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.

One of the major problems in the commercialization of avocados is the incidence of postharvest diseases, especially anthracnose (Colletotrichum spp.) and stem-end rot (Lasiodiplodia theobromae, Fusicoccum aesculi and Neofusicoccum spp.). As there is a lack of epidemiological information on these pathosystems, the objective of this study was to establish a method to detect quiescent infections and characterize their temporal progression and spatial pattern in a commercial orchard. Detection of quiescent infections was evaluated in flowers and fruits that were immature and in commercial harvest stage, treated with paraquat, ethrel or water. Treatment of flowers and immature fruits with paraquat led to rapid detection of Colletotrichum spp. In two seasons of a ‘Hass’ avocado orchard, the incidence of diseases was evaluated from open flowers to fruit harvest, totaling 11 evaluations at biweekly intervals. When fruits reached the harvest stage, the spatial distribution of diseased fruits in the trees was evaluated by means of dispersion index and modified Taylor’s law. Considering the evaluation of temporal disease progression, anthracnose was the most important disease, presenting a high initial incidence of 60 and 86% diseased flowers in the two seasons, respectively, while fruits showed an average disease incidence of 70 and 87%, respectively. Stem-end rot was observed only in fruits since the beginning of their development and presented low incidence (<8% fruits), significantly inferior to that of anthracnose. The diseases showed random dispersion within the trees, indicating that their initial inoculum is evenly distributed in the plants.

Coletores solares podem ser utilizados para o tratamento de substratos através dos princípios da solarização. Nesse sentido foi avaliado o efeito desta técnica no desenvolvimento de mudas de couve de três genótipos IAC: Orelha de Elefante, Pires 2 de Campinas e Verde-Escura. Os tratamentos foram compostos por substrato comercial + solo agrícola; substrato comercial + solo agrícola solarizados por 24h e substrato comercial + solo agrícola solarizados por 48h. Os diferentes tratamentos foram acondicionados em vasos de polietileno com capacidade de 300 mL, onde foram cultivados dois brotos de cada genótipo. Cada tratamento foi composto por cinco repetições, distribuídos em blocos ao acaso, em condições semi controladas de casa de vegetação. Passadas três semanas foram realizadas as avaliações do número de folhas, altura (cm), massa da matéria fresca (g) e seca (g) da parte aérea, diâmetro de caule (cm) e comprimento do sistema radicular (cm) de cada genótipo em cada tratamento. Os genótipos responderam de modo diferente à solarização, sendo o Pires 2 de Campinas o mais responsivo, quando cultivado em substratos solarizados por 24 horas, e o Orelha de Elefante por 48 horas.