Juan Antonio Herrera-González

The Colletotrichum genus is one of the ten most relevant pathogenic fungi in the post-harvest sector owing to its high infection rate in tropical fruits; however, the search for alternatives to synthetic fungicides is crucial because of their adverse effects on health and the environment. This study evaluated the efficacy of chitosan (CH), citral (CT), and hexanal (HX) against Colletotrichum asianum, as well as the toxicological potential of these treatments. In in vitro tests, 1.0% CH, 0.03% CT, and 0.06% HX significantly inhibited fungal development in parameters of radial growth, sporulation, fungal biomass, and germination by 78–100% (p < 0.05). Furthermore, the toxicity index was low to moderate for most concentrations using cucumber and tomato seed germination as a study model. Toxicokinetic predictions suggest that CH, CT, and HX molecules do not pose a danger to human consumption, suggesting that they are promising alternatives to chemical fungicides for the control of phytopathogenic fungi.

Resumen México es el principal productor y exportador de aguacate en el mundo. La principal zona productores es la Región Pacífico Centro de México (Jalisco, Michoacán y Nayarit) donde se cosecha el 96% de la producción nacional. Antracnosis en poscosecha de aguacate, llega a alcanzar entre 20 y 80% de pérdidas por el deterioro de la calidad del fruto de aguacate. El objetivo de la investigación fue diagnosticar el agente causal de antracnosis postcosecha de aguacate en la Región Pacífico Centro de México, el estudio se realizó entre 2019 y 2020. Se muestrearon frutos de aguacate completamente sano y se aislaron hongos patógenos causantes de antracnosis, se realizó una identificaron morfológica, molecular y filogenética, así como su desarrollo bajo estrés de fungicidas. Las características morfológicas indicaron que el hongo causante de antracnosis en postcosecha pertenece a Colletotrichum gloeosporioides sensu lato. Las pruebas moleculares y filogenética identificaron a los hongos como Colletotrichum siamense, hongo endófito, capaz de existir en dos condiciones de vida del fruto (pre y poscosecha). Este hongo bajo un estrés de fungicida permanece en estado inactivo como respuesta hasta que su efecto desaparece.

Postharvest avocado is susceptible to attack by Neofusicoccum parvum, 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 N. parvum, and the induction of enzymes related to the defense mechanisms of the fruit. N. parvum 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 N. parvum 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.

Blueberry (Vaccinium corymbosum L.) is a crop with great potential for exportation and is very important for its antioxidant properties. However, this fruit is susceptible to different factors of deterioration and attack by pathogens. Botrytis cinerea is the main cause of post-harvest losses in this crop. Antagonistic yeasts from the Debaryomyces hansenii species, which is of marine origin, have been proposed as an alternative method for fungal control. For this reason, this study evaluated the in vitro and in vivo antagonistic capacity of the yeast against B. cinerea. The in vitro growth of the fungus was inhibited by 90% and germination was reduced by 100%, and through the production of volatile organic compounds, the growth of the pathogen was inhibited by 32.5%. Photographic evidence by electron microscopy revealed the effects caused by D. hansenii on B. cinerea. The incidence study showed a 50% reduction in the incidence of the disease caused by B. cinerea in blueberries, while quality parameters—such as soluble solids, titratable acidity, and pH—presented stable values, delaying the maturation process of the fruits. Likewise, the rate of reduction in firmness and physiological weight loss was lower, and the blueberries preserved their quality for a longer time.

ISHS International Symposium on Strategies and Technologies to Maintain Quality and Reduce Postharvest Losses Natural coatings and essential oils effects on postharvest quality and antioxidant system of organic avocado (Persea americana Mill. 'Hass')