The weedEleusine indicaas an alternative host ofFusarium oxysporumf.sp.cubensetropical race 4 causing Fusarium wilt in Cavendish banana

Abstract

AbstractOne of the most common weeds in commercial and abandoned Cavendish banana farms,Eleusine indicawas tested on its role as an alternative host ofFusarium oxysporumf.sp.cubenseTropical Race 4 (FocTR4), causal agent of Fusarium wilt disease of banana. Different isolates of TR4 from various parts of a Cavendish banana were inoculated to the weedE. indicawith Cavendish cv. Grand Naine as banana control. Colonization ofFocTR4 in artificially inoculatedE. indicaand Grand Naine was confirmed through DNA‐based detection (real‐time PCR) from fungal cultures re‐isolated fromE. indicaand various parts of Grand Naine. Results showed thatE. indicacan be colonized after artificial inoculation by differentFocTR4 isolates. Percent TR4‐colonized samples ofE. indicawere, however, lower compared to the primary host Cavendish banana. AllFocTR4‐colonizedE. indicadid not show wilting and hence were asymptomatic. Compared toFocTR4 isolates re‐isolated from Cavendish banana Grand Naine, all re‐isolated various TR4 isolates from artificially inoculatedE. indicawere more pathogenic based on percent Fusarium wilt incidence when re‐introduced back to the primary host Cavendish banana. MoreFocTR4 isolates were significantly more aggressive based on shorter incubation period or number of days to onset of symptom expression, and were significantly more virulent based on higher severity of rhizome discoloration of Cavendish banana plantlets. AllFocTR4 isolates re‐isolated from eitherE. indicaor Grand Naine resulted to the same degree of leaf yellowing when re‐introduced to Cavendish banana. This study concludes thatE. indicacolonized byFocTR4 could serve as relevant reservoir of the pathogen in the field indicating that weed management should be integral to the management of Fusarium wilt disease of Cavendish banana.