Sprayable formulation of 1-methylcyclopropene (1-MCP) was tested as a preharvest application on European pears to determine the best timing and rate of 1-MCP application for maintaining fruit firmness and quality of trees during harvest and in storage after harvest. Two rates of 1-MCP, 0.06 and 0.13 g⋅L−1 active ingredient (a.i.) (minimum and maximum rates, respectively), were sprayed 1 week and 2 weeks before commercial harvest on two cultivars, Bosc and Comice, in 2017 and 2018. After 2 months in cold storage (0 ± 1 °C), differences in fruit firmness of both cultivars were observed among treatments. For ‘Bosc’, fruit treated with both rates 1 week before harvest were 50% firmer than nontreated control fruit. For ‘Comice’, fruit treated with the maximum rate both 2 weeks and 1 week before commercial harvest were 46% and 31% firmer than nontreated control fruit, respectively. However, after 4 months in storage, no differences in fruit firmness of both ‘Bosc’ and ‘Comice’ were observed among treatments. The sprayable 1-MCP application applied 2 weeks before commercial harvest also affected the fruit firmness on trees. The maximum rate of 1-MCP treatment consistently maintained the fruit firmness by 5.0 N compared with fruit treated with the minimum rate and nontreated controls. This effect was significant until 1 week after commercial harvest for both cultivars and until 2 weeks after commercial harvest for ‘Bosc’. The poststorage fruit firmness and overall eating quality of ‘Bosc’ were unaffected by the maximum rate of 1-MCP application as well as the extended harvest time. However, for ‘Comice’, the overall eating quality was negatively impacted by 1-MCP treatments. This study suggests that the maximum rate (0.13 g⋅L−1 a.i.) of 1-MCP application 2 weeks before commercial harvest maintains the fruit firmness of ‘Bosc’ for at least 2 weeks more and offers an extended harvest window for better preharvest management. Furthermore, this treatment improves the physiological fruit quality such as senescence scald during the poststorage period without significantly affecting the poststorage ripening of ‘Bosc’ after 4 months of storage.
Achala N. KC, Ann L. Rasmussen, and Joseph B. DeShields
Kristine R. Buckland, Cynthia M. Ocamb, Ann L. Rasmussen, and Lloyd L. Nackley
Widespread outbreaks of tomato powdery mildew (Leveillula taurica and Oidium neolycopersici) are problematic in fresh market tomato (Solanum lycopersicum) crops in western Oregon, USA. In western Oregon, fresh market tomatoes are frequently grown in greenhouses or high tunnels where conditions can promote diseases such as powdery mildew. Heightened concerns about worker safety limit the pesticides available for use in enclosed systems. We studied the efficacy of ultraviolet-C (UV-C) light applications under high-tunnel conditions compared with a standard fungicide program. Plants treated with UV-C had zero incidence of powdery mildew on all sample dates in the first trial. In trial 2, disease incidence was lower on UV-C treated plants than both grower standard and nontreated control early in the study while disease severity remained lower in UV-C than nontreated control and similar to grower standard treatment. Additional research is needed to optimize UV-C treatment intervals to minimize negative effects on plant growth and maximize powdery mildew control.