Adjacent lesions may coalesce to form larger, blighted areas on a leaf. |
 Lesions coalescing on a taro (Colocasia esculenta) leaf infecetd with the taro leaf blight pathogen, Phytophthora colocasia. |
 Banana (Musa sp.) black leaf streak lesions (caaused by the plant-pathogenic fungus, Mycosphaerella fijiensis) on a banana leaf; some are coalescing as disease progresses. |
Coalesce is to grow together, to fuse.
Etymology. 1541, from L. coalescere, from com- "together" + alescere "to grow up" (see adolescent).
Lesions on a leaf may coalesce over time as disease progresses to form large areas of leaf blight.