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. This coming season will see a repeat of this work.