Tomato Leaf Mold Research Articles

Piriformospora indica Suppresses Natural Incidence and Severity of Black Leaf Mold of Tomato Incited by Pseudocercospora fuligena Over Strobilurin and Triazole Fungicides with Enhanced Growth and Yield

Aim: To study the effect of Piriformospora indica-root colonisation and spraying of azoxystrobin, pyraclostrobin (strobilurins), propiconazole and tebuconazole (triazoles) fungicides for the management of black leaf mold of tomato. Study Design: Completely randomized design for lab; Randomized block design for field studies. Place and Duration of Study: College of Agriculture (Kerala Agricultural University), Vellayani and Coconut Reserarch Station, Balaramapuram, Thiruvananthapuram during 2022-2024. Methodology: In vitro evaluation of strobilurin and triazole fungicides against Pseudocercospora fuligena was done by poisoned food technique. Field evaluation of P. indica-colonized plants var. Vellayani Vijai was performed to assess the incidence and severity of black leaf mold of tomato over systemic fungicides. Results: The strobilurin fungicides partially and the triazoles completely inhibited the mycelial growth of the pathogen. P. fuligena was completely inhibited at 100 ppm of triazole fungicides, but at least 25 per cent growth was observed in strobilurin fungicides even at 1000 ppm. P. indica significantly reduced the natural incidence and severity of black leaf mold disease at 45 DAT and it extended to the entire crop period in the field condition. The disease incidence was 15.00 per cent in the P. indica-colonised plants; whereas it ranged from 28.12 to 31.85 per cent in the systemic fungicides sprayed plants; and in control plants, it was significantly high with 47.50 per cent. Similarly, the disease severity was least (PDI: 7.99) in the P. indica-colonised plants at 45 DAT. But the disease severity in the fungicides alone sprayed plants were 15.89 to 18.96; whereas in control plants, the severity was 40.83. Moreover, P. indica enhanced plant height, early flowering, fruit setting, flowers, fruits and average yield over control and systemic fungicides sprayed plants. Conclusion: P. indica confers tolerance to black leaf mold disease over the strobilurin and triazole fungicides apart from the enhanced crop yield.

Exploring the Antifungal Activity of Moroccan Bacterial and Fungal Isolates and a Strobilurin Fungicide in the Control of Cladosporium fulvum, the Causal Agent of Tomato Leaf Mold Disease.

The causal agent of tomato leaf mold, Cladosporium fulvum, is prevalent in greenhouses worldwide, especially under high humidity conditions. Despite its economic impact, studies on antifungal agents targeting C. fulvum remain limited. This study evaluates biocontrol agents (BCAs) as alternatives to chemical controls for managing this disease, alongside the strobilurin fungicide azoxystrobin. From a Moroccan collection of potential BCAs, five bacterial isolates (Alcaligenes faecalis ACBC1, Pantoea agglomerans ACBC2, ACBP1, ACBP2, and Bacillus amyloliquefaciens SF14) and three fungal isolates (Trichoderma spp. OT1, AT2, and BT3) were selected and tested. The in vitro results demonstrated that P. agglomerans isolates reduced mycelial growth by over 60% at 12 days post-inoculation (dpi), while Trichoderma isolates achieved 100% inhibition in just 5 dpi. All bacterial isolates produced volatile organic compounds (VOCs) with mycelial inhibition rates ranging from 38.8% to 57.4%. Likewise, bacterial cell-free filtrates significantly inhibited the pathogen's mycelial growth. Greenhouse tests validated these findings, showing that all the tested isolates were effective in reducing disease incidence and severity. Azoxystrobin effectively impeded C. fulvum growth, particularly in protective treatments. Fourier transform infrared spectroscopy (FTIR) analysis revealed significant biochemical changes in the treated plants, indicating fungal activity. This study provides valuable insights into the efficacy of these BCAs and azoxystrobin, contributing to integrated management strategies for tomato leaf mold disease.

First observation of the beetle Sericoderus lateralis consuming Cladosporium fulvum in a greenhouse tomato: potential for biological protection or risk to the crop?

For the first time, the mycophagous beetle Sericoderus lateralis (Gyllenhal, 1827) was documented feeding on tomato leaf mold ( Cladosporium fulvum Cooke, 1878) tissues. The phenomenon was observed during the years 2022 and 2023 in a hydroponic tomato greenhouse situated near the Czech-Polish border within the cadastre of Dolní Lutyně municipality in Czechia. Greenhouse and laboratory observations confirmed that adult and larvae feeding activity led to a reduction in tomato leaf mold lesions. In addition, there was a positive correlation between tomato leaf mold disease progression and increased populations of S. lateralis in the tomato crop. Petri dish observations confirmed egg laying occurred on a diet of tomato leaf mold. Further research is warranted to discern whether S. lateralis is a potential biological control agent for tomato leaf mold or if it acts to facilitate the spread of the disease by acting as a spore vector.

Transcription factor network analysis of the Cf-19-mediated resistance response in tomato infected by Cladosporium fulvum

Tomato leaf mold, caused by Cladosporium fulvum, is a common disease in tomato cultivation. The Cf-19 gene is an effective resistance gene to C. fulvum. Current studies have shown that the Cf-19-mediated resistance response pathway is regulated by a variety of TFs. In this study, in order to better understand the role of TFs in the Cf-19-mediated immune response of tomato against C. fulvum, differentially expressed TFs in different response stages were identified based on RNA-seq data. The results showed that a total of 37 families with 171 TF members were identified. These differentially expressed TFs were enriched in “nucleus” in the component category, “DNA-binding transcription factor activity” in the function category and “Regulation of transcription” in the process category in the Gene Ontology (GO) analysis results. Four pathways, including plant hormone signal transduction, MAPK signaling, plant-pathogen interaction and circadian rhythm, were enriched in the KEGG analysis results. Further analysis showed that 45 TFs were involved in the above four major pathways, and some TFs in different pathways had interaction relationships, which might be the key nodes mediating cross-talk between different pathways. EREB was predicted to be the core of multigroup interactions, and its interaction with WRKY80 is the node connecting the MAPK pathway and plant-pathogen interaction pathway. The function of the EREB gene was analyzed by VIGS, and it was found that the downregulated expression of this gene decreased the expression of WRKY80 and the disease resistance mediated by Cf-19.

Sensitivity of tomato leaf mould–causing Fulvia fulva to seven succinate dehydrogenase inhibitor (SDHI) fungicides in Nara Prefecture, Japan and high efficacy of isofetamid in controlling SDHI‐resistant isolates

AbstractLeaf mould caused by Fulvia fulva is a major disease of tomato in Japan. Resistance to several types of fungicides, including succinate dehydrogenase inhibitors (SDHIs), has been reported in isolates from Japan. In this study, we evaluated the sensitivity of F. fulva to SDHI fungicides, SDHI fungicide efficacy in controlling sensitive and resistant isolates, and the presence of mutations in the Sdh B gene, the target site of SDHI fungicides. The minimum inhibitory concentration (MIC) of six SDHI fungicides, excluding isofetamid, ranged from 0.1 to >100 μg/mL against mycelial growth of 45 F. fulva isolates collected in Nara prefecture, Japan, whereas that of isofetamid ranged from 0.1 to only 10 μg/mL. The peak MIC distribution of fluopyram and isofetamid was 10 μg/mL, that of inpyrfluxam was 100 μg/mL and was >100 μg/mL for the remaining SDHI fungicides. In a greenhouse inoculation experiment, only isofetamid controlled the highly resistant isolates with an MIC of 10 μg/mL and the remaining fungicides had MIC >100 μg/mL. In addition, moderately and highly resistant isolates were controlled by the application of isofetamid 6 h or 7 days before inoculation or 3 days after inoculation. Mutations in the Sdh B gene were not observed among sensitive, moderately resistant and highly resistant isolates, suggesting that mutations in other Sdh genes and/or changes in efflux pump expression were involved. Our results indicate the presence of cross‐resistance and different levels of sensitivity reduction among SDHI fungicides. Isofetamid showed the lowest resistance development among the tested SDHI fungicides and is considered effective in controlling tomato leaf mould.

Hexaconazole and binary mixtures of it plus fludioxonil efficiently control tomato leaf mold caused by Cladosporium fulvum

Leaf mold caused by Cladosporium fulvum is one of the most severe foliar diseases of tomato. We were interested in whether we could use a binary mixture of hexaconazole and fludioxonil for the management of tomato leaf mold. The results showed that hexaconazole with an EC50 value of 0.30 μg/ml could significantly inhibit the mycelial growth of C. fulvum. A total of 126 isolates collected from Shandong Province were used to determine their sensitivity to hexaconazole, and the data fit a bimodal curve with a mean EC50 value of 4.69 μg/ml. The optimal proportion of the binary mixture of hexaconazole and fludioxonil against C. fulvum was 1:2, and its synergistic ratio (SR) was 2.23. Field trials in 2018 and 2019 indicated that both hexaconazole and the binary mixture of hexaconazole and fludioxonil (1:2) had favorable protective and curative efficacy against tomato leaf mold. Applying hexaconazole at 67.50 g/ha resulted in higher efficacy than did flusilazole at 75.00 g/ha, which had been registered in China to control tomato leaf mold. In addition, a binary mixture of hexaconazole and fludioxonil (1:2) at 60.75 g/ha had an efficacy of 85%, which was significantly higher than that of a commercial binary mixture of fluopyram and trifloxystrobin at 150.00 g/ha. Even when applied at 20.25 g/ha, hexaconazole could also provide better efficacy than thiophanate-methyl could regardless of whether it was applied before or after the occurrence of tomato leaf mold. In summary, hexaconazole and its binary mixture with fludioxonil (1:2) could be favorable candidates for the management of tomato leaf mold.

Mapping of the Cladosporium fulvum resistance gene Cf-16, a major gene involved in leaf mold disease in tomato.

Tomato (Solanum lycopersicum) is widely cultivated and consumed worldwide. Tomato leaf mold, caused by Cladosporium fulvum, is one of the most devastating diseases in tomato production. At present, some tomato leaf mold resistance (Cf series) genes used in production gradually lose resistance due to the continuous and rapid differentiation of C. fulvum physiological races. The Cf-16 gene derived from the "Ontario7816" tomato cultivar has shown effective resistance in field trials for many years, but few studies have reported on the mapping of the Cf-16 gene, which has not been cloned, limiting its utilization in tomato breeding. Here, we mapped Cf-16 using a novel comprehensive strategy including bulk segregation analysis (BSA), genome resequencing and SSR molecular markers. A genetic analysis revealed that Cf-16 resistance in "Ontario7816" is controlled by one major dominant locus. The Cf-16 gene was mapped in a region of 2.6cM at chromosome 6 between two markers, namely, TGS447 and TES312, by using an F2 population from a cross between the resistant cultivar "Ontario7816" and susceptible line "Moneymaker." Two nucleotide-binding-site-leucine-rich repeat (NBS-LRR) resistance genes, namely, XM_004240667.3 and XM_010323727.1, were identified in this interval. They are strong candidates for the Cf-16 gene. The mapping of Cf-16 may speed up its utilization for breeding resistant tomato varieties and represents an important step forward in our understanding of the mechanism underlying resistance to tomato leaf mold.

A Novel Fuzzy C-Means based Chameleon Swarm Algorithm for Segmentation and Progressive Neural Architecture Search for Plant Disease Classification

This study proposed a novel framework for plant leaf disease identification. The proposed model consists of four steps including pre-processing, segmentation, feature extraction, and classification. At first, the unwanted noise and overfitting are removed, and also image contrast level is enhanced. Secondly, the Fuzzy C-Means (FCM) based Chameleon Swarm Algorithm (CSA) named as (FCM-CSA) is used for plant leaf diseased part segmentation. In the third stage, the feature extraction is performed using a fast GLCM feature extraction model. Finally, the Progressive Neural Architecture Search (PNAS) is used for plant leaf disease identification. The experimental investigations are carried out using MATLAB software with the Mendeley database. From this dataset, we have used Apple Cedar Apple Rust (ACAR), Cherry Powdery Mildew (CPM), Corn Common Rust (CCCR), Apple Healthy (AH), Grape Black Rot (GBR), Pepper Bell Bacterial Spot (PBBS), Potato Late Blight (PLB) and Tomato Leaf Mold (TLM) disease images. Different measures such as precision, recall, sensitivity, specificity, and accuracy results are used to validate the performance of the proposed model.

Physiological and transcriptome profiling revealed defense networks during Cladosporium fulvum and tomato interaction at the early stage.

Tomato leaf mold caused by Cladosporium fulvum (C. fulvum) is a serious fungal disease which results in huge yield losses in tomato cultivation worldwide. In our study, we discovered that ROS (reactive oxygen species) burst was triggered by C. fulvum treatment in tomato leaves. RNA-sequencing was used to identify differentially expressed genes (DEGs) induced by C. fulvum inoculation at the early stage of invasion in susceptible tomato plants. Gene ontology (GO) terms and Kyoto Encyclopedia of Genes and Genomes (KEGG) databases were used to annotate functions of DEGs in tomato plants. Based on our comparative analysis, DEGs related to plant-pathogen interaction pathway, plant hormone signal transduction pathway and the plant phenylpropanoid pathway were further analyzed. Our results discovered that a number of core defense genes against fungal invasion were induced and plant hormone signal transduction pathways were impacted by C. fulvum inoculation. Further, our results showed that SA (salicylic acid) and ABA (abscisic acid) contents were accumulated while JA (jasmonic acid) content decreased after C. fulvum inoculation in comparison with control, and quantitative real-time PCR to detect the relative expression of genes involved in SA, ABA and JA signaling pathway further confirmed our results. Together, results will contribute to understanding the mechanisms of C. fulvum and tomato interaction in future.

Identification of Cladosporium fulvum infection responsive genes in tomato through cDNA-AFLP

Tomato (Solanum lycopersicum) is one of the highest-value vegetable crops worldwide, but tomato planting can be easily affected by leaf mold. Tomato leaf mold disease is caused by Cladosporium fulvum, and plants carrying the Cf genes have effective resistance to C. fulvum. To identify leaf mold resistant varieties and screen for specific cDNA amplified fragment length polymorphism (cDNA-AFLP) molecular markers, tomato plants harbouring genes Cf-5, Cf-11, Cf-19, and the moneymaker (MM) tomato line (without Cf gene) were used as plant materials. The changes in reactive oxygen species (ROS) levels and antioxidant activities of plant leaves after inoculation of C. fulvum were measured. Ethylene (ETH), abscisic acid (ABA) and salicylic acid (SA) contents were also determined. The results revealed that the ROS levels in Cf-19 tomato were the most sensitive to C. fulvum inoculation, while in MM they were the least. The antioxidant enzymes of Cf-carrying plants exhibited different activities as compared to those of MM. In the cDNA-AFLP analysis data, the expression of ERF109, sedoheptulose-1,7-bisphosphatase (SBPase), L-ascorbic acid oxidase (AAO) and Thioredoxin H2 (TRX2) were different between Cf-gene carriers and MM plants. In summary, in the process of leaf–mold interaction, the outbreak of ROS and development of systemic acquired resistance (SAR) are tightly combined with antioxidant enzymes, including thioredoxin. Tomato plants carrying the Cf-19 gene appear to have stronger C. fulvum resistance.

Fungal dual-domain LysM effectors undergo chitin-induced intermolecular, and not intramolecular, dimerization.

Chitin is a homopolymer of β-(1,4)-linked N-acetyl-D-glucosamine (GlcNAc) and a major structural component of fungal cell walls. In plants, chitin acts as a microbe-associated molecular pattern (MAMP) that is recognized by lysin motif (LysM)-containing plant cell surface-localized pattern recognition receptors (PRRs) that activate a plethora of downstream immune responses. To deregulate chitin-induced plant immunity and successfully establish infection, many fungal pathogens secrete LysM domain-containing effector proteins during host colonization. The LysM effector Ecp6 from the tomato (Solanum lycopersicum) leaf mold fungus Cladosporium fulvum can outcompete plant PRRs for chitin binding because two of its three LysM domains cooperate to form a composite groove with ultra-high (pM) chitin-binding affinity. However, most functionally characterized LysM effectors contain only two LysMs, including Magnaporthe oryzae MoSlp1, Verticillium dahliae Vd2LysM, and Colletotrichum higginsianum ChElp1 and ChElp2. Here, we performed modeling, structural, and functional analyses to investigate whether such dual-domain LysM effectors can also form ultra-high chitin-binding affinity grooves through intramolecular LysM dimerization. However, our study suggests that intramolecular LysM dimerization does not occur. Rather, our data support the occurrence of intermolecular LysM dimerization for these effectors, associated with a substantially lower chitin binding affinity than monitored for Ecp6. Interestingly, the intermolecular LysM dimerization allows for the formation of polymeric complexes in the presence of chitin. Possibly, such polymers may precipitate at infection sites to eliminate chitin oligomers, and thus suppress the activation of chitin-induced plant immunity.

MMDGAN: A fusion data augmentation method for tomato-leaf disease identification

Tomato disease control is of great significance to ensure crop production and tomato disease classification study is an essential tool for doing so. In this paper, we propose a new data augmentation method based on deep threshold multi-feature extraction convolution GAN with Mixed Attention and Markovian Discriminator (MMDGAN) for tomato disease leaf classification. Firstly, in the generator of MMDGAN, a deep threshold multi-feature extraction module was proposed to improve the feature extraction of tomato disease leaves. Then, a mixed attention mechanism combined cross attention module with fused features-highlighting module was proposed to coordinate the overall generation of images. Finally, for the discriminator, Markov discriminator was used to strengthen the similarity judgment of local texture of images. Based on the open datasets PlantVillage, the Frechet Inception Distance (FID) score of healthy tomato leaf image, Leaf Mold, Leaf Curl and Spider Mite generated by MMDGAN were 159.3010, 164.4744, 230.3825 and 254.9866 respectively. Thereafter, a B-ARNet model is trained on synthetic and real images using transfer learning to classify the four categories of tomato diseases. The proposed method achieved an accuracy of 97.12%, with and F1 value of 97.78%. The proposed approach shows its superiority over the existing methodologies.

The Diversity of Passalora fulva Isolates Collected from Tomato Plants in U.S. High Tunnels.

High tunnels extend the growing season of high value crops, including tomatoes, but the environmental conditions within high tunnels favor the spread of the tomato leaf mold pathogen, Passalora fulva (syn. Cladosporium fulvum). Tomato leaf mold results in defoliation, and if severe, losses in yield. Despite substantial research, little is known regarding the genetic structure and diversity of populations of P. fulva associated with high tunnel tomato production in the United States. From 2016 to 2019, a total of 50 P. fulva isolates were collected from tomato leaf samples in high tunnels in the Northeast and Minnesota. Other Cladosporium species were also isolated from the leaf surfaces. Koch's postulates were conducted to confirm that P. fulva was the cause of the disease symptoms observed. Race determination experiments revealed that the isolates belonged to either race 0 (six isolates) or race 2 (44 isolates). Polymorphisms were identified within four previously characterized effector genes: Avr2, Avr4, Avr4e, and Avr9. The largest number of polymorphisms were observed for Avr2. Both mating type genes, MAT1-1-1 and MAT1-2-1, were present in the isolate collection. For further insights into the pathogen diversity, the 50 isolates were genotyped at 7,514 single-nucleotide polymorphism loci using genotyping-by-sequencing. Differentiation by region but not by year was observed. Within the collection of 50 isolates, there were 18 distinct genotypes. Information regarding P. fulva population diversity will enable better management recommendations for growers, as high tunnel production of tomatoes expands.

Understanding the mechanisms of resistance to tomato leaf mold: A review

Tomato leaf mold is a common disease in tomato production and severely impacts the growth, fruit quality and yield of tomato plants. Research on tomato leaf mold has a long history and has focused mainly on the differentiation of pathogen races, the structure and function of pathogen Avr gene products, the cloning of Cf resistance genes and the analysis of disease resistance mechanisms. Interactions between Cf and Avr are in accordance with the "gene-for-gene" hypothesis and typical Cf/Avr interactions are part of effector-triggered immunity (ETI). However, an increasing number of studies have proven that pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) is involved in the disease resistance response system mediated by Cf genes. In addition, different Cf genes have both similar and different roles in the disease resistance response, indicating that the disease resistance mechanism of Cf genes is complex. In this paper, progress in tomato leaf mold research was reviewed, and the regulatory mechanism underlying the Cf-mediated disease resistance response was thoroughly explored. We hope this summary will lay a foundation for research on tomato leaf mold disease resistance mechanisms and is applicable to breeding for disease resistance.

Transcriptome Analysis of the Cf-13-Mediated Hypersensitive Response of Tomato to Cladosporium fulvum Infection.

Tomato leaf mold disease caused by Cladosporium fulvum (C. fulvum) is one of the most common diseases affecting greenhouse tomato production. Cf proteins can recognize corresponding AVR proteins produced by C. fulvum, and Cf genes are associated with leaf mold resistance. Given that there are many physiological races of C. fulvum and that these races rapidly mutate, resistance to common Cf genes (such as Cf-2, Cf-4, Cf-5, and Cf-9) has decreased. In the field, Ont7813 plants (carrying the Cf-13 gene) show effective resistance to C. fulvum; thus, these plants could be used as new, disease-resistant materials. To explore the mechanism of the Cf-13-mediated resistance response, transcriptome sequencing was performed on three replicates each of Ont7813 (Cf-13) and Moneymaker (MM; carrying the Cf-0 gene) at 0, 9, and 15 days after inoculation (dai) for a total of 18 samples. In total, 943 genes were differentially expressed, specifically in the Ont7813 response process as compared to the Moneymaker response process. Gene ontology (GO) classification of these 943 differentially expressed genes (DEGs) showed that GO terms, including “hydrogen peroxide metabolic process (GO_Process)”, “secondary active transmembrane transporter activity (GO_Function)”, and “mismatch repair complex (GO_Component)”, which were the same as 11 other GO terms, were significantly enriched. An analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) revealed that many key regulatory genes of the Cf-13-mediated resistance response processes were involved in the “plant hormone signal transduction” pathway, the “plant–pathogen interaction” pathway, and the “MAPK signaling pathway–plant” pathway. Moreover, during C. fulvum infection, jasmonic acid (JA) and salicylic acid (SA) contents significantly increased in Ont7813 at the early stage. These results lay a vital foundation for further understanding the molecular mechanism of the Cf-13 gene in response to C. fulvum infection.

Identification method of vegetable diseases based on transfer learning and attention mechanism

Artificial Intelligence for disease identification is currently the focus of great research interest. Nonetheless, the approach has some problems, for example, identification takes a long time, has low accuracy, and is often limited to a single disease type. Here, we aimed to identify tomato powdery mildew, leaf mold and cucumber downy mildew against simple and complex backgrounds. We developed a vegetable disease identification model, DTL-SE-ResNet50, optimized by SENet and pre-trained by ImageNet to form a new model, SE-ResNet50. The SE-ResNet50 model was trained with the AI Challenger 2018 public database to obtain a new weight. The SE-ResNet50 model with the new weight was then trained by dual transfer learning with a self-built database to create the DTL-SE-ResNet50 model for the identification of vegetable diseases. The model was compared with convolutional neural networks EfficientNet, AlexNet, VGG19, and Inception V3. The experimental results showed that with the same experimental conditions, the identification precision of the new model reached 97.24%, and processing of a single image required 0.13 s. Compared with DTL-CBAM-ResNet50 and DTL-SA-ResNet50, three models has almost the same precision, but time consumption of DTL-SE-ResNet50 was 0.02 s higher than that of DTL-CBAM-ResNet50. Although the time consumption of DTL-SA-ResNet50 was 0.02 s higher than the proposed model, the precision was lower. At the same time, compared with the dual transfer learning model, the model’s precision was 4.1% higher, and the processing of a single image was 0.06 s shorter. Compared with convolutional neural networks, the precision of DTL-SE-ResNet50 was 3.19% higher than the best result, the time consumption of a single image was 0.58 s shorter; Recall and F1 also increased. The method proposed in this paper has high identification precision and short identification time, and it meets the requirements for accurate and rapid identification of vegetable diseases.

The Sperm Observation Kit Attached to Smartphone Enables In-Field Diagnosis of Leaf Mold and Cercospora Leaf Mold of Tomato through Microscopic Observation of the Conidiospores

The Sperm Observation Kit Attached to Smartphone Enables In-Field Diagnosis of Leaf Mold and Cercospora Leaf Mold of Tomato through Microscopic Observation of the Conidiospores

Fermentation Optimization, Fungistatic Effects and Tomato Growth Promotion of Four Biocontrol Bacterial Strains

Tomato is a widely cultivated crop that is important for its nutritional value and genetic diversity. Tomato production is seriously challenged by pests and diseases, among which tomato gray mold and leaf mold are particularly serious. Biological control is one of the most preferred methods for disease management in tomato production. At present, the fungi used to control tomato gray mold are mainly Trichoderma and yeast. Bacillus and actinomycetes are the most effective microorganisms for controlling tomato leaf mold. Tomato gray mold and leaf mold often occur at the same time during the production process, yet there are fewer strains for controlling both diseases at the same time. Biocontrol bacteria Pseudomonas azotoformans WXCDD51, Bacillus sp. WXCDD105, Bacillus subtilis BS and Bacillus amyloliquefaciens BS WY-1, which were isolated and screened in the previous stage, can prevent both tomato gray mold and leaf mold. Here, we optimized liquid fermentation for the four biocontrol bacterial strains together. We obtained the best fermentation medium formula and fermentation conditions for the four biocontrol bacteria. The broad-spectrum properties of the four biocontrol bacteria were tested, and, on this basis, compound strains were constructed. The control effect of single and compound strains on tomato gray mold and leaf mold was evaluated. Their potential effects on the growth of tomato seeds and seedlings were also studied. This research provides a foundation for the development and use of compound bacteria for growth promotion and disease management in tomato production.

Tomato leaf mold fungus (<i>Passalora fulva</i>) sensitivity to succinate dehydrogenase inhibitor fungicide in Mie Prefecture, Japan

Tomato leaf mold fungus (<i>Passalora fulva</i>) sensitivity to succinate dehydrogenase inhibitor fungicide in Mie Prefecture, Japan

Characterization of tomato leaf mould pathogen, Passalora fulva, in Croatia

Leaf mould (Passalora fulva) has emerged as an important disease of greenhouse-growing tomato crops in Croatia during the last decade. In order to establish sustainable control measures, the presence of P. fulva races was investigated, in vitro sensitivity of the fungus to several fungicidal products was tested, and susceptibility of some old tomato varieties was checked. Seventeen isolates were collected from different parts of Croatia and inoculated on tomato cv. ‘Moneymaker’ differentials with different resistance genes (Cf-2, Cf-4, Cf-5 and Cf-9) or without resistance genes (Cf-0). Based on symptoms appearance assessment, 11 isolates were determined as P. fulva race 2, two isolates as race 5, one isolate as race 2.5 and three isolate as race 0. Sequence analysis of the Avr2 gene of five P. fulva race 2 isolates showed and insertion of adenine at 117_119 bp compared to the reference Avr2 wild-type gene retrieved from GenBank®, which leads to amino acid change from Tyrosine to Valine (p. Tyr41ValfsX1) in Avr2 protein. Pathogenicity tests with a P. fulva race 2 isolate on seven old tomato varieties lead to the development of leaf mould symptoms on four of seven varieties. Sensitivity of a selected P. fulva race 2 isolate was examined on agar plates amended with four fungicides products which were authorized in Croatia at that time for control different diseases on tomato. According to the results, Signum® was significantly and constantly the most effective product across all assessment periods.