More targeted spraying and reduced plant loss are some of the early benefits being reported by nursery owners using a new weekly disease risk forecast service launched by industry body New Zealand Plant Producers Incorporated.

The service is provided free to NZPPI members by their agri-tech partners HortPlus, as part of the online NZPPI Plant Disease Management Platform.

It includes weekly emailed reports providing a seven-day disease risk forecast for myrtle rust, black spot and downy mildew, along with forecast information from local weather stations across New Zealand.

“The weekly risk reports are hugely valuable in helping to further refine our weekly spray programme targeting myrtle rust and downy mildew,” says Abby Lomas, who works in plant husbandry at the Rural Design nursery in Kaiwaka, Northland.

“When these are received on a Friday, they are reviewed in conjunction with the upcoming week's spray plan and our timing of application or treatment is adjusted according to localised risk.

“On at least two occasions now, we have managed to delay a treatment – saving time and resources, with no adverse effects on plant health.”

Lomas says the risk reports have allowed her team to adjust their myrtle rust spraying programme to more accurately reflect the local risk in the Kaiwaka area.

The reports have also made it possible for her team to undertake preventative measures in a more targeted way for other plant diseases, she says. When the risk forecast for downy mildew sporulation is high, her team leaps into action to ensure any infected plant material is pruned and disposed of before the increased risk period arrives, avoiding further spread.

Ardmore Nurseries Operations Manager Ryan Gibson agrees, saying the reports are “extremely valuable” for disease risk decision-making at the nursery he manages in Clevedon, south-east of Auckland.

“We are part of Plant Pass so we already do a regular fortnightly walk around to identify any signs of disease, but having this tool to let us know about current risk levels allows us to do an extra check when threat levels are higher.”

As a result of the tool, his team has been able to manage disease risk more proactively and reduce disease damage to the plants Ardmore Nurseries produces, he says.

In addition to the disease risk levels shown in the weekly reports, his team has also found valuable ways to utilise some of the other weather information they make available. That includes the humidity forecast, which they use as a risk indicator for other plant diseases, and the wind forecasts, which help his team determine ideal spraying days, he says.

NZPPI Biosecurity Manager Kathryn Hurr says she’s been pleasantly surprised by the response to the disease risk reports.

“We’ve had the Myrtle Rust climate model available online for the past two years, but after the regional demonstration workshops ended, we noticed that site traffic dropped. Now, with weekly reports delivered straight to people’s inboxes, it’s one less step to access this information. Feedback has been very positive: our members find this really useful.”

She says there is potential for additional disease models to be added in the future if they would be valuable to the industry.

HortPlus director Mike Barley congratulated NZPPI on its successful launch of the new disease risk forecasts.

“Working with NZPPI to introduce this new tool for plant producers has been a truly collaborative effort. Their expertise has made it possible for us to highlight high risk periods for diseases affecting their members and I’m thrilled we’ve been able to achieve that in a way growers of all experience levels can understand.

Barley said nurseries were critical in the expansion plans of many horticultural enterprises so many across the broader industry would be interested in NZPPIs efforts.

“There’s potential for us to introduce similar plant disease risk forecast reports in other areas and we are excited about where we could take this in future – not just in New Zealand but around the world.”

The team at Rural Design (L-R): Jack Warden, Dani McBride and Abby Lomas. The Rural Design nursery in Northland. Ardmore Nurseries in Clevedon.