Integrated pest management of nematodes in sweetpotatoes (PW17001)
What’s it all about?
This investment is tasked with bringing current and new information on nematode management and soil health to Australian sweetpotato growers.
Beginning in late 2018, it will run a series of masterclasses and other extension activities to bring the most up-to-date knowledge to industry, while conducting a range of field work to develop new knowledge. This field work will include surveys to identify region-specific nematode species and issues facing the Australian sweetpotato industry; the investigation of management approaches including cover crops, soil amendments, tillage options and more; and the evaluation of new nematicide technologies.
Since the last project update, on-farm surveys recommenced with the relaxation of COVID-19 restrictions. Due to long-running drought conditions over most areas, nematode numbers continued to be low.
The long-term farming systems trial in Bundaberg continued, with a second commercial sweetpotato crop planted in the intensive block. The previous rotation crop (Jumbo sorghum) was incorporated, with organic amendments applied and incorporated at bed formation. A second cover crop in the extensive trial (preformed beds) was mulched off, with the block to be planted to signal grass next.
Soil sampling to assess nematode populations, physical properties and biological activity continues throughout the long-term trial, pre-plant at the nematicide trial site, and future cover crop demonstration sites. A suitable site in Bundaberg was identified for nematicide trials, with plans underway and planting set for March 2021.
Several host range pot trials continue to evaluate potential cover crops for nematode resistance or susceptibility. Pathogenicity pot trials are also ongoing, evaluating commercial sweetpotato cultivars to gauge nematode infection susceptibility / resistance ratings.
A second herbicide trial is underway to investigate any ‘plant back’ effects of pre-plant herbicide treatments on sweetpotatoes post planting. A second factsheet Environment and herbicide performance was completed and distributed to growers.
Read this herbicide fact sheet:
Since the February 2020 update, Covid-19 travel restrictions have caused some disruption to research and extension activities. However, where possible, adaptations have been put in place so that the project team can continue to progress its work, with the following outcomes achieved:
- The first commercial sweetpotato crop was harvested from the long-term farming systems trial at the Department of Agriculture and Fisheries’ Bundaberg Research Facility. Soil samples for nematode, physical properties and soil biology analysis were taken just prior to the crop being dug, with data collected for yield and quality assessment. The results will be analysed to determine any correlation between soil characteristics, root knot nematode populations and soil biology.
- Activities to conduct smaller scale intensive sampling (especially on NSW farms) and on-farm cover crop trials were delayed, with Covid-19 border restrictions meaning that NSW agribusiness staff were contracted to collect soil surveys and facilitate possible cover crop trials in an effort to keep the research on track
- Pot trials continued, evaluating the nematode resistance or susceptibility of potentially suitable cover crops for use in sweetpotato faming systems. Signal grass, Sabi grass, Sunnhemp and Williams oats displayed good resistance to both to incognita and M. javanica. Pathogenicity pot trials also continue to evaluate commercially grown sweetpotato cultivars to gauge susceptibility or resistance ratings to nematode infection. Herbicide trials are underway to investigate efficacy in controlling sweetpotato volunteer plants.
Industry participants have been kept informed via various communication methods, including a Virtual Field Day in June 2020.
To date, the project team have achieved the following outcomes.
Four sweetpotato nematode masterclasses were held in the major production areas of Bundaberg, Cudgen and Atherton in Queensland. Sweetpotato growers were presented with up-to-date information about sustainable soil health management and a variety of nematode control options. Participants were encouraged to discuss how various management practices could be integrated into their sweetpotato farming systems.
Intensive field surveys have been conducted at over 90 sites to understand the occurrence of region-specific nematode species and identify any potential biosecurity issues. Previous cropping history and a range of soil parameters, such as soil type, organic carbon, pH and carbon dioxide respiration, will be used to assess the impact of these factors on nematode occurrence and population density.
Project results were communicated to farmers and researchers through field days and project updates held in Bundaberg and Cudgen.
Long-term farming system trial
A long-term farming system trial has been established at the Bundaberg Research Facility in Queensland and will run for the life of this project. It will assess a range of tillage options, soil amendments, cover crops and mulches to improve biological soil health and provide long-term sustainable nematode management.
The trial will assess practices including rotation crops, reduced tillage, traffic control and organic amendments. Various combinations of these practices will be trialed with regular monitoring of nematode populations, other soil/biological characteristics as well as yield data.
This project is a strategic levy investment in the Hort Innovation Sweetpotato Fund