Abstract

Potato (Solanum tuberosum) and tobacco (Nicotiana tabacum) are important crops that contribute significantly to Zimbabwe’s economic development. However, they are attacked by Fusarium species leading to reduced yields, quality and profitability for farmers. A study was conducted to investigate the diversity of Fusarium spp. causing wilt and rots in both crops in Zimbabwe. Plants displaying symptoms of wilting, root and tuber rots were collected during nationwide disease surveys. Fusarium spp.  were isolated and characterized morphologically, using pathogenicity tests and DNA sequencing targeting the internal transcribed spacer (ITS) region. Morphological characterization revealed the presence of Fusarium spp. that produced brown, grey, white and pink colonies on PDA. They also produced conidia of different shapes. All the Fusarium isolates induced some rotting, yellowing, and wilting in potatoes. Seven Fusarium spp., namely Fusarium falciforme, Fusarium foetens, Fusarium fujikuroi, Fusarium perseae, Fusarium longifundum, Fusarium nygamai, and Fusarium chlamydosporum, were identified through DNA sequencing. Furthermore, F. falciforme was most (41.67%) prevalent on tobacco, while F. foetens (25%) and F. fujikuroi (12.5%) were detected in both crops. This study highlighted the wide diversity of Fusarium spp. infecting potatoes and tobacco in Zimbabwe thus providing a base for developing management strategies against the pathogens. The 24 partial ITS sequences deposited in the GenBank database will be used in future studies to understand the diversity of Fusarium spp.

Key words: Fusarium, Internal-Transcribed-Spacer Region, mycotoxins, potato, tobacco, Zimbabwe.