ABSTRACT
A survey to investigate the occurrence of cassava anthracnose disease (CAD) and distribution of Colletotrichum spp. in cassava plantations in different eco-zones of the Reconcavo Region in Bahia, Brazil, investigated during the rainy season of 2014. A total of 50 cassava fields distributed among 18 municipalities were visited and intensity of anthracnose evaluated. The highest disease incidence (DI) (83.3%) was in samples collected in São Félix, and the lowest (34.4%), in Varzedo. Municipalities that presented the highest values for DI were located within the 'Af' Köppen-Geiger eco-zone, also presenting the highest values for the estimated McKinney disease index. Based on previous studies of multilocus phylogeny, seven different species of Colletotrichum were identified (Colletotrichum fructicola, Colletotrichum tropicale, Colletotrichum gloeosporioides s.s, Colletotrichum theobromicola, Colletotrichum siamense, Colletotrichum brevisporum and Colletotrichum plurivorum) and a new approach based on ERIC-PCR was used aiming to group the 82 isolates according to these findings. The highest percentage of genetic variance (> 78%) was among isolates within fields. Based on the survey and genetic analysis, C. fructicola is probably the main causal agent of cassava anthracnose in the Recôncavo Region, since this species was present with highest incidence in all eco-zones, 47.61, 42.86 and 57.14% for Af (tropical rainforest climate), As (tropical dry savanna climate) and Aw (tropical wet savanna climate), respectively. This study is the first report of C. fructicola lineages as the most likely pathogen causing anthracnose disease of cassava in Brazil, and these findings may be used to guide the selection of resistant varieties.
ABSTRACT
The objective of this work was to accomplish the isolation, molecular identification and characterizing the physiology of the causal agent of the algal spot in mango trees. For this purpose, the pathogen growth was assessed in different culture media, with subsequent observation and measurements of the filamentous cells. The molecular identification was made using mycelium obtained from leaf lesions and pure algae colonies grown in culture medium. Descriptions based on DNA sequencing indicated that the algae is Cephaleuros virescens. The algae must be isolated primarily in liquid medium for further pricking into agar medium. The highest mycelial growth average in Petri dishes occurred when the algae were grown in Trebouxia and BBM. Trebouxia enabled larger cells in the filamentous cells when compared to other culture media.
