Study of plant-parasitic nematodes in kūmara will prevent crop loss
24 February 2025
A study of plant-parasitic nematodes in kūmara will help growers to be proactive, which will prevent crop loss.
‘An important takeaway from the study is the need to raise awareness among growers about the key symptoms of nematode infection,’ says Ella Purvis, pictured right with Lincoln University colleague, Sandy Hammond. Ella is completing a thesis at Lincoln University, investigating the distribution, diversity, and abundance of plant-parasitic nematodes in New Zealand's kūmara-growing regions.
‘Recognising the signs of infection in kūmara—whether on foliage, roots, or tubers—is crucial,' says Ella. 'By understanding what to look for, growers can identify early warning signs of damage and take proactive measures to prevent crop loss.’
Ella’s project has explored an area that has not been studied in New Zealand before—the interaction between plant-parasitic nematodes and kūmara, a crop with deep cultural and economic significance.
‘I began the research process with soil sampling in key kūmara-growing regions, Kaitaia and Dargaville. To analyse the nematodes present, they were first extracted from the soil and then studied for their diversity and abundance. These findings provided insight into the key genera present and their population levels.
‘By using both morphological and molecular identification techniques, I was able to further classify these nematodes down to the species level. However, given the limited research in this area, explaining why we were observing these populations—and how environmental factors influence them—is a challenge.’
To address this, Ella explored variables such as soil composition and extreme weather events, including the impact of Cyclone Gabrielle.
Presence of plant-parasitic nematodes not alarming
‘Importantly, the results showed that the presence of plant-parasitic nematodes in these regions is currently not alarming. This is a vital message for kūmara growers, who generously allowed us to sample in their fields.
‘An important takeaway is the need to raise awareness among growers about the key symptoms of nematode infection. Recognising the signs of infection in kūmara—whether on foliage, roots, or tubers—is crucial. By understanding what to look for, growers can identify early warning signs of damage and take proactive measures to prevent crop loss.’
The recent Vegetables NZ and VR&I research roadshow in Dargaville provided the perfect platform to present this research to the right audience.
‘Sharing findings directly with growers made the work feel truly meaningful,’ says Ella. ‘The engagement was incredible—they have a personal stake in the results, and it was rewarding to bridge the gap between research and real-world application.
‘For my project, the roadshow helped raise awareness of this often-overlooked field, encouraging valuable discussions and knowledge-sharing. Events like this create an environment where people can connect over successes, challenges, and new ideas—all with the shared goal of supporting growth and innovation.’
Great to engage directly with growers
Vegetables NZ research, development and extension manager, Daniel Sutton says it's great to have the opportunity for researchers to engage directly with growers.
‘The impact of research is often limited by not being able to extend it to the people who stand to benefit the most from it, or have the ability to implement it.
‘This is what makes the Vegetable Research Roadshows such valuable events. They bring the latest research and results directly to growers.
‘The Dargaville event was very successful, with strong attendance and good engagement. The next roadshow events are in April. I’d like to encourage every grower who can, to attend.’