William C. Nesmith's Images
Organization: University of KentuckyUnit: Plant Pathology
Country: United States
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| 1 Images of 1 Subjects | View Subject List | View Image Details | View Thumbnails |
| Image | Subject Name | Scientific Name | Description |
|---|---|---|---|
| 5424468 | ozone | The spots usually start as small dark green water-soaked areas. Within 48 hours, the lesions change to a brown color then to a gray or white and appear as sunken necrotic areas bordered by chlorotic tissue (on dark tobacco you usually do not see any yellow halo). The spots are often concentrated along the side of the midrib and large secondary veins but can be found anywhere on the leaf. On expanding leaves the spots appear near the tip. Lower leaf surfaces may show no evidence of damage in the early stages. Lesions may run together causing the leaf surface to become necrotic and fall out. Symptoms may occur at any growth stage, but most commonly occur during periods of rapid growth. Older leaves are more susceptible.Dark tobacco types usually show less injury than burley types when at the same growth stage and exposed to the same level of ozone. |
