| 1570299 |
Asexual Spore |
Altenaria alternata (400X). December 1991 |
| 1570300 |
Asexual Spore |
Chains of conidia of Alternaria alternata (100X). December 1991 |
| 1406075 |
Symptoms |
needle symptoms |
| 1406074 |
Symptoms |
|
| 1494050 |
Symptoms |
|
| 1494051 |
Symptoms |
|
| 1436046 |
Symptoms |
Leaf spots are brown in color, circular and enlarge to about the size of a nickel. Concentric rings can be seen within the spots and these may coalese forming irregular areas on the foliage. Disease severity is positively correlated with cloudy, wet weather. The disease occurs primarily on mature leaves often beginning on the lower leaves and progressing to other leaves higher up on the stalk. |
| 1402024 |
Symptoms |
This fungal disease appears first on the older leaves as circular, brown spots (1/4 to 1 1/4 inches in diameter) with sharply defined margins. Concentric circles (rings) are often noticeable within the spots. As the leaves approach maturity, a yellowish "halo" of varying width often forms around the lesion. Lesions may merge, forming large areas of dead tissue. During humid weather, sporulation of the fungus may be abundant, giving the lesions a black, dusty appearance. Brown spot is most severe as the plant approaches maturity, and the disease progresses from the lower to the upper leaves. Disease severity depends much on the weather, the overall health of the plant, varietal tolerance, and harvest rate. |
| 1402025 |
Symptoms |
This fungal disease appears first on the older leaves as circular, brown spots (1/4 to 1 1/4 inches in diameter) with sharply defined margins. Concentric circles (rings) are often noticeable within the spots. As the leaves approach maturity, a yellowish "halo" of varying width often forms around the lesion. Lesions may merge, forming large areas of dead tissue. During humid weather, sporulation of the fungus may be abundant, giving the lesions a black, dusty appearance. Brown spot is most severe as the plant approaches maturity, and the disease progresses from the lower to the upper leaves. Disease severity depends much on the weather, the overall health of the plant, varietal tolerance, and harvest rate. |
| 1492176 |
Symptoms |
Alternaria ghostyeat on peach |
| 1440024 |
Symptoms |
Symptoms of the brown spot fungus first appear on the lower leaves. Spots are brown with sharply defined margins and may be surrounded by yellow halos. The primary distinguishing characteristics of brown spot are the dark concentric rings within spots that give it a target-like appearance. With magnification, reproductive structures of the casual agent are seen as tufts of black fungal spores (conidia). Under severe conditions, spots are numerous, may coalesce, and give the leaf a ragged appearance as the infected tissue falls out. |
| 1440025 |
Symptoms |
Symptoms of the brown spot fungus first appear on the lower leaves. Spots are brown with sharply defined margins and may be surrounded by yellow halos. The primary distinguishing characteristics of brown spot are the dark concentric rings within spots that give it a target-like appearance. With magnification, reproductive structures of the casual agent are seen as tufts of black fungal spores (conidia). Under severe conditions, spots are numerous, may coalesce, and give the leaf a ragged appearance as the infected tissue falls out. |
| 5358873 |
Symptoms |
Drybean plant showing symptoms of Alternaria leaf and pod spot caused by Aternaria alternata on a bean field in Colombia. |
| 5383187 |
Symptoms |
Lesions on pumpkin |
| 5383188 |
Symptoms |
Lesions on pumpkin |
| 5383189 |
Symptoms |
Dark mass of conidia |
| 5383190 |
Symptoms |
Lesions on pumpkin |
| 5365618 |
Symptoms |
Potato leaves showing Alternaria blight infection caused by Alternaria alternata. |
| 1497002 |
Symptoms |
Brown spot on tobacco |
| 1497003 |
Symptoms |
Brown spot on tabacco |
| 1524158 |
Symptoms |
Alternaria; Brown spot on lower leaf |
| 5332060 |
Symptoms |
|
| 5358420 |
Symptoms |
Melon plants with Alternaria leaf spot symptoms caused by Alternaria alternata f.sp. cucurbitae in the field.. |
| 5358421 |
Symptoms |
Melon leaves with Alternaria leaf spot symptoms caused by Alternaria alternata f.sp. cucurbitae in the field.. |
| 5358422 |
Symptoms |
A close-up shot of a melon leaf with Alternaria leaf spot symptoms caused by Alternaria alternata f.sp. cucurbitae. |
