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