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Blackleg of PotatoMuhammad Ammar
• Introduction Potato blackleg is a bacterial disease caused by the bacterium Pectobacterium atrosepticum. It is early potato disease and symptoms can be seen in early June
Infected Plant
•Casual agent
The bacterium Pectobacterium atrosepticum
Causal Agent Under Microscope
Pathogen Biology:A Gram-ve , rod-shaped
bacterium. Carried by contaminated seed tubers.
Cause disease when environmental
conditions are favorable.
Alternate Hosts
Lambs QuartersParslaneMallow
Symptoms Stems : •Stem of potato plants appear pale green or yellow.•At ground level, these affected stems appear black and rotted.Leaves: •Leaves at the top of affected stems may be small and have margins curled inward.Tubers:•In tuber , the flesh may be grey or brown and rotten.
Effected Stem
Infected Tubers
Rotten Brownish Flesh
Disease Cycle and Epidemiology• High soil temperatures and physical attack on seed
tubers, favor seed-piece decay.
• RH - 94 to 100% & temp - 21 to 29oC
• The blackleg bacterium survives poorly in soil.• The seed tuber is the most important source of
inoculum in the blackleg disease cycle.• The blackleg bacterium does not survive very
well outside of association with host plant tissue.
Disease Cycle
Management•Plant only certified, disease-free seed tubers
•Seed treatment
•Streptomycin sulphate 0.1 % for 10 min
•Streptocycline ( 100 ppm) and copper sulphate
( 40 ppm) for 30 min.
•Removal and destruction of infected plants as soon as symptoms are noticed.•Rotation also reduces the risk of infection arising from infected potatoes