In recent decades, increasing attention has been paid to food safety and organic horticulture. Thus, people are looking for natural products to manage plant diseases, pests, and weeds. Essential oils (EOs) or EO-based products are potentially promising candidates for biocontrol agents due to their safe, bioactive, biodegradable, ecologically, and economically viable properties. Born of necessity or commercial interest to satisfy market demand for natural products, this emerging technology is highly anticipated, but its application has been limited without the benefit of a thorough analysis of the scientific evidence on efficacy, scope, and mechanism of action. This review covers the uses of EOs as broad-spectrum biocontrol agents in both preharvest and postharvest systems. The known functions of EOs in suppressing fungi, bacteria, viruses, pests, and weeds are briefly summarized. Related results and possible modes of action from recent research are listed. The weaknesses of applying EOs are also discussed, such as high volatility and low stability, low water solubility, strong influence on organoleptic properties, and phytotoxic effects. Therefore, EO formulations and methods of incorporation to enhance the strengths and compensate for the shortages are outlined. This review also concludes with research directions needed to better understand and fully evaluate EOs and provides an outlook on the prospects for future applications of EOs in organic horticulture production.

Pitaya is a non-climacteric fruit that has white or red flesh with numerous small, black seeds. It has a high moisture content; however, water loss during handling and storage negatively affects the fresh weight, firmness and appearance of the fruit, decreasing market value. Application of compatible postharvest coatings has been shown to benefit postharvest quality of many crops. The objective of this study was to evaluate the effect of two commercial coatings on weight loss and quality of pitaya during storage. Pitaya fruit were commercially harvested and sorted for uniformity of size and freedom from defects. Fruit were briefly immersed in either a vegetable oil-based coating (VOC; Sta-Fresh^® 2981) or a carnauba-based coating (CC; Endura-Fresh™ 6100) according to manufacturer’s recommendations. Fruit immersed in tap water served as a control. Fruit were fan-dried at room temperature for 20 min, then stored at 7 °C with 85% relative humidity (RH) and evaluated for selected physical quality parameters each 5 days during 20 days. After each evaluation, fruit were peeled and frozen for later analysis of soluble solids content (SSC), total titratable acidity (TTA); on day 15 fresh samples were evaluated by an untrained consumer sensory panel. CC prevented exocarp shriveling for 15 days of storage, compared to uncoated pitaya (16.3% area affected); shriveling in VOC was intermediate and not significantly different from the other treatments. Mesocarp firmness remained constant throughout 15 days of storage regardless of treatment. Fruit exocarp h* angle increased slightly by day 20, becoming slightly less red, and there were no negative treatment effects for the other quality factors measured: SSC (11.33%), TTA (0.25%), weight loss (5.5%) or sensory evaluations (appearance, flavor, texture, firmness, and juiciness). After 20 days storage, appearance for fruit from all treatments was rated unacceptable due to development of anthracnose lesions. It was concluded that both CC and VOC maintained quality of pitaya for 15 days at 7 °C and 85% RH by delaying exocarp shriveling.

Storage at the putative chilling threshold temperature (CTT) to avoid chilling injury still limits postharvest handling of tropical fruit like banana in that ripening may occur at the CTT. To determine whether chilling injury (CI) symptoms would develop in mature green (MG) banana fruit if the CTT exposure was extended by inhibiting ethylene action and thus ripening, 1-methylcyclopropene (1-MCP) was applied. Individual ‘fingers’ from multiple ‘clusters’ of MG bananas were either immersed in water or 50 μg L⁻¹1-MCP (a.i.) solution and each treatment was divided into three subgroups for storage at 5.0°C (severe CI), 13.0°C (mild CI), or 14.0°C (CTT) ± 0.1°C. 1-MCP delayed ripening in terms of color change for 10 days for fruit stored at the CTT. Ethylene production by fruit at 5.0°C remained around 0.04 ng kg⁻¹s⁻¹with no obvious increase during 31-day storage. Ethylene production at 14.0°C (−1-MCP/+1-MCP) increased on Day 33 while increasing on Day 38 for 13.0°C fruit without 1-MCP and on Day 39 for fruit with 1-MCP. Peak climacteric ethylene occurred on Days 44 and 39 for 13.0 and 14.0°C fruit without 1-MCP, respectively, and on Days 59 and 51 for 13.0°C and 14.0°C 1-MCP-treated fruit, respectively. As hypothesized, longer exposure of MG banana fruit to the CTT of 14.0°C without onset of ripening as was allowed by prior 1-MCP treatment allowed CI to develop at that normally non-chilling temperature. Vascular browning was the first visual and most sensitive CI symptom in the experiment and was observed on Day 4 at 5.0°C, Day 10 at 13.0°C, Day 19 at 14.0°C without 1-MCP, and on Day 28 at 14.0°C with 1-MCP. Using a 1-MCP pre-treatment to remove the influence of ethylene from bananas stored at 13°C or 14°C also resulted in slight reduction in vascular browning severity. In conclusion, a putative safe temperature may become a CI temperature if the shelf-life-limiting factor is removed, allowing longer exposure. Chilling at the CTT caused relatively mild injury on fruit, and vascular browning is a sensitive indicator of CI status, while the light-adapted quantum yield of photosystem II [Y(II)] could be a non-destructive indicator of early CI stress in MG banana. Fruit at 13.0/14.0°C developed CI symptoms slightly later with 1-MCP than without 1-MCP. This suggests that ethylene might be involved in early CI symptom development.