Bacterial blight of cotton (angular leaf spot)
Angular, water soaked spots between the leaf veins turn brown and black, with black streaks along the veins and stems.
Crops it strikes
What you see
When to act
From the seedling stage to boll set, check the leaves of 20 plants at each of five spots every week, and after every storm. Spray copper early in the attack, when angular spots start to spread in wet, windy weather.
What to spray
Active ingredients only, never brands. The FRAC group tells how it works: switch to a different group next time, so the disease does not learn to survive it. Spray only when the damage is worth the cost, and only with products registered with the Fertilizer and Pesticide Authority for your crop. Follow the label. The Shopee and Lazada links only show who sells something with that active ingredient, not a recommendation of any seller or product.
How to prevent it
- Plant clean, delinted and treated seed from healthy fields: the bacterium rides on the seed.
- Plant resistant varieties where sold.
- Plow under crop residue after harvest, and rotate cotton with other crops.
- Stay out of the field while the leaves are wet, so you do not spread the bacteria.
- Remove volunteer cotton plants between seasons.
Not sure it is this one?
Many diseases look alike. Send a photo to Anee, the smart farm technician in anee.io. She reads it with your crop, its age and the weather, and tells you what it most likely is and what to do first. In Tagalog or English.