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Species of the genus Colletotrichum are among the most important plant pathogens globally, as they are capable of infecting many hosts—apple (Malus spp.) and other fruit and woody plant species—but also vegetable crops, cereals, legumes, and other annual and perennial herbaceous plants. The apple (Malus spp.) is attacked by various species from the genus Colletotrichum, whereby 27 different species from this genus have been described as the causative agents of apple bitter rot (ABR) and 15 as the cause of Glomerella leaf spot (GLS). These species generally belong to one of three species complexes: Colletotrichum acutatum, Colletotrichum gloeosporioides, and Colletotrichum boninense. The largest number of apple pathogens of the genus Colletotrichum belong to the species complex C. acutatum and C. gloeosporioides. However, further data on these species and the interactions between the species complexes of the genus Colletotrichum that cause these two apple diseases is needed for the development of effective control measures, thus ensuring successful and profitable apple cultivation. To contribute to this endeavor, a comprehensive review of the causative agents of ABR and GLS from the genus Colletotrichum is provided. In addition to presenting the species' current names, distribution, economic significance, and the symptoms they cause in apple, their development cycle, epidemiology, and molecular detection strategies are described, with a particular emphasis on control measures. [ABSTRACT FROM AUTHOR]

The bitter rot of apple is caused by Colletotrichum spp. and is a serious pre-harvest disease that can manifest in postharvest losses on harvested fruit. In this study, we obtained genome sequences from four different species, C. chrysophilum, C. noveboracense, C. nupharicola, and C. fioriniae, that infect apple and cause diseases on other fruits, vegetables, and flowers. Our genomic data were obtained from isolates/species that have not yet been sequenced and represent geographic-specific regions. Genome sequencing allowed for the construction of phylogenetic trees, which corroborated the overall concordance observed in prior MLST studies. Bioinformatic pipelines were used to discover CAZyme, effector, and secondary metabolic (SM) gene clusters in all nine Colletotrichum isolates. We found redundancy and a high level of similarity across species regarding CAZyme classes and predicted cytoplastic and apoplastic effectors. SM gene clusters displayed the most diversity in type and the most common cluster was one that encodes genes involved in the production of alternapyrone. Our study provides a solid platform to identify targets for functional studies that underpin pathogenicity, virulence, and/or quiescence that can be targeted for the development of new control strategies. With these new genomics resources, exploration via omics-based technologies using these isolates will help ascertain the biological underpinnings of their widespread success and observed geographic dominance in specific areas throughout the country. [ABSTRACT FROM AUTHOR]

Species of the genus Colletotrichum are among the most important plant pathogens globally, as they are capable of infecting many hosts—apple (Malus spp.) and other fruit and woody plant species—but also vegetable crops, cereals, legumes, and other annual and perennial herbaceous plants. The apple (Malus spp.) is attacked by various species from the genus Colletotrichum, whereby 27 different species from this genus have been described as the causative agents of apple bitter rot (ABR) and 15 as the cause of Glomerella leaf spot (GLS). These species generally belong to one of three species complexes: Colletotrichum acutatum, Colletotrichum gloeosporioides, and Colletotrichum boninense. The largest number of apple pathogens of the genus Colletotrichum belong to the species complex C. acutatum and C. gloeosporioides. However, further data on these species and the interactions between the species complexes of the genus Colletotrichum that cause these two apple diseases is needed for the development of effective control measures, thus ensuring successful and profitable apple cultivation. To contribute to this endeavor, a comprehensive review of the causative agents of ABR and GLS from the genus Colletotrichum is provided. In addition to presenting the species’ current names, distribution, economic significance, and the symptoms they cause in apple, their development cycle, epidemiology, and molecular detection strategies are described, with a particular emphasis on control measures.

The bitter rot of apple is caused by Colletotrichum spp. and is a serious pre-harvest disease that can manifest in postharvest losses on harvested fruit. In this study, we obtained genome sequences from four different species, C. chrysophilum, C. noveboracense, C. nupharicola, and C. fioriniae, that infect apple and cause diseases on other fruits, vegetables, and flowers. Our genomic data were obtained from isolates/species that have not yet been sequenced and represent geographic-specific regions. Genome sequencing allowed for the construction of phylogenetic trees, which corroborated the overall concordance observed in prior MLST studies. Bioinformatic pipelines were used to discover CAZyme, effector, and secondary metabolic (SM) gene clusters in all nine Colletotrichum isolates. We found redundancy and a high level of similarity across species regarding CAZyme classes and predicted cytoplastic and apoplastic effectors. SM gene clusters displayed the most diversity in type and the most common cluster was one that encodes genes involved in the production of alternapyrone. Our study provides a solid platform to identify targets for functional studies that underpin pathogenicity, virulence, and/or quiescence that can be targeted for the development of new control strategies. With these new genomics resources, exploration via omics-based technologies using these isolates will help ascertain the biological underpinnings of their widespread success and observed geographic dominance in specific areas throughout the country.

Apple grower in the Cheongsong region, Korea has reported the increased loss of apple yield due to severe bitter rot incidence. We noticed that this indience is because the Colletotrichum population has developed resistance to commonly used fungicides. We isolated 39 Colletotrichum isolates from 13 orchards in Cheongsong, and all the isolated Colletotrichum species were identified as C. siamense or C. fructicola. These 39 strains were tested for mycelial growth and conidial germination against 12 fungicides. trifloxystrobin (30–55% in recommended concentrations) was shown lower inhibitory effect on mycelial growth. However, the inhibition of conidial germination was shown higher than mycelial growth (62–100%). Kresoxim-methyl was shown lower inhibitory effect on mycelial growth (29–55%). conidial germination inhibitory effect was shown 51% to 96%. dithianon was shown diversity response to inhibition of mycelial growth (43–100%). tebuconazole was shown high inhibitory effect on mycelial growth (84–100%) and conidial germination inhibitory effect was shown to be 64 to 100%. metconazole has been found to display with high inhibitory effect on mycelial growth (79–100%) and conidial germination (70–80%). fluazinam was shown to possess high inhibitory effect on mycelial growth (87–100%) and conidial germination (94–100%). This study provides basic information for the effective management of apple bitter rot.

The pathogenicity of five isolates of Colletotrichum acutatum species complex (CASC) was tested on artificially injured apple fruits of the cultivar 'Golden Delicious' under laboratory conditions. Then, ten apple cultivars were tested for their relative susceptibility to CASC. Differences in the pathogenicity of the CASC isolates were confirmed in the test. The highest degree of pathogenicity was showed by the isolates from the strawberry and DCSBPM J1 from the apple. No cultivars were resistant to the pathogen. The disease incidence ranged from 57.5% to 100%. The individual cultivars showed different susceptibility to the tested isolates. The cultivars 'Braeburn', 'Jonagold' and 'Rubinola' showed the least susceptibility to the pathogen, while the cultivars 'Jonagored' and 'Otava' were recorded as the most susceptible to CASC. All the tested isolates were confirmed, by the conventional PCR method, to belong to CASC. The sequences of isolates DCSBPM J1 and DCSBPM 1209 were deposited in the GenBank.

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The use of microbial biocontrol agents for control of postharvest disease has been the subject of intensive research over the past three decades resulting in commercialization of several biocontrol products. The objective of this research was to test endospore-forming bacteria collected from apple leaves for suppression of bitter rot and blue mold on apple. Bacteria were collected from abandoned, low-input, organic, and conventionally managed orchards in Pennsylvania and were screened for their ability to produce endospores, hydrolyze chitin, reduce pathogen growth in vitro, and suppress postharvest disease in vivo. Several isolates reduced bitter rot lesion size on 'Rome Beauty' from 40–89% compared to untreated controls. Bacillus megaterium isolates, A3-6 and Ae-1, resulted in the greatest suppression of bitter rot lesion size. One isolate, A3-2, suppressed blue mold lesion size. Scanning electron microscopy of inoculated apple wounds suggests parasitism as a mode of action explains the suppression of bitter rot lesion size by isolate A3-6. Of the top seventeen isolates exhibiting biocontrol potential, 70% were collected from abandoned or unmanaged locations. This research demonstrates abandoned apple orchards can be a source of new biocontrol agents for control of postharvest diseases of apple. [ABSTRACT FROM AUTHOR]

The pathogenicity of five isolates of Colletotrichum acutatum species complex (CASC) was tested on artificially injured apple fruits of the cultivar ‘Golden Delicious’ under laboratory conditions. Then, ten apple cultivars were tested for their relative susceptibility to CASC. Differences in the pathogenicity of the CASC isolates were confirmed in the test. The highest degree of pathogenicity was showed by the isolates from the strawberry and DCSBPM J1 from the apple. No cultivars were resistant to the pathogen. The disease incidence ranged from 57.5% to 100%. The individual cultivars showed different susceptibility to the tested isolates. The cultivars ‘Braeburn’, ‘Jonagold’ and ‘Rubinola’ showed the least susceptibility to the pathogen, while the cultivars ‘Jonagored’ and ‘Otava’ were recorded as the most susceptible to CASC. All the tested isolates were confirmed, by the conventional PCR method, to belong to CASC. The sequences of isolates DCSBPM J1 and DCSBPM 1209 were deposited in the GenBank. [ABSTRACT FROM AUTHOR]

Bitter rot (BR), caused by Colletotrichum spp., is one of the most prevalent fungal diseases of apple worldwide. Some Colletotrichum spp. also causes Glomerella leaf spot (GLS), a disease restricted to a few regions worldwide. Recently, we reported the presence of C. siamense causing BR on low-chill apple cultivars in central Argentina. In further studies we detected the presence of apple leaf spot also associated to Colletotrichum spp. Thus, this study was focused to determine and characterize the Colletotrichum species involved in fruit rot and apple leaf spot diseases in Santa Fe, Argentina. A total of thirty-one isolates were obtained from symptomatic fruits and leaves. Morphological characteristics in combination with multilocus phylogenetic analysis revealed that Colletotrichum siamense is the single species associated with fruit rot and leaf spots on low-chill apples in Santa Fe, Argentina. Although in this study we obtained and characterized isolates of C. siamense from leaf spot, we found remarkable differences with typical GLS indicating that this disease is not present in Argentina until now. These findings will be useful to undertake studies of fungicide sensitivity and to understand the epidemiology of the disease in the region based on identified species. [ABSTRACT FROM AUTHOR]

Abstract The objective of this work was evaluate the effect of Eucalyptus staigeriana essential oil on Colletotrichum gloeosporioides and Greeneria uvicola mycelial growth and conidia germination on grapes, as well as its potential for the control of postharvest rot diseases and its effect on the organoleptic properties of grapes. The essential oil (EO) showed in vitro antifungal activity against both pathogens, with fungicidal effect on mycelial growth and on conidia germination at the concentrations of 1.0 and 0.5 μL mL−1, respectively. The EO volatile compounds had a fungistatic effect on the mycelial growth of C. gloeosporioides and a fungicidal effect on G uvicola. At postharvest, the EO reduced the incidence of ripe rot up to 75% and 86% in the preventive and curative treatments, respectively, and the incidence of bitter rot up to 54% in the curative treatment. Since the EO does not affect significantly grape sensory properties, it does not affect the consumption intention of grapes treated with the EO. The EO of E. staigeriana is efficient in the in vitro control of both pathogens; moreover, it is also efficient in the control of the incidence of postharvest fungal rot diseases, mainly in the curative treatment.

The abnormal brown sunken lesions were observed on cv. RubyS apple fruits in an orchard located in Gunwi, Gyeongbuk province, Korea. The primary observed symptoms such as small round sunken lesions and small black dots on the symptomatic area were different from the reported apple diseases. The affected apple fruits were sampled and subjected to isolation of the causal agent. Cultural and morphological characteristics of isolated fungal strain, designated KNUF-20GWA4, were similar to that of Colletotrichum spp. Based on multilocus sequence analyses using internal transcribed spacer regions and partial sequences of β-tubulin, glyceraldehyde-3-phosphate dehydrogenase, chitin synthase, and actin genes, strain KNUF-20GWA4 showed 99.2-100% similarities with C. aenigma ICMP 18608 and the isolate clustered together with several other strains of this species in the phylogenetic tree. To our knowledge, this is the first report of bitter rot on apple fruits caused by C. aenigma.

The use of microbial biocontrol agents for control of postharvest disease has been the subject of intensive research over the past three decades resulting in commercialization of several biocontrol products. The objective of this research was to test endospore-forming bacteria collected from apple leaves for suppression of bitter rot and blue mold on apple. Bacteria were collected from abandoned, low-input, organic, and conventionally managed orchards in Pennsylvania and were screened for their ability to produce endospores, hydrolyze chitin, reduce pathogen growth in vitro, and suppress postharvest disease in vivo. Several isolates reduced bitter rot lesion size on ‘Rome Beauty’ from 40–89% compared to untreated controls. Bacillus megaterium isolates, A3-6 and Ae-1, resulted in the greatest suppression of bitter rot lesion size. One isolate, A3-2, suppressed blue mold lesion size. Scanning electron microscopy of inoculated apple wounds suggests parasitism as a mode of action explains the suppression of bitter rot lesion size by isolate A3-6. Of the top seventeen isolates exhibiting biocontrol potential, 70% were collected from abandoned or unmanaged locations. This research demonstrates abandoned apple orchards can be a source of new biocontrol agents for control of postharvest diseases of apple.

The EFSA Plant Health Panel performed a pest categorisation of Colletotrichum fructicola Prihast., a well‐defined polyphagous fungus of the C. gloeosporioides complex which has been reported from all the five continents to cause anthracnose, bitter rot and leaf spotting diseases on over 90 cultivated and non‐cultivated woody or herbaceous plant species. The pathogen is not included in EU Commission Implementing Regulation 2019/2072. Because of the very wide host range, this pest categorisation focused on Camellia sinensis, Citrus sinensis, C. reticulata, Fragaria × ananassa, Malus domestica, M. pumila, Persea americana, Prunus persica, Pyrus pyrifolia and P. bretschneideri for which there was robust evidence that C. fructicola was formally identified by morphology and multilocus gene sequencing analysis. Host plants for planting and fresh fruits are the main pathways for the entry of the pathogen into the EU. There are no reports of interceptions of C. fructicola in the EU. The pathogen has been reported from Italy and France. The host availability and climate suitability factors occurring in some parts of the EU are favourable for the establishment of the pathogen. Economic impact on the production of the main hosts is expected if establishment occurs. Phytosanitary measures are available to prevent the re‐introduction of the pathogen into the EU. Although the pathogen is present in the EU, there is a high uncertainty on its actual distribution in the territory because of the re‐evaluation of Colletotrichum taxonomy and the lack of systematic surveys. Therefore, the Panel cannot conclude with certainty on whether C. fructicola satisfies the criterium of being present but not widely distributed in the EU to be regarded as a potential Union quarantine pest unless systematic surveys for C. fructicola are conducted and Colletotrichum isolates from the EU in culture collections are re‐evaluated. [ABSTRACT FROM AUTHOR]

Abstract The EFSA Plant Health Panel performed a pest categorisation of Colletotrichum fructicola Prihast., a well‐defined polyphagous fungus of the C. gloeosporioides complex which has been reported from all the five continents to cause anthracnose, bitter rot and leaf spotting diseases on over 90 cultivated and non‐cultivated woody or herbaceous plant species. The pathogen is not included in EU Commission Implementing Regulation 2019/2072. Because of the very wide host range, this pest categorisation focused on Camellia sinensis, Citrus sinensis, C. reticulata, Fragaria × ananassa, Malus domestica, M. pumila, Persea americana, Prunus persica, Pyrus pyrifolia and P. bretschneideri for which there was robust evidence that C. fructicola was formally identified by morphology and multilocus gene sequencing analysis. Host plants for planting and fresh fruits are the main pathways for the entry of the pathogen into the EU. There are no reports of interceptions of C. fructicola in the EU. The pathogen has been reported from Italy and France. The host availability and climate suitability factors occurring in some parts of the EU are favourable for the establishment of the pathogen. Economic impact on the production of the main hosts is expected if establishment occurs. Phytosanitary measures are available to prevent the re‐introduction of the pathogen into the EU. Although the pathogen is present in the EU, there is a high uncertainty on its actual distribution in the territory because of the re‐evaluation of Colletotrichum taxonomy and the lack of systematic surveys. Therefore, the Panel cannot conclude with certainty on whether C. fructicola satisfies the criterium of being present but not widely distributed in the EU to be regarded as a potential Union quarantine pest unless systematic surveys for C. fructicola are conducted and Colletotrichum isolates from the EU in culture collections are re‐evaluated.

Bitter rot caused by Colletotrichum species is a common fruit rotting disease of apple and one of the economically important disease in worldwide. In 2015 and 2016, distinct symptoms of bitter rot disease were observed in apple orchards in five regions of South Korea. In the present study, infected apples from these regions were utilized to obtain eighteen isolates of Colletotrichum spp. These isolates were identified and characterized according to their morphological characteristics and nucleotide sequence data of internal transcribed spacer regions and glyceraldehyde-3-phosphate-dehydrogenase. Molecular analyses suggested that the isolates of Colletotrichum causing the bitter rot disease in South Korea belong to 4 species: C. siamense; C. fructicola; C. fioriniae and C. nymphaeae. C. siamense and C. fructicola belonged to Musae Clade of C. gloeosporioides complex species while C. fioriniae and C. nymphaeae belonged to the Clade 3 and Clade 2 of C. acutatum complex species, respectively. Additionally, we also found that the isolates of C. gloeosporioides species-complex were more aggressive than those in the C. acutatum species complex via pathogenicity tests. Taken together, our results suggest that accurate identification of Colletotrichum spp. within each species complex is required for management of bitter rot disease on apple fruit in South Korea.

Bitter rot is an emerging disease of apple ( Malus domestica ) fruit in Ontario in part due to changing weather conditions. The disease was mostly documented in warm and humid regions such as the southern USA, and Central and South America. Thirteen Ontario orchards in the fall of 2019 and 15 in 2020 were scouted for bitter rot based on their previous history of the disease. 100 fruit were collected from ten asymptomatic trees per cultivar and two susceptible cultivars, 'Empire' and 'Ambrosia' were scouted per orchard. If an orchard did not have either one of these cultivars, 'Honeycrisp' or 'Gala' were used. The fruit was stored at 4-5 o C for five months and then left at 22 o C for two weeks and assessed thereafter for bitter rot symptoms. Monoconidial cultures of Colletrotrichum spp. were established from the symptomatic fruit using potato dextrose agar media with antibiotics at 22 o C 14-hour light cycles. The fungal isolates were divided into two groups based on colony morphology observations seven days after culturing. The first group showed light grey, cottony, aerial mycelium on top and a pink to dark red color on the reverse of the plate. The second group showed light to dark grey, cottony mycelium on top and dark green colonies on the reverse of the plate. It is difficult to identify Colletrotricuhum species solely based on morphology, therefore the representative isolates from each group were used for multilocus gene sequencing and species identification. Genomic DNA was extracted using the Qiagen DNeasy Plant Mini Kit according to the manufacturer's protocols. The ITS region was amplified and sequenced using the primers ITS-1F (Grades & Bruns 1993) and ITS-4 (White et al. 1990). Primers T1 and T2 (O'Donnell & Cigelnik 1997) were used to amplify and sequence the 750 bp region of the TUB gene. Primers GDF1 and GDR1 (Guerber et. al. 2003) were used to amplify a 280 bp region of the GADPH gene. Following an NCBI nucleotide blast search, the isolates from group 1 were identified as C. fioriniae .The ITS sequences of group 2 isolates were matched 100% to the Colletotrichum godetiae type strain CBS133.44 and they were 99% matched to the closest species C. Johnstonii CBS128532. The TUB sequences matched 100% identity to 20 sequences belonging to C. godetiae , 99.59 % identity to C. godetiae type strain CBS133.44, and 97.75% to C. Johnstonii CBS128532. The GADPH sequences matched with 100% identity to C. godetiae ON241087.1 or MT816329.1 and 99-99.5% identity to the type strain CBS133.44 and 98.61-99% identity to CBS128532. Based on the blast results the group 2 isolates were identified as C. godetiae and their sequences were submitted to GenBank with ID OP702962 for ITS and OP972240 and OP972241 for GADPH and OP972242 for the TUB gene. Out of 50 isolates collected in this work, 94% belonged to group 1 and 6% belonged to group 2. Koch's postulates were performed on selected isolates by artificial inoculation of 5 healthy detached fruits of the cultivar, 'Empire.' Fruit surfaces were wiped with 70% ethanol, dried, wounded with a sterile needle, and then inoculated with a 10 µl of spore suspension containing 1x10^6 spores /ml. Inoculated fruits were incubated in a humid chamber at 22°C in dark. Symptoms started to appear at 5 days post-inoculation and looked like small brown circular lesions which developed orange spore masses as they grew into larger lesions. The non-inoculated control fruit did not develop lesions. Fungal colonies were established from the spores collected from the inoculated fruit and found to have identical morphological characteristics to the original isolates. C. godetiae has previously been reported to cause bitter rot in apples from various countries in Europe (Baroncelli et al. 2014; Munda, 2014; Wenneker et al. 2016). C. fioriniae has previously been reported as the dominant species causing bitter rot in apples although other species including C. chrysophilum and C. noveboracense have also been reported as causal agents from the Eastern USA (Khodadadi et al. 2020). To the best of our knowledge, this is the first report of Colletotrichum godetiae causing the bitter rot of apples in Ontario, Canada.

Colletotrichum fructicola causes two important diseases on apple in Southern Brazil, bitter rot (ABR) and Glomerella leaf spot (GLS). In this pathosystem, the Colletotrichum ability to cause different symptoms could be related to differences of extracellular enzymes produced by the fungi. Thus, the objectives of this study were to compare the production of these enzymes between ABR- and GLS-isolate in vitro and to evaluate their involvement on infected apple leaves with C. fructicola. In agar plate enzymatic assay, ABR- showed significantly higher amylolytic and pectolytic activity than GLS-isolate. In contrast, for lipolytic and proteolytic no significant differences were observed between isolates. In culture broth, ABR-isolate also had higher activity of pectin lyase (PNL), polygalacturonase (PG) and laccase (LAC). Notably, LAC was significantly five-fold higher in ABR- than GLS-isolate. On the other hand, in infected apple leaves no significant difference was observed between isolates for PNL, PG and LAC. Although differences in extracellular enzymes of ABR- and GLS-isolate have not been observed in vivo, these results contributed to highlight the importance to investigate such enzymes in depth.

Bitter rot caused by the fungal genus Colletotrichum is a well-known, common disease of apple and causes significant yield loss. In 2013, six fungal strains were isolated from Fuji apple fruits exhibiting symptoms of bitter rot from Andong, Korea. These strains were identified as Colletotrichum fructicola and C. siamense based on morphological characteristics and multilocus sequence analysis of the internal transcribed spacer rDNA, actin, calmodulin, chitin synthase, and glyceraldehyde-3-phosphate dehydrogenase Pathogenicity tests confirmed the involvement of C. fructicola and C. siamense in the development of disease symptoms on apple fruits. This is the first report of C. fructicola and C. siamense causing bitter rot on apple fruit in Korea.

Colletotrichum spp. infections are an increasing threat to the fruit production industry worldwide, as a postharvest disease. Gaining knowledge on the susceptibility of apple fruit cultivars to Colletotrichum species is essential for specific breeding programs aiming to decrease the disease susceptibility of commercial apple cultivars. We investigated fruit susceptibility of nine apple cultivars at harvest and after storage, and studied the relationship of the susceptibility with fruit ripening characteristics. An accurate artificial inoculation technique, by wounding and injecting the spore suspension, was used to consistently follow-up the relative susceptibility symptoms of fruits. The nine apple cultivars studied, cvs. Pinova, Nicoter, Nicogreen, Golden Delicious, Gala, Elstar, Jonathan, Idared and Topaz, showed clear differences in susceptibility to C. fioriniae, main species causing problems in Europe, based on lesion expansion growth rate data. Cultivar Nicoter and Nicogreen were evaluated as less susceptible cultivars, while cv. Golden Delicious and cv. Pinova were classified as high susceptible cultivars. After three months of storage all fruit cultivars showed a higher susceptibility than at harvest. We further explored the link between fruit ripening characteristics and postharvest pathogen developments. Results showed significant higher Brix, ethylene production and respiration and significantly lower firmness and titratable acids after storage, with the extent of these changes being cultivar dependent. The ripening parameters respiration and Brix had a positive and the firmness a negative correlation with the lesion expansion growth rate of C. fioriniae after artificial wound inoculations. These experiments help to give a better insight in the susceptibility of different cultivars. Moreover, our data support the hypothesis that the extent of the necrotrophic fungal development depends on the fruit ripening stage. [ABSTRACT FROM AUTHOR]

Colletotrichum fructicola causes two important diseases on apple in Southern Brazil, bitter rot (ABR) and Glomerella leaf spot (GLS). In this pathosystem, the Colletotrichum ability to cause different symptoms could be related to differences of extracellular enzymes produced by the fungi. Thus, the objectives of this study were to compare the production of these enzymes between ABR- and GLS-isolate in vitro and to evaluate their involvement on infected apple leaves with C. fructicola. In agar plate enzymatic assay, ABR- showed significantly higher amylolytic and pectolytic activity than GLS-isolate. In contrast, for lipolytic and proteolytic no significant differences were observed between isolates. In culture broth, ABR-isolate also had higher activity of pectin lyase (PNL), polygalacturonase (PG) and laccase (LAC). Notably, LAC was significantly five-fold higher in ABR- than GLS-isolate. On the other hand, in infected apple leaves no significant difference was observed between isolates for PNL, PG and LAC. Although differences in extracellular enzymes of ABR- and GLS-isolate have not been observed in vivo, these results contributed to highlight the importance to investigate such enzymes in depth. [ABSTRACT FROM AUTHOR]

Fungi within the Colletotrichum acutatum species complex occur asymptomatically on plant parts of many different plant species. Leaves from apple orchards in southern Norway were sampled, frozen for five hours and incubated for six days to reveal presence of asymptomatic infections of C. acutatum. Number of leaves (incidence) and leaf area covered (severity) with conidial masses of C. acutatum were assessed biweekly on cv. Aroma from late May to late September during three growing seasons. The first finding of conidial masses occurred in the second half of July, and there was a higher incidence occurring in August and September. Sampling of leaves from fruit spurs and vegetative shoots of cvs. Aroma and Elstar showed that conidial masses of C. acutatum developed on leaves on both shoot types, and there was no difference in incidence between these two types. The fungus was detected on leaves from six of eight commercial orchards of cv. Aroma over three years, with a mean incidence of 5.5 %. After storage, bitter rot was found on apple fruit from all eight orchards. There was no correlation between incidence of conidial masses of C. acutatum on leaves and on fruit. In all orchards and seasons investigated, incidence and severity on leaves varied from 0 to 67 % and 0 to 85 %, respectively. The discovery of apple leaves containing conidial masses of C. acutatum clearly indicate for leaves as a potential source of inoculum for fruit infections. [ABSTRACT FROM AUTHOR]

Glomerella leaf spot (GLS) and bitter rot (BR), caused by Colletotrichum spp., are major diseases on apple in southern Brazil. Among integrated pest management tools for disease management in commercial orchards, fungicides remain an important component. This study aimed to identify Colletotrichum spp. from cultivar Eva in Paraná state orchards; evaluate their in vitro sensitivity to cyprodinil, tebuconazole, iprodione, and fluazinam; and determine the baseline in vitro sensitivity of these isolates to benzovindiflupyr and natamycin. Most isolates belonged to Colletotrichum melonis and C. nymphaeae of the C. acutatum species complex. The two species varied in sensitivity to fluazinam and tebuconazole, but no variability was found for any other fungicide. The lowest 50% effective concentration (EC 50 ) values of Colletotrichum spp. were observed for cyprodinil (mean EC 50 < 0.02) and benzovindiflupyr (mean EC 50 < 0.05); EC 50 values were intermediate for fluazinam (mean EC 50 < 0.33) and tebuconazole (mean EC 50 < 0.14), and they were highest for natamycin (mean EC 50 < 5.56) and iprodione (mean EC 50 > 12). Cyprodinil and fluazinam are registered for use in Brazil for apple disease management but not specifically for GLS and BR. Tebuconazole is one of the few products registered for Colletotrichum spp. control in apples. In conclusion, flowers and fruitlets can serve as sources of inoculum for GLS and BR disease; C. acutatum was the predominant species complex in these tissues; cyprodinil and fluazinam applications may suppress GLS and BR; and benzovindiflupyr and natamycin warrant further investigation for GLS and BR disease control of apple due to comparably high in vitro sensitivity.

This study investigated the biocontrol ability of Trichoderma harzianum CGMCC20739 (Tha739) against apple bitter rot caused by Colletotrichum gloeosporioides. In vitro tests, Tha739 inhibited the mycelial growth of C. gloeosporioides. Microscopic observation showed that Tha739 grew in parallel with, coiled around, and deformed the hyphae of C. gloeosporioides. Tha739-derived metabolites decreased the conidia production of C. gloeosporioides. In vivo tests, the lesion diameters of wounded apples treated with Tha739 1 h before C. gloeosporioides were lower than those of wounded apples treated with Tha739 after pathogen inoculation. In addition, compared with the apples inoculated with C. gloeosporioides only, the disease index of unwounded apples inoculated with Tha739 and C. gloeosporioides decreased by 2.17-fold. Furthermore, compared with the control, the total soluble solid contents of apples treated with Tha739 were 9.02 % and 1.54 % higher at 1 and 3 d, respectively. The titratable acidity contents of apples treated with Tha739 were 10.02 % and 14.58 % higher than those in the control at 1 and 3 d after treatment, respectively. The soluble sugar content and weight loss in Tha739 treatment group and control were not significantly different. The results showed that Tha739 could control apple bitter rot and maintain the nutritional quality of the fruit. Thus, T. harzianum Tha739 is a potentially biocontrol agent for harvested apples. • T. harzianum Tha739 inhibited mycelial growth of Colletotrichum gloeosporioides. • Tha739 metabolites decreased pathogen conidia production. • Tha739 effectively reduced lesion diameters of apples. • Nutritional quality of apples was maintained by Tha739. • Tha739 is a potentially biocontrol agent for harvested apples. [ABSTRACT FROM AUTHOR]

Upon the completion of a three-year evaluation of natural occurrence of storage diseases within a range of cultivars or advanced selections and a simultaneous assessment of their other characteristics, an apple ideotype has been proposed that could be used in breeding of new cultivars resistant to these diseases. The ideotype combines the potential of apples for long-term storage with higher skin thickness and toughness, a lower production of ethylene, a higher natural content of calcium, a higher content of total phenolic compounds and antioxidant capacity, a higher flesh firmness, and a higher acidity of juice expressed in pH values. For some of these characteristics, threshold values have been suggested in the paper. The genotypes preselected according to these criteria should be chosen on the basis of the final screening with Pezicula alba inoculum test. The result of the inoculation test should be equal to or better than the standard cultivar Gala. Future research is required to determine the feasibility of the ideotype in routine breeding programs.

In the course of a 3-year study the natural occurrence of storage diseases in ambient air storage with 1 to 2°C was evaluated on samples of 30 cultivars and advanced selections that were harvested from orchards with and without the use of fungicide treatments. Based upon the frequency of occurrence, bitter rot and grey mould were the most common diseases in this study followed by blue mould and brown rot. Fungicide treatments applied in the orchard with integrated plant protection reduced total fruit rotting with different cultivars two to four times. Significant losses caused by rotting usually took place in the last quarter of the normal storage life of each cultivar, but in the case of samples treated with fungicides it was mostly during the last month. Cultivars Angold, Gala, Florina, Melodie and Meteor proved to be partially resistant to the storage diseases, but the smallest shares of rotted fruits were recorded on apples of Zuzana andMelrose. Still, five advanced selections proved not to be so affected by fruit rotting asMelrose and Zuzana, from which HL 237 and HL 390 were the most remarkable. The majority of selections with resistance to storage diseases as well as Zuzana cv. contain Glockenapfel cv. in their pedigree.

A maçã é um dos mais importantes produtos agrícolas de Santa Catarina e a segunda mais importante fruteira de clima temperado do Brasil. No entanto, a produção brasileira está alicerçada em cultivares importadas suscetíveis a diversas doenças. A podridão amarga causada pelo fungo Glomerella cingulata (Stoneman) Spaulding & Schrenk, (forma imperfeita Colletotrichum gloeosporioides (Penz.) Sacc.) é uma das mais importantes doenças de verão, podendo causar perdas muito elevadas. No presente trabalho, a inoculação artificial de C. gloesporioides em frutos com e sem ferimentos objetivou verificar a diferença de evolução da podridão amarga e identificar possíveis fontes de resistência nas seleções e novas cultivares de macieira desenvolvidas pela Epagri. Verificou-se ampla variação na reação de resistência entre as cultivares e seleções estudadas. O estabelecimento e o desenvolvimento da podridão amarga mostrou-se muito mais rápido através de ferimentos. As seleções M-6/00 e M-13/00 manifestaram resistência superior à das atuais cultivares Gala, Fuji e Golden Delicious. Essas seleções também apresentaram resistência superior à cv. Melrose, indicada como resistente em outros estudos.Apple is one of the most important agricultural product of Santa Catarina State and represents the second most important temperate-zone fruit in Brazil. However the production is based on imported cultivars susceptible to many fungal diseases. Bitter rot caused by the fungus Glomerella cingulata (Stoneman) Spaulding & Schrenk, (amorphous = Colletotrichum gloeosporioides (Penz.) Sacc.), is one of the most important summer diseases of apple in southern Brazil. Severe damages may occur every year. In the present study, artificial inoculation of C. gloeosporioides on fruits with and without wounding was carried out to verify differences in the evolution of bitter rot and to identify sources of resistance to the disease among the new apple cultivars and selections of the Epagri breeding program. The establishment and the development of bitter rot on apple fruits were faster through wounds. The selections M-6/00 and M-13/00 showed higher level of resistance to bitter rot than the cultivars Gala, Fuji and Golden Delicious. These apple selections expressed an even higher level of resistance to this disease than cv. Melrose, indicated as resistant in previous studies.

The use of microbial biocontrol agents for control of postharvest disease has been the subject of intensive research over the past three decades resulting in commercialization of several biocontrol products. The objective of this research was to test endospore-forming bacteria collected from apple leaves for suppression of bitter rot and blue mold on apple. Bacteria were collected from abandoned, low-input, organic, and conventionally managed orchards in Pennsylvania and were screened for their ability to produce endospores, hydrolyze chitin, reduce pathogen growth in vitro, and suppress postharvest disease in vivo. Several isolates reduced bitter rot lesion size on 'Rome Beauty' from 40-89% compared to untreated controls. Bacillus megaterium isolates, A3-6 and Ae-1, resulted in the greatest suppression of bitter rot lesion size. One isolate, A3-2, suppressed blue mold lesion size. Scanning electron microscopy of inoculated apple wounds suggests parasitism as a mode of action explains the suppression of bitter rot lesion size by isolate A3-6. Of the top seventeen isolates exhibiting biocontrol potential, 70% were collected from abandoned or unmanaged locations. This research demonstrates abandoned apple orchards can be a source of new biocontrol agents for control of postharvest diseases of apple.

Detached Vitis vinifera (cv Chardonnay) inflorescences were inoculated with spore suspensions of either Colletotrichum acutatum or Greeneria uvicola at 25°C, and a combination of light microscopy, scanning electron microscopy and plating out of inoculated flowers on to dichloran rose bengal chloramphenicol agar was used to investigate the time frame for infection. Colletotrichum acutatum infection commenced within 2 h of inoculation, while infection by G. uvicola commenced between 12 and 18 h postinoculation. All parts of the flowers were infected by both fungi. [ABSTRACT FROM AUTHOR]

Cluster rots can be devastating to grape production around the world. There are several late-season rots that can affect grape berries, including Botrytis bunch rot, sour rot, black rot, Phomopsis fruit rot, bitter rot, and ripe rot. Tight-clustered varieties such as 'Pinot gris', 'Pinot noir', and 'Vignoles' are particularly susceptible to cluster rots. Symptoms or signs for these rots range from discolored berries or gray-brown sporulation in Botrytis bunch rot to sour rot, which smells distinctly of vinegar due to the presence of acetic acid bacteria. This review discusses the common symptoms and disease cycles of these different cluster rots. It also includes useful updates on disease diagnostics and management practices, including cultural practices in commercial vineyards and future prospects for disease management. By understanding what drives the development of different cluster rots, researchers will be able to identify new avenues for research to control these critical pathogens.

Highlights: [•] Positive correlation of maturation and firmness with fungal resistance was found. [•] Late-ripening cultivars show higher level of tolerance to fungal disease. [•] Tolerance to blue mold infection seems to be correlated with tolerance to bitter rot. [•] The result of sun-exposure impact on blue mold was not conclusive. [Copyright &y& Elsevier]

Greeneria uvicola causes bitter rot on Vitis vinifera (bunch grapes) and Muscadinia rotundifolia (muscadine grapes) in warm moist temperate and subtropical regions. This study investigated the phylogenetic relationship of G. uvicola representatives from Australia (67 isolates), the USA (31 isolates), India (1 isolate) and Costa Rica (1 isolate) and compared their pathogenicity and fungicide sensitivity. Differences in cultural and conidial morphology were observed between the isolates from Australia and the USA. Phylogenetic relationships were determined based on three gene regions: the ribosomal DNA ( rDNA) internal transcribed spacer 1 (ITS1-5∙8S-ITS2), 28S large subunit (LSU) nuclear rDNA and β-tubulin-2. Greeneria uvicola isolates were clearly differentiated into four groups: isolates from Australia and India; USA isolates from V. vinifera; USA isolates from M. rotundifolia; and the isolate from Costa Rica. All isolates were pathogenic on V. vinifera (cv. Chardonnay) berries although those originating from M. rotundifolia were not as aggressive as isolates from V. vinifera, irrespective of geographical origin. Sensitivity to pyraclostrobin and salicylhydroxamic acid (SHAM) was studied. Despite differences in fungicide applications, hyphal growth inhibition was not significantly different for geographical location, cultivar, tissue, year of collection or different spray regimes. For the Australian and USA isolates, fungal growth inhibition was significantly greater for pyraclostrobin than for SHAM, and was significantly greater for the combined treatment than for each of the fungicides applied singly. The aetiological and epidemiological knowledge of bitter rot collected through this study will aid better prediction and management strategies of this pathogen. [ABSTRACT FROM AUTHOR]

Abstract: The activity of two biological control agents, strains L1 and L8, previously identified as Aureobasidium pullulans, was tested on apple, artificially inoculated with Botrytis cinerea (grey mould), Colletotrichum acutatum (bitter rot) or Penicillium expansum (blue mould). The washed cells of antagonists controlled over 86% of three types of decay. The cell concentration of both antagonists was highly correlated with their efficacy, the R 2 ranging from 0.93 to 0.99. The highest concentration (108 CFUmL−1) of L1 and L8 provided the best control of B. cinerea, C. acutatum and P. expansum, although grey mould was completely inhibited also by a concentration one log lower (107 CFUmL−1). The population dynamics of L1 strain in ‘Gala’ apple increased almost 8-fold during the first 48h after treatment and remained elevated until 7d, revealing that, although the antagonist was isolated from the carposhere of peach fruit, it showed good adaptation in other wound environments. Preliminary in vitro trials were conducted in order to investigate the mechanisms of action of L1 and L8 strains and in a dual culture dish assay, the antifungal effects observed on pathogen mycelium growth could be attributed to the production of volatile organic compounds (VOCs) generated by the antagonists. The VOCs significantly inhibited the growth of all three tested pathogens compared to the control, albeit with a different rate. When L1 strain was introduced into the wound 12h from inoculum, it showed post-inoculation activity, the incidence of blue mould and bitter rot being reduced by 38% and 50% respectively, while the greatest inhibition of grey mould was observed when fruit were treated with the antagonist 6h from the inoculum. In conclusion, A. pullulans L1 and L8 strains could be considered good candidates for the development of biofungicides for postharvest application in the pomefruit industry. [Copyright &y& Elsevier]

With 3 figures and 4 tables Abstract Penicillium expansum and Colletotrichum acutatum cause blue mould and bitter rot of apples during storage which results in significant economic losses. Resistance to these pathogens in commercial apple cultivars has not been documented in the literature. An apple germplasm collection, from the centre of origin in Kazakhstan, is maintained in Geneva, New York. This collection represents a more diverse apple gene pool than commercial cultivars and was evaluated for resistance to the pathogens that cause blue mould and bitter rot. Resistance reactions were skewed towards susceptibility for both fungi and comprised the majority of accessions examined. However, resistance to P. expansum was confirmed in select accessions over multiple years. Maturation patterns and quality indices for soluble solids and acidity, which may also affect susceptibility, were highly variable and represent the genetic diversity of the germplasm collection. Resistance in four accessions to C. acutatum and two accessions resistant to both P. expansum and C. acutatum are reported here for the first time. Data from this study will serve as a foundation for conventional apple breeding programmes and molecular genetics investigations to provide resistance against blue mould and bitter rot in commercial apple varieties. [ABSTRACT FROM AUTHOR]

Leaves of sweet cherry, exposed to either paraquat or freezing to quickly senesce the leaf tissue, were incubated in about 100% RH at 25°C for 6 d. Sporulating colonies of Colletotrichum acutatum, the cause of anthracnose, developed on up to 100% of the paraquat-treated and frozen leaves, and on none of the untreated controls. Number of leaves and leaf area containing C. acutatum on naturally infected leaves increased over time from May to September. Mean incidence of C. acutatum on leaf blades on fruit spurs and vegetative shoots from eight orchard/year samplings were 41 and 33%, respectively. Secondary conidiation (formation of short hyphae and new conidia) from conidia applied to detached leaves took place 6 h after inoculation, but only up to 3% of the conidia formed new conidia. It may be concluded that asymptomatic sweet cherry leaves frequently host C. acutatum and may be a potential inoculum source for cherry fruit. [ABSTRACT FROM AUTHOR]

Either naturally infected or artificially inoculated sweet cherry (Prunus avium) buds on fruit spurs (mainly containing generative buds) and on 1-year-old shoots (mainly containing vegetative buds) were examined for presence of Colletotrichum acutatum prior to the beginning of spring growth in each of 4 years. Artificial inoculations were made during the growing seasons preceding the bud sampling. The plant material was incubated moist for either 14 (fruit spurs) or 21 (1-year-old shoots) days at 20°C. Following moist incubation at 20°C, C. acutatum frequently sporulated on buds of fruit spurs and shoots. The fungus sporulated in orange, short-thread or hornlike structures, mainly on distal parts of the buds, and was usually easily visible with the unaided eye. The incidence of infected buds on naturally infected and inoculated fruit spurs was 2 to 80% and 38 to 79%, respectively. Incidence on naturally infected and inoculated shoots was 0 to 53% and 4 to 45%, respectively. On buds within fruit spurs, the incidence of C. acutatum was significantly higher on generative than on vegetative buds. This investigation shows that buds can host C. acutatum and thus are likely to be an important source of primary inoculum for anthracnose of sweet cherry. [ABSTRACT FROM AUTHOR]

‘Golden Delicious’ apples were wound inoculated with conidial suspensions of either Colletotrichum acutatum or Penicillium expansum, then treated with heat (38 °C) for 4 days, sodium bicarbonate, and/or one of two heat tolerant biocontrol agents (yeasts). Following four months storage at 0 °C, the apples were left at room temperature for two weeks. Populations of antagonists were stable throughout the experiment and were higher on the heated than the non-heated fruit. Both antagonists reduced decay caused by P. expansum, whereas heat or heat in combination with either antagonist eliminated decay. Either heat or the antagonists alone reduced decay caused by C. acutatum, but a combination of the two was required to completely eliminate decay caused by this pathogen. Adding sodium bicarbonate to the heated or antagonist-treated fruit had little effect on decay caused by either pathogen but when used on non-heated fruit, it significantly reduced decay severity caused by P. expansum after four months at 0 °C. The goal of this research is to combine alternative methods of control to provide an effective substitute for synthetic pesticides. [Copyright &y& Elsevier]