Devastative disease of tobacco world.

1. Preparedby: M.kamaraj
Importance
Duringfavourable condition,newgenerations
of sporescanbe producedevery72hrs,less
than one propagule pergramof soil leadstoan
epidemic.
Symptoms
In seedlings:
 Black discolorationof the stemnearthe
soil level.
 Wet rot inhumid,seedlingblightindry
weather.
 Witheringanddryingof tips, Blighting
and dryingof the bottomleaves.
In the transplantedcrop:
 Necroticpatchesonthe stems.
 Infected plantwilts.
 Disc like platesinside of the stem.
 Blackeningandrottingof the leaves.
Casual agent
Phytophthora parasitica var. nicotianae
Spread
Soil borne,windborne,cropresidues
Favourable Conditions
• Frequentrainfallandhighsoil moisture.
• Highpopulationof root knotnematodes
Management
• Coverthe seedbedswithpaddyhuskor
groundnutshell at15-20 cm thick layer.
• Provide adequatedrainage inthe nursery.
Drenchthe nurserybedswith1 percent
Bordeaux mixture or0.2 percentCopper
oxychloride,twodaysbefore sowing.
Black discoloration of stem
Disk like plates inside of stem
Blighting and drying of bottom leaves
• Spraythe bedstwo weeksaftersowingwith
0.2 percent Metalaxyl or0.2 percent Captafol
or 0.2 per centCopperoxychlorideor1 per cent
Bordeaux mixture andrepeatafter10 days.
• Selecthealthy,disease free,resistantseeds
for transplanting.
• Remove anddestroythe cropresiduesand
affectedplantsinthe field.
Devastative disease of tobacco world: black shank

2. Preparedby: M.kamaraj