Fusarium wilt caused by Fusarium oxysporum. The earliest symptoms are the yellowing of the oldest leaves, generally on only one side of the plant. Wilting eventually affects the entire plant, causing collapse and death. Discoloration of the vascular tissue - closer view. The pathogen blocks flow of water and nutrients through the stem, resulting in wilting of the entire plant. Image courtesy of Clemson University - USDA Cooperative Extension.

Fusarium wilt causes discoloration of the vascular tissue. This browning extends far up the stem and is especially noticeable in petiole scars.