Xylella Action Group

Biosecurity and Emergency Response Manager Sophie Badland says there is no cure for the diseases caused by Xylella, including Pierce’s disease of grapevines. “A biosecurity response to Xylella is likely to be very complex, as there are several subspecies which affect different host plants, and multiple vectors that may or may not play a role in spreading the bacteria between hosts,” she says. “To further complicate things, there are a great many plant species known to be asymptomatic hosts – they can be infected with Xylella, but don’t show disease symptoms or appear to be negatively affected by it.”

In 2018 a group of industry Government Industry Agreement (GIA) signatories, the Ministry for Primary Industries, the Department of Conservation, the science community and Te Tira Whakamātaki (the Māori Biosecurity Network) established the Xylella Action Group in order to better prepare for an incursion of the pathogen. A literature review (nzwine. com) was carried out to determine the likely impacts should it arrive on New Zealand shores. More recently, an operational specifications plan has been developed, outlining the response actions that can be taken should Xylella be detected in New Zealand, says Sophie. “As we head into 2022, the Xylella Action Group is preparing to negotiate another operational agreement which will allow further readiness work to be jointly undertaken by GIA signatories.”

The work programme under the agreement is likely to include testing the operational specifications through a response simulation exercise, working through response costsharing arrangements pre-emptively, and understanding more about the emerging tools and technologies being developed to detect Xylella and reduce the impact it has on host plants, Sophie says. Some of these are outlined in previous article, including the Pierce’s disease-resistant vines developed at UC Davis. “New Zealand Winegrowers has been in touch with UC Davis and hopes to be able to import some of these varietals in a few years’ time, when foreign licensing is granted.”

In grapevines, the symptoms of Pierce’s disease generally appear mid to late summer and can look similar to water stress or leaf scorch. If you notice these symptoms in vines that shouldn’t be stressed, please get in touch with This email address is being protected from spambots. You need JavaScript enabled to view it. so testing can be arranged.