Black rootrot of cotton has been observed in 98 per cent of the farms regularly surveyed by NSW Agriculture in the Macquarie, Namoi, Gwydir and Macintyre valleys. The disease has potential to cause up to 40 per cent yield loss. The disease develops over time when the fungus T. basicola is present in adequate numbers within the vicinity of cotton roots when the environment is favourable for infection. The management strategy for this disease, therefore, could be based on four important components of the disease pyramid host, pathogen, environment and their interaction over the time.