Severity of mango (Mangifera indica L.) powdery mildew (Oidium mangiferae Berthet) and its relationship with ash discharge by a thermoelectric power plant.
Guillén-Sánchez D., Téliz-Ortiz D., Mora-Aguilera A., Nieto-Angel D., Cárdenas-Soriano E., Siebe-Grabach C., Villanueva-Jiménez J. A.
Author Affiliation: Universidad Autónoma del Estado de Morelos, Campus Oriente, Nicolás Bravo s/n, Parque industrial Cuautla, Xalostoc, Morelos, C.P. 62700, Mexico.
Revista Mexicana de Fitopatología 22 : 90-99
Abstract : The severity of mango powdery mildew (Oidium mangiferae), the pathogen conidial population, and number of fruits per panicle harvested were evaluated in 13 orchards in Mexico under alternative (AM) or traditional (TM) management. The orchards were located at different distances from a thermoelectric power plant (TPP) that uses oil for electricity generation. Disease severity was evaluated every 8-10 days using a logarithmic scale with 6 classes applied to 20 inflorescences from each of 5 mango trees per management system, 10 trees per orchard, on 3 flowering flushes. Severity was related to temperature frequency and relative humidity intervals. As the distance between orchards and the TPP increased, disease severity and number of conidia increased (r2=0.73), whereas ash deposit decreased (r2=-0.78). The mean disease severity on distant orchards was 0.83, 70.28 and 95.15%, while in orchards near the TPP, the value reached 0, 0.76 and 50.91% for the 1st, 2nd and 3rd flowering flushes, respectively. The maximum severity of powdery mildew coincided with temperatures between 13 and 20°C, and relative humidity of 22-60% (r2=0.95) during the first 2 flowering flushes; however, on the third, it coincided with temperatures of 20-25°C and relative humidity of 60-80%. The phenological flowering stages 1 (swollen bud) to 6 (full panicle elongation) were tolerant, stages 7 and 8 were susceptible, and stages 9, 10, and 11 (fruits 2 cm in diameter) were very susceptible to the disease. The average severity in the 3 flowering flushes in distant orchards was similar under AM (0.35, 69.9 and 94%) and TM (0.76, 97.1 and 97%). A similar result was observed in orchards near the TPP. Ash mean deposition in nearby orchards was greater (1.39 g/m2 of leaf) than in distant orchards (0.47 g). The number of fruits per panicle during the 3 flowering flushes was similar in nearby orchards (0.91, 1.21 and 0.31) and in distant orchards (0.71, 0.92 and 0.65).