Study of a new biocontrol fungal agent for avocado white root rot

Avocado white root rot is caused primarily by Rosellinia necatrix Prill. In this study, we buried bait twigs around avocado escape trees to recover non-pathogenic soil-borne fungi. First, we selected forty isolates: 19 were identified as R. necatrix and 21 as Entoleuca sp. The next step was to conduct pathogenicity tests on lupin and avocado plants, which showed that R. necatrix isolates were pathogenic in both types of plants, while Entoleuca sp. isolates were not. The optimal growth temperature in vitro for the Entoleuca sp. isolates was 30 °C. Dianthus caryophyllus was found to be a host to this fungus, while Olea europaea, Lupinus luteus, Asparagus officinalis and Fragaria ananassa were not. Next, Entoleuca sp. was artificially inoculated into avocado plants and recovered from the roots up to two years later. In this way, we tested the biocontrol of the disease using Entoleuca sp. in avocado plants artificially inoculated with R. necatrix. Most of Entouleca isolates (86%) controlled the disease, and we therefore concluded that they were effective biocontrol agents.