Verifying the biocontrol activity of novel film‐forming formulations of Candida sake CPA‐1: resilience in relation to environmental factors, rainfall episodes, and control of Botrytis cinerea on different hosts

BACKGROUND The efficacy of Candida sake CPA‐1 as a biocontrol agent against several diseases has been studied since it was isolated 20 years ago. However, it was only recently that two suitable and effective film‐forming formulations based on potato starch and maltodextrins were developed using the fluidized‐bed spray‐drying system. The present work aimed to confirm the capability of both novel formulations by testing their resilience on grapes at different temperatures (0, 22, and 30 °C), relative humidities (40% and 85%), and simulated rainfall levels. Another objective was to examine the control of Botrytis cinerea in different hosts. RESULTS The CPA‐1 cells from both dried formulations survived better than the liquid formulation on grapes stored at 0 and 22 °C regardless of the relative humidity. After simulated rainfall, potato starch formulation achieved significantly higher populations than maltodextrin formulation, although the highest reduction was −1.6 log N N0−1. A positive effect of cell establishment prior to the simulated rainfall was shown, and recovered cells from the potato starch formulation were significantly higher after 72 h of cell establishment. Finally, both formulations reduced the incidence and severity of B. cinerea on pears, apples, and tomatoes. CONCLUSION The potential of these novel film‐forming formulations of C. sake CPA‐1 was verified. The resilience of formulated C. sake was better than the commercialized liquid formulation, the adherence of the formulations to the grapes improved after an establishment period prior to rain exposure, and the control of B. cinerea was verified in a wider range of hosts. © 2019 Society of Chemical Industryinfo:eu-repo/semantics/acceptedVersio

Infection risk of Monilinia fructicola on stone fruit during cold storage and immersion in the dump tank

Monilinia spp. is the main pathogen responsible for postharvest losses of stone fruit. Several studies have examined the conditions for Monilinia spp. infection in the field, but very limited information is available about postharvest. Storing fruit for 1 day in the cold room or dumping fruit in a water tank are the most common handling operations during the postharvest of fruit. Then, the aim of this study was to investigate the risk of Monilinia fructicola infection for two peach and one nectarine cultivars during cold storage and water dump operations. A new methodology was performed using a dry inoculum of M. fructicola. A set of fruit was used as control to demonstrated that at 20 °C 60% relative humidity (RH) was not able to infect fruit, however, the disease was developed when was already infected. In addition, M. fructicola was able to infect and develop disease in fruit at 20 °C 100 RH. The storage of fruit with the presence of M. fructicola conidia on their surface for up to 30 days at 0 °C 100% RH or 4 °C 100% RH did not suppose an important risk of infection since only 3.3 and 3.8%, respectively of fruit were already infected. Overall, all treatments tested with the water dump operation gave optimal conditions to M. fructicola to infect fruit when it was superficially dry inoculated or it was immersed with water contaminated with conidia, increasing the need for water disinfection. In addition, when fruit was immersed in water free from M. fructicola conidia, the postharvest operation gave optimal conditions to develop infections already produced.info:eu-repo/semantics/acceptedVersio

Breeding strategies for identifying superior peach genotypes resistant to brown rot

A sustainable approach to control the incidence of brown rot in pre- and post-harvest management is to select genotypes with high contents of antioxidant compounds and tolerance to Monilinia laxa (Aderh. and Ruhland) Honey. In this study, 68 progenies of the ‘Babygold 9’ × ‘Crown Princess’ population from the EEAD-CSIC breeding program were screened under controlled conditions for a period of 3 years (2013–2015). Susceptibility to brown rot was evaluated after inoculating 20 healthy fruits per genotype with M. laxa. Brown rot incidence, lesion diameter, and colonization extent, as well as the severities of these issues, were calculated after 5 days of incubation. Physicochemical traits, such as fruit firmness and soluble solids content, were also recorded before and after storage. Titratable acidity, pH, and antioxidant composition were measured at harvest. Significant differences were found for pathogenic traits, as well as for contents of vitamin C, total phenolics, flavonoids, and anthocyanins, within genotypes in this population. Negative correlations were also found between the content of phytochemical compounds (such as anthocyanins and total phenolics), as well as disease incidence and severity. Differences in susceptibility to brown rot confirm the genetic variability available in these progeny. This allowed the selection of six genotypes highly resistant to brown rot of M. laxa, with high organoleptic properties and high phenol content, to be introduced in our peach breeding program.info:eu-repo/semantics/acceptedVersio

Novel film‐forming formulations of the biocontrol agent Candida sake CPA‐1: biocontrol efficacy and performance at field conditions in organic wine grapes

BACKGROUND: The biocontrol agent (BCA)Candida sakeCPA-1 has previously effectively reducedBotrytisbunch rot (BBR) andit was also suggested as a promising strategy to control sour rot in grapes under field conditions. However, biocontrol efficacyof solid formulations of CPA-1 has never been tested in field trials. The present study aims to confirm the efficacy against BBRand sour rot in grapes under field conditions of two novel formulations recently developed by the addition of biodegradablecoatings using a fluidized-bed spray-drying system.RESULTS: Novel film-forming formulations of the BCAC. sakeCPA-1 controlledB. cinereaas well as liquid formulation. Sour rotcontrol resulted better in the second season and severity reductions were more satisfactory than incidence control. Visual andcryoSEM observations revealed that film-forming treatments were uniformly distributed on plant surfaces. CPA-1 coating couldbe observed on grapes at harvest time.CONCLUSION: The results of this work suggest that solid formulations would be a competitive alternative to conventionalfungicides because they were easy to package and transport, and cell viability could be maintained for a long period of time.© 2018 Society of Chemical Industryinfo:eu-repo/semantics/acceptedVersio

Efficacy of electrolyzed water to inactivate foodborne pathogens on fresh-cut apples

Chlorine is the most common disinfectant used in the fresh-cut industry but nowadays environmental and health risks have led to the need to find new sanitizers. Electrolyzed water (EW) appears to be a promising alternative. In this work, disinfection efficacy of acidic (AEW) and neutral (NEW) electrolyzed water in fresh-cut apple slices inoculated with Escherichia coli, Listeria innocua or Salmonella choleraesuis was studied. Apple slices were inoculated with a 10(7) cfu/ml suspension of pathogens and treated with the sanitizer EW solutions, with 100 or 50 ppm of free chlorine solutions and with distilled water. Population reduction was determined 30 min after washings and untreated apple slices were used as control in all assays. AEW100 was the treatment with more effective bactericidal activity followed by NEW100 and AEW50. EW had higher or similar efficacy than chlorine treatments in all tested conditions

Predicted ecological niches and environmental resilience of different formulations of the biocontrol yeast Candida sake CPA-1 using the Bioscreen C

Environmental resilience of biocontrol microorganisms has been a major bottleneck in the development of effective formulations. Candida sake is an effective biocontrol agent (BCA) against Penicillium expansum, Botrytis cinerea or Rhizopus stolonifer, and different formulations of the BCA have been optimised recently. The objective of this study was to compare the relative tolerance of different dry and liquid formulations of the biocontrol yeast C. sake CPA-1 to interacting environmental conditions using the Bioscreen C. Initially, the use of this automated turbidimetric method was optimised for use with different formulations of the biocontrol yeast. The best growth curves were obtained for the C. sake CPA-1 strain when grown in a synthetic grape juice medium under continuous shaking and with an initial concentration of 105 CFUs ml−1. All the formulations showed a direct relationship between optical density values and yeast concentrations. Temperature (15–30 °C) and water activity (aw; 0.94–0.99) influenced the yeast resilience most profoundly, whereas the effect of pH (3–7) was minimal. In general, the liquid formulation grew faster in more interacting environmental conditions but only the yeast cells in the dry potato starch formulation could grow in some stress conditions. This rapid screening method can be used for effective identification of the resilience of different biocontrol formulations under interacting ecological abiotic conditions.info:eu-repo/semantics/acceptedVersio

Enhanced shelf-life of the formulated biocontrol agent Bacillus amyloliquefaciens CPA-8 combining diverse packaging strategies and storage conditions

Two effective biocontrol products (named as BA3 and BA4) based on Bacillus amyloliquefaciens CPA-8 have been reported as a potential alternative to chemical applications against brown rot caused by Monilinia spp. on stone fruit. To have practical use, this study aimed to describe the best packaging strategies (bags or flasks, atmosphere, and temperature of storage) to not only guarantee efficacy but also stability and ease of application of the products to be handled through the normal channels of distribution and storage. In terms of the viability neither the BA3 nor the BA4 product has been compromised after twelve months of storage. However, storage at 4 °C affected the stability and visual aspect of both CPA-8 formulations, mainly associated not only to the increase of RH but also aw. Moreover, it should be pointed out that flasks did not conserve refrigerated BA3 samples in a suitable way, since RH and aw increased noticeably making their visual properties unsightly after 10 months of cold storage. At that time, the BA4 products were better preserved at 4 °C when packaged in flasks. Finally, this study also demonstrated that the most suitable packaging conditions for long-term storability (stored at 22 °C) did not show any negative effect in the biocontrol efficacy of CPA-8 in nectarines artificially infected with M. fructicola and provide suitable product delivery and field application. In conclusion, these results contribute to the final stage of development of these two CPA-8 products, practically ready for registration, thus contributing to the environmental-friendly management of postharvest diseases in stone fruit.info:eu-repo/semantics/acceptedVersio

Impact of climate change environmental conditions on the resilience of different formulations of the biocontrol agent Candida sake CPA‐1 on grapes

Biocontrol agents have become componentsof integrated crop protection systemsfor controlling economically important fungal pathogens.Candida sakeCPA-1 is abiocontrol agent of fungal pathogens of fruits, both pre- and post-harvest. Whilethe efficacy of different formulations have been examined previously, few studieshave considered the resilience of different formulations under changing climaticconditions of elevated temperature, drought stress and increased atmospheric CO2.This study examined the effect of (a) temperature9RH9elevated CO2(400vs1000 ppm) on the temporal establishment and viability of two dry and one liquidC. sakeCPA-1 formulations on grape berry surfaces; (b) temperature stress (25vs35°C); and (c) elevated CO2levels. Results indicated that temperature, RH and CO2concentration influenced the establishment and viability of the formulations butthere was no significant difference between formulations. For the combined three-component factors, increased temperature (35°C) and lower RH (40%) reduced theviable populations on grapes. The interaction with elevated CO2improved theestablishment of viable populations of the formulations tested. Viable populationsgreater than Log 4 CFUs per g were recovered from the grape surfaces suggestingthat these had conserved resilience for control ofBotrytisrot in grapes.info:eu-repo/semantics/acceptedVersio

Efficacy of environmental friendly disinfectants against the major postharvest pathogens of stone fruits on plastic and wood surfaces

Disinfection of surface facilities during postharvest handling operation is an important practice to avoid secondary fruit infections at stone fruit packinghouses. The aim of this work was to evaluate the effect of six environmental friendly disinfectants against Monilinia fructicola, Penicillium expansum, Rhizopus spp., and Alternaria spp. on plastic and wood surfaces. Hydrogen peroxide, peracetic acid, sodium hypochlorite, Mico-E-pro®, Proallium FRD-N®, and DMC Clean-CNS® were used as the disinfectants. Untreated and surfaces treated with water were used as controls. Plastic and wood surfaces were sampled with Rodac plates at 2 and 24 h after treatments and the number of colonies were counted. In general, all disinfectants reduce the number of viable conidia from all studied surfaces. Hydrogen peroxide used in a concentration of 150 mg L−1 was the less effective disinfectant in all studied pathogens. The commercial product Mico-E-pro® composed of oregano, onion, and orange extract at a dose of 10 mg L−1 was the most effective disinfectant. Rhizopus spp. was the pathogen more resistant to the disinfectants followed by P. expansum, M. fructicola, and Alternaria spp. Water decreased the number of conidia adhered to the surface. In addition, the untreated control showed substantial conidia reduction after 24 h of artificial inoculation.info:eu-repo/semantics/acceptedVersio