Spatio-temporal spread of foot rot (Lasiodiplodia theobromae) in Jatropha curcas L. plantations in Yucatan, Mexico

摘要

Foot rot is one of the most important phytosanitary problems in Jatropha (Jatropha curcas L), causing plant death. The objective of this paper was to determine the epidemiology of foot rot. Consequently, the spatiotemporal spread of the disease and its relationships with the environment was determined in two commercial Jatropha plantations (Fs1 and Nb) in 2015. Incidence of the disease in the period from March to November was 0.43% to 4.76% for plot Fs1 and for plot Nb it was 2.54 to 16.66%, with a gradual increase in the first months and a faster increase in the last months in both plantations. Monthly incidence was adjusted to a linear form of three non-flexible models and the results showed that the Gompertz model provided a better explanation (R-2 = 0.099) for the advance of foot rot in the two plots, with an apparent rate of increase for plots Fs1 and Nb of 0.0034 and 0.047 respectively. The disease progresses speed is associated with higher temperatures and greater relative humidity (p ae&currency& =0.05). Moreover, the dispersion of the disease, calculated by the Morisita index, showed a random spread in the first stages of the epidemic and formed aggregates in subsequent stages. The analysis of auto correlation and the geospatial graphs showed that plants with the diseases were grouped in numbers of 4 to 6 in a north to south direction. The implications of the epidemiological behavior in the management of the disease will be discussed.