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Strawberry (Fragaria x ananassa) is an exquisite food, which provides health benefits, making it the berry with the highest production and export in Mexico. However, it is highly perishable, susceptible to postharvest damage, mainly by Botrytis cinerea and Rhizopus stolonifer, among others. The use of pesticides in preharvest is the control strategy of these pathogens; however, pesticides are documented to harm human health and the ecosystem, showing the need to explore friendly alternatives. Reagent grade chitosan (QGR) is an innocuous polymer with widely reported antifungal activity, while sodium octanoate (8:0) (OS) also has this property; however, so far it is unknown whether commercial grade chitosan (QGC) (the most suitable candidate to conduct a larger commercial study, due to its cost), available in Mexico, has the same effect. Therefore, the objective of this research was to evaluate the effectiveness of QGR and the QGR-OS composite in the protection of strawberry in postharvest and compare it with that of QGC and that of the QGCOS composite. The compounds were sprayed on the fruits and incubated simulating export conditions. The results showed significant reduction in the severity and incidence of postharvest strawberry fungal diseases after the application of QGR, QGC and QGR-OS, QGC-OS, but not that of OS applied alone. QGC and the QGC-OS composite are excellent candidates for use in a larger commercial study. [ABSTRACT FROM AUTHOR]

Plant diseases with a negative impact on strawberry yield (Fragaria × ananassa), such as anthracnose and fruit rot, are mainly controlled using pesticides, which can cause harmful effects; thus, new control alternatives for fruit decay are needed. Chitosan is a compound already evaluated for fungal disease control at postharvest. The aim of this study was to evaluate the in vitro and in vivo control activity of chitosan against post-harvest fungal strawberry pathogens, such as Colletotrichum gloeosporioides, Colletotrichum acutatum, Fusarium oxysporum and Phytophthora sp. The experimental design was completely random, with at least three repetitions for each chitosan treatment (5, 7.5, 10 and 15 mg mL-1). The data obtained were transformed with the x ≤05. function. A variance analysis (p≤0.05), and a Tukey's test (p≤0.05) were conducted using the SAS software. In vitro bioassays showed the anti-fungal effects of chitosan (5, 7.5, 10 and 15 mg mL-1) against all pathogens tested, which are related to the inhibition of mycelial growth and spore germination. The best results were observed in F. oxysporum and Phytophthora sp. with 100% of mycelial growth and spore germination inhibition. In vivo bioassays showed that strawberry fruit inoculated with mycelium or spores, and then immersed in chitosan (7.5, 10 and 15 mg mL-1), displayed a significant reduction (p≤0.05) in disease severity index after two treatments: 1) exposure for 7 d at 2±2.0 °C, and 2) for 3 d at room temperature (25±2.0 °C). The best results were observed in fruit treated with 15 mg mL-1 chitosan, which showed a disease severity range of 1-1.2 for fruit inoculated with mycelium and 1-1.6 with spores. These findings show that chitosan is a promising alternative in post-harvest disease control in strawberries. [ABSTRACT FROM AUTHOR]