Indigenous fungi with antagonistic potential against potato cyst nematodes in Kenya

Potato (Solanum tuberosum), which is the second most important food crop in Kenya, has various production constraints including potato cyst nematodes (PCN). This nematode which was first reported in 2014 is now ranked highest. The main option for managing nematode pests is use of synthetic nematicides but their usage is being phased out due to environmental risks, human health concerns, availability and cost. Thus, the need to develop safe, affordable and effective management strategies is very critical. Management of cyst nematodes using biological control agents is a viable alternative. The objective of the study was therefore to test the efficacy of indigenous nematophagous fungi against potato cyst nematodes in Kenya. Potato cyst nematodes were extracted by floatation from soil samples collected from major potato growing areas. Fungi were isolated from cysts by plating them on Potato Dextrose Agar (PDA). The effects of fungal suspensions on juvenile mortality was then determined. Completely Randomized Design (CRD) was used for the in vitro tests. Data were subjected to Analysis of Variance (ANOVA) using SAS version 9.1. Means were separated using Fisher’s protected Least Significance Difference (LSD) test at Pd”0.05. Fungi in nine genera were found associated with PCN; Trichoderma sp, Aspergillus sp, Fusarium sp, Penicillium sp, Paecilomyces sp, Acremonium sp, Chaetomium sp, Verticillium sp and Rhizopus sp. There was a significant isolate effects (P<0.05) on juvenile mortality. Juveniles treated with Paecilomyces isolate 1, Trichoderma isolates 1, 2 and 3 resulted in the highest mortality rates of 98-100%. This demonstrated that Trichoderma sp, and Paecilomyces sp are potential biocontrol agents of PCN.