A new toolkit for squash growers details a range of strategies to help reduce the impact of soilborne diseases, taking an agroecological “whole of farm” approach.
The newly released grower toolkit brings together work from the A Lighter Touch (ALT)-New Zealand Buttercup Squash Council project focusing on soilborne disease management.
Soilborne diseases (SBD) cause losses averaging around 30 percent a year for a sector with an export value of around $55 million.
SBD project member Chris Lambert harvesting buttercup squash during the project.
Drawing on knowledge gathered from researchers and industry, trial results and insights from demonstrations to date, the toolkit explains the factors that lead to a buildup of the pathogens that cause SBD, and identifies the main pathogens affecting buttercup squash. It then outlines strategies growers can consider, to reduce the impact of disease, including:
- Crop rotation – how current rotation crops influence susceptibility and pathogen hosting, and the suitability of other options.
- Service crops –the effect of existing service crops on pathogens and potential alternatives.
- Biological controls –an introduction to biological options, key considerations for successful integration, and an example programme.
- Other approaches – pathogen testing, crop nutrition, soil amendments, and cultural practices.
Project technical lead Dereck Ferguson says the toolkit is designed to help growers better understand SBD, and provide them with a range of management options.
Dereck Ferguson weighing squash during harvest.
The SBD project is not due to finish until March next year, and the toolkit will be updated with further data and knowledge stemming from the final two years of the project. This includes further pathology work designed to more precisely identify the causal pathogen strains, as well as the primary pathogens in the disease development cycle. It also includes work undertaken with pot trials focusing on mitigating the effects of SBD and determining which interventions are most effective.
Latest findings from the project have been shared at recent Vegetable Research Roadshow events, including results from the 2024/25 demonstration in Hawkes Bay where management options from the toolkit were applied.
At pre-harvest, fruit in the demonstration crop showed less sunburn, with 23% being affected, compared with 41% and 50% in the control areas. The fruit in the demonstration area also had a lower rejection rate, resulting in a 2.3T/ha increase in marketable yield, Dereck says.
Another project demonstration located in Gisborne did not show differences between the demonstration crop and the control, but some inputs that were used in the Hawke’s Bay trial were not applied by the grower. In addition, the grower had already started using several inputs recommended from the SBD project in their standard management practice.
While the toolkit is particularly focused on SBD management of buttercup squash, it also holds valuable insights for growers of other crops impacted by soilborne diseases. Other cucurbit and some vegetable crops, such as onions and process peas, can be affected by the same or similar soilborne pathogens, for example fusarium spp.
Poor drainage, soil compaction, low organic matter and poor soil water infiltration are issues that can be found in any cropping system and can all contribute to disease development. The toolkit has components which address many of these factors.
An example of disease affected squash.
Cultural control methods outlined in the toolkit, such as use of service crops, crop rotation, improving soil organic matter, improving soil structure, and nutrition, all have the ability to positively impact any soil-based pathogen. Biological controls may be more specific and require targeted research for each crop, Dereck says.
The toolkit is being launched to growers and advisors in the buttercup squash industry at meetings in Hawke’s Bay and Gisborne this month. Technical advisors from the project will talk through the components, and discuss how these have been implemented in project trials and demonstrations.
The toolkit meetings will be followed in mid-June by a visit to growers from plant pathologist and soilborne disease expert Dr Len Tesoriero. Supported by the project’s technical leads, Len will meet with growers on their farms to discuss their SBD challenges and management options.
Based in New South Wales, Len established his own consulting firm after a long career with the New South Wales (NSW) Department of Primary Industries. He maintains a role with the department as a visiting scientist, contributing to disease surveillance and mentoring younger plant pathologists.
