Each season, botrytis is a challenging disease to control while also complying with residue requirements for customer markets. This challenge is getting harder and was epitomised during the 2021/22 season when long periods of wet weather caused major rot issues for boysenberries. The situation has been exacerbated by the discovery of resistance to existing spray options. Field trials were undertaken to evaluate four biopesticides for botrytis control in the 2022/23 season, but the results were inconclusive.

Screening of biopesticide botrytis control continued in the 2023/24 season, and a separate trial was conducted to establish the residue profiles of some synthetic fungicides in boysenberries. The residue profiling of the fungicides provided results that may allow growers to use these products with a 42-day withholding period. One of the biopesticide options evaluated showed better activity against botrytis than the others, but not significantly.

Further trials were undertaken in the 2024/25 season. The trials showed the biological products did not reduce botrytis in boysenberries, with most treatments performing similarly to the untreated control under high disease pressure.

While results were largely inconclusive, the findings suggested two products may hold more promise than the third product evaluated, warranting further research. It also highlighted developing an improved technical protocol that would ensure suitable disease pressure to better evaluate products’ performance and deliver insights on efficacious biofungicides for the control of the target disease, which in this case was botrytis. Check out the project results in more detail.