Plant quarantine and diseases of cotton

Abstract

The Australian cotton industry has developed rapidly since the early 1960s when irrigation became available. Bacterial blight and Verticillium wilt have been present in Australia for many years and with Phytophthora boll rot have caused significant yield reductions. However, production areas have been kept free of several potentially important plant pathogens. More virulent races and strains of the blight and wilt pathogens have developed overseas and the introduction of these must be prevented. Standard plant quarantine procedures have achieved the level of protection required by the Australian cotton industry with the possible exception of the introduction of races of the bacterial blight pathogen by symptomless epiphytic transfer, The quarantine dilemma is whether to provide conditions favouring pathogen expression or to attempt to minimise the growth and development of the pathogen and other epiphytic micro-organisms, if present. The presence of soil and/or plant material on second-hand machinery imported from overseas constitutes a weak link in quarantine effectiveness. Second-hand machinery should be thoroughly cleaned prior to importation and carefully inspected by quarantine officers on arrival. The efficacy and feasibility of fumigation could be considered.