AUTHOR=Mulatu Afrasa , Megersa Negussie , Teferi Demelash , Alemu Tesfaye , Vetukuri Ramesh Raju 

TITLE=Biological management of coffee wilt disease (Fusarium xylarioides) using antagonistic Trichoderma isolates

JOURNAL=Frontiers in Plant Science

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2023.1113949

DOI=10.3389/fpls.2023.1113949

ISSN=1664-462X

ABSTRACT=<p>Coffee wilt disease (CWD) is a serious threat to the food security of small-scale farmers in Ethiopia, causing significant reductions in coffee yield. Currently, there are no effective control measures available against the causative agent of CWD, <italic>Fusarium xylarioides</italic>. The main objective of this study was therefore to develop, formulate, and evaluate a range of biofungicides against <italic>F. xylarioides</italic>, derived from <italic>Trichoderma</italic> species and tested under <italic>in vitro</italic>, greenhouse, and field conditions. In total, 175 <italic>Trichoderma</italic> isolates were screened as microbial biocontrol agents against <italic>F. xylarioides</italic>. The efficacy of two biofungicide formulations, wettable powder and water dispensable granules, were tested on the susceptible Geisha coffee variety in three different agro-ecological zones in southwestern Ethiopia over three years. The greenhouse experiments were set up using a complete block design, while in the field a randomized complete block design was used, with twice yearly applications of biofungicide. The test pathogen spore suspension was applied to the coffee seedlings by soil drenching, and the subsequent incidence and severity of CWD evaluated annually. The mycelial growth inhibition profiles of the <italic>Trichoderma</italic> isolates against <italic>F. xylarioides</italic> ranged from 44.5% to 84.8%. <italic>In vitro</italic> experiments revealed that <italic>T. asperelloides</italic> AU71, <italic>T. asperellum</italic> AU131 and <italic>T. longibrachiatum</italic> AU158 reduced the mycelial growth of <italic>F. xylarioides</italic> by over 80%. The greenhouse study indicated that wettable powder (WP) of <italic>T. asperellum</italic> AU131 had the highest biocontrol efficacy (84.3%), followed by <italic>T. longibrachiatum</italic> AU158 (77.9%) and <italic>T. asperelloides</italic> AU71 (71.2%); they also had a significant positive impact on plant growth. The pathogen-treated control plants had a disease severity index of 100% across all the field experiments, and of 76.7% in the greenhouse experiments. In comparison to untreated controls, the annual and cumulative disease incidence over the three years of the study period varied from 46.2 to 90%, 51.6 to 84.5%, and 58.2 to 91%, at the Teppi, Gera and Jimma field experimental locations. Overall, the greenhouse and field experiments and <italic>in vitro</italic> assays support the biocontrol potential of <italic>Trichoderma</italic> isolates, and <italic>T. asperellum</italic> AU131 and <italic>T. longibrachiatum</italic> AU158 in particular are recommended for the management of CWD under field conditions.</p>