Colletotrichum siamense is the main aetiological agent of anthracnose of avocado in south-eastern Brazil

Anthracnose caused by species of Colletotrichum is considered one of the main postharvest diseases for avocado. In this study, Colletotrichum isolates associated with avocado anthracnose, collected in different states of Brazil, were evaluated through phylogenetic analysis, morphological characterization, and pathogenicity assays. Moreover, the events during pathogen infection of avocados were examined by scanning electron microscopy. To assess the genetic diversity of 54 Colletotrichum isolates, partial sequence analysis of the gene gapdh was performed. According to the generated groupings and the geographical origins of isolates, a subset of 14 strains was selected for performing multilocus phylogeny analysis (using sequences of gapdh, act, tub2, and ApMat). Two species previously described were identified: C. siamense belonging to the C. gloeosporioides species complex and Colletotrichum karstii belonging to the C. boninense species complex. All Colletotrichum strains evaluated caused typical symptoms of anthracnose in avocado fruits. Conidia of the most virulent strain germinated between 6 and 12 hr after inoculation (hai). Penetration through wounds occurred 48 hai, tissue colonization occurred between 144 and 240 hai, and sporulation took place at 240 hai via the production of an acervulus, conidiophores, and conidia. The findings shed light on the aetiology of avocado anthracnose in Brazil and provide a better understanding of the infection process of this pathogen, which may assist in the development of disease management strategies.     

Phylogenetic and morphological identification of Colletotrichum boninense: a novel causal agent of anthracnose in avocado

In recent years, anthracnose has become a significant disease affecting avocado fruit in the state of Michoacan, Mexico, where it significantly reduces fruit quality and commercial yield. Anthracnose has been assumed to involve Colletotrichum gloeosporioides and C. acutatum as causal agents. However, because of the increasing incidence of anthracnose, a more precise identification of the Colletotrichum spp. involved in this disease has become desirable. During the years 2004–2007, avocado fruits of different sizes exhibiting brown‐black and reddish spots on the pericarp and soft rot in the mesocarp, were gathered from orchards in nine counties. Fungal isolates were cultured on potato dextrose agar, and among these, 31 were selected for molecular, morphological and pathogenicity analyses. The molecular approaches used sequence typing of the internal transcribed spacer region and the partial nuclear large ribosomal subunit, allowing the unequivocal identification of C. gloeosporioides (71%), C. acutatum (16%) and C. boninense (13%). This last species has not been previously reported as being associated with anthracnose symptoms in avocado fruits anywhere in the world. Various morphological characteristics such as the size and shape of conidia were determined, as well as the conidial mass colour. Pathogenicity tests performed with all three species were conducted by inoculating healthy fruits. In each case, identical symptoms developed within 3 days of inoculation. Knowledge of the Colletotrichum populations in the Michoacan state, including the newly encountered avocado pathogen C. boninense, will facilitate further studies addressing the relationships between these Colletotrichum spp. and their avocado host.     

Multilocus identification and thiophanate-methyl sensitivity of Colletotrichum gloeosporioides species complex associated with fruit with symptoms and symptomless leaves of mango

Colletotrichum spp. are known causal agents of anthracnose in a broad host range, causing severe losses. Currently, the most effective way to reduce disease is by fungicide application, which could give rise to resistant populations. This study aimed to determine the Colletotrichum species present in conventional and organic mango orchards and to evaluate their pathogenicity and sensitivity to the benzimidazole fungicide thiophanate-methyl. Seventy-one isolates from fruit with symptoms and symptomless leaves were obtained. From these, 20 representative morphotypes were analysed based on glyceraldehyde-3-phosphate dehydrogenase partial gene sequencing. A subset of 10 isolates based on different species, isolation source, and fungicide sensitivity was used for morphological and multilocus phylogenetic analysis. Colletotrichum queenslandicum was only identified in conventional production systems, C. chrysophilum only in organic systems, and C. asianum and C. siamense in both. Pathogenicity tests showed all species were pathogenic, and only C. asianum caused symptoms via both unwounded and wounded inoculation methods. Overall, 25.3% of isolates (n = 18) that belong to C. siamense, isolated from a conventional orchard, grew on thiophanate-methyl amended media at 1,000 µg/ml, suggesting high resistance. Resistance was not correlated with any common point mutations at positions 198 and 200 of the β-tubulin 2 protein, as commonly found in other fungal pathogens resistant to benzimidazole. The 74.7% remaining isolates (n = 53) belonging to the other species were sensitive, reaching 100% inhibition at <10 µg/ml. Even with benzimidazole application, anthracnose symptoms persist due to the emergence of pathogenic Colletotrichum subpopulations that are resistant to thiophanate-methyl.     

Characteristics and distribution of Colletotrichum species in coffee plantations in Hainan,China

Anthracnose caused by Colletotrichum species is a serious disease on a range of economically important hosts. To determine the Colletotrichum species in coffee plantations in Hainan, China, 55 isolates were obtained from Coffea arabica (arabica) and C. canephora var. robusta (robusta) in five counties. Initially, partial sequences of glyceraldehyde-3-phosphate dehydrogenase (GAPDH) were used to measure fungal genetic diversity. Then a subset of 23 isolates was selected to represent the range of genetic diversity, varieties and geographic origin for further multilocus phylogenetic analyses. These isolates belong to eight known Colletotrichum species from three Colletotrichum species complexes, including gloeosporioides (C. endophytica, C. fructicola, C. ledongense, C. siamense and C. tropicale), boninense (C. karstii), gigasporum (C. gigasporum), and one singleton species (C. brevisporum). Of these, C. siamense was isolated in all sampled counties and C. fructicola was identified in three counties. The other six species were isolated only in one or two counties. Only C. siamense and C. fructicola were isolated from arabica, whereas all eight species were isolated from robusta. Occurrence of C. brevisporum, C. endophytica, C. ledongense and C. tropicale in coffee has not been reported previously. Pathogenicity tests showed that all eight species were pathogenic to coffee leaves and fruit. In vitro tests showed that Colletotrichum isolates from coffee in Hainan were most sensitive to prochloraz, less sensitive to carbendazim, propiconazole and difenoconazole, and least sensitive to myclobutanil.     

Colletotrichum species associated with chili anthracnose in Australia

Phylogenetic relationships were determined for 45 Colletotrichum isolates causing anthracnose disease of chili in Queensland, Australia. Initial screening based on morphology, ITS and TUB2 genes resulted in a subset of 21 isolates being chosen for further taxonomic study. Isolates in the C. acutatum complex were analysed using partial sequences of six gene regions (ITS, GAPDH, ACT, CHS‐1, TUB2 and HIS3), and in the C. gloeosporioides complex were analysed using four gene regions (ITS, TUB2, ApMat and GS). Phylogenetic analysis delineated four Colletotrichum species including C. siamense, C. simmondsii, C. queenslandicum, C. truncatum and a new Colletotrichum species, described here as C. cairnsense sp. nov. This is the first reported association of C. queenslandicum, C. simmondsii and C. siamense with chili anthracnose in Australia; these species were previously associated with anthracnose on papaya and avocado. Furthermore, the dominant species causing anthracnose of chili in Southeast Asia, C. scovillei, was not detected in Australia. Inoculations on chili fruit confirmed the pathogenicity of C. cairnsense and the other four species in the development of chili anthracnose in Australia.     

Population structure,pathogenicity, and fungicide sensitivity of Colletotrichum siamense from different hosts in Hainan,China

Areca palm, rubber tree, and coffee are always planted adjacent to each other or intercropped with each other, and Colletotrichum siamense was found to be the dominant species of Colletotrichum from these crops in Hainan, China. To study the population structure, pathogenicity, and fungicide sensitivity of C. siamense from these three crops in Hainan, isolates were first identified by their morphological characteristics and multilocus phylogeny. Then both permutational multivariate analysis of variance (PERMANOVA) and pairwise F_ST analysis showed that the original host and geographical origin (counties) had significant effects on genetic variation in the C. siamense population, explaining 5.6% and 16.3% of genetic variation, respectively. There were significant genetic differentiations between coffee and rubber tree populations but the genetic differentiation was small (F_ST = 0.04), while significant differentiations were observed among all populations from different counties except those between Haikou and Chengmai. Pathogenicity analysis using artificial inoculation showed that isolates had significantly higher disease incidence and diseased lesion diameter on wounded leaves than on nonwounded leaves. However, the original host of an isolate and geographical origin did not significantly affect the pathogenicity of the C. siamense populations from these three hosts. In vitro tests showed that there were no significant differences in the sensitivity of C. siamense populations to carbendazim, prochloraz, difenoconazole, and propiconazole from different original hosts and geographical origins. The present study suggests that host specialization of C. siamense has not occurred yet in coffee, rubber tree, and areca palm.     

Pathogenicity of Colletotrichum species causing anthracnose of Capsicum in Asia

Anthracnose of chili is caused by a complex of Colletotrichum species, with recent surveys reporting at least 28 different species implicated. However, there have been very few studies to identify the relative pathogenicity of the various species or to optimize a bioassay to assess pathogenicity. A detached Capsicum fruit bioassay to determine the pathogenicity of a diverse geographical range of isolates of Colletotrichum scovillei showed fruit maturity, host genotype, and inoculation method all interact to affect infection and rate of lesion development. On Capsicum annuum ‘Bangchang’ fruit wounded prior to inoculation, pathogenicity was consistent regardless of fruit maturity. In contrast, without wounding there was variability in pathogenicity. On the relatively resistant host Capsicum chinense PBC932, pathogenicity was dependent on both the inoculation method and the maturity stage of the fruit. In addition, lack of correlation in pathogenicity of isolates between the two Capsicum lines indicated that there was host–isolate specialization that would make prediction of pathogenicity of isolates on host difficult. In a further study, 10 species of Colletotrichum isolated from diseased chili fruits in Asia caused anthracnose symptoms on C. annuum ‘Bangchang’ under all testing conditions, with large differences in aggressiveness. C. chinense PBC932 was generally more resistant to all the species, with smaller lesions produced in different host conditions. Colletotrichum javanense and C. scovillei were highly aggressive relative to other species, especially when inoculated on nonwounded fruit. Pathotype differences were identified within multiple isolates of C. scovillei and C. siamense, the two most frequently identified pathogenic species on chili.     

Phenotypic and genetic characterization of Colletotrichum isolates from Belgian strawberry fields

Colletotrichum isolates (457) were collected from strawberry plant tissues with and without typical anthracnose symptoms and from symptomless weeds in 19 Belgian strawberry fields. The isolates were characterized based on genetic, morphological and pathological features. Isolates were classified according to rDNA‐ITS sequencing: 97% of 211 representative isolates were C. acutatum, 2%C. gloeosporioides and 1%C. coccodes. The C. acutatum isolates belonged to the intraspecific groups A2 (33%), A3 (5%), A4 (50%), A5 (3%) and A7 (6%). Differences in spore morphology, growth rate and colony colour of a selection of 146 isolates confirmed the genetic grouping. Multiple Colletotrichum genotypes were detected in the same field. There was no association between the most common genotypes and geographic origin, presence or absence of symptoms, nor plant species or plant part. Representative Belgian Colletotrichum isolates were used in pathogenicity tests, together with European and American reference isolates. The C. acutatum A2 and the Belgian C. gloeosporioides isolates were the most aggressive on fruits, followed by C. acutatum A3, A4, A5, A7 and C. coccodes isolates. When inoculated into crowns, C. acutatum A2, A5 and American C. gloeosporioides isolates were the most aggressive, followed by C. acutatum A3 isolates. The A4 and A7 isolates and all European C. gloeosporioides isolates were non‐pathogenic on crowns. These data indicate that an unusually diverse Colletotrichum population is present in Belgium. The traditional differentiation between C. acutatum and C. gloeosporioides as causal agents of fruit and crown rot, respectively, proved not to be valid in Belgian strawberry fields.     

Aetiology of anthracnose on grapevine shoots in Brazil

Anthracnose is an important disease in vineyards in south and southeast Brazil, the main grape‐producing regions in the country. This study aimed to identify the causal agents of grapevine anthracnose in Brazil through multilocus phylogenetic analyses, morphological characterization and pathogenicity tests. Thirty‐nine Elsinoë ampelina and 13 Colletotrichum spp. isolates were obtained from leaves, stems and berries with anthracnose symptoms collected in 38 vineyards in southern and southeastern Brazil. For E. ampelina isolates, the internal transcribed spacer (ITS), histone H3 (HIS3) and elongation factor 1‐α (TEF) sequences were analysed. HIS3 was the most informative region with 55 polymorphic sites including deletions and substitutions of bases, enabling the grouping of isolates into five haplotypes. Colonies of E. ampelina showed slow growth, variable colouration and a wrinkled texture on potato dextrose agar. Conidia were cylindrical to oblong with rounded ends, hyaline, aseptate, (3.57–) 5.64 (?6.95) μm long and (2.03–) 2.65 (?3.40) μm wide. Seven species of Colletotrichum were identified: C. siamense, C. gloeosporioides, C. fructicola, C. viniferum, C. nymphaeae, C. truncatum and C. cliviae, with a wide variation in colony and conidium morphology. Only E. ampelina caused anthracnose symptoms on leaves, tendrils and stems of Vitis vinifera and V. labrusca. High disease severity and a negative correlation between disease severity and shoot dry weight were observed only when relative humidity was above 95%. In this study, only E. ampelina caused anthracnose symptoms on grapevine shoots in Brazil.     

Anthracnose of Christmas rose caused by <Emphasis Type="Italic">Colletotrichum</Emphasis> sp.

Leaf spots were found on Christmas rose (Helleborus niger) in Yamagata Prefecture, Japan, in October 2006. The morphology of the causal fungus was very close to that of Colletotrichum truncatum. Classifying the species from the sequences of the internal transcribed spacer regions of ribosomal DNA was inconclusive, and the isolates were identified only as Colletotrichum sp. Artificial inoculation confirmed the pathogenicity of isolates to the host plant and some legumes. We propose the name anthracnose of Christmas rose for this disease by Colletotrichum sp.     

Factors influencing biological traits and aggressiveness of Colletotrichum species associated with cashew anthracnose in Brazil

Anthracnose is the main fungal disease on cashew orchards in Brazil, occurring on both vegetative and reproductive organs of cultivated and noncultivated host plants. Understanding the effect of physical and chemical exogenous factors on the biological traits of Colletotrichum spp. and determining their host range are key to developing appropriate anthracnose control measures. The present study aimed to estimate the optimum temperatures for mycelial growth, sporulation, and conidial germination of seven Colletotrichum species (C. chrysophilum, C. fragariae, C. fructicola, C. gloeosporioides, C. queenslandicum, C. siamense, and C. tropicale) associated with cashew anthracnose in Brazil. Their aggressiveness on cashew leaves and six alternative host fruits, and their sensitivity to three fungicides were also investigated. The optimum temperatures for mycelial growth, sporulation, and conidial germination ranged from about 25 to about 33°C. All Colletotrichum species induced anthracnose symptoms on wounded cashew leaves, but none of them caused lesions on intact leaf surfaces. The Colletotrichum species, except for C. fragariae and C. fructicola, were pathogenic to wounded fruits of avocado, banana, guava, mango, and papaya, and some isolates also produced lesions on nonwounded fruit tissues. No symptoms were observed on passion fruits, regardless of the inoculation method. Mycelial growth, sporulation, conidial germination, and/or appressorial formation of the seven Colletotrichum species were inhibited by azoxystrobin, difenoconazole, and thiophanate-methyl to varying degrees. The present study will contribute to the development of forecasting models based on prevailing weather of cashew cropping zones and improve cashew anthracnose management in Brazil.     

Characterization and epidemiology of Colletotrichum acutatum sensu lato (C. chrysanthemi) causing Carthamus tinctorius anthracnose

In 2012, Colletotrichum isolates were collected from field‐grown safflower (Carthamus tinctorius) crops in central Italy from plants exhibiting typical anthracnose symptoms. Colletotrichum isolates were also collected from seed surfaces and from within seeds. The genetic variability of these isolates was assessed by a multilocus sequencing approach and compared with those from Colletotrichum chrysanthemi and Colletotrichum carthami isolates from different geographic areas and other Colletotrichum acutatum sensu lato‐related isolates. Phylogenetic analysis revealed that all of the strains isolated from C. tinctorius belonged to the species described as C. chrysanthemi, whereas all of the strains belonging to C. carthami had been isolated from Calendula officinalis. Phenotypic characterization of isolates was performed by assessing growth rates at different temperatures, morphology of colonies on potato dextrose agar (PDA) and the size of conidia. All C. chrysanthemi isolates from safflower had similar growth rates at different temperatures, comparable colony morphologies when grown on PDA and conidial sizes consistent with previously described C. chrysanthemi isolates. Pathogenicity tests were performed by artificially inoculating both seeds and plants and confirmed the seedborne nature of this pathogen. When inoculated on plants, C. chrysanthemi caused the typical symptoms of anthracnose on leaves. This is the first record of this pathogen on C. tinctorius in Italy, and it presents an updated characterization of Colletotrichum isolates pathogenic to safflowers in Europe.     

Characterization of Colletotrichum truncatum from papaya,pepper and physic nut based on phylogeny,morphology and pathogenicity

Colletotrichum truncatum (syn. C. capsici) has been identified as the causal agent of anthracnose on various hosts, predominantly pepper (Capsicum spp.) plants. The aim of this study was to determine whether C. truncatum isolates infecting papaya, pepper and physic nut in southeastern Mexico are morphologically, genetically and pathogenically different, in order to improve disease management strategies. A total of 113 C. truncatum isolates collected from five producer states were subjected to phenotypic characterization and divided into six different morphological groups. These morphological traits and the location of the isolates were used to select a subset of 20 isolates for further studies. Differences in the pathogenicity of the isolates were tested with a cross‐inoculation assay using pepper, papaya and physic nut. The pathogenicity tests revealed that all isolates could infect the three hosts and produce typical anthracnose symptoms, indicating a lack of host specificity for this species and therefore its pathogenic potential on other plants. Phylogenetic analysis using internal transcribed spacer (ITS) and glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) sequences of the C.   truncatum isolates from this study and reference strains was performed, grouping the isolates into a monophyletic clade. This study reports for the first time the characterization of C. truncatum causing anthracnose disease on three different hosts in Mexico.     

Acidified peel of litchi fruits selects for postharvestPenicillium decay

Litchi fruits are fumigated after harvest with sulfur dioxide (SO₂) to prevent their rapid browning. SO₂ blocks enzymatic activity but bleaches the fruits and, if this process is followed by dipping the fruit in dilute hydrochloric acid, the appealing red color is regained. Hot water brushing (HWB) is among the alternative methods that were developed to replace the use of SO₂. HWB reduced fungal population size on the surface of the fruit peel after treatment but did not eliminate fruit infection after storage. Whereas untreated fruits were infected with a variety of fungal species,Penicillium sp. was the only fungus that developed on the pericarp after storage in fruits that had been dipped in 1.5M HCl. Fruit treated by HWB followed by handling and storage under sterile conditions suffered greater decay than fruit stored under non-sterile conditions but with more ventilation. APenicillium sp. isolated from litchi grew well in liquid medium acidified to the pH range reported for SO₂ and HCl-treated litchi fruits. Morphological analysis identified fungal isolates asP. aurantiogriseum. Internal transcribed spacer sequence analysis of five isolates suggested a sequence similarity toP. commune. Our data support the hypothesis that dipping litchi fruit in hydrochloric acid eliminates infection by common opportunistic fungi and selects forPenicillium species that tolerate low pH. http://www.phytoparasitica.org posting April 30, 2004.     

Diversity of <Emphasis Type="Italic">Colletotrichum</Emphasis> species in coffee (<Emphasis Type="Italic">Coffea arabica</Emphasis>) plantations in Mexico

The aim of this study was to identify the Colletotrichum species associated with anthracnose symptoms in coffee (Coffea arabica L.) plantations in northern Puebla, Mexico. In 2013, five surveys were conducted in different production areas and at different altitudes. Symptomatic leaves, shoots, and ripe and unripe fruits of the coffee variety Red Caturra were collected. Isolates were obtained and the Colletotrichum species were identified morphologically and characterized by multilocus sequence analyses of the ACT, CAL, GAPDH, and TUB2 genes and the rDNA region. Additionally, pathogenicity tests were conducted using six isolates. We identified C. gigasporum, C. gloeosporioides, C. karstii (two isolates), C. siamense, and C. theobromicola. This is the first report of these five species infecting leaves of coffee. The symptoms caused by these species were characterized, but the species causing Coffee Berry Disease was not found. This is the first report of a complex of species affecting coffee plants in the same geographical area in Mexico, and suggests that other complexes of species may be important pathogens in coffee-producing areas elsewhere.     

Colletotrichum species causing anthracnose on avocado fruit in Mexico: Current status

Colletotrichum species cause anthracnose disease in tropical and subtropical fruit crops worldwide. Mexico is the main producer and exporter of avocado (Persea americana) globally and has yearly outbreaks of anthracnose on this crop. However, which specific Colletotrichum spp. cause these outbreaks in avocado-producing regions remain uncertain; thus, the objective of the present study was to identify the species responsible. A survey performed in six production regions of Mexico yielded 232 isolates, from which a subset of 104 strains was selected based on morphological characteristics and origin. This subset was sequenced and haplotypes were analysed in the gapdh partial gene. Finally, 31 strains were identified through multilocus phylogenetic analyses using the sequences of the internal transcribed spacer region and six loci. This study revealed the presence of two species previously reported in Mexico (C. karsti and C. godetiae), three novel records in Mexico (C. siamense, C. fioriniae, and C. cigarro), four novel records on avocado (C. chrysophilum, C. jiangxiense, C. tropicale, and C. nymphaeae), and two novel lineages (Colletotrichum sp. 1 and Colletotrichum sp. 2). C. siamense was the most prevalent, while the species reported for the first time on avocado, including the novel lineages, were the least prevalent. C. karsti was the most widespread (four regions), followed by C. siamense, C. jiangxiense, and C. chrysophilum (three regions). Pathogenicity tests showed that all species caused anthracnose on avocado fruit. These findings will be useful for improving the management of avocado anthracnose outbreaks in Mexico.     

Isolation and characterization of <Emphasis Type="Italic">Serratia rubidaea</Emphasis> from dark brown spots of tomato fruits

Bacterial contamination of fresh tomato fruits is of great concern. From naturally infected tomato fruits showing dark brown irregularly shaped spots, 36 bacterial isolates were recovered and identified on phenotypic characteristics and sequences of the gene encoding the 16S rRNA. Five isolates showing spots on tomato fruits in the pathogenicity test with healthy tomato fruits belong to the genus Serratia on the basis of phenotypic characteristics. One representative isolate of these has been further identified as a Serratia rubidaea by sequencing of the 16S rRNA gene. This is the first evidence showing that a S. rubidaea strain can cause spots on tomato fruits. Virulence of the S. rubidaea was also confirmed by the production and secretion of a large variety of enzymes capable of degrading the complex polysaccharides of the plant cell wall and membrane constituents. Nineteen bacterial isolates of the 36 did not induce any spot symptoms in a pathogenicity test on artificially infected tomato fruits although these are known as phytopathogenic bacteria. Five of these 19 bacterial isolates were identified as Ralstonia species on the basis of biochemical tests. Sequencing of the 16S ribosomal gene of one representative isolate revealed that the isolate is closely related to Ralstonia solanacearum. Six isolates of the 19 were related to Xanthomonas vesicatoria on the basis of biochemical tests and eight were related to the Enterobacteriaceae. One representative isolate of the Enterobacteriaceae could be identified by the 16S rRNA gene as Enterobacter cloacae subsp. dissolvens. The 12 other strains were related to Proteus mirabilis based on the 16S RNA gene sequence of one representative isolate. The isolates related to P. mirabilis did not produce any symptoms on artificially infected tomato fruits. The nucleotide sequences of S. rubidaea strain E9, E. cloacae strain E23, P. mirabilis strain E11, and R. solanacearum strain E15 have been deposited in the GenBank nucleotide sequence database under accession numbers HM585373 to HM585376.     

Identification and characterization of <Emphasis Type="Italic">Colletotrichum</Emphasis> spp. associated with chili anthracnose in peninsular Malaysia

Anthracnose fruit rot caused by Colletotrichum spp. is a serious post-harvest disease of chili fruits (Capsicum spp.). One hundred-thirty isolates of Colletotrichum spp. were isolated from anthracnose of green and red cayenne pepper (Capsicum annuum) and bird’s eye chili (Capsicum frutescens). The isolates were morphologically identified as Colletotrichum acutatum sensu lato (62 isolates), Colletotrichum truncatum (54 isolates), and Colletotrichum gloeosporioides sensu lato (14 isolates). Molecular identification and phylogenetic analyses were based on internal transcribed spacer regions, β-tubulin, actin, and glyceraldehyde-3-phosphate dehydrogenase genes, and the isolates were re-identified as C. scovillei (58 isolates), C. truncatum (54 isolates), C. siamense (11 isolates), C. fioriniae (four isolates), and C. fructicola (3 isolates). Maximum likelihood trees using combined sequences showed that isolates of the same species grouped in the same main clade with the isolates used for comparison. Pathogenicity testing showed that the tested isolates from each species were pathogenic towards green and red Capsicum annuum and Capsicum frutescens upon treatment of wounded fruit, using both the mycelial plug and conidial suspension methods. Only five isolates of C. truncatum and seven isolates of C. scovillei were found to be pathogenic upon treatment of unwounded fruit. The occurrence of five Colletotrichum spp. (C. siamense, C. fructicola, C. scovillei, C. fioriniae, and C. truncatum) associated with chili anthracnose in Peninsular Malaysia indicates that correct species identification is important to formulate not only effective disease management, but also effective quarantine policy.     

河北省苹果果实黑点病的症状与病原研究初报

为明确河北省苹果果实黑点病的症状类型及其对应的病原菌,本研究对河北省6个市的果园进行了病害调查和样品采集,并对引起不同症状类型的病果进行了病原菌的分离和鉴定.结果表明,河北省的套袋苹果黑点病可以分为四大类型,分别是萼洼黑点型、果面黑点型、果面晕斑型和梗洼褐斑型.除了果面晕斑型为单一病原侵染之外,其他类型的病斑均分离获得...     

Phenotypic,molecular and pathogenic characterization of Phlyctema vagabunda,causal agent of olive leprosy

Olive leprosy, caused by the fungus Phlyctema vagabunda, is a classic fruit rot disease widespread in the Mediterranean basin. From 2009 to 2013, new disease symptoms consisting of small circular necrotic leaf lesions, coin branch canker and shoot dieback were observed in Spanish and Portuguese olive orchards showing intense defoliation. Phlyctema‐like anamorphs were consistently isolated from leaves and shoots with symptoms. Representative isolates from affected leaves, shoots and fruits were characterized based on morphology of colonies and conidia, optimum growth temperature and comparison of DNA sequence data from four regions: ITS, tub2, MIT and rpb2. In addition, pathogenicity tests were performed on apple and olive fruits, and on branches and leaves of olive trees. Maximum mycelial growth rate ranged between 0.54 and 0.73 mm per day. Conidia produced on inoculated apple fruits showed slight differences in morphology among the representative fungal isolates evaluated. Phylogenetic analysis clustered all of the Phlyctema‐like isolates in the same clade, identifying them as Phlyctema vagabunda. On fruits, influence of wounding, ripening and cultivar resistance was studied, with cv. Blanqueta being the most susceptible cultivar. On branches, a mycelial‐plug inoculation method reproduced olive leprosy symptoms and caused shoot dieback. On leaves, Koch's postulates were fulfilled and the pathogen caused characteristic necrotic spots and plant defoliation. This is the first time that the pathogenicity of P. vagabunda in olive leaves has been demonstrated.