Evaluating biofumigant crops as a pre-plant treatment for avocado orchard establishment in sites with high Phytophthora root rot pressure

Brassica biofumigant crops are frequently grown and incorporated into fields prior to planting vegetable crops to reduce populations of nematodes and soilborne fungi. This approach was evaluated for application in avocado replant land infested with Phytophthora cinnamomi (Pc). In vitro Petri dish assays demonstrated that growth of Pc was inhibited by amending agar with dried leaf material of several brassica species, with Caliente (B. juncea) and BQ Mulch (a mix of B. napus and B. campestris) being most effective. However, these results were not observed during further glasshouse testing. The efficacy of these pre-plant biofumigants is currently being tested in a field trial on a commercial avocado orchard infested with Pc.