Occurrence of Alternaria alternata (Fr.:Fr.) Keissl. on potato tuber in Brazil

Abstract

The Alternaria alternata has been already isolated from potato leaves, in Brazil, however, the occurrence of this fungus on potato tuber has never been reported. This study aimed at confirming the occurrence of A. Alternata in lesions present in potato tubers. Thus, lesions on the diseased tubers were examined in a stereomicroscope, in order to prepare semipermanent microscope slides by removing the mycelium and fungal structures found on the infected tuber tissue. The conidia presented the shape of an inverted pear, light brown, with dimensions of 19.7-45.4 x 8.5-18.6 µm (28.3 x 12.5 µm), and 2-6 (4) transversal and 1-5 (2) longitudinal septa, while the conidia beaks measures were 2.6-11.9 µm (4.4 µm). These features characterized the fungus as A. alternata.

Keywords

• Solanum tuberosum L.
• mycology
• potato early blight