Diseases of neem, senna and pyrethrum.pdf

Diseases of neem, senna and pyrethrum

1. Siddu Lakshmi Prasanna
Course No.: PATH 2.7.1.
CourseTitle:DiseasesofFruit,Plantation,Medicinal
andAromaticcrops
By
Dr. SidduLakshmi Prasanna
Ph. D (Agri.)
Dept.ofPlantPathology

2. Neem
1)Phomatwigblight:Phomopsisazadiractae
2)Powderymildew:Oidiumazadiractae(Erysiphae)
3)Rootrot:Ganodermalucidum
4)Leafwebblight:Rhizoctoniasolani
5)Leafspot:Pseudocercosporasubsessilis
6)Bacterialwilt:Pseudomonasazadiractae
7)Angularleafspot:Xanthomonasazadiractae

3. Symptoms:
•ThediseaseismorepronouncedduringAugusttoDecember,thoughcanbe
observedthroughoutyear.
•Appearanceofsymptomsstartswiththeon-setofrainyseasonandbecomes
progressivelysevereinlaterpartoftherainyseasonandearlywinterseason.
•Theterminalbranchesaremainlyaffected.Thediseaseresultsinthe
progressivedeathofthetree,yearafteryear.
•Twigblightisthemajorsymptom.Diseasealsoresultsininflorescence
blightandfruitrotresultinginalmost100%fruityieldloss.
Phomatwigblight:Phomopsisazadiractae

4. Pathogen:
•Diseasespreadsthroughconidiathataredisseminatedbyraindroplets
andinsects.
•Thepathogenisalsoseed-borne.

5. Senna
1.Alternaria Leaf spot : Alternaria alternata
2.Damping off : Rhizoctonia bataticola

6. Leafspotisthemostseriousamongthediseasescausinglotofdamagetothe
sennacrop.
Theinfestedleavesdropoffprematurelyandaffecttheyieldconsiderably.
SYMPTOMS
•Thediseasebecomesvisiblefirstasminutepaleyellowspotsontheleaf
bladeanditsmargins.
•Asthespotgrowinsizetheybecomecircularandirregularinshapewith
theircoalesceandturndarkbrowntoblackincolour.
•Thelesionsvaryfromaminutespottoabout8mmdiameterinsize.
AlternariaLeafspot:Alternariaalternata

7. •Concentricringsareformedontheleaves.
•Spotsizeincreasesandcoverstheentireleafresultinginblighteningof
leaves.
•Withtheadvancementofthedisease,leaftipsandmarginsdieandthe
necrotictissuesincreaseinsize.
•Thediseaseisknowntoadverselyaffectthesennosidescontentinleaves
anditisinverselyproportionaltothediseaseintensity.
•Lossofsennosidesinseverelyaffectedleaveswasover60%ascomparedto
thatindisease-freeleaves.
•Inadvancedstagesthepodsarealsoaffectedwithbrownishblackspots.

8. Etiology
•Septatemycelium,eithertheconidiaorconidiophoresarecoloured.Conidia
havebothlongitudinalaswellastransversesepta(Dictyosporae)
Epidemiology
•Nutritionallypoorsoil,
•Temp28-35°CandRH85-90%arefavourable.
•Susceptiblehost.
DiseaseCycle:
•Primarysourceofinoculum:DormantmyceliaorSurvivesincropresidueor
throughuseofdiseasedseed.
•Secondarysourceofinoculum:Windborne/Rainspreadconidia.

9. Management
•Collectanddestroytheinfectedplantparts
•Usediseasefreeseed.
•Amendthenutritionalstatusofthesoil
•Reduceplantpopulation
•SpraymancozeborZineborRovral0.25%at15dayinterval.

10. Damping off: Rhizoctonia bataticola
SYMPTOMS
•IntheNorth-WesternIndia,sennaisaffectedbythedamping-off
diseaseatseedlingstage.
•Initiallywatersoakedlesionsappearonthecollarregionofthe
plant.
•Afterbrowndiscolorationfollowstheepidermallayercollapse.
Seedlingstoppledown.
•Thedamping-offinseedlingsisthemostdevastatingdisease.

11. Etiology
•Septatemycelia,sub-epidermalhaustoria
•Asexualsporesareabsentandmycelialstrandscauseinfection
•Vegetativestructure:Sclerotialbodies
Epidemiology
•Warmweather,soiltemp28-32°CwithoptimummoistureandneutralpH
PrimarySourceofInoculum:Sclerotialbodies
SeconderySourceofinoculum:Soilbornemycelialstrands

12. Diseasecycle
•ItisaDeuteromycetesfungusthatproducessclerotialbodieswhichare
sesamumseedlikevegetativerestingstructures.
•Undercongenialconditionsthesesclerotialbodiesgerminate,penetrate
insidethehostandcausesdisease.
•Themycelialstrandsinsidetheaffectedhostagaingerminateandcause
infectionanddiseasecyclecontinues.

13. Management:
•Destructionofdiseaseddebris.
•Deepploughingduringsummer.
•Croprotationwithnon-hostcrops
•Soilsterilization
•BiologicalcontrolwithT.viride
•Seedtreatmentwiththiramorcaptafolat2.5g/kgofseedgavegood
protection.
•SoildrenchingwithCarbendazim(0.1%)orMancozeb(0.2%).
•[email protected]/kgseed.

14. Pyrethrum

15. 1.Dampingoff:Pythiumspp.,Phytophthoraspp.
2.Wilt:Rhizoctoniasolani
3.Rust:Pucciniahoriana
4.Leafblotch:Septoriachrysanthemella
5.Greymold:Botrytiscinerea
6.Fusariumwilt:Fusariumoxysporumf.sp.solani
7.Rootrot:Sclerotiniaminor
8.Rayblight:Phomaligulicolavar.inoxydablis

16. Symptoms:
➢Preemergencedampingoff.
➢Watersoakedlesionsoncollarregion,leadingtorotteningand
dampingoff.
➢Stemsizereduction.
➢Topplingoverofseedlings&death.
➢Postemergencedampingoffandrottingofrootsofstemcuttings.
➢Plantswilldiesuddenly
Damping off : Pythiumspp. and Phytophthoraspp.

18. DiseaseCycle:
PSI:Oospores/Chlamydosporesinsoil.
SSI:Sporangiaspreadbyrainsplashes.
Management:
➢Pre-plantsterilizationofsoilmedium.
➢Betterdrainageandavoidexcessiveshade.
➢SoildrenchwithThiram/[email protected]/litor
Copperoxychloride@3g/lit.

19. Symptoms
•Infectionappearsinitiallyintheformofdarkbrown,necroticlesionsonthe
rootsandbasalpartsoftheplant,whichlaterturnintorootrotandwilt
symptoms,leadingtoprematuredeathanddesiccationofinfectedplants.
•Stolonsexhibitpinkishbrownlesionsinitially.Whichgraduallyturnsinto
darkbrownlesions.
•Laterturnsfromdarkbrowntoblackpatchesthatincreaseinsizeresultingin
softdecay.
Rootrotandwilt-Rhizoctoniasolani

21. Management
•Affecteddebrisdestruction
•Summerploughing
•Croprotation
•Soilsterilization
•BiologicalagentTrichodermaspp.
•Carbendizim0.1%orMancozeb0.25%assoildrenching.
•Seedlingsshouldbegrownindisease-freesoil.
•Raisednurserybedsshouldbeprepared.
•Nurserybedsshouldbedrenchedwith0.15%benomylor0.1%zineb.

22. Symptoms
•Infectedplantscanbesymptomless,especiallyduringhotanddryconditions.
Symptomsusuallyappearduringcooler,wetweatheranditmaytakeupto8
weeksbeforeinfectedplantsshowsymptomsduringperiodsofhotweather.
•Symptomsappearassmallwhitetoyellowspotsupto4mmwideonthe
uppersurfaceoftheleaf.
•Thesespotsmaybeslightlydimpledandbecomebrownasthedisease
progresses.Pustulesformontheundersideoftheleafjustbeneaththesmall
spotsobservedontheuppersurfaceoftheleaf.
Rust : Puccinia horiana

23. •Thesepustulesoriginallyappearasbufftopink-coloured.Astheyage,
theybecomewhite.
•Pustulesaremostcommononyoungleavesandflowerbractsbutcanbe
foundonanypartofthefoliageincludingflowers.
A.Earlysymptomsofyellowwhite,dimpledspotsontheupperleafsurface
B.Youngpinkbrownpustulesonundersurfaceoftheleaves

24. A.Youngpinkbrownpustulesonundersurfaceoftheleaves
B.Maturewhitepustulesonundersurfaceoftheleaf

25. Pathogen-Microcyclicandautoceiousrust,Uredialstageisabsent
Management:
➢Useofhealthysuckersforplanting.
➢Pickingofflowerleavesatplantingandreplanting.
➢SprayingwithWettableSulphur0.2%orZineb0.2%ormancozeb0.25
%orHexaconazole0.1%at10-15daysgap.
➢Croprotationwithnonhostcrop.

26. Symptoms:
➢Initiallysmallcircular/irregularbrownishblackspotsonleaveswithan
yellowhalo.
➢Largepatchesareformedduetomergingofsuchspotscoveringmajor
portionofleaf.
➢Leavesremainsmallandcurl.
➢Leavesshedorhangonthestemforsometime
➢Severeinrainyweather.
Leafblotch:Septoriachrysanthemella

28. DiseaseCycle:
PSI:Survivesincropresidueorthroughuseofdiseasesuckers.
SSI:Windborne/Rainspreadconidia.
Etiology
•Myceliumisseptateinterandintrecellularhaustoria,
•SexualsporesareAscosporesborneinpseudothecium.
•PrimarysourceofinoculumisAscospores(pseudothecium)
•Secondarysourceofinoculumsispycnidiospores
•Modeofspreadisinfecteddebrisinthesoilandrainsplash.

29. Management:
➢Adoptionofsanitarymeasures.
➢Controlledirrigation.
➢SprayCarbendazim/Benomyl0.1%orMancozeb0.2%orCOC
0.3%atfortnightlyintervals.

30. Symptoms:
➢Leafsymptomsstartfrommarginsandspreadtocenterandbasea
semicircularband.
➢Infectedstemsappearbleachedandoftenareassociatedwiththepresence
ofcottonymyceliumandsclerotia.
➢Stemgirdling,deathofupperplantsportions
➢Onflowers,infectionstartsasbrownwatersoakedspotsonlowerpetals
andflowerscoveredwithgreyishbrownpowderymassofspores.
➢Flowerbudsdonotopen.Sterilebuds
Grey mold : Botrytis cinerea

32. DiseaseCycle:
PSI:Haswidehostrange.Alsoproducessclerotia.
SSI:Wind/rainspreadconidiaorcontactbetweenhealthyand
diseased.
Management:
➢Adoptionofproperspacing.
➢SprayofCaptan0.2%orBlitox0.3%asandwhennecessary.