its symptoms.

plant diseases, its causal organisms and symptoms

1. Causal Organisms for Plant
Diseases & its Symptoms
Dr.SubhomaySinha, W.B.A.S. (Administration)
Assistant Director of Agriculture (Admn.)
Soil Survey, Malda

2. process that is Disease may be defined as a malfunctioning process that is
caused by continuous irritation by a pathogen and/or
environmental / abiotic factor resulting in some suffering
producing symptoms.
Disorder: The diseases caused by the deficiency of nutrients or
unfavourable environmental are sometimes termed as disorders or
physiological disorders.
APLANTDISEASE isanyabnormalconditionthatalterstheappearanceor
functionofaplant.Itisaphysiologicalprocessthataffectssomeorallplant
functions.Diseasemayalsoreduceyieldandqualityofharvestedproduct.

3. What are Physiological functions of a Plant
?
Photosynthesis
Respiration
Plant nutrition
Plant hormone functions
Photoperiodism& photomorphogenesis
Environmental stress physiology
Seed germination
Dormancy
Stomata function
Transpiration………etcPLANT PATHOGENS CAUSING A DISTURBANCEIN
THESE PHYSIOLOGICAL FUNCTIONS.

4. What is a pathogen / Pathogenic agent / Causal Organisms ?
A living or un-living agent (infectious agent) that can cause a disease
to the host plant is called a PATHOGEN / CAUSAL ORGANISM.

5. Plant Disease results only if all of these three factors occur
simultaneously. If one or more of the factors is not present, then
disease does not occur.
The Disease TriangleThe Disease Triangle

6. Causal Organisms for Plant Disease
BIOTIC FACTORS
:
Micro-organisms / Microbes like
Fungi, bacteria, virus, viroids, phytoplasma,
algaes, nematodes, higher parasitic plants etc
causing plant diseases through invasion.
The main categories of MICROBES that cause plant
diseases are FUNGI, BACTERIA, VIRUSESand
NEMATODES. Fungi account for around 85 per cent of
plant diseases followed by viruses, bacteria and
nematodes. Besides PHYTOPLASMA, PROTOZOAAND
ALGAEare also responsible for plant disease

7. Types of pathogens
Nematodes
Bacteria
Viruses
Fungi

8. Groups of Plant Pathogens -Fungi
•Vastmajorityarebeneficial.
•Cancausediseasestoplant,
human,andlivestock.
•Mostcannotbeseenwithouta
microscope.
•Devoidofchlorophyll.
•Composedofgrowingstructure
ofdelicate,thread-likefilaments
calledhyphae.
•Reproducebyformingspores.

9. Example of FUNGAL DISEASE SIGNS :
Leaf rust (common leaf rust in corn)
Stem rust (wheat stem rust)
Sclerotinia(white mold)
Powdery mildew
Leaf rust Stem rust Sclerotinia Powdery mildew
Plant Pathogens -Fungi

10. Example of FUNGAL DISEASE SYMPTOMS :
Birds-eye spot on berries (anthracnose)
Damping off of seedlings (phytophthora)
Leaf spot (septoriabrown spot)
Chlorosis(yellowing of leaves)
Birds-eye spot on berries
Damping off of seedlings
Leaf spot
Chlorosis
Plant Pathogens -Fungi

11. Groups of Plant Pathogens -Bacteria
•Extremelysmallorganism
requiringmicroscopetobeseen.
•Bacteriapopulationcanincrease
innumberinshorttimeperiod.
•Cellsclumptogetherinmasses
calledcolonies.
•Obtainfoodfromdeador
decayingorganicmatterorliving
tissue
www.foodmate.net
•Spread plant to plant by wind-driven rain.
•Gain entrance through natural plant openings or injuries.

12. BACTERIAL DISEASE SIGNS
(difficult to observe) :
Bacterial ooze
Water-soaked lesions
Bacterial streaming in water from a cut stem
Bacterial ooze
Water-soaked lesions
Bacterial streaming in water from a cut stem
Plant Pathogens -Bacteria

13. BACTERIALDISEASESYMPTOMS
:
Leafspotwithyellowhalo
Fruitspot
Canker
Crowngall
Sheperd’scrookstemendsonwoodyplants
Leafspotwithyellowhalo Fruitspot
Canker
Crowngall
Plant Pathogens -Bacteria

14. Groups of Plant Pathogens -Viruses
•Mostfamiliarbecausethey
causehumanandanimal
diseasessuchasinfluenza,polio,
rabies,smallpox,andwarts.
•Causesomedestructiveplant
diseases.
•Measureonlyaboutone-
millionthofaninchinsize.
•Arenotcompletelivingsystems,
butsurviveonlyinlivingcells.
University of Florida
•Plant Viruses are transmitted by insects which are called vectors.

15. VIRAL DISEASE SYMPTOMS
:
Mosaic leaf pattern
Crinkled leaves
Yellowed leaves
Plant stunting
Plant Pathogens -Viruses
Mosaic leaf
Crinkled leaf
Plant stunting
Yellowed leaves

16. Groups of Plant Pathogens -Nematodes
•Round, slender,
threadlikeworms.
•Someareparasiteson
animals,insects,fungi,
othernematodes,and
plants.
•Plant-parasiticnematodes
haveastylet.•Mostliveinthesoiland
feedinoronplant
roots.

17. Phytoplasmas,previouslycalled
MYCOPLASMA-LIKEORGANISMS
(MLO),areun-culturable,phloem-
limitedinsect-transmittedplant
pathogens.
Incontrasttobacteria,
phytoplasmasdonothavearigidcell
wall.
Phytoplasmasarepathogensofmany
Agriculturallyimportantplants,
includingcoconut,sugarcane,sesame
andsandalwood.
Theyarespecificallyresponsiblefor
thedisease“Phyllody”( Phyllodyis
theabnormaldevelopmentoffloral
partsintoleafystructures.)
Groups of Plant Pathogens -Phytoplasma
Phyllodyof Rose
Phyllodyof Sesame

18. Cephaleuros isaparasiticGreen
Algae,livingunderleafcuticle,
causingRedRustdiseaseinTea,&
Mango;AlgalleafspotonMagnolia
(GreenScurf)
Structure of Cephaleuros
Colony of Cephaleuroson Tea
Groups of Plant Pathogens -Algae

19. Groups of Plant Pathogens –Algae (contd…)
Green Scurf / Algal leaf spot on Magnolia
Greyishgreenbrownspotsonleaves.
Theleaftissuemaydiebeneaththe
spotsandtheleavesmaybecome
yellowanddropprematurely.
Thediseasecanbeeasilyrecognised
bytherustyredspotsonleavesand
sometimesonpetiolesandonyoung
twigsofMangoes.
Red Rust on Mangoes.
Algal leaf spot on Magnolia
Red Rust on Mangoes.

20. Groups of Plant Pathogens –Protozoa
PROTOZOA
aredefinedasadiverse
groupofunicellulareukaryoticorganisms.
thesetinyorganismscancauseavarietyof
diseasesinplants.Severalvarietiesof
cropplantscansufferfromprotozoan
diseases.Protozoasuponinfestation,
causesPhloemNecrosisinCoffee
PhloemNecrosisinCoffee
Protozoas

21. Groups of Plant Pathogens –Parasitic plants
Thepathogenicfloweringplants,canbeclassifiedasRoot
ParasitesorStemParasites.
RootparasitesareWitchweedandBroomrape(Orobanche).
StemparasitesincludeDodder(Cuscuta)andMistletoes.
Witchweed(Striga)
Striga(Witchweed)
attacks important
crops like maize,
sorghum, pearl millet,
rice, sugarcane &
legumes.
Root parasites
With a bell-like swelling form, the parasitic roots of Striga
attach to the roots of the host plants.
The pathogen develops underground, where it may spend
the next four to seven weeks before emergence, when it
rapidly flowers and produces seeds.
Striga
Strigaattaching with
host plant’s root

22. Broomrape
Broomrape(Orobanche)
Groups of Plant Pathogens –Parasitic plants
Root parasites
Orobanchehavenochlorophyll,theyaretotally
dependentonHostplantsfornutrients.
Broomrapeseedlingsputoutaroot-likegrowth,
whichattachestotherootsofnearbyhosts.
Onceattachedtoahost,thebroomraperobsitshost
ofwaterandnutrients.

23. Cuscuta(dodder)isaStemParasite.
Itsslender,twining,orange-yellow,leaf-lessstems
formconspicuoustangledmassonthehost.
Itcanphotosynthesizeitsownfood,butwaterand
nutrientsaredrawnfromthehostplant.
Doddersaremostimportantparasitesoflegumes.
Itcausesconsiderabledamagetoalfalfa,flax,
sugarbeet,onionandotherfruitandforestcrops.
MonocotsarelesspreferredbyStemparasites.
Italsotransmitvirus.
Dodder (Cuscuta)
Groups of Plant Pathogens –Parasitic plants
Stem parasites
Mistletoes are also stem
parasites
Dodder
Mistletoes
Dwarf Mistletoes

24. ABIOTICFACTORS
:Abioticfactorsresponsibleforplantdisease
are:
1.Deficiency /Excess of Nutrients
2.Light
3.Temperature
4.Relative Humidity
5.Soil Moisture
6.Soil Aeration
7.Soil pH
8.Soil Fertility
9.Abnormality in Soil Condition
10.Atmospheric Impurities etc.

25. ZincdeficienciesinSoilcauses“KHAIRADISEASE ofrice”.
Unfavourableenvironmentalconditioncausingplantdamagelike FROST
INJURY,PHYSIOLOGICALWILT etc.
SO
2
toxicityinaircauses
Blacktip
ofMango.
Modeficiencyinsoilresults
Whiptail
ofcauliflower.
Hollowandblackheart
ofpotatoiscausedbyexcessive
accumulationsofCO
2
instorage).
BitterpitofapplecausedbyCadeficiencyinsoil.
Necrosisinleafmargin ofgreenhouseplantsduetoMicronutrient
toxicity.
Some Examples of Abiotic Factors Causing Plant Diseases:

26. Symptoms due to ABIOTIC FACTORS
Black tip
of Mango
KhairaDisease of Paddy
Whiptail of cauliflower
Hollow heart of Potato

27. SYMPTOM aretheexpressionofthediseasecausedbythemanifestationof
thephysiologicalreactionoftheplantduetoharmfulactivityofthepathogen.
Herewearenotactuallyseeingthediseasepathogen,butratherasymptom
thatisbeingcausedbythepathogen.
Difference between SYMPTOM and SIGN of plant disease
SIGN-physicalevidenceofthepresenceofdiseasecausingagents( e.g.,mould
orfungalspores,bacterialooze),visiblethroughnakedeye.Here,thepathogen
itselfbecomesvisibleonthehostsurfaceintheformofitsorgansor
structures.eg.Sclerotia,Spores,Mycelium,Ooze,Cystetc.
bacterial ooze
fungal spores
Different signs of Plant Disease

28. Classification of Plant Diseases
A.On the basis of extent to which plant diseases associated with plant
1.LOCALIZED
2.SYSTEMIC
B.On the basis of mode of infection
1.SOIL BORNE
2.AIR BORNE
3.SEED BORNE
C. On the basis of symptoms of disease
1.RUSTS
2.SMUTS
3.ROTS
4.BLIGHT
5.LEAF SPOT
6.CANKER
7.WILT
8.DOWNY MILDEWS
9.POWDERY MILDEW
10.ANTHRACNOSE

29. Primarysymptomsarethedirectresultofpathogenactivityoninvaded
tissues(e.g.,swollenclubsinclub-rootaffectedcabbageareformedby
feedingoftherootknotnematode).
Ontheotherhand, Secondarysymptoms resultfromthephysiological
effectsofdiseaseondistanttissuesandun-invadedorgans(e.g.,wiltingand
droopingofbeanleavesinhotweatherdueto Fusariumrootrot).Rootis
infected,butsymptomsappearsonleavesthroughdroopingandwilting.
Primary Symptoms and Secondary Symptoms
Club-root of cabbage
Fusariumroot rot

30. Local symptomsare physiological or structural changes within a limited area of
host plant tissue around the infection site, such as leaf spots, galls, and cankers.
leaf spots leaf galls

31. Systemic symptomsare those involving the reaction of the entire / greater
part of the plant, such as wilting, yellowing, and dwarfing.
wilting
yellowing dwarfing

32. INFECTIOUS :
Allthediseasescausedby VIRUSESandVIROIDS
canbetransmittedfrominfectedhostplantstothehealthyplants
andarecalledinfectious.
NON-INFECTIOUS:
Non-infectiousdiseasescannotbetransmitted
toahealthyplant.
Classification of plant Diseases Based on Infection Process
Potato Spindle Tuber Disease transmitted by Viroids
Early blight of potato is a non –infectious disease

33. Classification of plant Diseases on the basis of occurrence and
distribution
2.EPIDEMIC/EPIPHYTOTIC:Adisease
occurringperiodicallybutinasevere
forminvolvingmajorareaofthecrop.
itmaybeconstantlypresentinlocality
butassumesevereformoccasionally
e.g.Rustofwheat,Lateblightof
tomato,PowderyMildewsofGrapes
1.ENDEMIC:whenadiseasesmoreor
lessconstantlyprevalentfromyearto
yearinamoderatetosevereformina
particularcountry.E.g.,Wartdisease
ofpotatoisendemictoDarjeeling.
Wart disease of potato
Rust of wheat

34. 4.PANDEMIC :Diseasesoccurring
throughoutthecontinentorsub-
continentresultinginmassmortality
e.g.,Lateblightofpotato.
3.SPORADIC:Diseaseswhichoccurat
veryirregularintervalandlocationina
moderatetosevereforme.g.,leaf
blights,wilt.
leaf blight of Maize
Late blight of potato

35. Thediseasesymptomsmaybemicroscopicormacroscopic.In Microscopic
Symptoms,theexpressionsofdiseaseareinthecellstructureorcell
arrangements,whichcanbeseenunderamicroscope.
In Macroscopic Symptomsthe expressions of disease on the surface of plant parts
that can be seen with the unaided eye in the form of symptoms on the plant.
Microscopic Symptoms and Macroscopic Symptoms
Macroscopic (morphological) symptomscan be classified as:
A.Necrosis
B.Hypoplastic
C.Hyperplastic

36. DISEASE
SYMPTOMS
MACROSCOPIC SYMPTOMS MICROSCOPIC SYMPTOMSNECROSIS
SPOT BLIGHT BLAST ROT DIE -BACK STRIPE HYDROSIS CANKER
HYPOPLASTIC
DWARFING
ROSETTIING
CHLOROSIS
MOSAIC
HYPERPLASTIC
LEAF CURL
SCAB
GALL
ROOT KNOT

37. It is localized or the general DEATH / DEGENERATION of
plant tissue (protoplast) due to invasion of disease causing
agent. It includes leaf spots, blight, rots, cankers, hydosis
etc.
Necrosis symptoms

38. Spotis a definite, localized, round to regular lesion, often with a border of a
different colour, characterized by its location (leaf spot, fruit spot) and colour
(brown spot, black spot).
Someexamplesofthenecroticsymptom
Angular leaf spot of beans
Septorialeaf spot of tomato
If numerous spots enlarge and merge, a large
irregular blotch or blight may develop, such as grey
leaf spot of tomato; black spot of rose; angular
leaf spot of beans, Tikkaleaf spot with yellow
halo, fruit spot etc.
Tikkaleaf spot of Groundnut

39. Blightisthesuddenortotaldiscolorationandkillingoflargeareaofaleaf,shoots
orstemsortheentireplant.Usuallyyoungtissuesareattacked.Thediseasenameis
oftencoupledwiththenameofthehostandthepartattacked,forexample—
blossomblight,twigblight,tipblightetc.itoccursmostlyduetobacterialinvasion.
Someexamplesofthenecroticsymptom
Bacterial blight of riceBacterial blight of beans

40. Blastis sudden death of young buds, flowers, or young fruitand failure to produce
fruit or seeds. such as Rice blast, Wheat Blast etc.
Someexamplesofthenecroticsymptom
Different symptoms of Rice blast disease
Different symptoms of wheat blast disease

41. Dampingoff:symptomsaredecayofseedinsoil,rapiddeathofgerminating
seedlingsbeforeemergence,oremergedseedlingssuddenlyshowswilting
symptoms,topplingover,anddyingfromrotatcollarregion.Thisiscommon
diseasefoundinseedbeds
Someexamplesofthenecroticsymptom
Damping off in seedbed.
Damping off

42. DIE-BACKis a plant disease, showing progressive browning and death of shoots,
branches, and roots starting at the tips then moving downward e.g. Die back of
chilli/ citrus / Mango.
Someexamplesofthenecroticsymptom
Die back of Citrus plant Die back of Mango plant
DIE-BACk

43. ROTSrefer to the decomposition and putrefaction of cells, tissues and organs.
The rot may be dry, watery or mushy such as bacterial soft rot.
Root rot of Beans
Someexamplesofthenecroticsymptom
Red Rot of sugarcane
ROTS
Root and Stem Rot

44. Dry rot of potato
Someexamplesofthenecroticsymptom
ROTS
Dry root rot of Lentil
Dry rot of Ginger
Dry rot

45. SOFT ROT diseases are caused by pathogens that secrete enzymes capable of
decomposing cell wall structure. Soft rots commonly occur on fleshy vegetables
such as potato, carrot, capsicum, squash, and tomato.
Soft rot on Capsicum Soft rot symptoms on carrot
Someexamplesofthenecroticsymptom
ROTS
SOFT ROT

46. BLACK ROT OF CRUCIFERS caused by the bacteria Xanthomonascampestrisp.v.
campestrisis also a plant disease where the vascular system is infected and leads
to necrosis of the leaves.
Symptoms of black rot on
cabbage transplants
V-shaped lesions on mature
cabbage
Someexamplesofthenecroticsymptom
ROTS
BLACK ROT

47. Someexamplesofthenecroticsymptom
ROTS
BLACK ROT OF GRAPE is a fungal
disease, resulting hardened, black
mummified fruit at the time of harvest.
BLACK ROT

48. BULBROT ofOnionisafungaldisease,
causingbythefungi Botrytisspp.White
fluffyfungalgrowthappearsonthebaseof
thebulbandlateritspreadthroughout
thebulb,withsmall,round,black
structures.
Bulb rot of Onion & Garlic
Someexamplesofthenecroticsymptom
ROTS

49. GRAYMOULDROT iscausedbyfungiin
thegenus Botrytis.Thediseaseis
characterizedbysoft,tantobrown
spotsorblotchesthatbecomecovered
withadustywhitemould.
Someexamplesofthenecroticsymptom
ROTS
GRAY MOULD ROT

50. HEARTROT isafungaldisease.Fungus
produceadiscoloured,lightweight,soft,
spongy,stringy,crumbly,orpowdery
heartdecay.Sugarbeet,Carrot,
Pineapplearepronetothistypeofrot.
Someexamplesofthenecroticsymptom
ROTS
HEART ROT
Heart rot of Carrot Heart rot of Pineapple
Heart rot of Sugarbeet

51. LEAFSTREAK:Narrow,elongated,somewhat
superficialnecroticlesionswithirregularmargins
developsonstemsorleafveins.TheCausal
OrganismisVirus.Example:Leafstreakvirusof
Maize
Leaf streak of Maize
Someexamplesofthenecroticsymptom
STREAK

52. LEAFSTRIPE:narrow,elongated,parallel,necrotic
lesionsdevelopsespeciallyinleaf.Thesediseasesare
specificofcerealsandgrasses .Bothfungusand
bacteriacausesthisstripesymptoms.
Someexamplesofthenecroticsymptom
Stripe
Helminthosporiumstripe of barley Red stripe of Sugarcane

53. WATER-SOAKING/HYDROSIS isatranslucentconditionoftissues
causedbywater,movingfromhostcellsduetorupturingofcellmembranes
intointercellularspaces.Examplesarelateblightlesionsonpotatoand
tomatoleaves,bacterialsoftrotoffleshyvegetables
late blight lesions on potato
Someexamplesofthenecroticsymptom
Hydrosis

54. CANKERisadefinite,dead,oftensunkenorswollenandcrackedareaonastem,
limb,trunk,tuber,fruitorrootsurroundedbylivingtissues.TheC.O.isoften
Bacteriaorfungi.
Citrus Canker on Fruits Tomato Canker on Stems
SomeexamplesoftheNecroticsymptom
Canker

55. Hypoplasia is the failure of plants or organs to develop fully i.e
to obtain normal size.
Abnormal size and pale colouration is the most common
hypoplasticsymptom.
HYPOPLASTIC SYMPTOMS

56. DWARFING is the under-development of the plant or some of its organs egMaize
Streak Virus, mosaic, curly top of beans etc.
Dwarfing of Maize plant due to Maize streak virus
SomeexamplesoftheHypoplasticsymptom
DWARFING
Dwarfing of Papaya plant due to Papaya Mosaic virus

57. ROSETTINGis the shortening of internodes of shoots and branches, producing
a bunchy growth habit example are the ground nut rosette.
SomeexamplesoftheHypoplasticsymptom
ROSETTING
Ground Nut Rosette VIRUS

58. ALBICATIONis the complete repression of leaf colour caused by viruses,
bacteria, fungi, and iron deficiency leading to whitening of leaf tissue.
ALBICATION
Broad Bean Stain Virus (BBSV) symptoms
on pea plants include whitening of
interveinaltissues.
SomeexamplesoftheHypoplasticsymptom

59. CHLOROSIS
istheyellowingorwhiteningofnormalgreentissueduetopartialor
completefailureofchlorophylltodevelop.Thissymptomcandevelopeddueto
differentdiseasescausingorganisms.
Chlorosisof Green leaves
CHLOROSIS
SomeexamplesoftheHypoplasticsymptom

60. MOSAICistheabnormalcolorationyellowing,reddening,bronzing,orpurplingin
localizedareasofleaveswherechlorophyllhasbeendestroyed.Thissymptoms
showsaclearingalongtheleafveins(veinclearing).
Turnip Mosaic virus on cabbage leaves
SomeexamplesoftheHypoplasticsymptom Mosaic
Yellow Mosaic virus on Okra leaf
Yellow Mosaic virus on Moongbean

61. HYPERPLASTIC SYMPTOMS
Hyperplasia is the over-development (in size and colour) of
the plant parts due to invasion of plant pathogen
.

62. LEAFCURLS
-overgrowthoftissueononesideofaleaforpetal
resultingtoleavesrolling.Thissymptomsappearsmostlyduetovirus
attackonplants.
Leaf Curl of Chilli Leaf Curl of Tomato
SomeexamplesoftheHypoplasticsymptom
LEAF CURLS

63. Leaf curl symptoms
SomeexamplesoftheHypoplasticsymptom
LEAF CURLS (contd….)
Leaf Curl of Papaya Leaf Curl of Tobaco Leaf Curl of Potato

64. Scabs
developscrustlike,moreorlesscircular,slightlyraisedorsunken
lesionsonthesurfaceofleaves,stems,fruit,ortubers.e.g.commonscabof
potato,applescabandwheatscab.
SomeexamplesoftheHypoplasticsymptom
SCABSSCABS
Potato Scab
Apple Scab

65. GALLSareabnormalgrowthsofplantcellsthatoccuronleaves,
twigs,roots,orflowersofmanyplants.
Mostgallsarecausedbyirritationand/orstimulationofplantcells
duetofeedingoregg-layingbyinsectssuchasaphids,midges,
wasps,ormites.
SometimesinvasionofFungiand/orBacteriacanresultsintogall
formation.
GALLS SomeexamplesoftheHypoplasticsymptom
Galls on Rhododendron shoot caused by Fungi. Galls on Olive shoot caused by Bacteria.

66. A WITCH'S BROOM or witches' broom is a deformity in a woody plants,
typically a tree, where a dense mass of shoots grows from a single point,
with the resulting structure resembling a broom or a bird's nest. It is
sometimes caused by pathogens, like Fungi, Insects, Mites, Nematodes ,
Phytoplasmaand viruses.
WITCH’S BROOM
SomeexamplesoftheHypoplasticsymptom
WITCH'S BROOM on Woody Plants

67. INTUMESCENCE is a condition in which numerous small calluses grow
on the surface of the leaves.They may occur on either the upper or
lower surface, and may be scattered over inter-veinaltissue or
clustered along the main veins.Intumescence does not appear to
harm the plant.
INTUMESCENCE
SomeexamplesoftheHypoplasticsymptom
Small calluses grow on the surface of the leaves by Intumescence

68. TUMOURS
aresymptoms,causedbypathogensthatstimulateuncontrolled
multiplicationofplantcells,resultingintheformationofabnormallylarge
structures.e.g.CrownGallonrose,causedbyBacteria Agrobacteriumtumefaciens.
Crown Gall on rose
SomeexamplesoftheHypoplasticsymptom
TUMOURSTUMOURS

69. CLUBROOT
symptomiswheretherootsappearswollen&club-shaped.Clubroot
isadiseaseofthemustardfamily(Brassicaceae/Cruciferae)causedbythe
fungus-likesoilpathogenPlasmodiophorabrassicaceae.
SomeexamplesoftheHypoplasticsymptom
CLUB ROOTCLUB ROOT
Club root of Cruciferous crops

70. ROOTKNOTS
aretheformationofgallsontherootswhichisasaresultof
nematodeinfection.
SomeexamplesoftheHypoplasticsymptom
ROOT KNOTSROOT KNOTS

71. Someexamplesofthenecroticsymptom
Wilting:Wiltingislossofturgorpressureinaplant
leadingtotemporaryorpermanentdroopingofleaves,
shoots,orentireplantsfromlackofwater,duetoinfection
bydifferentplantpathogens.Itisasecondarysymptoms.
Wiltingresultsduetoinfestationoffungusaswellas
Bacteria in the plant.
Bacterial wilt of tomato
Wilting

72. SIGN-physicalevidenceofthepresenceofdiseasecausingagents( e.g.,mould
orfungalspores,bacterialooze),visiblethroughnakedeye. Differentsignsof
plantpathogens,invadingaplantisexplainedherein.

73. Different SIGNS of plant disease
MyceliumorMouldGrowth :undersomeconditions,myceliaorfungal
growthininfestedplantpartsisreadilyvisibletothenakedeye.
Mycelium or Mould Growth

74. Mildews
Mildews consist of white, grey, brownish or purplish pathogen growth on the host surface.
Downy Mildews
Powdery Mildews
Different SIGNS of plant disease

75. RUST
appearsasrelativelysmallpustulesofthespores,usuallybreaking
throughthehostepidermis.Thepustulesmaybedustyorcompact,andred,
brown,yelloworblackincolour.
Rust
Different SIGNS of plant disease
Pea Rust
Wheat Rust

76. White blister like pustules appear on the lower leaves and other
parts of cruciferous plants which break open the epidermis and
expose white powdery masses of spores. This disease is also
called as White rust.
White Blister
White blister on Mustard leaves
Different SIGNS of plant disease

77. BLOTCH
consists of superficial growth of
Fungus / Bacterium, giving the affected plant
parts i.e., fruits and leaves a “Smoky (blotched)
appearance”, e.g. Sooty Blotch of Apple.
BLOTCH BLOTCH
Different SIGNS of plant disease
Sooty Blotch of Apple Bacterial fruit blotch of Cucurbits

78. Smutmeansasootyorcharcoallike
powder.
Theaffectedpartsoftheplantsshow
blackorpurplishblackdustyareas.
Symptomsusuallyappearonfloral
organs.Eg.WheatSmut,CornSmut
SMUT
Different SIGNS of plant disease
Wheat Smut Corn Smut False Smut of Paddy

79. ASclerotiumisacompact,oftenhardmassofdormantfungusmycelium.
Sclerotiaaremostlydarkincolourandarefoundmixedwiththehealthy
grainsasinthecaseofergotofwheatandrye.
Sclerotia
Dark coloredSclerotiumin the infected plant parts
Different SIGNS of Plant Disease

80. Massofbacterialcellsoozeoutonthesurfaceoftheaffectedorgans
wheretheymaybeseenasadroporsmearinseveralbacterialdiseases
suchasbacterialblightofpaddy,gummosisofstonefruitsandfireblight
ofappleandpear.
Theyformcrustsafterdrying.
EXUDATION
Ooze from bacterial blight of paddy
Causal organism comes out from the infected plant part through exudation.
Gum coming out from Gummosis of Stone fruit.