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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]

The peach palm (Bactris gasipaes Kunth) is a palm of great importance to the population of the Brazilian Amazon region. Its fruits are an important food source for the local population (Alves and Flores, 1982). Between 2018 and 2021, peach palm fruits with black rot symptoms were collected in the state of Pará, in the municipalities of Juruti (02 0 09' 08'' S 56 0 05' 32W) and Santarém (2 0 26' 22''S 54 0 41' 55''W), Brazil. Symptomatic fruits detach easily from the bunch. When sectioned, tissues with black coloration and mycelia with white to black coloration were found (Fig. 1a-b). The incidence of the disease in orchards ranged from 5 to 50%. Then, direct isolation, was done by transferring fragments of mycelia and spores to a plate containing potato dextrose agar (PDA). Morphological markers of the asexual phase were evaluated by cultivating the isolates in malt extract agar (MEA) with fragments of Saccharum officinarum culm (Mbenoun et al., 2014). The colonies initially showed a white coloration but turned dark after eight days of cultivation. Colonies produced white mycelia with hyaline, unicellular, rectangular primary conidia (5.6-8.8 µm) (n=30) in length and 2.8-4.0 µm (n=30) in width (Fig. 1e). In the dark-colored mycelia, secondary conidia that formed exhibited three distinct shapes: cylindrical, light brown, and (6.6-11.6 µm x 3.0-3.7 µm) (n=30) (Fig 1. f-i); oblong to globose shape (5.0-10.0 x 3.0-5.3 µm) (n=30) (Fig 1. g); and ellipsoid-shaped (7.0-13.0 x 3.0-4.0 µm) (n=30) (Fig 1. h). Furthermore, unicellular aleuroconidia, produced in dark-colored colonies, exhibited cell walls (10.8-17.5 x 5.4-8.4 µm) (n=30) with a warty, dark-brown, ovoid-shaped appearance (Fig 1. j-k). Genomic DNA was isolated from 4-day-old cultures, and ITS-rDNA and TEF-1α were amplified from ITS1/ ITS2 (White et al., 1990) and EF1F/EF2R (Jacobs et al., 2004), respectively. Sequences were deposited in GenBank (ITS: OL623838, OL623839, OM643316, OL623840, and OL623841) (TEF1: OL631623, OM643318, OM643317, OL631624, and OL631625). Bayesian analysis concatenated were conducted with MrBayes v. 3.2.7 (Ronquist et al., 2011). Clustered the five isolates with the Thielaviopsis ethacetica reference isolate IMI 50560 with Bayesian posterior probability (Bpp = 0.99). (Fig. 2). The pathogenicity test, was conducted using the five isolates, that were were inoculated on six fruits early maturity. After the fruit were washed with neutral detergent and water, 0.5-cm-deep wounds were made with a sterile penknife. Next, 1 mL of primary and secondary conidia suspension at 1 x 105 spores/mL was added to each wound. Six control fruit were inoculated with distilled water. The fruits were kept in incubators at 25 °C with a 12 h photoperiod. The experiment was conducted twice (Alves and Flores, 1982). After five days of inoculation, all inoculated fruit showed characteristic symptoms (Fig 1. c), whereas the control fruit remained asymptomatic (Fig 1. d). The fungus reisolated from all inoculated fruit exhibited the same morphological markers as the inoculated fungus, thus completing Koch's postulates. Thielaviopsis ethacetica is an important pathogen in several palm species in sugarcane and pineapple crops in different parts of the world (Mbenoun et al., 2014; Borgens et al., 2019). This study is the first record of T. ethacetica causing black rot in B. gasipaes fruit in Brazil.