A Boysenberries NZ-A Lighter Touch project has taken a proactive approach to resistance management in testing for reduced sensitivity to fungicides intensively used by the sector.
Botrytis cinerea (grey mould) is a challenging disease in boysenberries and in recent years several fungicides have been found to be compromised in their ability to control the disease.
Fungicide resistance management is a key priority for the horticulture industry, and Boysenberries NZ have made advances with screening for resistance to fungicides that have been used intensively in their crop protection spray programme over the past four years.
An increase in resistance to some fungicides used by Boysenberry growers has resulted in an increase in use of alternative active ingredients and Boysenberries NZ wanted to ensure the alternatives are still effective.
The resistance screening conducted as part of this project aimed to provide boysenberry growers with reassurance that these active ingredients remained effective for botrytis control, while also providing baseline sensitivity data. Alternatively, if resistance was established, growers would be advised to discontinue use of the products where there has been a history of heavy use, potentially reducing unnecessary costs and minimising the environmental impact.
Boysenberries with botrytis (grey mould). Credit: Geoff Langford
The testing, which was carried out by the Bioeconomy Science Institute established that botrytis is showing reduced sensitivity to the active ingredients assessed. Boysenberry growers will discontinue using products with these active ingredients and this information positions the boysenberry industry well to begin evaluating and integrating alternative botrytis control options into future crop protection strategies.
The project also gives real evidence to support the importance of adhering to good resistance management principles and guidelines for active ingredients as well as the potential flow on implications as to how this can affect an active ingredient’s performance and the viability for the whole industry.
The testing also provided valuable insights for other berryfruit and fruit sectors affected by botrytis, as with previous research funded by Boysenberries NZ for resistance screening.
BSI and the proprietors of the active ingredients assessed, both provided support for this project, indicating the importance of this work at an industry and research level.
The project represents a strong collaboration between industry, researchers, and registrants, and serves as a model for how all facets of the horticulture sector can work together to achieve improved crop protection outcomes for growers.
ALT Transition Technical Lead Bruno Gatimel says resistance screening has been highlighted as a critical element of effective resistance management.
ALT transition technical lead Bruno Gatimel.
“A Lighter Touch currently has work underway to identify who is currently engaged in resistance screening across New Zealand. It aims to highlight gaps, overlaps, and opportunities for coordination and improved alignment to gain a better understanding of resistance in New Zealand. The work undertaken as part of this project will contribute to that overall picture.”
Bruno says the developing threat of resistance also highlights the need for alternative control options in addition to synthetic chemistry. “An integrated approach to pest and disease management helps protect and extend the efficacy of existing crop protection tools.”
