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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]

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]

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]

Sooty moulds are saprophytic epiphytic fungi that grow mostly on insect secretions, but they can also be associated with plant secretions. In this study, we aimed to describe de interaction of Capnodium alfenasii sooty mould with the extrafloral shoot nectaries of Azadirachta indica. Anatomical and histochemical studies were carried out on serial sections of extrafloral shoot nectaries of A. indica without and with C. alfenasii infestation. The total soluble sugar content of the secreted nectar was determined, and the conidial germination of the fungus in distilled water and in dextrose and nectar solutions was evaluated. The shoot nectaries of A. indica are elongated structures that occur in pairs near the base of the petiole. The exuded nectar contains an average of 534.8 µg of total soluble sugars per µL of nectar and provides ideal conditions for conidial germination and fungal growth. C. alfenasii hyphae grow on the nectary, penetrate through breaks in the cuticle, travel under the cuticle and penetrate the secretory tissue by inter- and intracellular routes. The present report is the first to describe the interaction of C. alfenasii with the A. indica nectary, including the penetration of hyphae into nectariferous tissues and the plant defence mechanisms. [ABSTRACT FROM AUTHOR]