Applying plant protection products using drones is a step closer to reality now a trials permit has been issued for slug pellets.

The decision by CRD to grant an extrapolated trials permit (ETP) paves the way for an Extension of Authorisation for Minor Use (EAMU), which could lead to the first commercial application of a pesticide to food or feed crops in the UK by drone.

Market demand

The development is off the back of two years of work by Staffordshire-based technology company AutoSpray Systems, which first identified a market for heavy lift drones in UK agriculture in 2019. That autumn, similar to recent months, prolonged rain prevented growers from accessing land to drill seed or apply products such as slug pellets or pre-emergence herbicides.

The company’s co-founder Andy Sproson says Civil Aviation Authority (CAA) regulations haven’t explicitly excluded aerial application from unmanned aerial vehicles (UAVs) for some time. However, use must be justified and to do this, AutoSpray systems wrote a specific risk assessment which was submitted to the CAA and the case accepted in December 2022.

He says another missing piece of the puzzle was a pesticide regulatory framework with the data to show how the product behaves when applied from UAVs.

“Firstly, we had to prove our competency to the CAA. Thankfully, we were able to do so as the company has CAA Recognised Assessment Entity status. We also had to outline the benefits of using drones in this way,” he explains.

Andy says these include application to land when ground machinery would damage crops and/or soil structure, cause compaction and increase run-off/pollution risk.

“Drones can also be used to target applications when a blanket approach isn’t appropriate, or larger machinery isn’t as efficient, such as when spraying off patches of grassweed.

“We also required the backing of an existing product authorisation holder, and we now have this with Certis Belchim which distributes Sluxx HP ferric phosphate slug pellets in the UK,” he adds.

Permit success

With the ETP granted, AutoSpray Systems and Certis Belchim will now conduct ballistics testing to demonstrate to regulators that the spreadability of the Sluxx HP pellet is as good as its proven to be from conventional applicators.

Once this data is submitted to CRD, it’s hoped an EAMU will be granted and growers with access to a large payload drone – like the XAG P100 Pro imported by AutoSpray Systems – will be able to apply Sluxx HP slug pellets from the air.

In work carried out last year, the XAG specialist agricultural drone broadcast cover crop seed into standing cereals at speeds of 30-35kph. Furthermore, work rates of 15-20ha/hr is possible with one drone, multiple batteries, a generator, and fast charger. The same will apply to slug pelleting.

“It’s the first time a new application method has been made available to growers for many years and offers an option that compliments conventional machinery,” highlights Andy.

Drift data

He added that AutoSpray Systems has already worked with HSE-CRD and Silsoe Spray Applications Unit to gather spray drift data to show liquid products can be applied safely and effectively with its drones.

This sets up the possibility of further collaboration between the firm and agrochemical manufacturers, which could soon facilitate spraying of pre-emergence herbicides or late blight fungicides from the air with an unmanned aerial system (UAS).