Blackleg is a plant disease of potato caused by pectolytic bacteria that can result in stunting, wilting, chlorosis of leaves, necrosis of several tissues, a decline in yield, and at times the death of the potato plant.

1. Blackleg of Potato
Muhammad Ammar

2. • 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

3. •Casual agent
The bacterium Pectobacterium atrosepticum
Causal Agent Under Microscope

4. Pathogen Biology:
 A Gram-ve , rod-shaped bacterium.
 Carried by contaminated seed tubers.
 Cause disease when environmental
conditions are favorable.

5. Alternate Hosts
Lambs Quarters
Parslane
Mallow

6. 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.

7. Effected Stem

8. Infected Tubers

9. Rotten Brownish Flesh

10. 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.

11. Disease Cycle

12. 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