<i>Macrophomina phaseolina</i>: Spatio-Temporal Dynamics of Inoculum and of Disease in a Highly Susceptible Crop

Abstract

Mihail, J. D. 1989. Macrophomina phaseolina: Spatio-temporal dynamics of inoculum and of disease in a highly susceptible crop. Phytopathology 79:848-855. The spatio-temporal dynamics of microsclerotia of Macrophomina the first fallow period. Charcoal rot symptom development and mortality phaseolina were investigated over 2 yr in a field plot of 100 contiguous were strongly influenced by the timing of host reproduction and unaffacted quadrats (1.52 X 3.05 m), arranged in a 10 X 10 grid. The population by plant density. Unexpectedly, during the second epidemic, symptom of microsclerotia increased from a preplant population of 8.9 micro- expression declined following a period of cool weather. During both sclerotia per gram to 98.6 per gram after two successive crops of the epidemics, a large patch of high charcoal rot mortality was visually evident latex-producing plant Euphorbia lathyris. Inoculum remained spatially and statistically confirmed by the high-order positive autocorrelation as aggregated over the 2 yr as measured by Morisita's index of dispersion. measured by Moran's I statistic. Spatio-temporal autocorrelation analysis However, the large patch of quadrats with a similar inoculum level, was used to find a model that would account for the observed temporal demonstrated by the high-order positive autocorrelation measured by changes in mortality patterns for the two epidemics and in inoculum Moran's I statistic, was not detectable at the end of the second growing density patterns during the two fallow periods. season, largely as a result of continuing cultivation operations during