DFNet

June 04, 2024 | Crop Protection |

Scientists at the Federal University of Pelotas in Brazil undertook a study to determine the cause of stem canker in pitaya (Hylocereus costaricensis) in the region of Pará, Brazil. Pitaya, a cactus cultivated in tropical and subtropical regions, has seen increased orchard installations across Brazil, with some diseases linked to phytopathogens reported. In Pará, a fungus resembling the genus Neoscytalidium was frequently associated with stem canker symptoms in pitaya.

To identify the pathogen, researchers isolated it from symptomatic pitaya cladodes and conducted macroscopic and microscopic analyses, molecular analysis, and pathogenicity tests. The pathogen exhibited rapid growth on potato dextrose agar (PDA), with light gray colonies turning dark gray over 14 days. Microscopic evaluation revealed septate and branched hyphae, and ellipsoid to ovoid conidia with smooth walls, typically measuring 7.2-12x3-7.8μm.

Molecular analysis using ITS and TUB2 sequences showed 100% identity with Neoscytalidium dimidiatum, confirmed by BLAST analysis. Phylogenetic analysis placed the isolate close to those from China and Vietnam. Pathogenicity tests confirmed Neoscytalidium dimidiatum as the causal agent of stem canker in pitaya in Pará. These findings provide a basis for future studies on managing this disease.

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