INFECTION OF COTTON BY ASPERGILLUS FLAVUS - EPIDEMIOLOGY OF DISEASE

The amount of damage done to cotton seeds by Aspergillus flavus is nil in the central valley (San Joaquin Valley) of California. Results of our experiments indicate that A. flavus is not apt to be a problem in that area. This is because bolls escape infection, due to the prevailing low relative humidity which allows them to open and dry quickly. Other conditions for infection (namely inoculum potential of the fungus and air temperature) are adequate in the San Joaquin Valley and also in southern California. Moderate to relatively large amounts of infection may occur in southern California, depending upon weather conditions. But in each of the years 1965, 1966, and 1967, significant amounts of seed infection occurred. This is because bolls are prone to infection, and to aflatoxin accumulation, for a greater length of time in southern California than in the San Joaquin Valley. Skip-row planting (4 rows planted and 4 rows unplanted), together with chemically induced defoliation of the lowermost third part of the plants, offers some hope for control of the problem in the field. © 1969.