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Select fields free of crop residues or volunteer potato or tomato plants
Prepare land to improve drainage
Avoid starting cultivation during heavy rains
In case of potato, use disease-free seeds and resistant varieties (e.g. Hill Star)
Follow recommended spacing (do not overcrowd plants)
Do not overuse fertilisers, especially Nitrogen fertilisers
Monitoring
Observe plants regularly from the early stage of crop
Look for symptoms such as:
Blackish water soaked lesions occur on the leaves; Whitish sporulation of the pathogen can be seen around the margin of the lesions, particularly on the underside of the leaf.; On stems, late blight causes brown to black lesions; The lesions commonly occur at the junction of the leaf and stem where water may accumulate or on clusters of leaves at the top of the stem.
The disease spread very quickly over the entire field killing all foliage and causing the death of the entire plant
Since the disease can cause huge crop losses, it is advisable to use protective fungicides when the disease symptom first appear to reduce the disease spread
In wet weather conditions, application of systemic fungicides at 21 day intervals is a necessity
Direct Control
Direct Control
Restrictions
Take appropriate personal and environmental precautions when applying pesticides
Propineb WP; mix 2 g/L and apply 5-7 days intervals
WHO hazard class IV; Contact fungicide; Alternate with systemic fungicide
Mancozeb WP; Contact fungicide, mix 2 g/L and apply 5-7 days intervals
WHO hazard class IV; Alternate with systemic fungicide
Fluazinam SC; Contact fungicide, mix 0.5-1 ml/L and apply 5-7 days intervals
WHO hazard class III
Metalaxyl+ mancozeb; Systemic fungicide, miz 2.5 g/L and apply 14-21 days intervals
WHO hazard class IV; Alternate with contact fungicide
Dimethomorph + mancozeb (WP)l mix 2.5 g/L and apply 14-21 days intervals
Systemic fungicide; WHO hazard class III
Chlorothalonil WP; mix 3 ml/L and apply 5-7 days intervals
Contact fungicide; WHO hazard class IV
AUTHOR(S): K.P. Somachandra (Department of Agriculture)
CREATED/UPDATED: March 2014 PRODUCED BY: Plantwise
