Species of the Colletotrichum gloeosporioides and C. boninense complexes associated with olive anthracnose

The taxonomic status of Colletotrichum gloeosporioides sensu lato (s.l.) associated with olive anthracnose is still undetermined and the pathogenic ability of this species complex is controversial. In the present study, isolates obtained from olive and provisionally identified as C. gloeosporioides s.l. on the basis of morphological and cultural features were reclassified using ITS and TUB2 as DNA barcode markers and referred to seven distinct species, recently separated within C. gloeosporioides (C. aenigma, C. gloeosporioides sensu stricto (s.s.), C. kahawae, C. queenslandicum, C. siamense and C. theobromicola) and C. boninense (C. karstii) species complexes. Furthermore, isolates of C. kahawae were ascribed to the subspecies ciggaro by analysing the GS gene. A single isolate, not in either of these two species complexes, was not identified at the species level. In pathogenicity tests on detached olive drupes some of these species, including C. aenigma, C. kahawae subsp. ciggaro, C. queenslandicum, C. siamense and C. karstii, were shown to be weakly pathogenic. Moreover, they were found very sporadically on olive. In contrast, some isolates of C. gloeosporioides s.s. and isolates of C. theobromicola proved to be virulent on both green and ripening olives. This study gives a better insight into both the aetiology and the epidemiology of olive anthracnose and might have implications for biosecurity and quarantine because C. theobromicola has never been reported in major European olive‐producing countries.     

Chili anthracnose: Colletotrichum taxonomy and pathogenicity

Chili anthracnose is caused by Colletotrichum species mostly associated with the acutatum, truncatum and gloeosporioides complexes. Since 2009 the Colletotrichum taxonomy has been extensively revised based on multigene phylogenetics, which has had a large impact on the number of species known to cause anthracnose disease of chili. This review discusses (i) the taxonomy of Colletotrichum spp. infecting chili, and (ii) the impact of Colletotrichum pathotypes on breeding for resistance to anthracnose. To date, 24 Colletotrichum species have been identified as pathogens of chili anthracnose, with the three main pathogens being C. scovillei, C. truncatum and C. siamense. Identification of several pathotypes within these three Colletotrichum species, particularly pathotypes that can overcome resistance in the related Capsicum species, Ca. chinense and Ca. baccatum, will be of major concern to plant breeders as they develop resistant chili genotypes from the transfer of resistance genes from these Capsicum species into Ca. annuum. Accurate identification of the Colletotrichum species causing anthracnose and improved understanding of the biology of the Colletotrichum species and their interaction with the host will enable the application of improved integrated disease management techniques.     

Lack of host specificity of Colletotrichum spp. isolates associated with anthracnose symptoms on mango in Brazil

The aim of the present study was to analyse the genetic and pathogenic variability of Colletotrichum spp. isolates from various organs and cultivars of mango with anthracnose symptoms, collected from different municipalities of São Paulo State, Brazil. Colletotrichum gloeosporioides isolates from symptomless citrus leaves and C. acutatum isolates from citrus flowers with post‐bloom fruit drop symptoms were included as controls. Sequencing of the ITS region allowed the identification of 183 C. gloeosporioides isolates from mango; only one isolate was identified as C. acutatum. amova analysis of ITS sequences showed larger genetic variability among isolates from the same municipality than among those from different populations. fAFLP markers indicated high levels of genetic variability among the C. gloeosporioides isolates from mango and no correlation between genetic variability and isolate source. Only one C. gloeosporioides mango isolate had the same genotype as the C. gloeosporioides isolates from citrus leaves, as determined by ITS sequencing and fAFLP analysis. Pathogenicity tests revealed that C. gloeosporioides and C. acutatum isolates from either mango or citrus can cause anthracnose symptoms on leaves of mango cvs Palmer and Tommy Atkins and blossom blight symptoms in citrus flowers. These outcomes indicate a lack of host specificity of the Colletotrichum species and suggest the possibility of host migration.     

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.     

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.     

A new anthracnose disease of pyrethrum caused by Colletotrichum tanaceti sp. nov

A new pathogen of pyrethrum (Tanacetum cinerariifolium) causing anthracnose was described as Colletotrichum tanaceti based on morphological characteristics and a four‐gene phylogeny consisting of rDNA‐ITS, β‐tubulin (TUB2), glyceraldehyde‐3‐phosphate dehydrogenase (GAPDH) and actin (ACT) gene sequences. The fungus produced perithecia in culture, requiring an opposite mating type isolate in a heterothallic manner. The initial infection strategy on pyrethrum leaves involved the formation of appressoria followed by production of multilobed infection vesicles in the epidermal cells. Infection and colonization then proceeded through thinner secondary hyphae, which resulted in the initial production of water‐soaked lesions followed by black necrotic lesions. The infection process was suggestive of a hemibiotrophic infection strategy. Moreover, phylogenetic analysis clearly showed that C. destructivum, C. higginsianum and C. panacicola were separate species that also had similar intracellular hemibiotrophic infection strategies as C. tanaceti, which all clustered in the C. destructivum complex. Colletotrichum spp. were detected at 1% incidence in seed of 1 of 19 seed lines, indicating the potential for seed as a source of inoculum into crops. Colletotrichum tanaceti was detected in leaf lesions from 11 of 24 pyrethrum fields surveyed between April and July 2012, at a frequency of 1·3–25·0% of lesions. Anthracnose probably contributes to the complex of foliar diseases reducing green leaf area in pyrethrum fields in Australia.     

Most Colletotrichum species associated with tree tomato (Solanum betaceum) and mango (Mangifera indica) crops are not host‐specific

An important constraint for crop production in Colombia is the high incidence of anthracnose caused by Colletotrichum species. Although several studies have focused on these fungi, the relationship between the different fungal species within the genus and their hosts and whether they display any host preference or host specificity has yet to be examined. In Colombia, diseases caused by Colletotrichum species are particularly severe in mango (Mangifera indica) and tree tomato (Solanum betaceum) crops. In a previous investigation, the Colletotrichum phylogenetic species attacking these crops were identified. The present study aimed to determine whether isolates collected from tree tomato and mango showed host preference or host specificity by assessing aggressiveness, spore density, latent period, and fitness of each strain on the two hosts. In the departments of Cundinamarca and Tolima, Colombia, isolates were collected from plants that presented typical anthracnose symptoms and were identified as C. acutatum, C. asianum, C. boninense, C. gloeosporioides, C. tamarilloi and C. theobromicola. Inoculation of conidia of each isolate onto both hosts showed isolates had no host preference and only the C. gloeosporioides isolate showed host specificity. However, in general, isolates produced a higher spore density when inoculated on the alternate host, which may indicate a difference in the degree of adaptation to each host. Statistical analyses of the assessed parameter values revealed that isolates use different infection strategies when infecting each host. In light of these results, the implications of using quantitative estimations of fitness when studying fungal pathogens are discussed.     

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.     

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.     

A quantitative real‐time PCR assay for detection of Colletotrichum lindemuthianum in navy bean seeds

Bean anthracnose is a seedborne disease of common bean (Phaseolus vulgaris) caused by the fungal pathogen Colletotrichum lindemuthianum. Using seed that did not test positive for the pathogen has been proven to be an effective strategy for bean anthracnose control. To quantify the extent of anthracnose seed infection, a real‐time PCR‐based diagnostic assay was developed for detecting C. lindemuthianum in seeds of the commercial bean class navy bean. The ribosomal DNA (rDNA) region consisting of part of the18S rDNA, 5^.8S rDNA, internal transcribed spacers (ITS) 1, 2 and part of the 28S rDNA of seven races of C. lindemuthianum, 21 isolates of Colletotrichum species and nine other bean pathogens were sequenced with the universal primer set ITS5/ITS4. Based on the aligned sequence matrix, one primer set and a probe were designed for a SYBR Green dye assay and a TaqMan MGB (minor groove binder) assay. The primer set was demonstrated to be specific for C. lindemuthianum and showed a high sensitivity for the target pathogen. The detection limit of both assays was 5 fg of C. lindemuthianum genomic DNA. To explore the correlation between the lesion area and the DNA amount of C. lindemuthianum in bean seed, seeds of the navy bean cultivar Navigator with lesions of different sizes, as well as symptomless seeds, were used in both real‐time PCR assays.     

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.     

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.     

Molecular and phenotypic characterization revealed six <Emphasis Type="Italic">Colletotrichum</Emphasis> species responsible for anthracnose disease of small cardamom in South India

Small cardamom (Elettaria cardamomum Maton) is extensively cultivated in the Western Ghats of South India either as a monocrop under the forest trees or as an intercrop along with arecanut and coffee plantations. Colletotrichum species responsible for severe outbreaks of anthracnose on small cardamom in South India are reported. Small cardamom anthracnose, popularly known as “Chenthal”, manifests itself on the foliage as yellowish lesions, which later coalesce to form large blighted areas. In advanced stages, the affected leaves dry up giving a burnt appearance to the plant. Twenty-five isolates of Colletotrichum were isolated from leaves of small cardamom in Karnataka, Kerala and Tamil Nadu states of India. The isolates were characterized through morphological studies and multilocus phylogenetic analysis (ITS, ACT, CHS-1, GAPDH, TUB2, CYLH3, GS and ApMat gene regions) to test whether different species are present and identified: C. karstii (2 isolates), C. gloeosporioides (1), C. siamense (7), C. syzygicola (6), Colletotrichum sp (5), and C. guajavae (4), as the cause of anthracnose on small cardamom for the first time. Pathogenicity of the six species was confirmed. To our knowledge, this is the first detailed study of Colletotrichum species which cause anthracnose diseases on small cardamom.     

Species from the Colletotrichum acutatum,Colletotrichum boninense and Colletotrichum gloeosporioides species complexes associated with tree tomato and mango crops in Colombia

Colletotrichum species cause typical anthracnose symptoms in tree tomato and mango. To characterize species of Colletotrichum in these two crops in Colombia, 91 isolates were collected from several localities. Phylogenetic analyses using nuclear gene sequencing of the ITS region and the glyceraldehyde 3‐phosphate dehydrogenase (GAPDH) gene allowed the identification of three groups: acutatum, gloeosporioides and boninense. These three groups were further confirmed using two additional genomic regions (chitin synthase 1 and actin) for 30 isolates representative of the three previously identified complexes and one genomic region (ApMat) for the Colletotrichum gloeosporioides complex strains. The entire approach permitted a robust strain identification that allowed phylogenetic species recognition (PSR) based on the identification of well‐supported monophyletic clades and concordance between individual and multilocus phylogenies. Morphological and physiological assays were also conducted. Isolates that were morphologically identified as C. gloeosporioides showed high phenotypic diversity. Pathogenicity data revealed a considerable degree of host preference.     

Identification of Colletotrichum siamense causing litchi pepper spot disease in mainland China

Litchi (Litchi chinensis) pepper spot disease results in black spotting symptoms on litchi fruits. This disease was first observed on litchi cultivar Guiwei, in Guangzhou, China, in 2009, and then found widespread in other litchi-growing regions of China. Colletotrichum isolates were consistently recovered from typical black spot lesions of diseased fruits with frequency ranging from 83% to 100%. Three representative Colletotrichum isolates from Maoming, Guangzhou and Shenzhen were selected for identification and pathogenicity testing in the field. Based on morphology and phylogenetic analysis using the ribosomal internal transcribed spacer region (ITS), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), calmodulin (CAL), actin (ACT), β-tubulin (TUB2) and glutamine synthetase (GS) gene sequences, the three isolates were identified as C. siamense. In the pathogenicity experiments, typical symptoms appeared on the inoculated litchi fruits, including black spots and green patches around these black spots. These symptoms were consistent with the symptoms originally observed in the field. Colletotrichum siamense was successfully reisolated from the typical black spot lesions of the inoculated litchi fruits. To the authors' knowledge, this is the first report on characterization of C. siamense as the causal agent of litchi pepper spot disease in mainland China by successful inoculation on fruits under field conditions.     

Ribosomal DNA Sequence Comparisons of Colletotrichum Graminicola from Turfgrasses and other Hosts

The 5.8S ribosomal gene and the flanking internal transcribed spacers (ITS) 1 and 2 from Colletotrichum graminicola isolates causing anthracnose disease of Agrostis palustris and Poa species were sequenced. Although bootstrap support was not high, two major groups were observed with both UPGMA and parsimony algorithms, one containing isolates from A. palustris and another with isolates from Poa spp. The ITS sequences were also compared with those of isolates of C. graminicola and C. sublineolum from Sorghum spp., Zea mays and Rottboellia cochinchinesis as well as other Colletotrichum species. Except for one isolate from P. annua in Texas, the ITS1 and ITS2 sequences of turfgrass isolates always grouped separately from C. graminicola or C. sublineolum from non-turfgrass hosts with high bootstrap support. ITS sequences of the turfgrass isolates were more similar to those of other species of Colletotrichum, such as C. coccodes and C. dematium, than they were to C. graminicola isolates from other hosts. Turfgrass isolates have ITS sequences which are not identical to those of isolates from Zea mays and Sorghum species demonstrating diversity among fungi conventionally classified as C. graminicola.     

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.     

Identification and characterization of Colletotrichum species associated with anthracnose disease of banana

Banana (Musa spp.) is one of the five most abundantly produced fruits in the world and is widely planted in tropical and subtropical areas. Banana anthracnose is one of the main diseases during the growth and postharvest storage period of banana, seriously affecting quality and production. In this study, 24 samples of banana anthracnose were collected near the cities Nanning, Qinzhou, Baise, and Chongzuo in Guangxi Province, China. Based on colony features, conidial and appressorial morphology, and sequence analysis of several genomic regions (internal transcribed spacer [ITS] region, glyceraldehyde-3-phosphate dehydrogenase [GAPDH], actin [ACT], β-tubulin [TUB2], chitin synthase [CHS-1], calmodulin [CAL], and the intergenic region of apn2 and MAT1-2-1 [ApMAT]), the 32 Colletotrichum isolates obtained were identified as five species: C. fructicola (41%), C. cliviicola (28%), C. siamense (16%), C. karstii (9%), and C. musae (6%). A conidial suspension (10⁶ spores/ml) was used to inoculate banana seedlings for pathogenicity tests by applying 20 μl to wound sites. Lesions caused by C. musae developed most rapidly while those of C. karstii took the longest time to develop. This is the first report of C. siamense, and C. karstii associated with banana anthracnose in China, and the first report of C. fructicola and C. cliviicola associated with banana anthracnose worldwide.     

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.     

Characterization of Alternaria species associated with potato foliar diseases in China

The population structure of Alternaria species associated with potato foliar diseases in China has not been previously examined thoroughly. Between 2010 and 2013, a total of 511 Alternaria isolates were obtained from diseased potato leaves sampled in 16 provinces, autonomous regions or municipalities of China. Based on morphological traits and molecular characteristics, all the isolates were identified as Alternaria tenuissima, A. alternata or A. solani. Of the three species, A. tenuissima was the most prevalent (75·5%), followed by A. alternata (18·6%) and A. solani (5·9%). Phylogenetic analysis based on sequences of the internal transcribed spacer (ITS) region of ribosomal DNA (rDNA) of representative Alternaria isolates showed that A. solani was distinct from the two small‐spored Alternaria species. Phylogenetic analysis of the partial coding sequence of the histone 3 gene divided the same collection of isolates into three main clades representing A. tenuissima, A. alternata and A. solani, respectively. The pathogenicity of the isolates on detached leaves of potato cv. Favorite did not differ significantly between the three species or between isolates from different geographical origins. The results indicate that the population structure of Alternaria species associated with potato foliar diseases differs from that reported previously in China. This is the first report of A. tenuissima causing potato foliar diseases in China.