Flower Blight Research Articles

First report of Erwinia pyrifoliae causing flower blight and fruit rot on greenhouse-grown Fragaria × ananassa in the United States.

Erwinia pyrifoliae causes disease of pear (Pyrus spp.), apple (Malus spp.), and strawberry (Fragaria × ananassa) (Wenneker and Bergsma-Vlami 2015), which are economically important commodities in the US. Disease symptoms on pear and apple are indistinguishable from those caused by the non-quarantine fire blight pathogen, E. amylovora (Kim et al. 1999), which also causes disease on strawberries (Atanasova et al. 2005). Samples of greenhouse-grown strawberry 'Albion' from Ohio were submitted to the Purdue Plant and Pest Diagnostic Lab in December 2023. Fruits were stunted with brown lesions, while sepals and pedicels had brown-black water-soaked lesions. Cut fruit exuded bacterial ooze from the main vascular bundle. Bacterial streaming was observed microscopically from symptomatic tissue which tested positive with the E. amylovora ImmunoStrip® (Agdia Inc., Elkhart, IN); reported by the manufacturer to cross-react with E. pyrifoliae. Isolation from symptomatic tissue produced pure cultures on sucrose peptone agar and Kings medium B after incubation at 27°C for 48 hr, and colonies appeared circular and white/opaque. Crude DNA extractions were prepared by boiling colony suspensions in Tris-EDTA buffer. Two independent real-time PCR tests specific for E. pyrifoliae (Lehman et al. 2008; Yasuhara-Bell et al. 2024) produced positive results. Conventional PCR using an E. pyrifoliae-specific primer set targeting a divergent region between pstS and glmS genes (Wensing et al. 2011) also produced positive results. The amplicon was Sanger-sequenced and deposited into NCBI GenBank (Accession PP757383). BLASTn analysis using the Nucleotide collection and Whole-genome shotgun contigs revealed top matches (100% query coverage; 97.5% identity to type strain DSM 12163) with E. pyrifoliae only; next closest match was E. amylovora (53% query coverage). To confirm Koch's postulates, immature fruit of six healthy strawberry 'Albion' plants were wounded with a sterile pipette tip and then submersed in a bacterial suspension in sterile deionized water (DI H2O) (3.1×107 cells/ml). Fruit of six additional plants were mock inoculated using sterile DI H2O. Plants were placed in plastic bags for 48 hr at room temperature with a 12-hr photoperiod. Symptoms were first observed on inoculated plants 1.5 days post-inoculation (DPI). Brown discoloration was observed within fruit and as spreading lesions on fruit pedicels by 4 DPI; mock-inoculated plants remained asymptomatic. Bacterial streaming from symptomatic tissue allowed successful re-isolation of the bacterium. Molecular testing confirmed isolates to be E. pyrifoliae, thus completing Koch's postulates. Following initial confirmation, additional samples of infected strawberry ('Albion' and 'GB96') from the same greenhouse were confirmed positive for E. pyrifoliae by molecular testing and sequencing. To our knowledge this is the first time Erwinia pyrifoliae was detected in the US. There are many known pathways of introduction from Asia and Europe; however, pstS-glmS sequence comparison with strawberry isolates from the Netherlands (sequences provided by M.J.C. Pel) suggests this US strawberry strain is unique, but most closely related to Japanese strains (98.5% identity). Potential origin of this strain is unknown, but comparative genomics studies to investigate relatedness among strains are planned.

Establishment of an Infection System for Gentian (Gentiana spp.) Sclerotial Flower Blight Disease.

Gentians (Gentiana spp.) as floriculture crops are constantly exposed to several fungal and viral pathogens in the field. Among the fungal diseases afflicting gentian production, gentian sclerotial flower blight caused by Ciborinia gentianae incurs economic losses, as it affects flowers before and after harvest. Currently, preventive measures for this disease are limited, and no resistant cultivars have been reported. This is partly because of the lack of a reliable infection system that could promote research on this plant-fungus interaction. In this study, Gentiana plant tissue culture material was inoculated with C. gentianae culture filtrate. We successfully demonstrated non-ascospore-mediated infection of C. gentianae. Inoculation of individual hyphal structures present in the culture filtrate suggested that sclerotial primordia are the main agents of this infection. Interestingly, our results indicated that primary infection of C. gentianae occurs in petals rather than leaves, which enables systemic infection and therefore mirrors the fungus's infection strategy observed in the field. Moreover, we showed that (i) non-ascospore hyphal structures can also cause disease in flowers grown in the field, and (ii) ascosporic infection can also be observed using the in vitro system, opening possibilities for both practical and basic research aimed to combat gentian sclerotial flower blight disease.

First report of Botrytis cinerea causing flower blight on macadamia in South Africa

AbstractMacadamia cultivation plays significant role in the economy of South Africa. Despite its importance, the industry grapples with disease‐related challenges, notably flower blight, which threatens substantial economic losses by affecting yield and nut quality. In 2022, diagnostic services at the Agricultural Research Council and the Forestry and Agricultural Biotechnology Institute received macadamia flowers displaying blight symptoms. Employing two methods for fungal isolation, 25 isolates were obtained which were classified into one group based on morphological characteristics. DNA analysis identified the isolates as Botrytis cinerea. The pathogenicity testing was conducted on macadamia flowers to confirm Koch's postulates. This is the first report of B. cinerea affecting Macadamia integrifolia Maiden & Betche in South Africa, underlining its potential threat to the industry.

Biological Control Activities of Rhizosphere Fungus Trichoderma virens T1-02 in Suppressing Flower Blight of Flamingo Flower (Anthurium andraeanum Lind.).

Flower blight caused by Neopestalotiopsis clavispora is an emerging disease of flamingo flower (Anthurium andraeanum Lind.) that negatively impacts flower production. The use of rhizosphere fungi as biocontrol agents is an alternative way to control this disease instead of using synthetic fungicides. This research aimed to screen the potential of rhizosphere fungi, Trichoderma spp., with diverse antifungal abilities to control N. clavispora and to reduce flower blight in flamingo flowers. A total of ten isolates were tested against N. clavispora by dual culture assay, and T1-02 was found to be the most effective isolate against N. clavispora, with inhibition of 78.21%. Morphology and molecular phylogeny of multiple DNA sequences of the genes, the internal transcribed spacer (ITS), translation elongation factor 1-α (tef1-α), and RNA polymerase 2 (rpb2) identified isolate T1-02 as Trichoderma virens. Sealed plate method revealed T. virens T1-02 produced volatile antifungal compounds (VOCs) against N. clavispora, with inhibition of 51.28%. Solid-phase microextraction (SPME) was applied to trap volatiles, and GC/MS profiling showed VOCs emitted from T. virens T1-02 contained a sesquiterpene antifungal compound-germacrene D. The pre-colonized plate method showed that T. virens T1-02 aggressively colonized in tested plates with inhibition of 100% against N. clavispora, and microscopy revealed direct parasitism onto fungal hyphae. Furthermore, the application of T. virens T1-02 spore suspension reduced the disease severity index (DSI) of flower blight in flamingo flowers. Based on the results from this study, T. virens T1-02 displays multiple antagonistic mechanisms and has the potential ability to control flower blight of flamingo flowers caused by N. clavispora.

Evaluation of Camellia Cultivars and Selections for Growth, Cold-hardiness, Flowering, and Disease Resistance in Tennessee, USA

Susceptibility to low-temperature injury and diseases is a major concern associated with ornamental camellia production. To comprehensively understand their growth, cold-hardiness, flowering, and disease resistance, 24 camellia (Camellia spp. and hybrids) cultivars and selections were evaluated in McMinnville, TN, USA (USDA plant hardiness zone 7a). During Mar 2011, camellias were planted in the field plots. Plant height and canopy width were measured annually from 2011 to 2019, and low-temperature damage was recorded in 2014 and 2023. The flowering duration was recorded each year from 2011 to 2020. The Camellia Yellow Mottle Virus, monochaetia leaf spot (Monochaetia sp.), edema, flower blight (Ciborinia camelliae), and flower spot (Botrytis cinerea) severity (% affected) were evaluated from Oct to Nov in 2016 and 2017. The season-long area under the disease progress curve (AUDPC) was calculated. Cultivars Arctic Snow and Pink Icicle exhibited the greatest height, and Autumn Spirit, Elaine Lee, Arctic Snow, and Survivor had the widest canopy width, whereas Shishigashira had the lowest height and canopy width. ‘April Remembered’, ‘April Rose’, ‘Arctic Snow’, ‘Ashton’s Ballet’, ‘Autumn Carnival’, ‘Autumn Spirit’, ‘Elaine Lee’, ‘Survivor’, and C. chekiangoleosa selection were least affected by winter low temperatures, whereas ‘Korean Snow’, ‘One Alone’, C. sasanqua selection, ‘Pink Icicle’, and ‘Shishigashira’ were severely damaged. ‘Arctic Snow’ flowered most reliably (6 of 8 years), whereas ‘April Remembered’, ‘April Rose’, ‘Ashton’s Ballet’, ‘Autumn Spirit’, and ‘Survivor’ flowered five times. ‘Korean Fire’, ‘Classic Pink’, ‘Maroon Mist’, and ‘Spring’s Promise’ displayed the highest virus severity and AUDPC. ‘Arctic Snow’, C. sasanqua selection, and the C. chekiangoleosa selection had no viral symptoms. C. sasanqua selection and ‘Red Aurora’ were significantly impacted by edema disorder, with severity ratings of ∼43% and 26%, respectively. Monochaetia leaf spot severity was highest in ‘Red Aurora’ and ‘Spring’s Promise’, whereas ‘Anacostia’, ‘Arctic Snow’, ‘Ashton’s Ballet’, ‘Autumn Spirit’, ‘Classic Pink’, ‘Kuro Delight’, ‘One Alone’, ‘Pink Icicle’, ‘Shishigashira’, and ‘Survivor’ exhibited the least monochaetia leaf spot severity and AUDPC. Flower blight and flower spot were observed only in ‘Arctic Snow’ and ‘Survivor’. These findings will aid landscapers and nursery growers with selecting and managing camellia cultivars effectively.

Molecular Characterization of Ciborinia camelliae Kohn Shows Intraspecific Variability and Suggests Transcontinental Movement of the Pathogen.

Ciborinia camelliae Kohn is the causal agent of camellia flower blight. The fungus infects only the flowers of camellias. C. camelliae isolates obtained from symptomatic samples, collected in 13 different localities worldwide, were characterized by Multi-Locus Sequence Typing (MLST) using the following: (i) a nuclear ribosomal DNA internal transcribed spacer; (ii) subunit 2 of β-tubulin (β-TUB II), (iii) elongation factor 1-α (EF1α); and (iv) glycerol-3-phosphate dehydrogenase (GPDH). The variability of the strains was assessed using a universally primed-polymerase chain reaction (UP-PCR) with six universal primers. Gene sequence comparison showed high similarity among all the European strains and highlighted the diversity of the New Zealand and Chinese representative strains. The profiles obtained by UP-PCR confirmed the significant diversity of extra-European strains and identified subgroups within the European population. The presence of shared genetic profiles obtained from strains isolated in different countries (New Zealand and France) suggests the movement of strains from one location to another, which is probably due to the exchange of infected plant material. Moreover, our study shows the overall high intraspecific variability of C. camelliae, which is likely due to the sexual reproduction of the fungus, suggesting the risk of emergence of new pathotypes adapting to novel camellia varieties.

Efficacy of calcium propionate against fungicide-resistant fungal plant pathogens and suppression of botrytis blight of ornamental flowers

Conventional fungicides are used in IPM programs to manage fungal plant pathogens, but there are concerns about resistance development in target organisms, environmental contamination, and human health risks. This study explored the potential of calcium propionate (CaP), a common food preservative generally recognized as safe (GRAS) to control fungicide-resistant plant pathogens, mainly Botrytis cinerea, and botrytis blight in ornamentals. In-vitro experiments using mycelium growth inhibition indicated a mean EC50 value for CaP (pH 6.0) of 527 mg/L for six isolates of Botrytis cinerea as well as 618, 1354, and 1310 mg/L for six isolates each of Monilinia fructicola, Alternaria alternata, and Colletotrichum acutatum. In vitro efficacy tests indicated CaP equally inhibited mycelium growth of fungal isolates sensitive and resistant to FRAC codes 1, 2, 3, 7, 9, 11, 12, and 17 fungicides. CaP at 0.1% (pH 6.0–6.5) reduced infection cushion (IC) formation in vitro, botrytis blight on petunia flowers, and botrytis blight of cut flower roses with little to no visible phytotoxicity. Although higher concentrations strongly inhibited infection cushion formation, they did not improve efficacy and exhibited phytotoxicity. We hypothesize that high concentrations may create tissue damage that facilitates direct fungal penetration without the need for infection cushion and subsequent appressoria formation. This study indicates the potential usefulness of CaP for blossom blight disease management in ornamentals if applied at concentrations low enough to avoid phytotoxicity.

Diversity and pathogenicity of species of Botrytis, Cladosporium, Neopestalotiopsis and Pestalotiopsis causing flower diseases of macadamia in Australia

AbstractFlower diseases threaten macadamia production, but there is a limited understanding of their aetiology. This study was undertaken to establish the ecology of the causal agents in commercial orchards in Australia. Raceme samples at different developmental stages were collected from 42 commercial macadamia orchards during the 2018–2020 flowering seasons. Morphological and molecular phylogenetic analyses of the isolates obtained from the samples with symptoms revealed that 16 fungal species, including two Botrytis spp., six Cladosporium spp., six Neopestalotiopsis spp. and two Pestalotiopsis spp., were associated with the flower blights. Twelve of the fungal species were identified as new records in macadamia. A comparison of the fungal genera showed that Neopestalotiopsis spp. (48%) and Cladosporium spp. (47%) were the most prevalent in the majority of macadamia production regions and were obtained from all four raceme developmental stages. The genus Botrytis was more commonly distributed (16%) in the production areas where humidity was high and was mostly isolated from the mature developmental raceme stages. Based on in planta infection assays under field conditions, the fungal pathogens varied in aggressiveness on macadamia racemes, with B. cinerea, B. macadamiae, C. cladosporioides, C. devikae, N. drenthii, N. macadamiae, N. maddoxii, N. vheenae, P. macadamiae and P. telopeae as the most aggressive and C. angulosum and C. proteacearum as the least aggressive. This study improves our understanding of the aetiology and distribution of the causal agents of flower blight complex in macadamia.

In-vitro evaluation of novel fungicides against leaf spot and flower blight of marigold by different techniques

Leaf spot and flower blight caused by Alternaria zinniae is serious disease of marigold causing yield loss of 50-60 % in crop. Many previously used fungicides showed resistance against the pathogen. So, the present investigation was carried out with an objective to study the efficacy of new fungicides available in the market using poison food technique, well diffusion technique and disc diffusion technique. Three fungicides such as azoxystrobin +tebuconazole, tebuconazole + sulphur, Metalaxyl were evaluated at the concentration of 0.1%, 0.15%, 0.2% respectively. The present investigation revealed that Azoxystrobin + Tebuconazole recorded maximum mycelial growth inhibition of 96.85% followed by Tebuconazole + Sulphur 96.40% and Metalaxyl of 95.50% in poison food technique. Similarly, Azoxystrobin + Tebuconazole showed the highest inhibition of mycelial growth (88.10%), followed by Tebuconazole + Sulphur (86.36%), and Metalaxyl (84.38%) in well diffusion technique. In a same manner Azoxystrobin + Tebuconazole showed the highest inhibition of mycelial growth (77.73%), followed by Tebuconazole + Sulphur (75.10%), and Metalaxyl (72.25%) in disc diffusion method. Further the effectiveness of new fungicides may be tested under field condition against Alternaria zinniae.

A Genome Resource for Ciborinia camelliae, the Causal Agent of Camellia Flower Blight.

Ciborinia camelliae Kohn is a camellia pathogen belonging to family Sclerotiniaceae, infecting only flowers of camellias. To better understand the virulence mechanism in this species, the draft genome sequence of the Italian strain of C. camelliae was obtained with a hybrid approach, combining Illumina HiSeq paired reads and MinIon Nanopore long-read sequencing. This combination improved significantly the existing National Center for Biotechnology Information reference genome. The assembly contiguity was implemented decreasing the contig number from 2,604 to 49. The N50 contig size increased from 31,803 to 2,726,972 bp and the completeness of assembly increased from 94.5 to 97.3% according to BUSCO analysis. This work is foundational to allow functional analysis of the infection process in this scarcely known floral pathogen. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

New Group of Fungicides as the Potential Source of Management of Leaf Spot and Flower Blight of Marigold

Background: Leaf spot and flower blight caused by Alternaria zinniae is serious disease of marigold causing yield loss of 50-60% in crop. Many previously used fungicides showed resistance against the pathogen. So the present investigation was carried out with an objective to study the efficacy of new fungicides available in the market using poison food technique. Methods: Eleven fungicides such as azoxystrobin, tebuconazole, azoxystrobin + tebuconazole, difenoconazole, azoxystrobin + difenoconazole, tebuconazole + sulphur, wettable sulphur, mancozeb, metalaxly, chlorothalonil, chlorothalonil + metalaxly were evaluated at the concentration of 0.1%, 0.15% ,0.1%, 0.1%, 0.1%, 0.15%, 0.25%, 0.3%,0.2%, 0.3% and 0.3% respectively. Result: The present investigation revealed that Azoxystrobin + Tebuconazole recorded maximum mycelial growth inhibition of 96.85% followed by Tebuconazole + Sulphur 96.40% and Metalaxyl of 95.50%. The least inhibition of 18.92% was recorded by wettable sulphur.

Trichoderma asperellum behave as antagonist to control leaf spot and flower blight of Marigold

Alternaria zinniae (Pape, 1942) causes leaf spot and blossom blight in marigolds, resulting in yield losses of 50-60 % in tropical and subtropical climates. Chemical controls can have a negative influence on ecosystems and agronomic control approaches are difficult to execute change to Chemical control are highly toxic, enhance biodegradation and cause environmental pollution after repeated use. Potential adverse effects on the earth and prolonged use have prompted a complete exclusion or limited utilization of most chemicals and an urgent need for eco-friendly and efficient tools. In vitro evidence for the possible use of Trichoderma spp. for biocontrol of marigold leaf spot and flower blight has been reported in previous investiga-tions. In this study, we used a dual culture approach to investigate the antagonistic and myco-parasitic properties of 4 Trichoderma asperellum strains against Alternaria zinniae in vitro.

Novel and diverse mycoviruses co-infecting a single strain of the phytopathogenic fungus Alternaria dianthicola.

Alternaria dianthicola is a pathogenic fungus that causes serious leaf or flower blight on some medicinal plants worldwide. In this study, multiple dsRNA bands in the range of 1.2-10 kbp were found in a Alternaria dianthus strain HNSZ-1, and eleven full-length cDNA sequences of these dsRNA were obtained by high-throughput sequencing, RT-PCR detection and conventional Sanger sequencing. Homology search and phylogenetic analyses indicated that the strain HNSZ-1 was infected by at least nine mycoviruses. Among the nine, five viruses were confirmed to represent novel viruses in the families Hypoviridae, Totiviridae, Mymonaviridae and a provisional family Ambiguiviridae. Virus elimination and horizontal transmission indicated that the (-) ssRNA virus, AdNSRV1, might be associated with the slow growth and irregular colony phenotype of the host fungus. As far as we know, this is the first report for virome characterization of A. dianthus, which might provide important insights for screening of mycovirus for biological control and for studying of the interactions between viruses or viruses and their host.

Sources, Detection, and Inoculum Quantification of Flower Blight Pathogens in Macadamia.

Dry flower disease caused by Pestalotiopsis/Neopestalotiopsis spp., green mold caused by Cladosporium spp., and gray mold caused by Botrytis spp., collectively known as flower blight cause significant yield losses in macadamia. Potential sources of inoculum of the various pathogens in macadamia tree canopy were examined using pathogenicity tests and a multiplex quantitative PCR (qPCR) assay developed in this study. The qPCR assay detected and quantified the relative abundance of the inoculum of flower blight pathogens. The assay revealed that remnant racemes contributed a high amount of inoculum of all the three groups of flower blight pathogens, while the yellow halo leaf spot contributed only Pestalotiopsis/Neopestalotiopsis species. The amount of conidia per gram of remnant racemes ranged from 7 × 103 to 2 × 104 for dry flower disease, 3 × 103 to 1× 104 for green mold, and 5 to 8 × 103 for gray mold pathogens. Conidia of Pestalotiopsis/Neopestalotiopsis species quantified from leaf spots varied from 1 × 102 to 1 × 103 per cm2. Pathogenicity tests performed on developing racemes under field conditions, using conidial suspensions from both sources of inoculum (remnant racemes and yellow halo leaf spot), resulted in severe flower bight symptoms. Disease severity was not significantly different (P > 0.05) when remnant racemes were incubated directly with the developing racemes compared with inoculation with conidial suspension from the material. This suggests that racemes from preceding seasons that remain in the tree canopy carryover inoculum between seasons and should be removed as a control option for flower blights in macadamia orchards.

In-vitro Evaluation of Fungicides against Leaf Spot and Flower Blight of Marigold

Marigold belonging to family Asteraceae, are most common in plant kingdom. It is an important commercial ornamental plant and garden flower. It is found in different colours and different fragrance. Yellow colour is most common. Leaf spot and flower blight is serious disease of marigold causing yield loss in crop. The present investigation was carried out with an objective to study the efficacy of new fungicides available in the market in in-vitrocondition. Eleven fungicides such as azoxystrobin, tebuconazole, azoxystrobin + tebuconazole, difenoconazole, azoxystrobin + difenoconazole, tebuconazole + sulphur, wet sulphur, mancozeb, metalaxly, chlorothalonil, chlorothalonil + metalaxly were evaluated at the concentration of 0.1%, 0.15% ,0.1%, 0.1%, 0.1%, 0.15%, 0.25%, 0.3%,0.2%, 0.3%, and 0.3% respectively. it has been found that combination of azoxystrobin + tebuconazole recorded mycelia growth inhibition of (97.30%) followed by tebuconazole + sulphur (95.95%) and Metalaxly of 95.05%. The least inhibition of 18.47% was recorded by wettable sulphur. Further the effectiveness of new fungicides may be tested under field condition against Alternaria zinniae.

Antimicrobial Property of Some Ethnobotanicals against Flower Blight of Marigold

Marigold is infected with more than ten diseases all over the world. Flower blight, caused by Alternaria zinniae, is a severe threat to marigold cultivation in India and Odisha, resulting in economic losses. The research aimed to look at the efficacy of several botanicals that are readily available in in-vi tro circumstances. At 10% and 20% concentrations, eight plant extracts, including Aloe vera, Azadirachta indica, Allium sativum, Zingiber officinale, Curcuma longa, Phyllanthus emblica, Withania somnifera, and Ocimum tenuiflorum were tested against the pathogen. At a 10 percent concentration, Allium sativum inhibited mycelial growth the most, with 77.93 percent, followed by Phyllanthus emblica (63.38 percent), and Curcuma longa (53.99 percent). The least inhibited plant was Ocimum tenuiflorum, which showed 1.41 percent inhibition. The result at 20% concentration followed the same result as the 15% concentration. Allium sativum had the highest level of inhibition at 87.32 percent, followed by Phyllanthus emblica (85.92 percent) and Curcuma longa (73.71 percent). Ocimum tenuiflorum had the least inhibition, with 10.80 percent. The presence of Allicin in Allium sativum may explain its effectiveness against marigold flower blight, although more research is needed. Furthermore, the effective plant products against marigold flower blight could be evaluated in the field.

The First Mitochondrial Genome of Ciborinia camelliae and Its Position in the Sclerotiniaceae Family.

Ciborinia camelliae is the causal agent of camellia flower blight (CFB). It is a hemibiotrophic pathogen, inoperculate Discomycete of the family Sclerotiniaceae. It shows host and organ specificity infecting only flowers of species belonging to the genus Camellia, causing serious damage to the ornamental component of the plant. In this work, the first mitochondrial genome of Ciborinia camellia is reported. The mitogenome was obtained by combining Illumina short read and Nanopore long read technology. To resolve repetitive elements, specific primers were designed and used for Sanger sequencing. The manually curated mitochondrial DNA (mtDNA) of the Italian strain DSM 112729 is a circular sequence of 114,660 bp, with 29.6% of GC content. It contains two ribosomal RNA genes, 33 transfer RNAs, one RNase P gene, and 62 protein-coding genes. The latter include one gene coding for a ribosomal protein (rps3) and the 14 typical proteins involved in the oxidative metabolism. Moreover, a partial mtDNA assembled from a contig list was obtained from the deposited genome assembly of a New Zealand strain of C. camelliae. The present study contributes to understanding the mitogenome arrangement and the evolution of this phytopathogenic fungus in comparison to other Sclerotiniaceae species and confirms the usefulness of mitochondrial analysis to define phylogenetic positioning of this newly sequenced species.

Morphotypes of Ciborinia camelliae Kohn infecting camellias in Italy

Ciborinia camelliae Kohn is the causal agent of camellia flower blight. The pathogen infects only flowers of camellias, causing serious damage to the plant. Seventy-one strains were collected from six Italian regions and were characterized at the phenotypic and genetic level. Morphotypes were identified based on their phenotypic differences in culture media. The Italian population consisted of eleven morphotypes. Internal transcribed spacer (ITS) regions of twenty-two isolates belonging to the different morphotypes were sequenced. All morphotypes have identical ITS sequences. The closest match of the ITS with the strain ICMP 19812 of Ciborinia camelliae from New Zealand (Massey University Arboretum, Palmerston North, 100% sequence identity), and the morphological features confirmed the presence of a variable population of C. camelliae in six different Italian regions.

First report of <i>Alternaria alternata</i> causing flower blight on <i>Camellia sinensis</i> in Hefei, China

Flowers are an essential organ for sexual reproduction of higher plants. Severe lesions along with flower blight on tea (<italic>Camellia sinensis</italic>) plants were observed in the experimental tea plantation located in Hefei (China). The pathogens isolated from diseased flowers matched the morphological peculiarity of <italic>Alternaria alternata</italic>. The species characteristics of <italic>A. alternata</italic> were further confirmed by both pathogenicity tests and multi-gene phylogenetic analyses by using internal transcribed spacer (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and beta-tubulin (TUB). The combined phylogeny analysis using sequences derived from the ITS, GAPDH and TUB showed that the isolated pathogens belong to the genus <italic>Alternaria</italic>. Pathogenicity tests conducted on healthy tea flowers and leaves manifested typical symptoms of flower blight while weaker symptoms of leaf spot, demonstrating the<italic> A. alternata</italic> isolates were the causal agents of flower blight disease on tea plants. This fungus is first reported as a pathogen causing flower blight on <italic>C. sinensis</italic> in this study.

First Report of Fusarium graminearum Causing Flower Blight On Hemp (Cannabis sativa) in Kentucky.

In October of 2020, a grower in Boyle County, KY, reported mold and blight symptoms on flowers of field-grown hemp. Plants were approaching harvest, and the mold was affecting 100% of the cultivar 'White CBG' being grown for cannabinoid (CBD) extraction. Mycelium colonized the flower heads and any seeds within bracts. Affected flower bracts were necrotic, and mycelium and necrosis in the most severe cases also encompassed adjacent (sugar) leaves. Necrotic symptomatic tissue was collected, disinfested in 10% bleach for one minute, and cultured on acidified potato dextrose agar (APDA). Each isolate was single-spored, transferred to PDA, stored in 15% glycerol at -80°C and maintained at room temperature under blacklight blue and fluorescent bulbs on a 12-hour light-dark cycle. Colonies produced white-pink mycelia with a dark red pigment on the undersides. Conidia collected after 7-9 days were falcate and septate (5 to 6). No microconidia were produced. Macroconidia measured 35.4-49.7 µm x 3.4-5.8 µm (n=50). The strains produced blue-black fertile perithecia on carrot agar when induced according to the method of (Bowden and Leslie, 1999). To confirm pathogenicity, flowers of hemp cultivars 'Lifter', 'Trump Towers', 'Wife' and 'White CBG' were inoculated in the greenhouse with a representative fungal strain (20Hemp010). Plants were inoculated at two different stages: when the styles were still green or after they had become senescent. Macroconidia were collected from 7- to 9-day-old cultures grown under a 12-hour light-dark cycle. Plants were spray-inoculated with a 5 x 105 per ml conidial suspension in 0.05% Tween 20 until runoff. Flower heads were individually covered with clear plastic bags and incubated for 72 h at 95-100% humidity under greenhouse benches to avoid direct light. Bags were removed after 72 h and returned to the bench. Greenhouse conditions were 23-25°C with a 14-hour photoperiod and 50% RH. Symptoms developed 7 dai in 1% of the flowers inoculated when styles were green, and 36% of the flowers that had senescent styles. Symptoms were similar to those initially noticed in Boyle County, including necrotic flower bracts and sugar leaves, and visible fungal growth. Symptoms were more severe on plants inoculated when styles were necrotic. Recovered fungi were morphologically similar to 20Hemp010. Genomic DNA was extracted from the mycelium with the Zymo Research Quick-DNA Fungal/Bacterial Miniprep Kit. A fragment of the translation elongation factor 1-alpha 1 gene was amplified with primers EF1 and EF2 as described by (O'Donnell et al. 1998). Amplicons were sequenced and the consensus (MZ407909) was compared with the NCBI GenBank Refseq database by BLASTn. The top hit was Fusarium graminearum with 100% identity (JF270185.1). Pairwise alignments via MycoBank Fusarium MLST and Fusarium-ID also revealed a top hit of F. graminearum with 100% identity (AY452957.1). Conidial and colony morphology were also consistent with F. graminearum (Leslie and Summerell, 2006), thus we conclude that this species was the causal agent of the flower blight and mold. The same disease was subsequently confirmed on hemp in Breathitt and Franklin Counties in KY in 2020. This is the first report of this disease in KY, although F. graminearum has been reported previously causing a similar flower blight on hemp in NY and NC (Bergstrom et al., 2019, Thiessen et al. 2020). Fusarium graminearum is common in KY as a cause of Fusarium head blight on wheat and Gibberella ear rot on corn. In cereals, fungal infection is facilitated by the production of the mycotoxin deoxynivalenol (DON), which is harmful to humans and livestock (Desjardins and Hohn, 1997). As hemp production in Kentucky continues to rise for production of CBD products and edible grains, accumulation and concentration of DON in these products could become a concern.