Pome Research Articles

Classification of Codling Moth-Infested Apples Using Sensor Data Fusion of Acoustic and Hyperspectral Features Coupled with Machine Learning

Codling moth (CM) is a major apple pest. Current manual method of detection is not very effective. The development of nondestructive monitoring and detection methods has the potential to reduce postharvest losses from CM infestation. Previous work from our group demonstrated the effectiveness of hyperspectral imaging (HSI) and acoustic methods as suitable techniques for nondestructive CM infestation detection and classification in apples. However, both have limitations that can be addressed by the strengths of the other. For example, acoustic methods are incapable of detecting external CM symptoms but can determine internal pest activities and morphological damage, whereas HSI is only capable of detecting the changes and damage to apple surfaces and up to a few mm inward; it cannot detect live CM activity in apples. This study investigated the possibility of sensor data fusion from HSI and acoustic signals to improve the detection of CM infestation in apples. The time and frequency domain acoustic features were combined with the spectral features obtained from the HSI, and various classification models were applied. The results showed that sensor data fusion using selected combined features (mid-level) from the sensor data and three apple varieties gave a high classification rate in terms of performance and reduced the model complexity with an accuracy up to 94% using the AdaBoost classifier, when only six acoustic and six HSI features were applied. This result affirms that the sensor fusion technique can improve CM infestation detection in pome fruits such as apples.

Evaluation of confirmatory data following Article 12 MRL review and modification of the existing MRLs in pome fruits for pyridaben.

In accordance with Article 6 of Regulation (EC) No 396/2005, the applicant Nissan Chemical Europe SAS submitted a request to the competent national authority in the Czech Republic to modify the existing maximum residue levels (MRLs) in pome fruits and to evaluate the confirmatory data identified in the framework of the MRL review under Article 12 of Regulation (EC) No 396/2005 as not available. To address the data gaps on residue trials, new trials according to the Good Agricultural Practices (GAPs) on apples, pears, medlars, quinces, loquats/Japanese medlars, apricots, peaches and beans with pods evaluated during the MRL review were not provided. These data gaps are not addressed. However, residue trials on apples and pears for an alternative GAP were provided and resulted by extrapolation in an MRL proposal for pome fruits lower than the current (tentative) MRL in EU legislation. The provided information may require a revision of the existing MRLs for pome fruits, apricots, peaches and beans with pods. Information on storage temperature of samples from the feeding study and a validated analytical method for animal commodities were submitted. The two data gaps on animal commodities were satisfactorily addressed. Adequate analytical methods for enforcement are available to control the residues of pyridaben in plant matrices under consideration and in all animal matrices, where currently an limit of quantification (LOQ) of 0.02 mg/kg is considered at the validated LOQ of 0.01 mg/kg. Based on the risk assessment results, EFSA concluded that the short-term and long-term intake of residues resulting from the uses of pyridaben according to the reported agricultural practices is unlikely to present a risk to consumer health.

Would You Like Wood or Plastic? Bin Material, Sanitation Treatments, and Bin Inoculum Levels Impact Blue Mold Decay of Stored Apple Fruit.

Blue mold, caused primarily by Penicillium expansum, is a significant postharvest disease of apples. It not only causes economic losses but also produces mycotoxins that contaminate processed fruit products, which contributes to food waste and loss. Previous research has shown that packing and storage bins harbor Penicillium spores and that steam and hot water efficiently reduce spore inoculum levels. However, studies using wooden and plastic bins regarding their ability to harbor spores, the effect of chemical sanitation treatments on spore levels, and the impact of rinsate from treated bins on apple fruit decay have not been investigated for the Mid-Atlantic area (Okull et al. 2006; Rosenberger 2009). We evaluated different sanitation treatments (chemical and physical) to reduce P. expansum inoculum levels on wooden and plastic bins. We determined that wooden bins bound P. expansum spores four orders of magnitude higher than plastic. When both bin types were treated with steam (wooden) or sterile hot water (plastic), Thyme Guard, or Academy, all treatments resulted in significantly (P < 0.05) lower spore levels compared to untreated controls. Although, plastic bins retained lower numbers of spores after inoculation with contaminated spore rinsate and required much higher concentrations of P. expansum spores in rinsate to retain spores at levels that would lead to decay on apple fruit. Overall, we demonstrated that plastic bins retain fewer spores than wooden bins and that both can be sanitized by various physical or chemical treatments. We envision that our findings will be applicable in the future as the techniques implemented in this study were used to investigate industry-relevant questions. Our goal is that the research techniques and findings become feasible with advancements in technology and/or accompany other shifts in existing processes in commercial pome fruit packing and storage facilities.

Evaluation of confirmatory data following the Article 12 MRL review and modification of the existing maximum residue levels for penconazole in various crops.

The applicant Syngenta Crop Protection AG submitted a request to the competent national authority in Germany to evaluate the confirmatory data that were identified for penconazole in the framework of the maximum residue level (MRL) review under Article 12 of Regulation (EC) No 396/2005 as not available. Moreover, in the application submitted to Germany, the applicant also included a request to raise the existing MRLs in pome fruits, raspberries and blackberries. To address the data gaps, detailed results on the metabolism substudy in tomato, a new storage stability on metabolites CGA127841, CGA132465 and CGA190503 and new residue trials were submitted. The data gap on metabolism was considered satisfactorily addressed. The data gap on complete sets of residue trials analysing simultaneously for monitoring and risk assessment residue definitions was considered addressed for raspberries, blackberries, pumpkins and watermelons; not addressed for pome fruits, stone fruits, grapes, gooseberries, tomatoes and aubergines. The new information provided justified an increase of the existing MRLs for pome fruits, plums, blackberries and raspberries and a revision of the risk assessment performed for penconazole. Adequate analytical methods for enforcement are available to control the residues of penconazole on the commodities under consideration at the validated limit of quantification (LOQ) of 0.01mg/kg. Based on the risk assessment results, EFSA concluded that the short-term and long-term intake of residues resulting from the use of penconazole according to the reported agricultural practices is unlikely to present a risk to consumer health.

Genetic diversity and phylogenetic relationships of apple chlorotic leaf spot virus isolates from Malus, Pyrus and Prunus hosts in Latvia

AbstractThe prevalence of apple chlorotic leaf spot virus (ACLSV) in different Rosaceae species, mainly from cultivated apple (Malus domestica), pear (Pyrus communis), plum (Prunus domestica), apricot (Prunus armeniaca) and wild plants of genus Amelanchier, Cotoneaster, Crataegus, Malus, Prunus and Sorbus were studied. ACLSV was found in cultivated M. domestica, P. communis, P. domestica and wild‐growing Malus, including M. sylvestris. Thirty‐four sequences of the ACLSV coat protein gene were obtained and compared with 372 homologous sequences from GenBank to evaluate the genetic diversity of the virus in Latvia and worldwide. The sequence identities varied from 79.6% to 98.4% at the nucleotide level and 84.5% to 100% at the amino acid level. Phylogenetic analyses clustered ACLSV pome fruit isolates into three genetic types but isolates from stone fruits into four phylogenetic groups. Three genetic types of ACLSV pome and stone fruit isolates were identified in Latvia. Two of them were previously characterized as type B6 and P205. The third genetic type was newly recognized among the stone fruit isolates and distinguished from other virus isolates by amino acid substitutions in three positions, Ser14, Asn23 and Leu72. Two natural recombinants, LV27 and NZ5, were detected among ACLSV isolates from Latvia, and recombination events were identified for the first time in wild‐growing Malus, confirming that recombination is a common process in the ACLSV population.

Fibulorhizoctonia psychrophila, causal agent of lenticel spot in pome fruit, rarely detected in Dutch pear and apple orchards

Fibulorhizoctonia psychrophila causes lenticel spot in stored pome fruit. A Dutch survey revealed that damage can be observed regularly in individual lots at low incidence to occasionally incidences above 25% after storage for five months or longer under specific controlled atmosphere storage conditions. The source of inoculum of the psychrophilic pathogen is not known. A species-specific TaqMan PCR assay was developed to quantify the pathogen DNA in orchard litter considered as potential inoculum source. 2008 samples of various litter types such as dead leaves, fallen fruits and mummies and necrotic tissues of grasses and weeds, collected in 2009–2012 in ten apple and twenty pear orchards, were analyzed. Although other fruit rot pathogens such as Neofabraea alba, Cadophora luteo-olivacea and Stemphylium vesicarium were detected in the samples at high incidences in earlier studies, F. psychrophila was only detected in three samples. The results show that F. psychrophila is not ubiquitously present in Dutch orchards at traceable concentrations. The main sources of the disease remain unknown. Possibly, the pathogen is present on storage bins or dust in storage facilities.

Exposure to lambda-cyhalothrin and abamectin drives sublethal and transgenerational effects on the development and reproduction of Cydia pomonella

The codling moth Cydia pomonella (Lepidoptera: Tortricidae) is a major invasive pest of pome fruits and walnuts worldwide. Lambda-cyhalothrin (LCT) and abamectin (AM) have been frequently used in C. pomonella control, but control of this pest is very difficult because shortly after hatching, larvae of this insect bore tunnels and hide inside host plant fruit. In this study, a simulated field spray bioassay method was developed against neonate larvae of C. pomonella and concentration-response bioassays were conducted to evaluate the susceptibility of the neonate larvae to LCT and AM. Exposure of neonate larvae to sublethal concentration (LC30) of LCT or AM significantly reduced the survival rate of larvae (4th and 5th instars), lowered the mean weight of larvae and pupae, and decreased the daily maximal number of eggs laid and the total number of eggs laid (fecundity) per female. The sublethal effects, including reduced body mass, mean fecundity and net reproductive rate, extended mean generation time, and shortened oviposition period, were also found in transgenerational offspring. Furthermore, the transgenerational maternal effects were more obvious for AM than LCT, in comparison to the control. Additionally, the estimated population size was decreased by exposure to LC30 of LCT and AM, and the observed reduction of fecundity and population size within and across generations was likely the result of the downregulation of the reproduction-related vitellogenin gene (CpVg) after exposure to LC30 of LCT and AM. These results provide a better understanding of the overall effects of LCT and AM on C. pomonella and the transgenerational effects which should be taken into consideration when using insecticides in order to control C. pomonella.

Molecular identification of carboxylesterase genes and their potential roles in the insecticides susceptibility of Grapholita molesta.

Grapholita molesta is one of the most damaging pests worldwide in stone and pome fruits. Application of chemical pesticides is still the main method to control this pest, which results in resistance to several types of insecticides. Carboxylesterase (CarE) is one of the important enzymes involved in the detoxification metabolism and tolerance of xenobiotics and insecticides. However, the roles of CarEs in insecticides susceptibility of G. molesta are still unclear. In the present study, the enzyme activity of CarEs and the mRNA expression of six CarE genes were consistently elevated after treatment with three insecticides (emamectin benzoate, lambda-cyhalothrin, and chlorantraniliprole). According to spatio-temporal expression profiles, six CarE genes expressed differently in different developmental stages, and highly expressed in some detoxification metabolic organs. RNAi-mediated knockdown of these six CarE genes indicated that the susceptibility of G. molesta to all these three insecticides were obviously raised after GmCarE9, GmCarE14, GmCarE16, and GmCarE22 knockdown, respectively. Overall, these results demonstrated that GmCarE9, GmCarE14, GmCarE16, and GmCarE22 play a role in the susceptibility of G. molesta to emamectin benzoate, lambda-cyhalothrin, and chlorantraniliprole treatment. This study expands our understanding of CarEs in insects, that the same CarE gene could participate in the susceptibility to different insecticides.

Evaluation of the Antimicrobial Potential and Characterization of Novel T7-Like Erwinia Bacteriophages

The recent outbreak of blight in pome fruit plants has been a major concern as there are two indistinguishable Erwinia species, Erwinia amylovora and E. pyrifoliae, which cause blight in South Korea. Although there is a strict management protocol consisting of antibiotic-based prevention, the area and the number of cases of outbreaks have increased. In this study, we isolated four bacteriophages, pEp_SNUABM_03, 04, 11, and 12, that infect both E. amylovora and E. pyrifoliae and evaluated their potential as antimicrobial agents for administration against Erwinia-originated blight in South Korea. Morphological analysis revealed that all phages had podovirus-like capsids. The phage cocktail showed a broad spectrum of infectivity, infecting 98.91% of E. amylovora and 100% of E. pyrifoliae strains. The antibacterial effect was observed after long-term cocktail treatment against E. amylovora, whereas it was observed for both short- and long-term treatments against E. pyrifoliae. Genomic analysis verified that the phages did not encode harmful genes such as antibiotic resistance or virulence genes. All phages were stable under general orchard conditions. Collectively, we provided basic data on the potential of phages as biocontrol agents that target both E. amylovora and E. pyrifoliae.

Virusi i viroidi kruške

One of the most common fruit species in the world is the pears. Compared to stone and small fruit trees, pears and other pome fruits are infected by a lesser number of viruses and viroids. The majority of commercial pear cultivars do not exhibit symptoms on their leaves, fruits, or other plant parts due to viruses. Only foliage and fruits show symptoms in susceptible cultivars. Apple stem pitting virus (ASPV), apple stem grooving virus (ASGV), apple chlorotic leafspot virus (ACLSV), and apple mosaic virus (ApMV) are widespread and economically significant pear viruses. Pear blister canker viroid (PBCVd) and apple scar skin viroid (ASSVd) are the most dangerous viroids infecting pears.

Xylella fastidiosa Not Detected on Tree Crops After Five Years of Survey

With the Xylella fastidiosa outbreak in Europe affecting olive and other major crops, the Jordanian Ministry of Agriculture (MoA) signaled a red warning light to prevent its entry into Jordan. An intensive survey was performed from 2016 to 2021 to assess its spread in Jordan across a range of agricultural crops in parallel to the previously published survey on olives. Grapevine (no. of samples: 899), stone fruit trees (1,480), citrus fruit trees (1,225), pome fruit trees (292), and ornamental plants (1,351) growing in Jordan were sampled. Both symptomatic and asymptomatic plants were sampled, in addition to collecting potential insect vectors from Hemiptera species. Plant samples were tested by enzyme-linked immunosorbent assay kits, and their results were confirmed by conventional polymerase chain reaction (PCR) using three sets of primers. Insect samples were tested using RST31/RST33 PCR. The obtained results did not show any confirmed positive results in any sample. These results indicate that X. fastidiosa has not been detected in Jordan despite a comprehensive survey. These results also demonstrate the importance of the monitoring and inspection programs executed by the MoA for detection of X. fastidiosa and identifying its potential insect vectors; these programs should be continued to prevent the entry of this bacterium and its potential insect vectors into Jordan from the neighboring countries.

A glycoside hydrolase superfamily gene plays a major role in Penicillium expansum growth and pathogenicity in apples

Penicillium expansum is an important postharvest pome fruit pathogen causing massive spoilage of stored fruits and high economic losses. The present study aimed to identify an essential gene of P. expansum and to investigate its effect in postharvest apple infection. Cytoscape and RNA-sequencing analysis identified a P. expansum PeBgl1 gene which was a hub gene and also upregulated expression at three key time points (1, 3, and 6 h) during apple infection. The PeBgl1 gene was 798 bp in length, encoded 265 amino acids and had high homology with glycoside hydrolase superfamily of P. expansum. The PeBgl1 gene affected the colony morphology especially the colony color and delayed fungal growth both of P. expansum both in vivo and in vitro. This gene also decreased the pathogenicity of P. expansum in apples. Based on these results, we conclude that PeBgl1 is responsible for growth and pathogenicity in P. expansum.

Exploring Antimicrobial Peptides Efficacy against Fire Blight (Erwinia amylovora).

Antimicrobial peptides (AMPs) are a various group of molecules found in a wide range of organisms and act as a defense mechanism against different kinds of infectious pathogens (bacteria, viruses, and fungi, etc.). This study explored the antibacterial activity of nine candidates reported in the literature for their effect on human and animal bacteria, (i.e., Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa) against Erwinia amylovora (E. amylovora), the causal agent of fire blight disease on pome fruits. The antibacterial activity of these peptides against E. amylovora was evaluated in vitro using viable-quantitative PCR (v-qPCR), fluorescence microscopy (FM), optical density (OD), and transmission electron microscopy (TEM), while the in vivo control efficacy was evaluated in treating experimental fire blight on pear fruits. With a view to their safe and ecofriendly field use in the future, the study also used animal and plant eukaryotic cells to evaluate the possible toxicity of these AMPs. Results in vitro showed that KL29 was the most potent peptide in inhibiting E. amylovora cell proliferation. In addition, the results of v-qPCR, FM, and TEM showed that KL29 has a bifunctional mechanism of action (lytic and non-lytic) when used at different concentrations against E. amylovora. KL29 reduced fire blight symptoms by 85% when applied experimentally in vivo. Furthermore, it had no impact on animal or plant cells, thus demonstrating its potential for safe use as an antibacterial agent. This study sheds light on a new and potent antibacterial peptide for E. amylovora and its modes of action, which could be exploited to develop sustainable treatments for fire blight.

Metabolic functional redundancy of the CYP9A subfamily members leads to P450-mediated lambda-cyhalothrin resistance in Cydia pomonella.

The evolution of insect resistance to pesticides poses a continuing threat to sustainable pest management. While much is known about the molecular mechanisms that confer resistance in model insects and few agricultural pests, far less is known about fruit pests. Field-evolved resistance to synthetic insecticides such as lambda-cyhalothrin has been widely documented in Cydia pomonella, a major invasive pest of pome fruit worldwide, and the increased production of cytochrome P450 monooxygenases (P450s) has been linked to resistance in field-evolved resistant populations. However, the underlying molecular mechanisms of P450-mediated insecticide resistance remain largely unknown. Here we found that functional redundancy and preference of metabolism by P450s genes in the CYP9A subfamily confer resistance to lambda-cyhalothrin in Cydia pomonella. A total of four CYP9A genes, including CYP9A61, CYP9A120, CYP9A121, and CYP9A122, were identified from Cydia pomonella. Among these, CYP9A120, CYP9A121, and CYP9A122 were predominantly expressed in the midgut of larvae. The expression levels of these P450 genes were significantly induced by a lethal dose that would kill 10% (LD10 ) of lambda-cyhalothrin and were overexpressed in a field-evolved lambda-cyhalothrin resistant population. Knockdown of CYP9A120 and CYP9A121 by RNA-mediated interference (RNAi) increased the susceptibility of larvae to lambda-cyhalothrin. In vitro assays demonstrated that recombinant P450s expressed in Sf9 cells can metabolize lambda-cyhalothrin, but with functional redundancy and divergence through regioselectivity of metabolism. CYP9A121 preferred to convert lambda-cyhalothrin to 2'-hydroxy-lambda-cyhalothrin, whereas CYP9A122 only generated 4'-hydroxy metabolite of lambda-cyhalothrin. Although possesses a relatively low metabolic capability, CYP9A120 balanced catalytic competence to generate both 2'- and 4'-metabolites. Collectively, these results reveal that metabolic functional redundancy of three members of the CYP9A subfamily leads to P450-mediated lambda-cyhalothrin resistance in Cydia pomonella, thus representing a potential adaptive evolutionary strategy during its worldwide expansion. © 2022 Society of Chemical Industry.

High-throughput detection of a large set of viruses and viroids of pome and stone fruit trees by multiplex PCR-based amplicon sequencing.

A comprehensive diagnostic method of known plant viruses and viroids is necessary to provide an accurate phytosanitary status of fruit trees. However, most widely used detection methods have a small limit on either the number of targeted viruses/viroids or the number of samples to be evaluated at a time, hampering the ability to rapidly scale up the test capacity. Here we report that by combining the power of high multiplexing PCR (499 primer pairs) of small amplicons (120-135bp), targeting 27 viruses and 7 viroids of fruit trees, followed by a single high-throughput sequencing (HTS) run, we accurately diagnosed the viruses and viroids on as many as 123 pome and stone fruit tree samples. We compared the accuracy, sensitivity, and reproducibility of this approach and contrast it with other detection methods including HTS of total RNA (RNA-Seq) and individual RT-qPCR for every fruit tree virus or viroid under the study. We argue that this robust and high-throughput cost-effective diagnostic tool will enhance the viral/viroid knowledge of fruit trees while increasing the capacity for large scale diagnostics. This approach can also be adopted for the detection of multiple viruses and viroids in other crops.

An Overview of Pest and Disease Occurrence in Organic Pome Fruit Orchards in Europe and on the Implementation of Practices for Their Control

There is limited data regarding the specific problems faced by organic fruit growers when dealing with plant protection, particularly at a European Union level, though some general knowledge about pest and disease incidence can be found. Such information is crucial to improve the efficacy of a targeted knowledge transfer to organic fruit growers and advisors aiming at an increased adoption of innovative practices. A survey was thus carried out in seventeen European countries (16 EU member states and Switzerland), within the framework of the EU-funded project BIOFRUITNET, aiming at filling this knowledge gap also in terms of research needs. A questionnaire including a section about general aspects of orchard management (functional biodiversity, fertilization management, varietal/rootstock selection) and a section specifically dedicated to pest and disease occurrence and management in organic orchards was utilized to interview about 250 professionals (farmers and advisors), 155 of which were involved in pome fruits (including apple and pear) production. The analysis of the answers related to plant protection pointed out a varied situation about pest and disease occurrence in apple and pear orchards across Europe, though related to the zonal location of the respondent. However, more than 50% of respondents generally considered just few among the most damaging ones, normally co-occurring in the orchards. Interestingly, regardless of the respondents’ nationality or zonal location, more pests than diseases were indicated as relevant agents threatening organic pome fruits production. Nevertheless, only few measures promoting functional biodiversity in the orchards resulted in being broadly implemented in all regions. The analysis of the data underlines the strong demand for the development of a toolbox of measures that can be integrated successfully into the general orchard management strategy including the successful enhancement of functional or general biodiversity.

OPPORTUNITIES FOR THE DEVELOPMENT OF AN ORCHARD FARM WITH PARTICULAR EMPHASIS ON LOGISTIC ELEMENTS

The aim of the study is to assess the possibility of improving internal transport and storage of pome fruit (including apples) in an orchard farm located in Wilkonice. The research material was collected on the basis of an interview questionnaire with the owner of an orchard farm in May 2022. Secondary data came from the Central Statistical Office and a literature review. Fruit growing is one of the important areas in the Polish agricultural sector. In terms of sales volume, Poland is a leading producer of apples, both in Europe and in the world. In 2014, as a result of the embargo imposed by Russia, Poland lost the possibility of exporting fresh vegetables and fruits to it. Among other things, this situation caused problems with their sale and distribution. Therefore, in order to increase the profitability of Polish fruit farms, it was necessary to reduce the outlays incurred for fruit production and to find new distribution channels, ensuring constant access to markets. Based on the conducted interview questionnaire, it should be concluded that modern techniques used in internal transport logistics allow minimizing the number of trips from the orchard to the place of storage of pome fruit. Thus, they contribute to reducing the cost of producing 1 kg of these fruits and minimize the time spent on this process. In addition, new refrigeration technologies are the most effective way to extend the shelf life of pome fruit, which may result in the long-term sale of crops at higher prices and the acquisition of permanent contractors, guaranteeing continuous receipt of goods.

Comparative Penicillium spp. Transcriptomics: Conserved Pathways and Processes Revealed in Ungerminated Conidia and during Postharvest Apple Fruit Decay.

Blue mold, caused by Penicillium spp., is an impactful postharvest disease resulting in significant economic losses due to reduced pome fruit quality and mycotoxin contamination. Using two Penicillium species with different levels of aggressiveness, transcriptomics were implemented in order to identify genes expressed during apple fruit decay and loci expressed in ungerminated conidia. Total RNA was isolated from ungerminated conidia and decayed apple fruit infected with P. expansum R19 or P. polonicum RS1. There were 2442 differentially expressed genes (DEGs) between the R19 and RS1 in apple. Comparisons within species between apple and conidia revealed 4404 DEGs for R19 and 2935 for RS1, respectively. Gene ontology (GO) analysis revealed differential regulation in fungal transport and metabolism genes during decay, suggesting a flux in nutrient acquisition and detoxification strategies. In R19, the oxidoreductase GO category comprised 20% of all DEG groups in apple verses conidia. Ungerminated conidia from both species showed DEGs encoding the glyoxylate shunt and beta-oxidation, specifying the earliest metabolic requirements for germination. This is the first study to identify pre-loaded transcripts in conidia from blue mold fungi, reveal unique genes between species expressed during apple decay, and show the expression dynamics of known fungal virulence factors. These findings will enable development of targeted approaches for blue mold abatement strategies.

Monilinia fructigena Suppressing and Plant Growth Promoting Endophytic Pseudomonas spp. Bacteria Isolated from Plum.

Brown rot caused by Monilinia spp. fungi causes substantial losses in stone and pome fruit production. Reports suggest that up to 90% of the harvest could be lost. This constitutes an important worldwide issue in the food chain that cannot be solved by the use of chemical fungicides alone. Biocontrol agents (BCAs) based on microorganisms are considered a potential alternative to chemical fungicides. We hypothesized that endophytic bacteria from Prunus domestica could exhibit antagonistic properties towards Monilinia fructigena, one of the main causative agents of brown rot. Among the bacteria isolated from vegetative buds, eight isolates showed antagonistic activity against M. fructigena, including three Pseudomonas spp. isolates that demonstrated 34% to 90% inhibition of the pathogen's growth when cultivated on two different media in vitro. As the stimulation of plant growth could contribute to the disease-suppressing activity of the potential BCAs, plant growth promoting traits (PGPTs) were assessed for bacterial isolates with M. fructigena-suppressing activity. While all isolates were capable of producing siderophores and indole-3-acetic acid (IAA), fixating nitrogen, mineralizing organic phosphate, and solubilizing inorganic phosphate and potassium, only the Pseudomonas spp. isolates showed 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity. Overall, our study paves the way for the development of an eco-friendly strategy for managing M. fructigena pathogens by using BCAs including Pseudomonas spp. bacteria, which could also serve as growth stimulators.

BIOLOGICAL CONTROL OF CODLING MOTH, CYDIA POMONELLA (L.) IN APPLE ORCHARDS OF BULGARIA USING GINKO® DISPENSERS

The codling moth, Cydia pomonella (L.) (Lepidoptera: Tortricidae), is a significant pest of pome fruit and walnut orchards worldwide and it is a particular problem in Bulgaria. Codling moth resistance to many insecticides has been recently detected in Bulgaria. Codling moth (CM) mating disruption with Ginko® dispensers was evaluated in four successive years from 2019 to 2022 as part of an anti-resistance strategy. In an isolated 3 ha apple orchard in the Plovdiv district of South-Central Bulgaria, close to the town of Perushtitsa, field tests were conducted for the control of the codling moth (CM), C. pomonella, via mating disruption (MD) using pheromone Ginko® dispensers. The pheromone dispensers were hung in the upper third of tree canopies with a density of 500 dispensers/ha before CM flight started. Dynamics of CM flights was monitored by pheromone traps installed in the trial plot and in a conventionally treated reference orchard. Two types of baits were used in the traps: PHEROCON® CM L2–codlemone lures and PHEROCON® CM DA COMBO-P + AA lures (Trécé Inc., USA) in the orchards for mating disruption. The PHEROCON® CM L2 lures were changed at 4-week intervals and PHEROCON® CM DA COMBO-P + AA lures at 8-week intervals. PHEROCON® VI Delta sticky traps baited with PHEROCON CM DA COMBO- P + AA lures and standard CM L2 caps were installed, for comparison, in a reference orchard located in the Plovdiv region. Fruit infestation was periodically assessed till the harvest time. In both years fruit damage remained lower till late July and increased slightly only in August. At harvest, fruit damage remained below 1%. It was obvious that mating disruption could be useful strategy for the control of codling moth in Bulgarian apple orchards, specifically when the plot is isolated from external sources of infestation and the population density of the pest is low.