There has been a tremendous amount of Angular leaf Spot on this years tobacco crop, especially the commercial crop. The conditions that worsen Angular leaf spot are:
Excessive Fertilization – Excess nitrogen, especially ammoniated nitrogen will encourage the Angular leaf spot infection and spread of infection. This can be widely seen this year in the small scale crop which uses less fertilizer has far less, if any, Angular Leaf Spot compared to the Commercial crop
Rainy or severe weather conditions – Where fungal diseases are stronger enough to penetrate the leaf surface Angular Leaf Spot requires a break or wound in the leaf to affect it so severe weather conditions generally cause the breaks or wounds that enable the Angular Leaf Spot Bacteria to affect the plant.
Successive Tobacco crops in one land (crop Rotations). The Angular leaf Spot bacteria can be carried over in stalks from year to year. One year break in land rotation will be better than continuous and two years break will be better than one.
Your common fungicide sprays that currently being spraying on crops will have no effect on control of Angular leaf Spot. Bion, which is a plant activator, will help the plant fight Angular Leaf Spot from within. On small scale trials we have done this year there was a marked difference in disease where the Bion was used.
We currently have a product on trial at Kutsaga called Kasagumycin which is an anti-biotic which is showing a lot of promise in controlling Angular Leaf Spot.
Most importantly remember clean hygiene and a good spray program, both Fungal and bacterial, in seedbeds will limit your disease in the field.
