Response of Selected Pyrethrum Genotypes to Bud, Wilt and Crown Rot Diseases under Controlled Conditions

Abstract

Fungal infections specifically bud disease, wilt, and crown rot are the major contributors to the reduction in both the quality and quantity of pyrethrin production, affecting many farmers in Kenya and globally. This study aimed to evaluate the pathogenicity of dominant fungal species collected from farmers' fields and assess how selected pyrethrum genotypes respond to these diseases. A greenhouse trial was conducted using completely randomized design in a split-plot layout, where genotypes served as main plots and fungal species as subplots, each replicated three times. Bud disease was evaluated two weeks after inoculation using a 1–3 scale, crown rot was assessed after two months on a 0 – 2 scale, and wilt disease was monitored every two weeks over 126 days using a 0 – 6 scale. Data collected focused on both pathogen aggressiveness and genotype responses. Among the fungi tested, Fusarium oxysporum was the most virulent, causingsevere wilt, followed by Fusarium solani and Fusarium avenaceum. Clone 4 demonstrated the highest tolerance to wilt, followed by Clones 3, 1, 2, and lastly P4. In terms of resistance to bud disease, the ranking from most to least tolerant was Clone 4, Clone 1, Clone 2, Clone 3, and P4. For crown rot, susceptibility increased in the order of Clone 4, Clone 3, Clone 1, Clone 2, and P4. The variability in pathogenic aggressiveness is attributed to the genetic diversity among the fungal species. Likewise, differences in resistance levels among genotypes are due to varying genetic traits. Utilizing tolerant genotypes presents a sustainable approach to managing these fungal diseases. Further research is recommended to identify the specific genes responsible for resistance, which could be valuable in future crop improvement programs