alternaria leaf blight of cantaloupe

Alternaria leaf blight-Alternaria leaf blight has mostly round lesions with a bulls-eye or concentric ring structure, as do many Alternaria diseases on other crops. Fortunately, lesions do not occur on stems or fruit. However, in severe cases sufficient defoliation can occur to cause loss of fruit of quality either by lower soluble sugars and/or sunscald on fruit. Alternaria leaf blight doesn’t seem to be an important problem most years. Fungicide schedules designed to control gummy stem blight or anthracnose seem to also control Alternaria leaf blight.
Figure 1. Alternaria Leaf Blight disease Figure 1. Alternaria leaf blight on cantaloupe leaf. Note large, mostly circular lesions with concentric rings.
Figure 2. Image of several cantaloupe leaves with Alternaria leaf blight lesions. Figure 2. Image of several cantaloupe leaves with Alternaria leaf blight lesions.
Figure 3. Close-up of a leaf with Alternaria leaf blight. Note concentric ring structure of lesions. Figure 3. Close-up of a leaf with Alternaria leaf blight. Note concentric ring structure of lesions.
Figure 4. Image of a leaf with lesions of Alternaria leaf blight just beginning to coalesce. Note chlorotic halos. Figure 4. Image of a leaf with lesions of Alternaria leaf blight just beginning to coalesce. Note chlorotic halos.
Figure 5. A close-up of an individual lesion of Alternaria leaf blight. Figure 5. A close-up of an individual lesion of Alternaria leaf blight.
Figure 6. Cantaloupe fruit exposed to possible sunburn due to Alternaria leaf blight. Figure 6. Cantaloupe fruit exposed to possible sunburn due to Alternaria leaf blight.