SCREENING SELECTED ISOLATES OF ENDOPHYTIC Fusarium oxysporum FOR BIOLOGICAL CONTROL OF BANANA NEMATODES IN TISSUE CULTURE BANANA

Abstract

Studies were carried out to investigate the efficacy of selected isolates of endophytic Fusarium oxysporum, against banana nematodes under greenhouse and field conditions. Greenhouse experiments involved the use of two isolates 4MOC321 and 11SR23, tested against Pratylenchus goodeyi in two experiments. Isolate V5W2 was used as a positive standard. The field experiments involved the assessment of three isolates V5W2, Emb2.4o and Eny 7.11o from bananas in Uganda, against banana nematodes in both on-farm and on-station trials. Dessert banana cv. Giant Cavendish and cv. Grand Nain were used in all experiments. The on-station trial assessed the response of two month old banana plants, inoculated with one of the three V5W2, Emb2.4o and Eny 7.11o isolates and challenged with mixed nematode species (P. goodeyi and Helicotylenchus multicinctus) one month later. The on-farm trial assessed the performance of two month old banana plants inoculated with each of the three isolates and planted into a field naturally infested with nematodes (P. goodeyi, H. multicinctus and Meloidogyne spp.). All endophyte isolates significantly suppressed nematode populations and damage to bananas in both greenhouse and field studies. Results from the greenhouse experiment demonstrated a significant reduction of P. goodeyi population by >50 % and percentage root necrosis was reduced by >30 % by the endophytes. Fusarium oxysporum isolates 4MOC321 and 11SR23 also enhanced plant growth. In the on-station trial, the endophytes suppressed nematode population densit by >45 % and reduced percentage root necrosis by >20 %. Nematode damage was also significantly lower in endophyte treated plants compared with control plants in on-farm trial. Isolates Eny7.11o and XIV V5W2 enhanced plant growth as compared to the control treatments. Banana yields were significantly increased following endophyte treatments. Carry-over effect of endophytes to suckers was also evident. Suckers from endophyte inoculated plants had higher percentage root colonization compared to non-inoculated plants. The study has demonstrated the potential of endophytic F. oxysporum to suppress key plant parasitic nematode populations under field conditions and, promote banana plant growth and yield.