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Apical bud break and early vegetative shoot growth improving the mango malformation development: a new point of view

Cabrera-Huerta, Eugenia, Sandoval-Islas, Jose Sergio, Villegas-Monter, Angel, Nava-Diaz, Cristian, Mora-Aguilera, Jose Antonio
Journal of plant pathology 2018 v.100 no.3 pp. 513-521
Fusarium, budbreak, cultivars, disease outbreaks, juveniles, mango malformation disease, nursery crops, pathogenesis, pathogens, phenology, resting periods, scanning electron microscopes, shoots, virulence
Mango malformation induced by Fusarium spp. is one of the most destructive diseases worldwide. The production losses vary from 50 to 80%. Mango growth is intermittent being characterized by resting periods (RP) intercalary between each vegetative flow. Each new flush promotes changes in the intensity of epidemics, but the interaction of the RPs on the pathogen virulence and pathogenesis are unknown. To provide some information about this interaction, the effect of Fusarium spp. infection on incubation periods (PI), maximum severity (Ymax) and days to maximum severity (DYmax) was compared in nursery plants of cvs ‘Mallika’ and ‘Haden’ inoculated in the resting and active early growth (juvenile) stages, using the veneer grafting technique to end the rest phase in 2016. When both cultivars were inoculated in the resting stage, at 14 and 0 incubation days before grafting (dbg), ‘Haden’ was more susceptible than ‘Mallika’ showing quicker PIs and greater DYmax and Ymax in 42, 55 and 82% respectively. Likewise, ‘Haden’ shoots inoculated during resting stages or active early growth, at 22 days after grafting (dag), had a shortest PI and DYmax values, by up to 32 and 45% respect to mature inoculated shoots that remained attached to the plant. Ymax was not affected by the phenology of the inoculated shoots and PI were higher only in shoots inoculated at 75–85 dag (P < 0.05%). Middle and apical cross sections of mature and juvenile ‘Haden’ and ‘Mallika’ shoots observed under scanning electron microscope showed contrasted anatomical differences in tissue differentiation.