Peter Cousins, Mid North Mesonet Weather Station

Detailed regional weather data is improving crop management and reducing spray drift.

The Mid North Mesonet pilot project, funded by PIRSA and delivered by the Ag Excellence Alliance, is a $1.4M state of the art automatic weather station network.

Operational since mid-2019, this innovative network of 41 individual weather stations spread across the Mid North, northern Adelaide Plains and northern Yorke Peninsula of South Australia is playing a significant role in reducing crop damage resulting from spray drift in the area.

Spray drift occurs when herbicides or pesticides move significant distances from their site of application, usually as a result of direct drift or through surface temperature inversions.

Sprays must be applied in accordance to the label directions, which state not to spray in inversions.

But without the Mesonet, it has been very difficult to determine when an inversion occurs and farmers may have been unwittingly responsible for off target damage.

The off-target inversion drift application can result in extensive damage to broadacre, viticulture and horticultural crops many kilometres away from the application site. Drift may also contaminate rainwater and compromise water quality in rivers, streams and dams as well as having an impact on human health.

It is estimated that the potential loss in value of production and market access from spray drift in the Mid North and Yorke Peninsula is as high as $178M per annum.

Spaying decisions based on accurate data

The Mesonet is the first of its kind in Australia and only the third in the world, and gives producers highly accurate and targeted local weather information and data to reduce the risk of spray drift.

“Producers can cause a lot of damage to their crops and the environment if they spray at the wrong time,” explains Peter Cousins, a consultant involved in the project.

“The Mesonet was established to let producers know when they should, and shouldn't be spraying.

“It’s all about applying pesticides at the right time, and not wasting them.”

The data generated by the Mesonet is accessible via a web app, and is free to the public.

Data available includes, but is not limited to, vertical temperature difference (inversion), harvest code of practice, wind speed, temperature, relative humidity, delta-T, dew point and rainfall.

“Often, farmers might check the Mesonet two or three times before spraying,” said Peter.

“We have a traffic light system to let them know when is a good time to spray - green means go, yellow indicates for them to be careful and red means don’t spray.

One year since its launch,  feedback on the Mesonet has been overwhelmingly positive, and has influenced farmers’ spraying practices.

“A lot of farmers are saying it’s incredible and how useful the information is,” said Peter.

“They’re particularly impressed with the wide area the Mesonet covers, and the data has encouraged them to make practice changes.

“They’ve told us they’d previously always followed a traditional rule of thumb for spraying - spraying an hour and a half after sunrise, and stopping an hour and a half before sunset.

“But since they have used the Mesonet, they’ve noticed that these rules are rarely right.

“By using the information generated by the Mesonet, they are now much more informed and confident around when and when not to spray.”

Farmers in the Riverland Mallee area, another hotspot for spray drift, are also expected to benefit from a Mesonet, with construction on a further 30 individual weather stations due to be completed in November 2020.