Pilot testing ofKloeckera apiculata for the biological control of postharvest diseases of citrus

The efficacy of the yeastKloeckera apiculata, strain 34-9, in controlling postharvest decay of citrus fruit was evaluated in small-scale and pilot tests in commercial packinghouse. Kloeckera apiculata grew efficiently on different media and maintained its antagonistic activity against spore germination ofPenicillium italicum. In small-scale experiments with citrus fruits dipped in the yeast cell suspension, the development of decay in citrus was effectively inhibited. The yeast was compatible with a mixture of low concentration of a commonly chemical fungicide. In packinghouse tests, combining the yeast with 40 mg/kg Carbendazim (MBC) resulted a reduction in the incidence of decay to a level equal to that of the commercial treatment of 200 mg/kg MBC. The efficacy of the strain 34-9 could also be maintained under packinghouse conditions at a cell concentration of the yeast antagonist as low as 10⁶ cells/ml. No significant difference in the efficacy ofK. apiculata was found in either the drench or the spray application systems tested in citrus packinghouse. Scanning electron microscopy revealed attachment of the yeast cells to the pathogen hyphae. The high antagonistic activity of strain 34-9 against citrus blue mould may be related to its capability to compete withPenicillium italicum, for space and nutrients and /or involvement of directly antagonist of the yeast on the fungus.     

The effects of Kloeckera apiculata on the cuticular waxes of navel orange fruit

Kloeckera apiculata 34-9 was selected from the rhizosphere soil for its high efficacy in controlling citrus green and blue mold. In this study, the effect of the antagonistic yeast K. apiculata on citrus cuticular wax was investigated in ripening Newhall navel orange (Citrus sinensis L. Osbeck). Our results show that K. apiculata triggers the production of cuticular waxes and surface wax morphology changes in the fruit surface. 15 K. apiculata-responsive differentially expressed genes (DEGs) were identified for wax metabolism by using the Affymetrix citrus genome GeneChip. Using GC–MS, 46 wax compounds were found in the Newhall fruit surface. On one hand, esters including docosanoic acid, 1,2,3-propanetriyl ester and 9-hexadecenoic acid, 9-octadecenyl ester were up-regulated approximately twofold in the treatment condition compared with the control; and on the other hand, the fatty acids and fatty alcohols decreased by 74.4% and 72.3%, respectively, in the treatment condition. The new wax production and increased hydrophobicity of the Newhall surface resulting from the treatment may influence spore adhesion and germination. Furthermore, the response of the fruit waxes to the K. apiculata stimulus is likely to be regulated by intra-cellular H₂O₂ signaling. This study demonstrated the response fruit waxes to K. apiculata in Newhall navel oranges, thus providing new clues that aid our understanding of the mechanisms of action of antagonistic yeasts in postharvest fruits.     

Supplementary Antimold Activity of Phosethyl AL, A New Brown Rot Fungicide for Citrus Fruits

Phosethyl Al (= Aliette) is a new and promising postharvest fungicide against brown rot of citrus fruits. Its effectiveness in controlling green mold (Penicillium digitaum), the major citrus fruit pathogen, was studied on artificially inoculated fruit and compared with that of sodium o-phenylphenate (SOPP) and thiabendazole (TBZ). In vitro and in vivo experiments have shown that phosethyl Al is capable — although to a lesser extent than SOPP and TBZ — of inhibiting growth of P. digitatum and reducing the incidence of decay of citrus fruits, caused by a wild-type, and apparently also by a benzimidazole-resistant strain of this fungus. The influence of times of treatment and modes of application (including temperature and duration of treatment, rinsing of the fruit) on the effectiveness of phosethyl Al, SOPP and TBZ in controlling green mold was studied and discussed. It is concluded that, under conditions of natural infection, phosethyl Al can be used for the postharvest control of Phytophthora-caused brown rot without any apparent increase in the incidence of green mold in the treated fruits.     

Chlorine Dioxide for Reduction of Postharvest Pathogen Inoculum during Handling of Tree Fruits

Alternatives to hypochlorous acid and fungicides are needed for treatment of fruit and fruit-handling facilities. Chlorine dioxide was evaluated and found effective against common postharvest decay fungi and against filamentous fungi occurring on fruit packinghouse surfaces. In vitro tests with conidial or sporangiospore suspensions of Botrytis cinerea, Penicillium expansum, Mucor piriformis, and Cryptosporiopsis perennans demonstrated >99% spore mortality within 1 min when the fungi were exposed to aqueous chlorine dioxide at 3 or 5 μg · ml^-1. Longer exposure times were necessary to achieve similar spore mortalities with 1 μg · ml^-1. Of the fungi tested, B. cinerea and P. expansum were the least sensitive to ClO₂. In comparison with the number recovered from untreated control areas, the number of filamentous fungi recovered was significantly lower in swipe tests from hard surfaces such as belts and pads in a commercial apple and pear packinghouse after treatment of surfaces with a 14.0- to 18.0-μg · ml^-1 ClO₂ foam formulation. Chlorine dioxide has desirable properties as a sanitizing agent for postharvest decay management when residues of postharvest fungicides are not desired or allowed.     

Improving Biocontrol Activity of Pichia guillermondii Against Post-harvest Decay of Oranges in Commercial Packing-houses by Reduced Concentrations of Fungicides

Three commercial tests were conducted in 2000-2001 in two commercial packing-houses (Muravera and Villacidro) located in Sardinia, Italy, to evaluate the efficacy of biological, chemical and integrated treatments against Penicillium digitatum and P. italicum on naturally inoculated orange fruit. Damage caused by the packing-house processing line was also assessed. Treating orange fruits with the yeast Pichia guilliermondii (strain 5A) in the processing line generally led to a significant reduction of post-harvest decay compared to the processed control, while the commercial product Aspire®, based on Candida oleophila , was ineffective in inhibiting the pathogen when applied alone. The integrated application of thiabendazole or imazalil with the biocontrol agents significantly improved the control of fruit decay. Using thiabendazole at concentrations of 0.1 and 1.2 g L -1 , led to similar inhibition of fruit decay in two trials. Both yeasts were equally able to colonize the fruit actively during storage. Passing fruits through the packing line caused a significant increase in fruit decay.     

Genome sequencing and analysis of <Emphasis Type="Italic">Kloeckera apiculata</Emphasis> strain 34-9, a biocontrol agent against postharvest pathogens in citrus

Kloeckera apiculata, as the anamorphic state of Hanseniaspora uvarum from the Ascomycota phylum, plays an important role in the inhibition of fungal diseases in plants and spontaneous wine fermentation. This study was performed to sequence and analyze the whole genome of K. apiculata strain 34-9; This analysis provides further genomic features and assists functional research. The complete genome was determined using an Illumina HiSeq 2000 system applying paired-end and mate-pair methods to construct four reads libraries. The data assembly of all the reads resulted in a total genome size of 8.1 Mb, including 106 contigs, which were assembled into 41 scaffolds with a 31.95 % G+C content and a 234X sequence coverage. The performance of the gene prediction and functional annotation revealed that 2724 of 3786 protein-coding genes matched the KOG database, and 1127 genes were classified into GO categories. Further genome features analyses found 1066 microsatellite sites, 71 tRNAs, 3 rRNAs and 3 microRNAs in the genomic DNA. A prediction of the metabolic pathways identified potentially crucial genes for explaining the phenylalanine pathway involved in biocontrol. Comparisons with the typical yeasts Lachancea thermotolerans, Kluyveromyces lactis and Saccharomyces cerevisiae revealed the particularity and difference of K. apiculata strain 34-9. The genome alignments among Hanseniaspora vineae T02/19AF, K. apiculata DSM 2768 and 34-9 indicated numerous homologous regions distributed over the genomes between strain DSM2768 and 34-9. A SSR analysis identified that mono- and tri- nucleotide repeat types were more abundant in all six types, likely affecting the evolution of K. apiculata.     

A transcriptomic approach highlights induction of secondary metabolism in citrus fruit in response to <Emphasis Type="Italic">Penicillium digitatum</Emphasis>infection

Background  

Postharvest losses of citrus fruit due to green mold decay, caused by the fungus Penicillium digitaum, have a considerable economic impact. However, little is known about the molecular processes underlying the response of citrus fruit to P. digitatum.     

Biological Control of Green Mould Decay in Postharvest Chinese Bayberries by Pichia membranaefaciens

The effect of the yeast antagonist Pichia membranaefaciens for control of green mould decay caused by Penicillium citrinum or Verticicladiella abietina and natural decay in postharvest Chinese bayberries (Myrica rubra Seib & Zucc.), and the possible mechanisms were investigated. The results showed that 1 × 10⁹ colony‐forming units (CFU)/ml of washed cell suspensions of the yeast provided better control of green mould decay than yeast in culture broth at the same concentration. Treatment with cell‐free culture filtrates or autoclaved cell cultures had little effect on disease incidence. The concentration of a washed cell suspension of P. membranaefaciens had a significant effect on efficacy in controlling disease incidence. At a concentration range from 1 × 10⁶ to 1 × 10⁹ CFU/ml, the higher the concentration of the antagonist, the lower was the incidence of the disease. In the inoculated wounds of Chinese bayberries, populations of P. membranaefaciens increased by approximately 145‐ and 41‐fold, respectively, after incubation at 20°C for 2 day or at 1°C for 8 day. P. membranaefaciens significantly induced activities of two defence‐related enzymes chitinase and β‐1, 3‐glucanase in Chinese bayberries. The in vitro experiment showed that spore germination and germ tube elongation of the two pathogens were markedly inhibited by washed cell suspensions of P. membranaefaciens. In addition, P. membranaefaciens significantly reduced natural decay in Chinese bayberries. These results indicate that P. membranaefaciens can effectively reduce fruit decay possibly by directly inhibiting pathogen growth and indirectly by inducing disease resistance. Thus, we suggest that P. membranaefaciens has potential as a biocontrol agent to control fruit decay in Chinese bayberries during postharvest storage.     

Biological Control of Postharvest Diseases of Peaches and Nectarines by Yeasts

Abstract Biocontrol activities of a total of 103 yeast isolates were tested against postharvest diseases of peaches. Seven isolates, with the best efficacy in reducing the number of infected wounds or lesion sizes of Penicillium expansum and Botrytis cinerea, were selected for further large‐scale experiments. In large‐scale experiments, all selected isolates were significantly effective (P ≤ 0.05) in reducing the number of infected wounds and the diameter of lesions caused by P. expansum, B. cinerea, and Monilinia fructicola. DR52 was significantly superior to all the other yeasts in effectiveness against all three pathogens. The efficacy of the other yeast antagonists against B. cinerea and P. expansum was almost equal, while the control of M. fructicola was inferior. DR52 was selected for further storage experiment because its efficacy was higher against the three pathogens and it also showed a different random amplified polymorphic DNA‐polymerase chain reaction pattern compared with other isolates. DR52 was identified by Centraalbureau voor Schimmeelcultures (Baarn, The Netherlands) as Kloeckera apiculata. K. apiculata completely controlled both pathogens after 30 days of storage. Its efficacy declined to an 83.4% reduction in B. cinerea incidence and an 87.5% reduction in P. expansum incidence after 45 days of storage.     

A new improved strategy for the selection of cold-adapted antagonist yeasts to control postharvest pear diseases

Postharvest diseases cause considerable losses of harvested fruits during transportation and storage. Many yeast species have been reported as good antagonists against postharvest pear pathogens. In this work, we used a novel selection strategy that involves the isolation of yeasts from washing fluids, showing biocontrol activity against a regional Penicillium expansum strain (primary screening), originally obtained from fruit wounds after long time storage at ?1/0°C. About 26 isolates representative of the 11 yeast species identified in the 27 selected washing waters were chosen to be evaluated in a secondary screening against a regional Botrytis cinerea strain on pear wounds. Among yeasts tested, 38% showed complete control of P. expansum, but only 15% reduced the decay incidence of B. cinerea to 60–80% at ?1/0°C. These results reveal that some of the yeasts found can be biological alternatives to fungicides in the control of P. expansum and B. cinerea infections. Based on the data obtained, our strategy seems to be much more effective than the previously reported methods in obtaining successful biocontrol agents.     

Screening and identification of epiphytic yeasts with potential for biological control of green mold of citrus fruits

Epiphytic yeasts isolated from the surface of citrus fruits, harvested in several orchards in the Souss-Massa-Draa Valley, Agadir, Morocco, were in vivo screened for antagonistic activity against Penicillium digitatum, the causal agent of green mold of citrus. From a total of 245 yeast strains assessed for their biocontrol activity against P. digitatum, fifteen reduced the incidence of disease to less than 50%. The effectiveness of the best selected yeast strains showed that Pichia anomala (YT73), Debaryomyces hansenii (YT22) and Hanseniaspora guilliermondii (YT13) were the most effective, with a reduction of green mold incidence from 65 to ~80%, compared to the control. The identification of the fifteen selected yeast strains was carried out through an integrated approach including phenotypic and genotypic (sequencing of D1/D2 domain of 26S rDNA encoding gene) methods. These 15 selected were identified as: H. guilliermondii, D. hansenii, H. uvarum and P. anomala. The study of the dynamics of two of the best strains, H. guilliermondii and D. hansenii, showed that these strains can grow rapidly, by approximately 2 log units, in citrus fruit wounds. Such rapid growth in wounds indicates that these antagonist yeasts are excellent colonizers of citrus wounds and can thrive on citrus fruits as a substrate.     

Penicillium digitatum infection mechanisms in citrus: What do we know so far?

Penicillium digitatum is the major source of postharvest decay in citrus fruits worldwide. This fungus shows a limited host range, being able to infect mainly mature fruit belonging to the Rutaceae family. This highly specific host interaction has attracted the interest of the scientific community. Researchers have investigated the chemical interactions and specialized virulence strategies that facilitate this fungus's fruit colonization, thereby leading to a successful citrus infection. There are several factors that mediate and affect the interaction between P. digitatum and its host citrus, including hydrogen peroxide modulation, secretion of organic acids and consequently pH control, and other strategies described here. The recently achieved sequencing of the complete P. digitatum genome opened up new possibilities for exploration of the virulence factors related to the host-pathogen interaction. Through such techniques as RNAseq, RT-PCR and targeted gene knockout mediated by Agrobacterium tumefaciens, important genes involved in the fungal infection process in citrus have been reported, helping to elucidate the molecular mechanisms, metabolites and genetic components that are involved in the pathogenicity of P. digitatum. Understanding the infection process and fungal strategies represents an important step in developing ways to protect citrus from P. digitatum infection, possibly leading to more productive citriculture.     

An integrated approach with Trichoderma harzianum DGA01 and hot water treatment on control of crown rot disease and retention of overall quality in banana

A biological control of crown rot disease of banana fruit was analysed using an integrated approach combining hot water treatment and Trichoderma harzianum strain DGA01. Treated fruits were stored at 22–25 °C and 90–95% relative humidity for 2 weeks. The bioefficacy of fungal antagonist in vitro towards crown rot-causing pathogens, namely Lasiodiplodia theobromae, Thielaviopsis paradoxa, Colletotrichum musae and Fusarium verticillioides, was enhanced by 11.41% following hot water treatment (50 °C, 20 min). DGA01 germinated on the fruit 48 h after inoculation and parasitised the pathogen. Postharvest application showed that hot water treatment and conidial suspension of DGA01 (10⁶ ml^?1) applied singly performed significantly better than the untreated control in reducing the incidence of crown rot, but were not as effective as the fungicide. The combination of hot water treatment and DGA01 gave 93% control of fruit decay which was comparable with fungicide treatment of 95%. The quality of fruit was markedly improved in hot water treatment + DGA01 as compared to those dipped in fungicide solution. The inconsistencies of single treatments, by DGA01 or hot water dips, in controlling crown rot such as variation in severity of disease among treatments and within a treatment, were lessened by dipping the fruit in DGA01 conidial suspension following hot water treatment.     

6,7-Dimethoxycoumarin,a citrus phytoalexin conferring resistance against Phytophthora gummosis

6,7-Dimethoxycoumarin was isolated from the bark of citrus trunks, branches and fruit peels following inoculation with the fungus Phytophthora citrophthora. The compound inhibited growth in vitro of Phytophthora citrophthora, Verticillium dahliae, Penicillium digitatum, P. italicum, Colletotrichum gloeosporioides, Diplodia natalensis and Hendersonula toruloidea.     

Effect of preharvest spraying Cryptococcus laurentii on postharvest decay and quality of strawberry

Application of a suspension (log 8.0/ml) of Cryptococcus laurentii prior to harvest led to a reduction in Botrytis cinerea decay of strawberries stored at 4 or 20 °C, for 12 or 4 days, respectively. The frequency of spraying antagonist significantly influenced disease incidence in strawberry fruit. The best inhibition of disease was achieved when fruit sprayed C. laurentii with three applications that began 6 days prior to harvest, and the incidence of gray mold and natural decay treated with this method was 21% and 11%, compared with 88% and 62% in the control after storage at 20 °C for 4 days. A similar result occurred in the treated fruit after storage at 4 °C for 12 days. Dilation plate counts on Rose Bengal agar and scanning electron microscopy results showed that three applications with C. laurentii at 6, 3 and 0 days before harvest improved its ability to colonize the epidermis of strawberry fruit in the greenhouse and during storage compared to single application. In addition, antagonistic yeast spraying before harvest could reduce the weight loss, delay the decrease of the firmness and ascorbic acid, but had no significant effect on the contents of soluble solids, titratable acidity and fruit surface color. These results suggested that preharvest spraying with C. laurentii might be a promising alternative to fungicide application for decay control of strawberry.     

Efficacy assessment of Candida oleophila (strain O) and Pichia anomala (strain K) against major postharvest diseases of citrus fruits in Morocco

Two yeasts, Candida oleophila (strain O) and Pichia anomala (strain K), were previously selected for their antagonistic activity against postharvest diseases on apples and pears. The objective of the study was to determine the efficacy of both antagonistic yeast's against wound postharvest pathogens of citrus fruits. The efficacy of both strains (applied at 10(5), 10(6) and 10(8) CFU/ml) was assessed against Penicillium digitatum and P. italicum inoculated after one hour (at a concentration of 10(5), 10(6) and 10(7) spores/ml) on citrus varieties 'clementine' and 'valencia-late'. Fruits were incubated for one week at 24 degrees C before measurement of lesion diameter. The protective levels were positively correlated with high concentration of antagonist and low concentration of pathogen. Highest protective levels (from 73 to 100%) were detected with the application of strain O or strain K at 10(8) CFU/ml whatever the pathogen (applied at 10(5) spores/ml) and the citrus variety. The antagonistic activity of both strains was also dependent on the incubation period before pathogen Inoculation. The protective level increased with time between application of the antagonist and inoculation of fungal spores. Whatever the yeast strain (10(8) CFU/ml). the protective level exceed 70% when wounded oranges were inoculated with P. digitatum or P. italicum (both at 10(6) spores/ml) 12 hours after yeast treatment. These protective levels reached 100% when the incubation period separating the antagonist application and the pathogenic inoculation was 24 hours. On the other hand, high protective levels (< 80%) were also observed against the sour rot decay on citrus variety 'clementine' caused by Geotrichum candidum inoculated at concentration of 10(6) spores/ml when strain O or strain K were applied at 10(8) CFU/ml 24 hours before pathogen. All these results support the potential practical application of both strains against major postharvest pathogens on citrus.     

High Incidence of Preharvest Colonization of Huanglongbing-Symptomatic Citrus sinensis Fruit by Lasiodiplodia theobromae (Diplodia natalensis) and Exacerbation of Postharvest Fruit Decay by That Fungus

Huanglongbing (HLB), presumably caused by the bacterium “Candidatus Liberibacter asiaticus,” is a devastating citrus disease associated with excessive preharvest fruit drop. Lasiodiplodia theobromae (diplodia) is the causal organism of citrus stem end rot (SER). The pathogen infects citrus fruit under the calyx abscission zone (AZ-C) and is associated with cell wall hydrolytic enzymes similar to plant enzymes involved in abscission. By means of DNA sequencing, diplodia was found in “Ca. Liberibacter asiaticus”-positive juice from HLB-symptomatic fruit (S) but not in “Ca. Liberibacter asiaticus”-negative juice. Therefore, the incidence of diplodia in fruit tissues, the impact on HLB-related postharvest decay, and the implications for HLB-related preharvest fruit drop were investigated in Hamlin and Valencia oranges. Quantitative PCR results (qPCR) revealed a significantly (P < 0.001) greater incidence of diplodia in the AZ-C of HLB-symptomatic (S; “Ca. Liberibacter asiaticus” threshold cycle [C_T] of <30) than in the AZ-C of in asymptomatic (AS; “Ca. Liberibacter asiaticus” C_T of ≥30) fruit. In agreement with the qPCR results, 2 weeks after exposure to ethylene, the incidences of SER in S fruit were 66.7% (Hamlin) and 58.7% (Valencia), whereas for AS fruit the decay rates were 6.7% (Hamlin) and 5.3% (Valencia). Diplodia colonization of S fruit AZ-C was observed by scanning electron microscopy and confirmed by PCR test and morphology of conidia in isolates from the AZ-C after surface sterilization. Diplodia C_T values were negatively correlated with ethylene production (R = −0.838 for Hamlin; R = −0.858 for Valencia) in S fruit, and positively correlated with fruit detachment force (R = 0.855 for Hamlin; R = 0.850 for Valencia), suggesting that diplodia colonization in AZ-C may exacerbate HLB-associated preharvest fruit drop.     

Enhancement of the biocontrol agent Candida oleophila (strain O) survival and control efficiency under extreme conditions of water activity and relative humidity

The objective of this work is to evaluate the ability of some additive substances in protecting the biocontrol agent Candida oleophila (strain O) against the adverse effects of environmental factors, such as water activity (a_w, 0.93 and 0.98) and relative humidity (75% and 98%). The protection obtained with various protectant substances, skimmed milk (SM), peptone, maltose, sucrose, sorbitol, lactose and polyethylene glycol was assayed under in vitro and in vivo conditions. The yeast cells with the highest level of protecting agents (1%) had higher viability than those with low protectant levels (0.1% and 0.5%). SM, sucrose and sorbitol improved significantly the C. oleophila survival on apple fruit surface by 80.8%, 42.26% and 37.27% and gave a significant protection (from 96% to 100%) against Penicillium expansum under dried conditions. The highest strain O density and efficacy was obtained with SM. Under experimental conditions reflecting practical conditions, SM applied in combination with the strain O resulted in improved biocontrol efficacy by 74.65%. Therefore, SM could be used as material substrate with the best sugar protectants during the formulation process of this antagonistic yeast for eventual pre-harvest application.     

Effect of an Antagonistic Yeast in Combination with Microwave Treatment on Postharvest Blue Mould Rot of Jujube Fruit

The potential of using an antagonistic yeast alone or in combination with microwave treatment for controlling blue mould rot of jujube fruit, and its effect on postharvest quality of fruit, was investigated. The results showed that the growth of Penicillium citrinum was completely inhibited by a 2450‐MHz microwave heating for 2 or more minutes in vitro. The population density of P. citrinum in surface wounds of fruit treated with microwave treatment for 2–3 min was significantly lower than that of controls. When tested on jujube fruit, antagonistic yeast or microwave treatment, as stand‐alone treatment, the disease incidence of infected wounds was reduced from 100% to 45.0% and 36.0%, and lesion diameters were reduced from 1.92 cm to 1.50 cm and 1.38 cm, respectively. However, in fruit treated with a combination of Metschnikowia pulcherrima and microwave treatment, the disease incidence of infected wounds and lesion diameters was only 21.0% and 1.00 cm, respectively. The natural decay incidence on jujube fruit treated with the combination of microwave treatment and M. pulcherrima was 6.2% after storage at 2 ± 1°C for 45 days and at 22°C for 7 days. None of the treatments impaired quality parameters of fruits. Thus, the combination of microwave treatment and M. pulcherrima could provide an alternative to synthetic fungicides for controlling postharvest blue mould rot of jujube fruit.     

Efficacy assessment of Pichia guilliermondii strain Z1, a new biocontrol agent,against citrus blue mould in Morocco under the influence of temperature and relative humidity

The interactions of Penicillium italicum, which causes blue mould, and antagonistic yeast Pichia guilliermondii strain Z1 were examined in controlled environments, to determine the influence of relative humidity (RH) (45%, 75%, 85%, 98%, and 100%) and temperature (T) (5, 10, 15, 20, and 25 °C). All main effects and interactions were significant (P ? 0.05), with the exception of interactions RH×T and strain Z1 (BCA)×RH×T. In the pathogen control, the lesion diameter of blue mould developed under all environmental conditions but was the largest at a RH range between 98% and 100%, independent of the temperature. The efficacy of strain Z1 appeared to be independent of the environment and reduced disease incidence by more than 85% in all environmental conditions. Rapid colonization of the antagonistic yeast strain Z1 on citrus wounded sites was recorded during the first week at 5 °C. Colonization then stabilized at ±6.9 × 10⁶ CFU/ml for 30 days. This indicates that P. guilliermondii is able to adapt itself and colonize the wound sites prior to the arrival of the pathogen, displaying greater efficiency than when colonizing wounds after pathogen. The antagonist was capable of growing in low concentrations of orange juice (0.1–5%), with greatest growth at 5%. Applying strain Z1 (1 × 10⁸ CFU/ml) as a formulated product significantly reduced the incidence of infected fruits and the percentage of infected wounds relative to the pathogen control. Disease control with formulated product (45%) was slightly lower than that obtained with thiabendazole (20%) or strain Z1 culturable cells (25%). These results suggest that strain Z1 may be a useful BCA for control of blue mould under varying environmental conditions, and control may be enhanced by combining with other eco-friendly post-harvest treatments or improved formulation.