Cercospora leaf spot
Round-to-angular spots with pale grey centres and dark reddish-brown margins that yellow and drop the leaves in warm, humid weather.
- Pathogen
- Fungus (Cercospora)
- Spreads by
- Wind & rain-splashed spores; seed & debris
- Favoured by
- Warm, humid, wet weather
- Main risk
- Leaf spotting, drop & defoliation
Overview
Cercospora leaf spot is a common fungal disease of pulses (mung, urd and others), sesame, cole crops and many field and vegetable crops. It shows as small round to angular spots, typically with a pale grey or tan centre and a distinct dark reddish-brown to purple margin, sometimes with a yellow halo.
As the spots multiply and merge, the leaves yellow, dry and drop, so a heavy attack defoliates the plant from the older leaves up, weakening it and reducing pod/seed fill and yield. It is favoured by warm, humid, wet weather, spreads by wind- and rain-splashed spores, and carries over on infected crop debris and (in several crops) on the seed. Management is the standard leaf-spot package: clean/treated seed, rotation, sanitation and protective fungicides.
How to identify it
- Small round to angular spots with a pale grey or tan centre and a dark reddish-brown to purple margin, often with a yellow halo.
- Spots that multiply and merge, especially on the older leaves, so the leaf yellows, dries and drops.
- Bottom-up defoliation in a heavy attack, weakening the plant and reducing pod/seed fill.
- Favoured in warm, humid, wet weather and in dense, poorly-ventilated crops.
What causes it and when
- Cercospora fungi, spread by wind- and rain-splashed spores and carried on infected crop debris and (in several crops) the seed.
- Favoured by warm, humid, wet weather with leaf wetness, and by dense, closed canopies.
- Builds up through the season, so it is often worst in the later stages of the crop.
- Different Cercospora species affect different crops, but they behave and are managed similarly.
Cultural & organic control
- Use clean, healthy (and where relevant treated) seed and grow tolerant varieties.
- Rotate with non-host crops, and remove and destroy infected crop debris that carries the fungus over.
- Give open spacing and good ventilation so the canopy dries, and avoid excess nitrogen and dense stands.
- Treat seed with a recommended bio-agent (e.g. Trichoderma) where advised.
Chemical control
- Spray protectively from the first spots, before heavy spotting and leaf drop set in.
- CIB&RC-registered fungicides for the crop (e.g. mancozeb and other recommended protectants/systemics) are used and rotated to avoid resistance.
- Cover the foliage, especially the older lower leaves, and observe the pre-harvest interval.
- Confirm the current recommendation for your crop and area with your local KVK.
Prevent it coming back
- Use clean/treated seed, tolerant varieties and crop rotation, and destroy infected debris.
- Manage spacing, ventilation and nitrogen for a drier, less-favourable canopy.
- Scout the lower leaves from mid-season and spray protectively, rotating fungicide groups.
Crops most at risk
Where this problem is called out in our crop guides — open a crop for the full package of practices.
Frequently asked questions
My pulse/sesame leaves have spots with grey centres and dark edges. What is it?
Those round-to-angular spots with pale grey or tan centres and dark reddish-brown margins (often with a yellow halo) are Cercospora leaf spot. As they multiply the leaves yellow, dry and drop, defoliating the plant from the bottom up. Use clean/treated seed, rotate crops, open up the canopy, and spray protectively from the first spots.
How much does Cercospora leaf spot cut yield?
It depends on how early and how heavily it defoliates. Light spotting is minor, but a heavy attack that yellows and drops the leaves — especially before and during pod/seed fill — cuts yield significantly, because the plant loses the leaf area it needs to fill pods and seed. Acting from the first spots, before heavy defoliation, protects the most yield.
How do I keep it from coming back each season?
Because it carries over on infected debris and seed, the key steps are clean or treated seed, crop rotation with non-hosts, and destroying infected crop debris after harvest. Add tolerant varieties, open spacing and ventilation for a drier canopy, and protective sprays from the first spots. Together these break the carry-over and reduce the disease each season.
Symptoms and control measures follow ICAR, KVK and state agricultural-university package-of-practices; any named chemical is a registered use. Always read the product label and confirm the dose for your crop and zone. editorial policy.