Etiología y epidemiología de la necrosis floral del zapote mamey (Pouteria sapota (Jacq.) H.E. Moore y Stearn) en guerrero, México

SUMMARY: In Alpoyeca, Guerrero, México, floral necrosis is a disease of unknown etiology that occurs with high incidence (80 to 100 %) in sapotes mamey (Pouteria sapota) and reduces the productivity of commercial orchards. The objectives of the present study were to determine the etiology and temporal progress of the disease. Penicillium olsonii and Alternaria alternata were isolated from necrotic flowers, and Pestalotiopsis paeoniicola was isolated from asymptomatic flowers. The pathogenicity of the fungi was verified in asymptomatic flowers in 2005 and 2006. P. olsonii and A. alternate, inoculated in a conidial suspension (1 × 103 conidia mL^-1 caused necrosis, wilting, rot, and floral abscission at 5 d and 8 d, respectively. P. paeoniicola induced petal necrosis after 8 d. The temporal progress of floral necrosis was studied on 10 mamey sapote trees from May to August of 2005, with a final incidence varying between 80 and 100 %. Fifty percent of the epidemics fit the Gompertz model, 30 % fit the logistic model, and 20 % fit the monomolecular model. Disease incidence was associated with relative humidity of 65 to 75 % (r = 0.80) and greater than 5 km h^-1 wind speed (r = 0.75). The conidial densities of Alternaria sp. and Pestalotiopsis sp. were correlated with relative humidity from 70 a 90 % (r_Alternaria = 0.75 and r_{Pestalotiopsis} = 0.80) and with greater than 5 km h^-1 wind speed for Alternaria sp. (r_Alternaria = 0.70. In Alpoyeca, Guerrero, floral necrosis of mamey was induced by Penicillium olsonii and Alternaria alternata. The intensity of the disease was correlated with relative humidity and wind speed.