The most important symptom of wilt of cotton (caused by Fusarium oxysporum vasinfectum) is

The most important symptom of wilt of cotton (caused by Fusarium oxysporum vasinfectum) is Discolouration of tissues and the plugging of vessels by hyphae.
Fusarium wilt, caused by the fungus Fusarium oxysporum f. sp. vasinfectum, is a major disease of cotton capable of causing significant economic loss. The fungus persists in the soil as chlamydospores and association with the roots of susceptible, resistant and non-cotton hosts as well as in seed.
Symptoms include yellowing, stunting, and death of seedlings and yellowing and stunting of older plants.