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Characterization of Pythium spp. associated with root rot of tobacco seedlings produced using the float tray system in Zimbabwe
Author(s) -
Mufunda Fortunate,
Muzhinji Norman,
Sigobodhla Tertu,
Marunda Mike,
Chinheya Cleopas Chenayi,
Dimbi Susan
Publication year - 2017
Publication title -
journal of phytopathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.53
H-Index - 60
eISSN - 1439-0434
pISSN - 0931-1785
DOI - 10.1111/jph.12613
Subject(s) - metalaxyl , pythium , pythium aphanidermatum , biology , fungicide , root rot , azoxystrobin , potato dextrose agar , internal transcribed spacer , damping off , horticulture , botany , seedling , agar , phylogenetic tree , biological pest control , biochemistry , genetics , bacteria , gene
The study was undertaken to identify and characterize Pythium isolates associated with root rot disease of tobacco seedlings as a first step towards developing management strategies for the pathogen. A total of 85 Pythium isolates were collected from diseased tobacco seedlings during 2015–2016 tobacco growing season. The isolates were identified to species level using sequencing of the internal transcribed spacer region. Thereafter, a subset of the isolates was tested for sensitivity to the commonly used fungicides, metalaxyl, azoxystrobin and a combination of fenamidone/propamocarbby growing isolates on Potato Dextrose Agar plates amended with the fungicides. The sequence analysis of the ITS ‐ rDNA identified Pythium myriotylum as the dominant Pythium species associated with the root rot of tobacco seedlings in Zimbabwe . Pythium aphanidermatum and P. insidiosum were also identified albeit at lower frequencies. Phylogenetic analyses of the ITS region of the P. myriotylum isolates showed little sequence diversity giving rise to one distinct clade. The fungicide sensitivity tests showed that metalaxyl provided the best control of P. myriotylum in vitro, as compared to other fungicides. To the best of our knowledge, this is the first comprehensive study to determine and characterize Pythium species associated with root rot of tobacco in the float seedling production system in Zimbabwe.