William C. Nesmith's Images
Organization: University of KentuckyUnit: Plant Pathology
Country: United States
| 21 Images of 10 Subjects | View Subject List | View Image Details | View Thumbnails |
| Image | Subject Name | Scientific Name | Description |
|---|---|---|---|
| 5424469 | Pythium diseases | Pythium spp. | A float tray showing an area with advanced stunting and yellow of infected plants. |
| 5424470 | Pythium diseases | Pythium spp. | Pythium infected roots seen coming out the bottom of the float tray on the right, healthy roots on the left. |
| 5424467 | ozone | The spots usually start as small dark green water-soaked areas. Within 48 hours, the lesions change toa 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. | |
| 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. | |
| 5424454 | blue mold | Peronospora tabacina | Underside of an infected leaf with spots showing a darker border. |
| 5424455 | blue mold | Peronospora tabacina | Close-up of infected spots which start out yellow then become necrotic with age. |
| 5424458 | blue mold | Peronospora tabacina | Plant stem cut near the soil line revealing infected, darkened vascular tissue. |
| 5424459 | blue mold | Peronospora tabacina | Plants with stem cut in cross section showing infected, darkened vascular tissue as a ring. |
| 5424460 | blue mold | Peronospora tabacina | Plant with stem cut both in cross section and tangentially to reveal infected, darkened vascular tissue. |
| 5424463 | Fusarium wilt | Fusarium oxysporum f.sp. nicotianae | A one-sided yellowing when looking at the whole plant, an individual leaf, or both. |
| 5424464 | Fusarium wilt | Fusarium oxysporum f.sp. nicotianae | A one-sided yellowing when looking at the whole plant, an individual leaf, or both. |
| 5424465 | Fusarium wilt | Fusarium oxysporum f.sp. nicotianae | Stalk cut to reveal darkened vascular tissue. |
| 5424478 | Tomato Spotted Wilt Virus | Tospovirus TSWV | Infected plant in the field showing symptoms on one side of leaves that might be confused with Fusarium wilt. |
| 5424466 | Fusarium wilt | Fusarium oxysporum f.sp. nicotianae | Stalk cut to reveal darkened vascular tissue. |
| 5424462 | Phytophthora blight | Phytophthora nicotianae | Characteristic disking of pith tissue of the lower stem (shank) of an infected tobacco plant. |
| 5424473 | Rhizoctonia damping-off, blight and rot | Rhizoctonia solani | Shot-hole symptoms seen after infected tissue drops from the leaf. |
| 5424475 | Tobacco Ringspot Virus | Nepovirus TRSV | Single TRSV-infected plant. |
| 5424476 | Tobacco Ringspot Virus | Nepovirus TRSV | Leaf on left with ringspots and small areas of "oak leaf" symptom. |
| 5424477 | Tobacco Streak Virus | Ilarvirus TSV | It is characterized by striking patterns of necrotic leaf tissue usually bearing a close relation to the veins. Some leaves may be affected on one side only. Midribs have dead streaks and the small veins are darkened. Stalks can show depressed dead areas. Apparently normal-growing plants develop necrosis, puckering, and curling of the young leaves. Affected plants appear permanently injured and likely to die; this severe stage soon passes, however, and the plants resume apparently normal growth, with only the originally affected leaves being misshapen and dwarfed. |
| 5424471 | Rhizoctonia damping-off, blight and rot | Rhizoctonia solani | Plants usually rot at the soilless mix surface and continue to rot until the entire plant dies. |
| 5424472 | Sclerotinia rot | Sclerotinia sclerotiorum | Infection is usually seen on a group of plants in a float tray. As the plants die and more air gets into this area, the advance of the fungus is limited by the less humid conditions created. |
