Effects of disease on different accessions of Cleome gynandra

Abstract

Background: Pathogenicity tests were conducted to ascertain the response of four Cleome gynandra accessions against pathogenic fungi, which were isolated from four areas of three different provinces of Zimbabwe.
Aim: The aim of this study was to further assess the pathogens effects on four different accessions of C. gynandra on pathogenicity, disease incidence and severity, to ascertain the extent of damage of pathogens on different accessions before commercial production of C. gynandra commences.
Setting: Fusarium chlamydosporum, Fusarium verticillioides, Albugo laibachii with red pustules and the other with green, Alternaria alternata, and Fusarium equiseti, Sarocladium striticum, Cladosporium pseudocladosporioides, Fusarium oxysporum, Alternaria senecionicola, isolates were evaluated to fulfil Koch’s postulates.
Methods: A total of 1 × 10⁻⁶ inoculum was taken soon after preparation and inoculated using a dressmaker’s pin to prick on 3, 15 cm plant stem’s xylem vessels per planting station, representing three replicates laid in a CRD. Disease progress was monitored for 42 days from the day of inoculation, on 7-day intervals.
Results: Upon analysis of variance, it was found that accessions significantly responded differently for both area under disease progress curve (AUDPC) and disease incidence to the isolates (p = 0.02; p = 0.009, respectively). There were interactive effects. Accession 4 (CG KENYA) obtained from the Republic of Kenya showed high susceptibility with a low AUDPC of 7.4 and the highest being 8.1 against the other Accession 3 (CGMRGP-Marondera) from Marondera, Zimbabwe, with a low AUDPC of 7.4 and the highest being 8.0, Accession 1 (CGZIM) from Chipinge, Zimbabwe, with a low AUDPC of 7.3 and the highest being 7.9, and Accession 2 (CGGUR) from Guruve, Zimbabwe, had least disease severity with a low AUDPC of 7.2 and the highest being 7.9.
Conclusion: Accessions 2 and 3 are recommended for further evaluations.
Contribution: Koch’s postulates were fulfilled, and the best accessions were selected.