Blossom blight is a destructive disease of plums (Prunus salicina) when humid and temperate weather conditions occur in Chile. Disease incidence ranging from 4 to 53% has been observed. Symptoms include light brown petal necrosis, starting as light brown mottles or V-shaped necrosis at the margins of the petals, progressing to the stamen and pistils. In this study, the etiology of blossom blight of plums was determined. High- and low-sporulating isolates of Botrytis were obtained consistently from blighted blossoms and apparently healthy flowers of plums. Based on colony morphology, conidial production and molecular phylogenetic analysis, these high- and low-sporulating isolates were identified as B. cinerea and B. prunorum sp. nov., respectively. Phylogenetic analysis of the genes glyceraldehyde 3-phosphate dehydrogenase (G3PDH), heat-shock protein 60 (HSP60), and DNA-dependent RNA polymerase subunit II (RPB2) grouped B. prunorum isolates in a single cluster, distantly from B. cinerea and other Botrytis species. The phylogenetic analysis of necrosis and ethylene-inducing protein (NEP1 and NEP2) genes corroborated these results. Analysis of the internal transcribed spacer region and large-subunit (26S) ribosomal DNA and detection of Boty and Flipper transposable elements, were not useful to differentiate between these Botrytis species. Both species were pathogenic on plum flowers and the fruit of plums, apples, and kiwifruits. However, B. prunorum was less virulent than B. cinerea. These pathogens were re-isolated from inoculated and diseased tissues; thus, Koch’s postulates were fulfilled, confirming its role in blossom blight of plums. B. cinerea was predominant, suggesting that B. prunorum may play a secondary role in the epidemiology of blossom blight in plums in Chile. This study clearly demonstrated that the etiology of blossom blight of plums is caused by B. cinerea and B. prunorum, which constitute a species complex living in sympatry on plums and possibly on other stone fruit trees.

An herbaceous/grassy-like flavor has been reported by Chilean producers of Regina sweet cherry. There are no previous academic reports related to this flavor occurrence. Sweet cherries from five phenological stages were collected from six orchards with high herbaceous flavor incidence spanning Chilean production zones during the 2019/2020 season. Four experienced panelists tasted the fruit to identify the off-flavor incidence and intensity from four phenological stages, and the same cherries were analyzed for volatile compounds. Thirty-nine volatiles were identified and semi-quantified using solid-phase microextraction (SPME) and GC-MS. The highest off-flavor incidence was found at the bright red (stage 3) and mahogany colors (stage 4). No single volatile explained the herbaceous flavor consistently among orchards. However, it appeared that the off-flavor was related to delayed ripening in cherries, with more C6 aldehydes and less esters. Furthermore, rainfall and the elevation of the orchard had a significant effect on the incidence of off-flavor. Preharvest practices that promote fruit ripening along with avoiding early harvests are recommended to reduce the incidence of herbaceous flavor in Regina.

In many fruit trees, the thinning of buds, flowers, or fruits is used to increase the leaf area-to-fruit ratio (LA:F) and reduce competition for carbohydrates. Meanwhile, calcium (Ca) sprays during fruit development are also used to increase fruit quality and postharvest storage. Such practices have been recommended to increase fruit firmness and reduce fruit cracking in sweet cherries. To understand the effects of foliar Ca sprays and crop load reductions in the combination ‘Lapins’/‘Colt’, trained as the Kym Green Bush, a factorial experiment to determine the interactions between both managements was established in the Central Valley of Chile during the 2018/2019 growing season. Two levels of crop load (CL) were established—thinned (50% crop load) and unthinned (100% crop load) during Stage I of fruit development (31 days after full bloom, DAFB). Three timings of foliar applications of CaCl₂ (TFA; 0.8%) were evaluated: early 26 DAFB, later 39 DAFB, or late 62 DAFB. Natural fruit contents and concentrations of Ca were determined on unsprayed control trees. Fruit from the thinned trees were significantly larger and heavier and had a higher titratable acidity than unthinned trees did. Significant interactions between TFA and CL were observed for SSC, without a clear trend. Thinned trees were less affected by pedicel detachment, browning, and fruit decay after 45 d of storage (0 °C). In unthinned trees, a foliar CaCl₂ spray at Stage I allowed a higher fruit firmness than CaCl₂ sprays at Stage II and III of fruit development. The CaCl₂ applications at 39 or 62 DAFB reduced the incidence of cracking in thinned trees. Natural Ca concentrations decreased during fruit development, indicating a cessation of Ca import and a dilution by subsequent growth. Our results suggest that the early reduction of crop load has positive effects on fruit quality and condition during storage, and early Ca sprays (Stage I) improve fruit textural properties, even under high crop loads.

BACKGROUND: Kiwifruit ( Actinidia deliciosa (A. Chev.) C.F. Liang et A.R. Ferguson cv. ‘Hayward’) is usually harvested firm, unripe, and with a high starch content, and thus fruit do not always achieve a suitable soluble solid concentration (SSC), and soft texture when ripe. A high dry matter concentration at harvest can be used to predict fruit sweetness at ripening. However, fruit softening capacity is difficult to predict because of the interaction between postharvest practices and biochemical processes that occur at 0°C. OBJECTIVE: To understand the effect of ethylene on restoring the lost softening capacity of kiwifruit treated with1-methylcyclopropene (1-MCP) alone or in combination with modified atmosphere packaging (MAP) or controlled atmosphere storage (CA). METHODS: The effect of ethylene (100 μl l ^–1 for 12 h at 20°C) on kiwifruit harvested at commercial maturity (6.2% SSC) and treated with 1-MCP (1 μl l ^–1 , 24 h) and packed in perforated bags (PB) or MAP for 60, 90 or 120 days at 0°C and ripened at 20°C for 17 days was determined. The effect of ethylene applied at 100 μl l ^–1 for 24, 48 or 72 h was also evaluated on fruit treated with 1-MCP (1 μl l ^–1 , 24 h) subjected to 108 days of CA (2% O ₂ and 5% CO ₂ ) and a further 30 days in PB at 0°C. RESULTS: Both 1-MCP and MAP reduced fruit softening after 60 and 90 days at 0°C, and delayed fruit ripening at 20°C. A synergistic effect of 1-MCP and MAP extended those results to 120 days at 0°C. Ethylene treatment restored the ripening of MA fruit but not the 1-MCP-treated fruit stored for 60 days at 0°C or when it was packed in MA bags for 90 days at 0°C. Ethylene for 48 h prevented the ‘hard core’ texture observed in CA with 1-MCP treated fruit. CONCLUSIONS: Kiwifruit treated with 1-MCP and/or packed with MA requires a minimum time at 0°C before to induce ripening by ethylene treatment (100 μl l ^–1 for 12 h at 20°C). Ethylene treatment avoids ‘hard core’ development on 1-MCP treated fruit stored in CA.

The use of protective covers, such as high tunnels, is recognized as an effective technology to reduce rain-induced fruit cracking in sweet cherries; however, there is a lack of information concerning the effects of this production system on the fruit’s mineral concentration, quality, and postharvest life. This study assesses the feasibility of using high tunnels on ‘Santina’ sweet cherries under the Mediterranean climate of the Central Valley of Chile to obtain earlier harvests of high-quality fruit with long storage life. The study included two plots: Plot 1 during the 2018/2019 growing season, and Plot 2 during the 2019/2020 growing season. High temperatures and relative humidity inside the high tunnels during bloom and fruit set decreased fruit yield, particularly in Plot 1. On average, trees inside the high tunnels were harvested 11 days earlier than those in the open. Fruit from covered trees were significantly larger (13%) and softer (10%) than those from the outside. Fruit quality characteristics, such as soluble solids concentration and titratable acidity, were not affected by high-tunnel-protected cultivation. Fruit from covered and uncovered trees maintained the firmness differences obtained at harvest between treatments, but showed similar postharvest quality after 45 days at 0 °C and a further 3 days at 20 °C on the other characteristics. The covered fruit had lower Ca concentrations (7.7 mg 100 g⁻¹) and higher K:Ca, Mg:Ca, and N:Ca ratios. Significant relationships were found between Ca or K:Ca and fruit firmness at harvest. Lower Ca concentrations in the fruit may explain the lower firmness of fruit grown under plastic covers. There were no differences between covered and uncovered cherries in either cracking susceptibility or induced pitting. ‘Santina’ cherries were very sensitive to pitting damage, but this is not associated with the fruit’s Ca concentration. The results obtained show that high tunnels influenced fruit yield, development, and quality, and emphasize that the fruit’s Ca concentration under this growing condition plays a significant role in the firmness of ‘Santina’ sweet cherries.