Gray Mold Rot Research Articles

In vitro and in vivo antifungal activity of different bacterial isolates against Botrytis gray mold of tomato

Gray mold rot, caused by Botrytis cinerea, is considered as one of the most harmful fungal diseases affecting postharvest tomato fruits. In the current work, we explore the biocontrol potential of 174 bacterial strains isolated from tomato rhizosphere, argan rhizosphere and a vermicompost to control this fungal pathogen. The in vitro dual culture study of isolated bacterial strains and the fungus-causing pathogen revealed that 31 isolates exhibited a substantial antifungal activity against B. cinerea mycelial growth. The inhibition rates ranged from 55.36 to 85.07%. Twelve bacterial strains which showed the highest antifungal properties (more than 79.6%) were subsequently investigated for their ability to produce compounds with antifungal activity, including diffusible substances, volatile compounds and hydrocyanic acid. These strains were then evaluated in vivo for their ability to reduce fruit decay caused by the fungus. Indeed, isolates VC-B1 (from vermicompost), RS-TB3, and RS-T6 (from the rhizosphere of tomato root), and RH-TB11 (from the tomato rhizoplane) released the most active diffusible substances, which totally inhibited the mycelial growth of B. cinerea. In addition, bacterial strains RS-TB1 and RS-T6 isolated both from the tomato rhizospheric soil were among the isolates that produced the most effective volatile compounds. They reduced the mycelial growth of the fungal pathogen by 75.36% ± 7.24% and 72.94 ± 4.129% respectively. Moreover, RS-TB3, RS-TB4, RH-TB1, and VC-B1 exhibited the highest production of hydrocyanic acid, followed by RS-TB1, VC-3, and VC-13. In vivo bioassays showed disease reduction ranging from 37.92% to 93.14%, with VC-1, VC-5, and RS-T4 showing the highest efficacy. This study identifies several bacterial strains with high potential for biocontrol of B. cinerea in postharvest tomatoes, presenting a promising alternative to chemical fungicides for managing gray mold rot.

Promising antifungal behavior of biosynthesized bimetallic silver-copper oxide nanoparticles and Bacillus safensis against some strawberry rots

Promising nanomaterials combined with beneficial microbes contributed to bio-modulations that might increase yields. In order to combat several fungal infections that invade strawberries (Fragaria ananassa), this study assessed the interactions between the synthesized CuO NPs, bimetallic Ag–CuO NPs, and Bacillus safensis (BS-22) under various treatment circumstances. The effectiveness of BS-22, CuO NPs, and bimetallic Ag–CuO NPs against four different pathogens that cause gray mold disease and root rot on strawberry plants was determined. It was possible to successfully extract twenty-four endophytic bacterial isolates from hygienic strawberry plants that were indigenous. BS-22 isolate, which produced the most hydrogen cyanide (HCN), siderophores, gibberellic acid (GA3), and indole-3-acetic acid (IAA), was identified molecularly as Bacillus safensis. The most extensively studied treatments (foliar CuO NPs at 200 ppm + foliar Ag–CuO NPs at 200 ppm + BS-22) decreased the frequency and severity of black root rot disease in strawberry plants. Foliar CuO NPs (50 ppm) + foliar Ag–CuO NPs (50 ppm) showed significant increase of the total suspended solids (TSSs), total antioxidant capacity (TAC) content, and the total polyphenols content compared to the control and other treatments. The same treatment recorded the highest value in all characters of cell wall components except lignin character where BS-22 treatment had the best effect. All tested treatments significantly decreased disease incidence and severity when strawberry fruit stored at 22 °C ± 2 for 25 days on average. According to this study, foliar CuO NPs (200 ppm) + foliar Ag–CuO NPs (200 ppm) + BS-22 (as a soil drench) might be used as a substitute for gray mold and root rot diseases in strawberry development and biocontrol.

Gum Arabic-incorporated thymol/salicylic acid composite coatings control grey mould and brown rot in ‘Angeleno’ plums

Gum Arabic-incorporated thymol/salicylic acid composite coatings control grey mould and brown rot in ‘Angeleno’ plums

Growth Inhibition of Botrytis cinerea Fungus on Strawberry (Fragaria sp.) Using Kaffir Lime (Citrus hystrix) Leaf Essential Oil Emulsion

Post-harvest damage is caused by biological factors such as the attack of Botrytis cinerea pathogenic fungi. causes gray mold rot disease to be a source of problems in strawberry production. This study aims to determine the potential of kaffir lime leaf essential oil emulsion as an antifungal against Botrytis cinerea. The fungus was isolated from strawberry fruit samples that showed symptoms of gray mold disease. Fungal isolation was carried out through the direct planting method and antifungal inhibitory ability test by food poisoned method with potato extract agar media. This experiment used a completely randomized design consisting of 6 treatments with 5 repetitions. The results showed that kaffir lime leaf essential oil emulsion contains secondary metabolites that can inhibit 100% of the growth of Botrytis cinerea pathogenic fungal colonies. Essential oil concentrations of 0.10%, 0.15%, and 0.20% had a significant effect on the growth of Botrytis cinerea pathogenic fungi.

Changes in the prevalence of fungal species causing post‐harvest diseases of carrot in Finland

AbstractPost‐harvest diseases cause significant economic losses in the carrot production chain. In this study, storage losses and fungal pathogens causing them were analysed in the carrot yield from 52 different field plots in four areas in Finland in 3 years (2016–2018). Over 30,000 carrots were sampled and analysed at three time points during cold storage at 0–1°C. In March, after 5–6 months' storage, the average loss due to diseases was 20%–21% every year. Decay of the root tip was the most common disease symptom, followed by pits on the side and black rot in the crown, detected in 69.2%, 15.0% and 9.0% of the symptomatic samples, respectively. Both intensive carrot cultivation practice and early timing of harvest increased storage losses. Pathogens in 3057 symptomatic carrot tissue samples were isolated by culturing, and fungal species were identified. The most common fungal species detected were Mycocentrospora acerina, Botrytis cinerea and Fusarium spp., especially F. avenaceum. However, the frequency of different pathogens varied between the different years and time points during storage. Species‐specific PCR tests revealed that M. acerina and F. avenaceum were present in many early time‐point samples where they could not yet be detected by the culturing method. In Finland, this study on carrot post‐harvest diseases is the first large‐scale survey in which the fungal pathogens were isolated and identified by laboratory tests. In comparison with the previous studies, Fusarium spp. were detected more frequently in this study, while grey mould and Sclerotinia rot were less frequent.

Exploring the Mycovirus Sclerotinia sclerotiorum Hypovirulence-Associated DNA Virus 1 as a Biocontrol Agent of White Mold Caused by Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum is a necrotrophic fungal pathogen causing white mold on many important economic crops. Recently, some mycoviruses such as S. sclerotiorum hypovirulence-associated DNA virus 1 (SsHADV-1) converted S. sclerotiorum into a beneficial symbiont that helps plants manage pathogens and other stresses. To explore the potential use of SsHADV-1 as a biocontrol agent in the United States and to test the efficacy of SsHADV-1-infected United States isolates in managing white mold and other crop diseases, SsHADV-1 was transferred from the Chinese strain DT-8 to United States isolates of S. sclerotiorum. SsHADV-1 is readily transmitted horizontally among United States isolates of S. sclerotiorum and consistently conferred hypovirulence to its host strains. Biopriming of dry bean seeds with hypovirulent S. sclerotiorum strains enhanced resistance to white mold, gray mold, and Rhizoctonia root rot. To investigate the underlying mechanisms, endophytic growth of hypovirulent S. sclerotiorum in dry beans was confirmed using PCR, and the expression of 12 plant defense-related genes were monitored before and after infection. The results indicated that the endophytic growth of SsHADV-1-infected strains in plants stimulated the expression of plant immunity pathway genes that assisted a rapid response from the plant to fungal infection. Finally, application of the seed biopriming technology with SsHADV-1-infected hypervirulent strain has promise for the biological control of several diseases of wheat, pea, and sunflower.

Development of trait-specific genetic stocks derived from wild Cicer species as novel sources of resistance to important diseases for chickpea improvement

AbstractLow level of resistance to major diseases such as ascochyta blight (AB), botrytis grey mould (BGM) and dry root rot (DRR) in the cultivated chickpea genepool necessitates harnessing wild Cicer species. Sixty-eight accessions belonging to eight annual wild Cicer species and seven chickpea cultivars were screened for AB, BGM and DRR under controlled environmental conditions over the years. Intra-accession variability was observed among wild Cicer accessions for each disease. Hence, progenies of single resistant plants were selected for further evaluations and the trait-specific genetic stocks (TGS) were developed for each disease after re-screening following the single seed descent method. For AB, a high level of resistance was identified in four accessions belonging to tertiary genepool species, ICC 17334 (Cicer judaicum), ICC 17302, ICC 17308 and ICC 20177 (C. bijugum). Nine accessions, ICC 17160, ICC 17264, ICC 17270, ICC 20170, ICC 20186, ICC 20225, ICC 20247, ICC 20251 and IG 72941 of primary (C. reticulatum) and one accession, ICC 20190 of secondary (C. echinospermum) genepool species were resistant to BGM whereas, four accessions, ICC 20187 (C. reticulatum) and ICC 20218, ICC 20244 and ICC 20257 (C. echinospermum) were resistant to DRR. Development and utilization of these TGS in chickpea pre-breeding will assist in developing disease-resistant chickpea cultivars with broad genetic base.

Antifungal activity of volatile organic compounds from essential oils against the postharvest pathogens Botrytis cinerea, Monilinia fructicola, Monilinia fructigena, and Monilinia laxa.

Gray mold and brown rot, caused respectively by Botrytis cinerea and Monilinia spp., are fungal diseases responsible for significant losses during the storage of fruit and vegetables. Nowadays, the control of postharvest diseases is shifting towards more sustainable strategies, including the use of plant secondary metabolites. In this study, the antifungal activity of Origanum vulgare, Thymus vulgaris, Thymus serpyllum, Melaleuca alternifolia, Lavandula officinalis, Lavandula hybrida, Citrus bergamia, Rosmarinus officinalis, Cinnamomum zeylanicum essential oils (EOs) in vapor phase was tested in vitro against B. cinerea, Monilinia fructicola, Monilinia fructigena, and Monilinia laxa. For the experiments, a protocol using a volatile organic compounds (VOC) chamber was designed. Results indicate a dose-dependent inhibitory activity of all the tested EOs, with O. vulgare, T. vulgaris, and T. serpyllum being the most active ones, with minimum inhibitory concentrations (MIC) of 22.73, 45.45, and 22.73 µl/L, respectively, against B. cinerea and a range between 5.64 and 22.73 µl/L against the three Monilinia spp. Overall, B. cinerea presented lower sensitivity to vapor-phase EOs than any of the Monilinia strains, except for the C. zeylanicum EO, which consistently showed higher inhibition against B. cinerea. Among the three Monilinia spp., M. fructicola was the least sensitive, while M. fructigena was the most sensitive. The use of VOC chambers proved to be a reliable protocol for the assessment of antimicrobial activities of EOs. These results suggest that the VOC emitted by the tested EOs are effective towards important decay-causing fungi, and that they could be used for the control of gray mold and brown rot in in vivo trials.

Effects of Commercial Natural Compounds on Postharvest Decay of Strawberry Fruit

Gray mold and Rhizopus rot, which is caused by Botrytis cinerea and Rhizopus stolonifer, respectively, are the most destructive forms of postharvest decay of the strawberry fruit. In this work, we tested the effectiveness of the control on the postharvest decay of the strawberry fruit (Fragaria × ananassa Duch cv. ‘Monterey’) following postharvest applications of six commercial natural compounds: chitosan-based coating compound (1% of ‘ChitP’, ‘ChitS’, ‘ChitK’, ‘ChitO’), commercial essential oil (EOs) products based on grapefruit seed extract (0.5% of ‘GraFr’), sweet orange (0.5% of ‘SwOr’), a product that included eugenol, geraniol, and thymol EO, (0.4% of ‘EuGeTh’), an organic compound as humic acid (0.5% w/v of ‘HuAc’), and, lastly, methyl jasmonate plant growth regulator (1% v/v ‘MeJA’). Strawberries were dipped in solution for 30 s and incubated at room temperature (20 ± 0.5 °C) or at cold storage conditions (4 ± 0.5 °C) following 4 days of shelf life at 20 °C. The treatments with ‘ChitP’, ‘ChitS’, and ‘ChitO’ provided ~30%–40% reduction of gray mold in cold storage conditions, while the ‘MeJA’, ‘SwOr’, and ‘GraFr’ with high activities of volatile substances were more effective at controlling gray mold at room temperature. ‘HuAc’, ‘ChitK’, and ‘ChitO’ were more effective at controlling Rhizopus rot in both cold storage (~50%) and room temperature conditions.

Symptomology of the Main Fungal Diseases of the Tomato (Lycopersicon Esculentum) and Its Management

The tomato (Lycopersicon esculentum) is the second most important vegetable crop after the potato in the world. It is a hot season crop; it requires a warm and cool climate. The plant is strongly affected by unfavorable climatic conditions. The warm and cool climatic conditions offer an ideal condition for the development of many diseases of leaf plants, stems and soils. The main fungal diseases of the tomato are: Damping of seedlings, Downy mildew, Alternaria, Gray mold, Septriosis, Powdery mildew, Root and crown rot, Fusarium wilt, Verticillium wilt, Cladosporiosis, Corky root, Sclerotiniosis, Anthracnosis, Pink rot and Stemphyliosis. In our work wa have cited for each disease the main symptoms and their of control.

Tannins-lignin mixed nanoformulations for improving the potential of neem oil as fungicide agent.

Sustainability and circular economy are increasingly pushing for the search of natural materials to foster antiparasitic treatments, especially in the case of economically relevant agricultural cultivations, such as grapevine. In this work, we propose to deliver neem oil, a natural biopesticide loaded into novel nanovectors (nanocapsules) which were fabricated using a scalable procedure starting from Kraft lignin and grapeseed tannins. The obtained formulations were characterized in terms of size and Zeta potential, showing that almost all the nanocapsules had size in the suitable range for delivery purposes (mean diameter 150-300nm), with low polydispersity and sufficient stability to ensure long shelf life. The target microorganisms were three reference fungal pathogens of grapevine (Botrytis cinerea, Phaeoacremonium minimum, Phaeomoniella chlamydospora), responsible for recurrent diseases on this crop: grey mold or berry rot by B. cinerea and diseases of grapevine wood within the Esca complex of diseases. Results showed that grapeseed tannins did not promote inhibitory effects, either alone or in combination with Kraft lignin. On the contrary, the efficacy of neem oil against P. minimum was boosted by more than 1-2 orders of magnitude and the parasite growth inhibition was higher with respect to a widely used commercial pesticide, while no additional activity was detected against P. chlamydospora and B. cinerea.

An Extensive Review of Strawberry (Fragaria×ananassa) Diseases and Integrated Management Approaches: Current Understanding and Future Directions

Strawberry production has increased by more than double in the past two decades. Meanwhile, it is also susceptible to various diseases which have become a limiting factor in its yield increment. Indiscriminate use of chemicals in the management of diseases has brought several adverse effects to the environment and human health. Thus, this review aims to present the different diseases of strawberries including their epidemiology, disease cycle, and symptoms. Moreover, the focus has been given to Integrated Management. More than ten dozen of literature including journal articles, books, websites, and organizational reports were thoroughly reviewed to get the related information. Botrytis grey mold rot, anthracnose, strawberry leaf spot, powdery mildew, and red stele are the major fungal diseases whereas angular leaf spot is the serious bacterial disease of strawberries. It is severely infected by viruses such as strawberry mottle virus and crinkling and vein banding virus. In addition to this nematode causes ring spots, root-knot, and root lesions on strawberries. Integrated disease management approaches should be adopted for effective and sustainable management. It may include cultural methods, physical methods, use of bio-control agents, botanical fungicides, and at last chemicals if the disease is severe.

Biocontrol and Biostimulant Effect of a Fungal-Derived Extract in Commercial Varieties of Strawberry (Fragaria x ananassa Duch.)

Objective: Strawberry postharvest fruits and plants are mainly affected by the fungus Botrytis cinerea (B. cinerea), which causes grey mould rot. Biological control agents and biostimulants can effectively control this fungus and promote plant growth. This study aimed to evaluate the capacity of a novel fungal-derived extract called culture filtrate (CF) to biocontrol grey mould rot in postharvest strawberries and plants while promoting plant growth. Methods: The CF extract was obtained from the liquid culture of a strawberry pathogenic fungus, gauze-filtered and inactivated by autoclave. The Fragaria x ananassa cultivars Camino Real, Benicia, and Merced were used. For the postharvest assay, fruit natural decay was evaluated by simulating real storage conditions. For the phytopathological assays, first-generation plants inoculated with B. cinerea were evaluated 26 days post infection. The effect of CF on plant growth and biomass promotion was evaluated 60 days post treatment (DPT). Results: The treatment with CF yielded healthier fruits of the three varieties, which presented minor severity of grey mould symptoms compared to the controls treated with water or potato dextrose broth (PDB) by 7 DPT. For instance, 40% of Camino Real, 80% of Benicia, and 20% of Merced fruits presented an incipient lesion (severity 1), whereas no fruits treated with water or PDB showed this minor level of infection. On the contrary, around 50% and 70% of the control fruits presented the highest level of severity. Moreover, CF pre-treatment of Benicia “mother plants” protected first-generation untreated plants. Likewise, the best biostimulant effect was observed for Benicia plants, which presented an increased number of leaves and runner production 60 DPT. Conclusion: The fungal-derived extract CF constitutes a promising alternative to be used as a biological control agent of B. cinerea in strawberry. CF efficiently controlled the causal agent of grey mould in harvested strawberries and first-generation untreated plants. Yet, showed a minor effect as a plant growth promoter. Thus, the current study opens up the possibility to develop "phytovaccines" using extracts of almost any fungus, including pathogenic ones, as long as they are previously inactivated.

Essential Oils Reduce Grey Mould Rot of Apples and Modify the Fruit Microbiome during Postharvest Storage.

Botrytis cinerea is the causal agent of grey mould rot of apples. The efficacy of biofumigation with thyme (Thymus vulgaris), savoury (Satureja montana), and basil (Ocimum basilicum) essential oils (EOs) at 1%, 0.5%, and 0.1% concentrations were tested against B. cinerea. In vitro, the results showed 100% growth inhibition at 1% concentration for all oils. Subsequent biofumigation experiments on apples of cultivar 'Opal' with 1% EOs showed that, after 60 d storage, thyme and savoury EOs significantly reduced grey mould rot incidence (average incidence 2% for both treatments) compared to the control (7%). Analyses of quality indicated slightly higher fruit firmness for 1% thyme at 30 d and slightly higher titratable acidity for 1% thyme and savoury at 60 d. Sampling of the atmosphere inside the cabinets was performed to characterize and quantify the volatile components of EOs released through biofumigation. Though thymol and p-cymene were the main components of thyme EO, the antimicrobial activity was mainly due to the presence of thymol and, to a lower extent, of carvacrol. In savoury EO, carvacrol and p-cymene were the main components, whereas in basil EO, linalool and estragole were mainly present. Metabarcoding analyses showed that the epiphytic microbiome had higher richness and evenness compared to their endophytic counterpart. By the end of shelf-life, treatments with thyme EO reduced B. cinerea abundance compared to the inoculated control for both endophytes (from 36.5% to 1.5%) and epiphytes (from 7.0% to 0.7%), while favouring a significant increase in Penicillium species both in endophytes (from 0.2% to 21.5%) and epiphytes (from 0.5% to 18.6%). Results indicate that thyme EO (1%) and savoury EO (1%) are equally effective in hampering grey mould rot development in vivo.

Exploring the Efficacy of Biocontrol Microbes against the Fungal Pathogen Botryosphaeria dothidea JNHT01 Isolated from Fresh Walnut Fruit.

Biological control by antagonistic microorganisms are an effective and environmentally friendly approach in postharvest disease management. In order to develop a biocontrol agent for fresh walnut fruit preservation, the potential biocontrol effects of Bacillus amyloliquefaciens RD.006 and Hanseniaspora uvarum FA.006 against the main fungal pathogen of walnuts were evaluated. Botryosphaeria species showed the highest detection, and the JNHT01 strain showed the strongest pathogenicity. Bot. dothidea JNHT01 caused gray mold and brown rot on fresh walnuts, and its incidence rate reached 100% after an 8 days incubation. The growth of this fungal strain can be promoted by lighting, with a maximum growth rate achieved at a pH of 7 and at 28 °C. B. amyloliquefaciens RD.006 and H. uvarum FA.006 supernatants at a concentration of 1-15% v/v showed antifungal activity. The mycelial growth inhibition rates of Bot. dothidea JNHT01 were 23.67-82.61% for B. amyloliquefaciens RD.006 and 1.45-21.74% for H. uvarum FA.006. During Bot. dothidea JNHT01 growth, the biomass, nucleic acid leakage, and malondialdehyde content gradually increased, while the DPPH scavenging capacity and SOD activity decreased. The B. amyloliquefaciens RD.006 and H. uvarum FA.006 strains showed antifungal activity by damaging fungal cell membranes and reducing fungal antioxidant activity. Moreover, the antifungal effect of B. amyloliquefaciens RD.006 was higher than that of H. uvarum FA.006. Hence, the RD.006 strain of B. amyloliquefaciens can be considered a potential biocontrol agent for the management of postharvest walnut diseases caused by Bot. dothidea.

COS-OGA Applications in Organic Vineyard Manage Major Airborne Diseases and Maintain Postharvest Quality of Wine Grapes.

In most wine-growing countries of the world the interest for organic viticulture and eco-friendly grape production processes increased significantly in the last decade. Organic viticulture is currently dependent on the availability of Cu and S compounds, but their massive use over time has led to negative effects on environment health. Consequently, the purpose of this study was to evaluate the effectiveness of alternative and sustainable treatments against powdery mildew, gray mold and sour rot under the field conditions on Nero d’Avola and Inzolia Sicilian cultivars. In detail, the efficacy of COS-OGA, composed by a complex of oligochitosans and oligopectates, and its effects in combination with arbuscular mycorrhizal fungi (AMF) were evaluated to reduce airborne disease infections of grape. COS-OGA combined with AMF induced a significant reduction in powdery mildew severity both on Nero d’Avola and Inzolia with a mean percentage decrease of about 15% and 33%, respectively. Moreover, COS-OGA alone and combined with AMF gave a good protection against gray mold and sour rot with results similar to the Cu–S complex (performance in disease reduction ranging from 65 to 100%) on tested cultivars. Similarly, the COS-OGA and AMF integration provided good performances in enhancing average yield and did not negatively impact quality and microbial communities of wine grape. Overall, COS-OGA alone and in combination could be proposed as a valid and safer option for the sustainable management of the main grapevine pathogens in organic agroecosystems.

Control of Grapevine Downy Mildew by an Italian Copper Chabasite-Rich Zeolitite

The progressive reduction in the quantities of copper regulated by the European Union is focusing the research on new formulations with a reduced copper content but equally effective. In this regard, the activity of an Italian copper chabasite-rich zeolitite, which proved to be effective against grapevine grey mold and sour rot, was assessed against downy mildew. A two-year study was carried out in the Abruzzo region, Italy, in a cv. Montepulciano vineyard. The applications of the copper zeolitite showed the same good results obtained by a standard integrated/conventional strategy based on contact and systemic fungicides. At harvest, in both trial years, the plants with infected bunches in the untreated control ranged from 86.25% to 100%, compared to 15–30% of the treated plants. Furthermore, infected bunches and berries of the untreated control vines were 70–100% while treated ones never exceeded 2.32%. Furthermore, an increase in the polyphenol content and color intensity in wines made from vines treated with copper zeolitite was confirmed and appeared to be particularly evident in hot and dry seasons. The activity of copper zeolitite towards downy mildew, the potential use against grey mold and sour rot and the protection of grapes from high temperatures indicate that this product is a promising tool for a viticulture environmentally friendly control strategy.

Chemical compositions and in vitro antifungal activities of essential oils obtained from different Origanum species against postharvest gray mold rot of persimmon fruit

ISHS VII International Symposium on Persimmon Chemical compositions and in vitro antifungal activities of essential oils obtained from different Origanum species against postharvest gray mold rot of persimmon fruit

Effect of cold atmospheric plasma on the gray mold rot of postharvest mulberry fruit

Mulberries are a kind of berries with high nutritional value and delicious taste; however, their shelf life is extremely short, and are perishable and difficult to preserve. Recently, cold atmospheric pressure plasma (CAP) holds a great potential as an efficient, economical and ecofriendly method for food sterilization. Herein, this study investigated the effects of CAP treatment with different time (0, 0.5, 1, 2 and 3min) and different strength (0, 2 and 3 V) on mulberries. The results showed that Botrytis cinerea (B. cinerea) is the primary post-harvest rot-causing fungus of mulberries, and CAP can effectively reduce the rot rate of mulberries during storage and inhibit the growth of B. cinerea. In addition, this study explored the sterilization mechanism of CAP on B. cinerea, and found that CAP can destroy the structure of B. cinerea, affected its metabolism. It inhibited the growth of spores and hyphae of B. cinerea, and caused intracellular ROS accumulation in large quantities, caused a redox imbalance in B. cinerea. Meanwhile, CAP didn't adversely affect the quality of mulberries. These findings can be used to promote the development of CAP as an emerging means of disinfection and preservation of fresh berries.

First Report of Post-Harvest Gray Mold on Hyacinth Bean (Lablab purpureus) Caused by Botrytis cinerea in Korea.

Hyacinth bean (Lablab purpureus L.) is a highly proteineous legume under the family Fabaceae. It is native to Africa, cultivated throughout the world, and recently introduced vegetable in Korea. In April 2020, approximately 10 to 15% of the total harvested pods showed gray mold rot symptoms after 3-5 days of storage at 4 °C in Jeonju, Jeonbuk province, Korea. The symptoms observed were irregular, water-soaked spots become brown or gray with white hyphae were appeared on the infected pods. Diseased tissue was excised, and surface sterilized by immersing in 1% sodium hypochlorite (NaOCl) for 1 min, rinsed three times with sterilized distilled water, placed on potato dextrose agar (PDA) plates, and incubated at 20 ± 2°C for 7 days. A total of five morphologically similar fungal isolates (HBGM001 to HBGM005) were obtained from diseased samples; isolate HBGM002 and HBGM005 were selected for identification. The fungus produced initially white colonies, after 7 days it changes to gray to dark colonies with dark mycelium that sporulated abundantly on PDA at 20ºC. The conidia (n = 50) were single-celled, ellipsoid or ovoid in shape, and 6.11 to 13.9 × 4.8 to 9.4 μm in size for HBGM001 isolate and 5.81 to 14.1× 4.5 to 9.6 μm in size for HBGM005. Conidiophores (n = 15) arose solitary or in groups, straight or flexuous, septate, with an inflated basal cell brown to light brown, and measured 103 to 420× 7 to 25 μm for HBGM001 isolate and 101 to 415 × 5 to 23 μm for HBGM005 isolate. After two weeks, the fungus formed several black sclerotia (n = 20) ranging from 0.5 to 4.2 × 0.5 to 3.4 mm for HBGM001 isolate and 0.4 to 4.4 × 0.3 to 3.3 mm for HBGM005 isolate near the edge of the Petri dish. Morphological characters were consistent with those of Botrytis cinerea Pers.: Fr. (Ellis 1971). As for molecular identification, the internal transcribed spacer (ITS) and three nuclear protein-coding genes (glyceraldehydes-3-phosphate dehydrogenase gene [G3PDH], heat-shock protein 60 gene [HSP60], and DNA-dependent RNA polymerase subunit gene [RPB2]) were amplified using primer pairs ITS1/ITS4 (White et al. 1990), G3PDH-F/G3PDH-R, HSP60-F/HSP60-R, and RPB2-F/RPB2-R (Staats et al. 2005), respectively. The ITS, G3PDH, HSP60, and RPB2 sequences of HBGM002 and HBGM005 isolates (GenBank accession number MT439648 and MT968495 for ITS; MT439649 and MT968496 for G3PDH; MT439650 and MT968497 for HSP60; MT439651 and MT968498 for RPB2 respectively) were 99% to 100% identical to those of B. cinerea (KY364366, KF015583, KJ018758, and KJ018756, respectively). To determine pathogenicity, five disinfected pods were pinpricked (3 sites per pod) with sterile needles and 50 µl of conidial suspension (1 × 105 conidia/ml) was inoculated by pipetting into the wounds. An analogous five pods, serving as controls, were inoculated with sterile distilled water. All the pods were placed in a growth chamber and maintained a temperature of 20±2ºC and a relative humidity >80%. After 5 days, gray mold symptoms developed on the inoculated pods, whereas no symptoms appeared on control pods. The pathogen was re-isolated from the inoculated pods, fulfilling Koch's postulates. B. cinerea has been reported causing gray mold in Hyacinth bean in China, Taiwan and India (Farr and Rossman 2021). To our knowledge, this is the first report of B. cinerea causing post-harvest gray mold on hyacinth bean in Korea. The disease could represent a threat for hyacinth bean post-harvest and storage and management strategies should be investigated and applied.