“When pesticides are used on farms and in forests, the wind can carry droplets of the sprays far away from the targeted area, potentially causing severe damage to neighbouring crops and harming the environment,” Roten says. “Spray drift has wreaked havoc on wine grapes and kiwifruit in several New Zealand orchards recently, causing several hundred thousand dollars worth of damage.”

“Agrichemicals can cause severe damage to natural ecosystems as well, especially when they land in surface waters, as most aquatic species are very sensitive to these chemicals.”

Other experts have also pointed out that spray drift exposes people and animals to harmful substances from pesticides.

In an effort to address the issue, Lincoln Agritech’s Chemical Application, Research and Training group (CART) has conducted a six-year Government-funded research programme to find out more about pesticide spray drift movements and how to mitigate them.

The project, funded by the Ministry of Business, Innovation and Employment (MBIE), involved a range of tasks, including measuring pesticide drift on typical New Zealand crops, as well as analysing the effectiveness of drift-reducing technologies and training people in how to use them.

Project Co-ordinator, Dr Scott Post, says the Lincoln Agritech group worked with a number of experts over the course of the project.  “We were lucky to co-ordinate such a high-quality research team. We worked with scientists from SCION to model spray drift, with specialists from Plant Protection Chemistry in Rotorua to research how sprayed droplets land on leaves, and with scientists from the University of Otago to find out how pesticide vapour can drift from the applied area.”

The team worked in various primary idustries such as forestry, horticulture and arable, dealing with crops including kiwifruit, grapes, apples, potato and shelterbelts.  

Part of the research involved conducting complex experiments to measure pesticide drift on typical New Zealand crops under practical conditions. The team worked to improve mathematical models on drift and measured the vapour drift of 200 different pesticides.

Dr Post says the research has advanced the team’s knowledge about pesticide drift in New Zealand conditions and helped to improve AGDISP (‘Agricultural Dispersal’), the internationally-recognised software for assessing drift risks in the agriculture and forestry sectors. “AGDISP is used by many pesticide regulators around the world. The software helps to evaluate the potential drift in a large number of different spraying situations where no measurements are available.”

The project team continuously shared results and information with a group of relevant stakeholders. 

“We interacted with producers, staff from councils and EPA, as well as spray contractors and manufacturers of sprayers and chemicals,” Dr Post says. “This ensured that the project provided outcomes are in line with the requirements of the primary sectors and the environment.”

The team also analysed the effectiveness of the latest Drift Reduction Technologies (DRT), which refer to small changes or additions to pesticide sprayers.  

“We found that these technologies could reduce drift by 33 to 59 percent,” says Dr Post. “Results like these encouraged us to start training people in the spraying business to use drift reduction approaches.”

Roten says it was also important to work closely with organisations like GrowSafe, Zespri, Horticulture New Zealand and the Foundation for Arable Research, as well as aerial spray contractors in the agricultural aviation industry. “This allowed us to reach many professionals and to educate them on the importance of working to reduce environmental impacts. Nevertheless, we do not think that our job is over now that the project has ended. Our engagement in this kind of outreach will continue.”

Dr Post says new technologies are also needed, both to support the work of spraying professionals and to equip public authorities with tools that can help them to monitor drift.

With this in mind, the final part of the research programme involved a collaboration with specialists at the University of Auckland to develop electronic sensors that could detect and measure the amount of received drift on crops.

“Drift of agrichemicals can’t be avoided completely, whether in conventional or in organic farming,” Dr Post says. “Nevertheless, we think it is possible to use our sensors to direct and improve sprayers’ performance when the operator knows how much drift is happening and where it is going.”

Photo: This Proptec Atomiser uses hydraulic fans to promote uniform droplet sizes and greater air assistance, potentially reducing spray drift.