Effect of Conventional and Alternative Products on Postharvest Disease Control in Avocados

Abstract

Postharvest diseases constitute a serious problem for avocado commercialization. Thus, the present study aimed to evaluate the effect of conventional and alternative products in controlling diseases affecting ‘Hass’ avocados in the field and in the postharvest by carrying out physicochemical characterization of fruits subjected to postharvest treatments. In the field, besides the management adopted by the farmer, seven products were sprayed three times during fruiting for evaluation. Postharvest products were diluted in water or in oxidized polyethylene wax and shellac. Water treatments with potassium phosphite, Soil-Set®, chlorine dioxide, thyme essential oil, sodium bicarbonate, lemon grass essential oil and thiabendazole reduced the incidence of diseased fruits, and anthracnose, the main disease, was controlled with sodium bicarbonate, lemon grass essential oil and thiabendazole. Greater soluble solids content was found for control (water), chlorine dioxide, acibenzolar-S-methyl and thiabendazole. For the products that reduced anthracnose, there was no correlation between the disease and the physicochemical parameters, evidencing that the disease control is not associated with delayed ripening. For wax treatments, diseases were not controlled, and the fruits presented lower titratable acidity with thyme essential oil, sodium bicarbonate, control (wax), acibenzolar-S-methyl and lemon grass essential oil. Control and thyme essential oil were highlighted for maintaining the green coloration of the fruit skin for the shortest period. Under field conditions, azoxystrobin, thiabendazole, difenoconazole+azoxystrobin and acibenzolar-S-methyl+azoxystrobin reduced the occurrence of diseased fruits, while anthracnose control was only obtained with azoxystrobin.

In vitro and in vivo Application of Eco-friendly Treatments to Control Postharvest Stem-end Rot of Naturally Infected Avocado (cv. Pollock)

“…According to Fischer et al (2018), soluble solids of avocado treated with sodium bicarbonate have been slightly reduced compared to the untreated control and this finding is in conformity with the results of the present research. These also agree with Fischer et al (2018) who reported that flesh firmness and peel colour of sodium bicarbonate treated avocado did not show a significant difference when compared to the control.…”

“…The US FDA recommends that sodium bicarbonate could be applied on food substrates with no limitation other than Good Manufacturing Practice (GMP) specifications (eCFR, 2020 Fischer et al (2018) reported that avocado (cv. Hass) fruits treated with 2% w/v sodium bicarbonate have exhibited a significant reduction in postharvest disease of 'anthracnose'.…”

Extension of Avocado Fruit Postharvest Quality Using Non-Chemical Treatments

“…Consequently, several research efforts aimed towards finding safer alternative technologies have been made in the past decade or so. These alternative methods can be classified into physical heat treatments (such as hot water dips, steaming, dry heat and forced air), irradiation, controlled atmospheres, electrolysed water, biological control, plant extracts (such as essential oils) and elicitors (e.g., chitosan and jasmonates) [17]. This review explores the different types of postharvest constraints of avocados and the non-chemical treatments available to alleviate their impacts.…”

“…Most of the injuries can act as port of entries for postharvest pathogens after ripening during marketing. Therefore, severely damaged fruits can be easily isolated and culled before marketing [17]. Injuries, such as lenticel damage, instantly become apparent after any form of mishandling as they cause small dark spots about 1-5 mm diameter appear, which are more severe when fruit are harvested wet [19].…”

In vitro Antifungal Activity of Plant Extracts, Hydrolates and Essential Oils of Some Medicinal Plants and Control of Cucumber Anthracnose

“…Plant diseases are responsible for considerable losses in crops of economic importance. For the control of plant diseases, chemical, physical and biological methods have been used [1,2,3]. However, the indiscriminate use of chemical agents in agriculture causes serious risks to the environment and to the human health, creating a trend to the use of alternative methods of disease control.…”