Chitosan and GRAS Substances: An Alternative for the Control of <i>Neofusicoccum parvum</i> In Vitro, Elicitor and Maintenance of the Postharvest Quality of Avocado Fruits

Postharvest avocado is susceptible to attack by <i>Neofusicoccum parvum</i>, which has been reported to cause black spot in avocado pulp. Therefore, it is necessary to look for alternatives for its control with products that are low-cost, effective and without risks to human health and the environment, and that also stimulate the defense mechanisms of the fruit. The aim was to evaluate the effect of basic and GRAS substance treatments on the in vitro control of <i>N. parvum</i>, and the induction of enzymes related to the defense mechanisms of the fruit. <i>N. parvum</i> was isolated from avocado fruit. Morphological and molecular identification was performed. In vitro and in vivo treatments were made for the control of pathogens and the induction of defense mechanisms in the fruit with basic and GRAS substance treatments based on chitosan and GRAS substances. The basic and GRAS substance treatments inhibited the development of <i>N. parvum</i> mycelium by 80–100%. In addition, they induced the activation of enzymes related to the defense mechanisms of the fruit (PAL, POD and PPO). The best basic and GRAS substance treatments, both in vitro and in vivo, were those based on chitosan (0.5%) and cinnamon essential oil (2.5%) when they were applied combined in the form of an emulsion.