Toenail rot may be caused by trauma, but also need to be alert to the causes of onychomycosis, nail psoriasis, etc., it is recommended to consult a doctor for diagnosis in a timely manner. 1. Toenail ulceration may be the toenail by extrusion, knocking and other traumatic injuries after the toenail cracking, at the same time, the subnail tissue inflammation ulceration, resulting in toenail ulceration symptoms. 2. If accompanied by itchy feet, foot odor, erosion between the toes and other symptoms, we need to be vigilant about fungal infection caused by tinea pedis and tinea cruris. 3. If accompanied by symptoms such as pitting on the toenails, loss of luster of the nail plate, thickening of the nails, or even localized loss of the nail plate, it is necessary to be vigilant for nail-type psoriasis. The above are some of the possible reasons, it is recommended to consult a doctor in time, and diagnosed by a professional doctor after checking.