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Cacao (Theobroma cacoa L.) is an important tropical fruit tree used in chocolate production. Among the biotic problems interfering with fruit production, phytopathogenic fungi stand out. During a visit to cocoa production areas in the municipality of Medicilândia, Pará, Brazil (Amazon region), we observed cocoa fruits with dark lesions and greyish‐white cottony mycelia growth. In order to determine the aetiological agent's identity, we extracted DNA and amplified part of the TEF‐1α and RBP2 genes and compared them with sequences in GenBank using the BLASTn tool. Based on molecular results and phylogenetic analysis, the isolates were identified as Calonectria hawksworthii. Inoculations in cacao fruits showed symptoms after 6 days and were similar to those collected in the field, confirming the postulates. This study is the first report of Ca. hawksworthii causing cocoa bean rot worldwide. [ABSTRACT FROM AUTHOR]

A high frequency of plants showing symptoms of wilting and root rot has been observed in tomato‐producing areas in Santarém and Belterra, Pará, Brazil. These plants showed symptoms ranging from yellowing to wilting, with roots displaying reduced development and darkening of the xylem. Four fungal isolates, derived from a collection of 12 obtained from symptomatic plants, were chosen for identification using both morphological and phylogenetic species concepts. To determine the identity of the fungi, DNA was extracted and used in PCR reactions. PCR products were sequenced from the TEF‐1α and RBP2 regions and compared with sequences in GenBank using BLASTn. Based on the phylogenetic analyses, the isolates were identified as Fusarium falciforme and Fusarium suttonianum, belonging to the species complex Fusarium solani – (FSSC), and Fusarium triseptatum, belonging to the species complex Fusarium oxysporum – (FOSC). The fourth isolate, COUFPI 295, grouped within a clade of F. kalimantanense and F. sangayamense from FOSC. The fulfilment of Koch's postulates confirmed that all isolates induced symptoms of root rot and concomitant reduction in root mass, leading to observable wilting symptoms. This is the first report of F. suttonianum, F. falciforme and F. triseptatum causing root rot and wilt in tomato plants in Brazil. [ABSTRACT FROM AUTHOR]

Isolates from the Fusarium fujikuroi species complex, mainly F. sacchari, have been reported to be the causal agents of pokkah boeng in sugarcane in Brazil. However, inadequate information was available on the occurrence and genetic diversity of F. sacchari in Northeast Brazil, which is a limiting factor on management. Thus, isolates of F. subglutinans sensu lato from sugarcane plants with symptoms of pokkah boeng were evaluated using the sexual cross‐fertility to determine species. All the isolates produced black perithecia when they were crossed with the test isolates of F. sacchari. Three weeks after the crossing, the formation of fertile ascospores cirri was observed. Thirty‐four isolates were self‐sterile hermaphrodites, while 21 were fertile only as males. Five isolates were homothallic. The effective size [Ne(f)] of the population as a function of the frequency of hermaphrodites and female sterile strains was 95.5%. The F. sacchari isolates were separated into four genetic groups independent of geographic location. The mean of polymorphism among all populations was 79%, and the average unbiased genetic diversity (uh) was considered moderate (0.31). This study in addition to confirming that F. sacchari as the main species associated with pokkah boeng in sugarcane in Northeast Brazil, reveals the relationship of mating type and genetic diversity of F. sacchari. The unrestricted gene flow between regions is probably the best explanation for the low geographic correlation. This knowledge will help in the adoption of management measures with fungicides or resistant cultivars. [ABSTRACT FROM AUTHOR]

Fourteen Rhizoctonia isolates obtained from coriander plants with symptoms of damping-off and web blight were collected in vegetable production areas between the years 2015 and 2017 in five geographical regions of Brazil. Identification was performed using phylogenetic analysis of the internal transcribed spacer region of ribosomal DNA, evaluation of morphological characteristics and pathogenicity test. Phylogenetic analysis revealed seven isolates belonging to the AG4-HGI group and two isolates to the AG2-2LP group; two isolates of the genus Rhizoctonia did not group with any anastomosis group, representing a new lineage, and two Waitea sp. isolates and one binucleate isolate grouped with Ceratobasidium ramicola. Based on nuclear staining, thirteen isolates were multinucleated, while one isolate was binucleated. The isolates of Rhizoctonia produced irregularly shaped and brown sclerotia, while the Waitea isolate produced orange sclerotia. In plants the formation of hymenia with the presence of unicellular basidiospores was observed. The basidiospore-producing fungus is represented by the new phylogenetic lineage of Rhizoctonia. All isolates were pathogenic in coriander seedlings, causing damping-off. This is the first report of Rhizoctonia solani (AG4-HGI and AG2-2LP), Waitea sp and C. ramicola in coriander in Brazil. [ABSTRACT FROM AUTHOR]

Sansevieria trifasciata plants showing symptoms of leaf blight were observed in Teresina City, Brazil. Based on morphology and the phylogenetic analysis of DNA sequences of the EF-1α and ITS regions, two isolates of Neoscytalidium dimidiatum were identified. Pathogenicity tests showed that the isolates caused leaf blight on S. trifasciata, in addition to Sansevieria cylindrica, and fulfilled Koch's postulates. To the best of our knowledge, this report is the first to describe N. dimidiatum on Sansevieria in Brazil. [ABSTRACT FROM AUTHOR]

Fusarium verticillioides is an important plant pathogen causing infections on ears and/or stalks of maize. This study aimed to compare sexual reproduction parameters in populations of F. verticillioides from distinct regions in the different Brazilian climatic zones where maize is grown. Fertility and effective population size were calculated from data generated by crossing field isolates with female fertile testers. Three hundred fungi isolates were obtained from maize kernels with Fusarium ear rot symptoms in different geographic regions of Brazil in the years 2012 and 2013. For the entire population, 231 out of 300 isolates were cross-fertile with tester isolates. MAT1–1 and MAT1–2 idiomorphs of the fertile isolates segregated in a 105:126 ratio. Female isolates (hermaphrodites) accounted for 96 out of 231 fertile isolates, while 135 were male-only isolates. The ratio of mating types within the population [Ne(mt)] was 99% of the count for the Brazilian population when the mating type idiomorphs were used as predictors to estimate the population size. However, when this calculation was made on the basis of the female fertile isolates, the Ne(f) was 83%. When the total population was divided by geographical/climatic regions, the frequencies of female fertile isolates were 33 out of 80 fertile isolates from the Northeast (equatorial tropical climate); 49 out of 73 fertile isolates from the Central-West (tropical climate); and only 14 out of 78 fertile isolates from the South (temperate climate), indicating that the sexual reproduction in F. verticillioides is likely favored by a tropical climate in Brazil. Brazilian populations of F. verticillioides show high fertility and high effective population size, suggesting the possibility of frequent sexual reproduction in the field, especially in populations from Tropical Climate regions of Brazil. [ABSTRACT FROM AUTHOR]

Fusarium udum is the causal agent of a wilt disease on pigeon pea (Cajanus cajan) in tropical regions. This species shares morphological characteristics with F. oxysporum, leading to misidentification when the diagnosis is solely based on morphological markers. The sexual stage of this fungus was observed on stems of Cajanus in India and was formally described as Gibberella indica. In Brazil, a wilt disease is reported on Crotalaria, but the etiological agent has not been identified correctly so far. In this study, we tested the hypothesis that the causal agent of a wilt on Crotalaria belongs to the same species pathogenic to C. cajan. Strains obtained from diseased Crotalaria spp. were characterized through molecular phylogeny of TEF, TUB and RPB2, laboratory crosses, morphological markers, and pathogenicity tests. Strains from Crotalaria from Brazil formed a well-supported clade with F. udum strains from Crotalaria and Cajanus from other countries. Strains from Brazil intercrossed among themselves and also with others from all geographic regions, and formed fertile perithecia, defining a distinct mating population inside the Fusarium fujikuroi species complex. One strain obtained from Cajanus cajan in India is indicated as epitype, and female-fertile tester strains of both mating types were selected for the identification of field isolates through sexual crosses. These results confirm that the species associated with wilt disease on Crotalaria and Cajanus is F. udum. Wilt symptoms caused by F. udum in Cr. ochroleuca are described and illustrated. [ABSTRACT FROM AUTHOR]