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The objective of this study was to evaluate the use of an ethanol vapor release pad and a saprophytic yeast Cryptococcus infirmo-miniatum (CIM) to reduce decay and maintain postharvest quality of intact or fresh-cut sweet cherries (Prunus avium) cv. Lapins and Bing. Intact or fresh-cut fruit were packed in perforated clamshells (capacity 454 g) and stored at 1, 10 or 20 °C for up to 21, 14 and 8 d, respectively. For ethanol treatment, a pad made with silica gel powder containing 10 g ethanol and covered with perforated film, which allows ethanol vapor to diffuse gradually, was attached to the upper lid of the clamshells. Ethanol treatment caused accumulation of ethanol in the packaging headspace, about 10 μL L−1 with little change within 14 d at 1 °C, 23 μL L−1 at d 1 and decreased to 15 μL L−1 at d 10 at 10 °C, and 26 μL L−1 at d 1 and decreased to 13 μL L−1 at d 3 at 20 °C. Ethanol content in fruit was less than 9 mg kg−1 in all the control fruit, and increased to 16, 34 and 43 mg kg−1 in ethanol-treated fruit at 1, 10 and 20 °C, respectively. Nonetheless, a sensory taste panel did not perceive any flavor difference from the ethanol treatment. The ethanol treatment retarded softening, darkening, and acid decrease in fruit as well as discoloration of the stems, and extended shelf-life of intact cherries. Ethanol reduced brown rot (Monilinia fructicola) in fresh-cut cherries stored at 20 °C, but not at 1 and 10 °C. A pre-packaging dip in CIM completely controlled brown rot in inoculated fresh-cut cherries stored at 1 °C, and in naturally infected cherries at 20 °C.

The objective of this research was to develop a model to predict, at-harvest, the risk of grey mould in pear fruit (Pyrus communis) in long-term cold storage based on multiple variables including: i) density of Botrytis cinerea DNA on fruit surfaces at harvest; ii) fungicide application within 4 weeks before harvest; iii) rainfall within 2 weeks before harvest; and iv) a relative orchard tree-growth and management rating. The model classified grey mould risk as low, moderate, high, or extreme. Data were collected for 2 years in six pear orchards in New Zealand and for 3 years in eight pear orchards in the Mid-Columbia district of Oregon and Washington, USA. Risk predictions varied from low to extreme, and the corresponding grey mould incidence varied from 0.1 to 14.0%. The multiple R-square was 0.973 when all predictors were included. The Spearman rank correlation coefficient (rs) relating the predicted grey mould risk level to the actual incidence of grey mould in pear fruit was 0.882 (P ¼ 0.000). The decay risk prediction model presented herein appears robust and gave reliable predictions of grey mould risk in d’Anjou and Bosc pear fruit from Oregon–Washington and New Zealand in all three years.

The objectives of this study were to develop primers and a real time PCR protocol for the postharvest biocontrol yeast Cystofilobasidium infirmominiatum ( Cim ). The application of this technology was developed to quantify Cim on the surfaces of apple, two pear cultivars, and sweet cherry fruit treated over a range of concentrations. Statistically significant relationships were observed between Cim DNA on fruit surfaces, expressed as μg/m 2 , and CFU/L of dip suspensions for apple, pear, and sweet cherry. In addition, the relationship for each fruit was significantly different from the other three fruits. Threshold values of concentrations of Cim DNA on the fruit surface were calculated based on regression equations and a dose of 2.0 × 10 11 CFU/L of dip suspension, the dose for optimum decay control, and were 4.8, 7.0, 16.5, and 25.2 μg/m 2 for Bosc pear, Lapins sweet cherry, d’Anjou pear, and Golden Delicious apple, respectively. Monitoring Cim DNA concentration on fruit surfaces will assure that Cim is being properly applied to fruit and that a sufficient number of cells are present for optimum decay control.

The objectives of this study were to examine the effect of several rates of 1-MCP from 10 to 100 nL L −1 on stem end decay caused by Botrytis cinerea and to evaluate the effects of prestorage treatment with 1-MCP, hexanal, and 1-MCP + hexanal on decay of d’Anjou pear ( Pyrus communis L.) fruit in long-term cold storage. 1-MCP at 300 nL L −1 reduced bull's-eye rot and Phacidiopycnis rot. Stem end gray mold also was reduced by 1-MCP at 300 nL L −1 , and reduction at rates from 10 to 100 nL L −1 was significant in one of two trials. Snow-mold rot was reduced by 1-MCP at 30 nL L −1 . Hexanal alone reduced snow mold but increased blue mold caused by Penicillium expansum . The combination of 1-MCP and hexanal affected decay similar to 1-MCP. However, hexanal in combination with 1-MCP negated the effect of 30 nL L −1 1-MCP on firmness but did not counteract the effect of 300 nL L −1 1-MCP. Thus, a combination of 1-MCP and hexanal at optimized rates may reduce storage decay, control superficial scald, and allow normal ripening of d’Anjou pear fruit.

A hot water pressure process (HWP) was evaluated for its effect on conidia of Penicillium expansum and on development of blue mold, gray mold, and mucor rot of d'Anjou pear fruit. Spores were removed from the water system through dilution and also as a result of hot water in the system that was lethal to the spores. When the system was heated, viable spores were not detected after 2-4 h of operation. Reductions in decay in the HWP system were 36, 29, and 13% for Botrytis cinerea, Mucor piriformis, and P. expansum, respectively. The response of P. expansum appeared related to the length of time fruit was in cold storage. Heat injury was observed on fruit treated with 40 and 50 °C water but not on fruit at 30 °C nozzle temperature. The HWP system described in this study should be considered as a component of an integrated decay control strategy.

A manually operated high-pressure hot-water washing system consisting of a boiler, hot-water mixing tank, contact loop, heat exchanger, spray mixing tank, high-pressure hot-water washing manifold, low-pressure fresh water rinse manifold, and pressure pump was constructed and installed in a packingline. The system developed 20–50 ◦ C washing water at pressures up to 980 kPa. ‘d’Anjou’ pears (Pyrus communis L.), shortly after harvest, and after storage for 3 and 4 months in regular air (RA) or for 4, 7 and 8 months in controlled atmosphere (CA) at −1 ◦ C were washed through the packingline with different wetting agents (0.1% Silwet, 0.01 and 0.1% Defoamer, and water), water pressures (regular and high-pressure (210–980 kPa)), water temperatures (control (tap water, 4–22 ◦ C), 40 ◦ C, and 50 ◦ C), and brushes (soft and firm), respectively. The effect of the washing conditions on fruit quality was investigated after 1 month of storage at −1 ◦ Ct o simulate shipping condition, and then again after 1 week at 20 ◦ C to simulate marketing condition. Hot-water caused severe heat scald. When nozzle temperature was 50 ◦ C, the incidence of heat scald increased to over 50% for the fruit stored in RA for 3 months. Combined with hot-water, 540 kPa high-pressure washing increased the incidence of friction discoloration. There were lower incidences of friction discoloration and heat scald for fruit stored in CA for 7 months, in comparison to that in RA for 3 months. However, those fruit did not ripen properly as indicated by a high extractable juice content. Fruit washed at harvest had minor incidences of friction discoloration regardless of different brushes, water pressures, and wetting agents. Fruit washed after storages in either 4 months RA or 4 or 8 months CA suffered a high incidence of friction discoloration including scuffing symptoms and pressure marking. The firm brushes caused a higher incidence of friction discoloration mainly because of scuffing symptoms. However, no differences were found between different water pressures and wetting agents with respect to friction discoloration. Fruit stored for 4 months RA suffered 26–28% friction discoloration in comparison to 16–18% in CA stored fruit with firm brush washing. Extended CA storage increased friction discoloration even with soft brush washing. The results suggest that a washing system with high-pressure spray

An integrated approach was studied for control of postharvest brown rot of sweet cherry fruit. System components included a preharvest application of propiconazole, a postharvest application of a wettable dispersible granular formulation of the yeast Cryptococcus infirmo-miniatus (CIM) Pfaff and Fell, storage in modified atmosphere, and storage at 2.8 °C for 20 days or −0.5 °C for 42 days. Preharvest propiconazole and postharvest CIM were similarly effective for control of brown rot. A significant propiconazole–CIM synergism was observed. Modified atmosphere significantly reduced brown rot compared to air-stored fruit. The storage temperature regime effect was inconsistent. This integrated decay control approach was effective and is especially relevant since postharvest fungicide options for cherry are limited.

Incidence of wounding in commercially-harvested `d'Anjou' and `Bosc' pear fruit, healing of wounds to decrease decay caused by Botrytis cinerea, Mucor piriformis, Penicillium expansum, and Penicillium solitum at −1°C, 20°C, and 28°C, and formation of compounds potentially involved in resistance were determined. Use of a blue food coloring to make wounds on fruit more visible on packinghouse lines was evaluated. Over 4 years, an average of 2.9% of `d'Anjou' pear fruit were wounded during harvest and handling. In `Bosc' pears, average incidence of wounding was 4.3% where fruit was harvested by workers paid by the hour, and 13.9% where workers were paid by the number of bins harvested. Susceptibility of wounds to infection by M. piriformis, P. expansum, and B. cinerea at −1°C decreased rapidly during the first 2 weeks, 4 weeks, and 8 weeks, respectively. The percent of wounds that stained well with food coloring was similar to the decay susceptibility curve for P. expansum at −1°C. Susceptibility of wounds to decay in fruit held at 20°C decreased almost linearly from 0 to 2 days. After 2 days at 20°C, 78% of the wounds absorbed stain, a significantly higher percent than were susceptible to decay. Prestorage heat treatment of fruit to 28°C for 24 h prior to inoculation decreased susceptibility of wounds to infection by both P. expansum and P. solitum. In commercial packinghouses, use of a 10% solution of blue food coloring to enhance visibility of wounds in pear fruit resulted in removal of 40% of punctured fruit compared with 22% removal without staining. Histochemical tests of cell walls near wounds showed an accumulation of callose, suberin, tannins and pectic substances, as well as gums and starch, within 4 days after wounding. Lignin was not detected in wound tissue.

The yeasts Cryptococcus laurentii (strain HRA5), Cryptococcus infirmominiatus (strain YY6), and Rhodotorula glutinis (strain HRB6) were tested as biocontrol agents of postharvest diseases of apple and pear in semi-commercial and commercial trials. The yeasts effectively controlled decay when applied in a drench or line spray. The yeasts were not adversely affected when treated fruits were stored in a controlled atmosphere consisting of 1% oxygen and 99% nitrogen. In a commercial trial, the most effective treatments for control of blue mold of pear were a combination of C. laurentii and C. infirmo-miniatus (91% control) and the commercially recommended high rate (528 μg/ml) of thiabendazole (88% control). In the commercial apple trial, the most effective treatments for blue mold were C. infirmo-miniatus combined with 264 μg/ml thiabendazole (91% control), C. infirmo-miniatus combined with C. laurentii (84% control), and thiabendazole alone at 528 μg/ml (79% control). The combination of C. laurentii with 264 μg/ml of thiabendazole was significantly more effective for control of blue mold on pear than thiabendazole at 528 μg/ml whenever any thiabendazole-resistant spores were present in the inoculum.

Six yeast strains isolated from the surface of pear fruits were evaluated for their ability to control postharvest blue mold (caused by Penicillium expansum ) on Golden Delicious apple fruits. All strains significantly reduced blue mold incidence and severity when applied simultaneously with the pathogen. Cryptococcus infirmo-miniatus strain YY6 and Cryptococcus laurentii strain HRA5 were the most effective, and populations in apple wounds increased approximately 1.2 log units within 10 days at 0°C and approximately 1.4 log units in 2 days at 5, 10, or 20°C. Control of blue mold by these two yeasts alone or in combination with a low dose of thiabendazole (15 μg/ml) was tested at 5, 10, and 20°C. Yeasts combined with thiabendazole controlled the disease significantly better at all temperatures (except at 10°C during 1994) than the low dose of thiabendazole alone, and the control was comparable to that achieved using a commercially recommended high dose of thiabendazole (525 μg/ml). C. infirmo-miniatus controlled disease incidence better than C. laurentii at 5, 10, and 20°C during 1993 and 1994. On sweet cherry, C. infirmo-miniatus or C. laurentii combined with a low dose (20 μg/ml) of iprodione controlled brown rot caused by Monilinia fructicola as did a high dose (1175 μg/ml) of iprodione.

Thirty-one morphologically different strains of yeasts and yeast-like fungi, isolated from the surface of pear fruits, were evaluated for biocontrol potential of blue mold on d'Anjou pear fruits. Seven yeast strains (Cryptococcus albidus strain HRB2, C. infirmo-miniatus strain YY6, C. laurentii strain HRA5, Rhodotorula aurantiaca strain YCL5, and R. glutinis strains HRA3, HRA4 and HRB6) reduced incidence of blue mold on pears. C. laurentii HRA5 and R. glutinis HRB6 were most effective for reduction of incidence and severity of blue mold. C. laurentii HRA5 and R. glutinis HRB6 combined with a low dose of thiabendazole (TBZ) (15 μg ml−1) gave significantly better disease control at 5, 10 and 20 °C than either TBZ or the yeast alone and was comparable to disease control achieved using a commercially-recommended high dose of TBZ (525 μg ml−1). C. infirmo-miniatus strain YY6 was most effective for the control of Mucor rot of pears. C. laurentii HRA5, C. infirmo-miniatus YY6, and R. glutinis HRB6 reduced incidence and severity of gray mold of pears and were more effective when combined with a low dose of TBZ. Side rot of Bosc pears was completely controlled by C. laurentii HRA5, C. infirmo-miniatus YY6 and R. glutinis HRB6, whereas TBZ was ineffective. Bull's-eye rot of pears was completely controlled by all yeasts when they were combined with a low dose of TBZ. Populations of C. laurentii HRA5, C. infirmominiatus YY6 and R. glutinis HRB6 in pear wounds increased approximately 1.3 log units within 10 days at −1 °C and 1.7 log units in 2 days at 5, 10 and 20 °C. Addition of cell-free supernatants of yeast cultures to wounds did not suppress decay, and substances inhibitory to fungal germination were not detected on culture plates.

‘Bosc’ pears ( Pyrus communis , L.) harvested at commercial maturity with flesh firmness (FF) of 75 Newton (N) from the southern district of Oregon were stored in either air or step-wise low O 2 at −1 °C during the 1992–'93 and 1993–'94 seasons. The levels of O 2 in the step-wise low O 2 storage were maintained and increased from 0.5% for four months to 1.0% for two months, and finally to 1.5% for two months while the CO 2 concentration in the storage was kept below 0.05%. Air-stored fruit were capable of ripening normally with good dessert quality after one, two, and three months of storage. These fruit softened to between 9.7 N and 15.0 N and reached the ethylene climacteric peak on day 7 or 8 of ripening at 20 °C. The ripened fruit developed a buttery and juicy texture as indicated by an apparent reduction of extractable juice (EJ) from 67 ml juice per 100 g fresh weight (FW) of unripened pulp tissue to less than 45.0 ml juice per 100 g FW of ripened pulp tissue. Fruit in air storage for four and five months reached the ethylene climacteric peak on day 4 of ripening but did not soften properly. Fruit stored in step-wise low O 2 for six, seven and eight months reached the ethylene climacteric peak on day 6 of ripening. Step-wise low-O 2 -stored fruit softened properly to 12 N or lower and reduced EJ to 49 ml 100 g −1 FW (six and seven months of storage) or 59 ml 100 g −1 FW (eight months of storage) on day 8 of ripening. Based on the analyses of ethylene production, fruit softening and reduction of EJ during ripening, fruit stored in the step-wise low O 2 storage for six, seven and eight months maintained a physiological state similar to the fruit stored in air for one to three months. The combination of prestorage heat (28 °C for one day) and step-wise low oxygen storage effectively reduced side rot by 60 and 63% in 1993 and 1994, respectively. Even greater decay control was obtained with the fungicides imazalil and Exp10412A on inoculated fruit, and thiabendazole plus captan on non-inoculated fruit.

The effects of soil moisture, temperature, and nutrient availability on the population dynamics of Mucor piriformis were studied using moisture levels from −0·1 to −40 kPa, temperatures from −1 to 25 °C, and three nutrient levels adjusted with pear juice. All three factors affected the population dynamics of M. piriformis in soil. Few interactions occurred among the factors, and no interactions were observed consistently. Populations of M. piriformis were higher in soil at −0·1 kPa than in drier soils. Propagule density was highest in soil at 5 and 10° during the first 30 d of the study but greater at −1 and 5° during the last 30 d. Propagule density consistently increased as soil nutrient concentration increased. Results are discussed in relation to dynamics of M. piriformis in pear orchard soils.