Poster Presentation Science Protecting Plant Health 2017

Biological control of grapevine trunk diseases using endophytic bacteria (#355)

Jennifer M Niem 1 2 , Regina B Baaijens 1 , Benjamin Stodart 2 , Sandra Savocchia 1 2
  1. National Wine and Grape Industry Centre, Charles Sturt University, Wagga Wagga, NSW, Australia
  2. School of Agriculture and Wine Sciences, Charles Sturt University, Wagga Wagga, NSW, Australia

Grapevine trunk diseases (GTDs) are considered serious problems of grapevines worldwide. Eutypa dieback (ED) and Botryosphaeria dieback (BD) caused by species within the Diatrypaceae (primarily Eutypa lata) and Botryosphaeriaceae families are among the top five priority diseases in the Australian wine grape industry.  Current management of these diseases is through remedial surgery and fungicide treatments of pruning wounds.  However, registered fungicides for GTDs are limited and some only offer short term protection.  Biological control offers an alternative management strategy against GTDs.  There are limited studies on the use of biocontrol agents (BCAs) against BD and ED, and for ED varying levels of success have been achieved.  Preliminary studies in our laboratory showed 11 endophytic bacteria isolated from grapevines to be antagonistic against four GTD pathogens: Diplodia seriata, Neofusicoccum parvum, N. luteum and E. lata.  In vitro and dual culture assays of these bacterial endophytes showed varying degrees of mycelial growth inhibition for the four pathogen species tested. Of the 11 bacterial isolates, three (BCA 11, 13, and 18) that exhibited the greatest mycelial growth inhibition were selected for in planta assays using detached grapevine canes.  Canes were artificially wounded and inoculated with N. luteum conidia 24 hrs after inoculation with the selected bacterial isolates.  Re-isolations from canes after four weeks revealed the lowest disease incidence at 28% when canes were inoculated with bacterial isolate BCA 13.  BCA 11 and 18 resulted in 89% and 100% disease incidence, respectively.  Control cuttings inoculated with N. luteum resulted in 100% disease incidence.  These preliminary results indicate that endophytic bacteria may be good candidates for biocontrol and in future may be incorporated into a GTD management strategy. Molecular identification and biochemical characterisation of these bacteria is ongoing.