Thirty Degrees: A Foliar Programme on a South Devon Vineyard
Updated: Sep 13
Some v
ineyard blocks are planted on ground a tractor can get across. Others are planted on ground a tractor can get across carefully, in the right conditions, with a driver who knows the site. And some are planted where the honest answer is that it shouldn't be attempted at all.
This block sits in the South Hams, in the valley country between Dartmoor and the coast. Rows at roughly 1.5 metres. Ground falling away at thirty degrees in places. It is the kind of site where the planting decision was made for the sun and the drainage, and the machinery problem was accepted as part of the deal.
The problem with a slope
A loaded sprayer on a thirty-degree gradient is not a job anyone should be relaxed about. Weight transfer on a side slope, wet grass between rows, a full tank shifting as the machine moves — the combination is why hillside vineyards across Europe have historically been worked by hand, by winch, or from the air.
There is a second cost that shows up later. Ground machinery on a slope in damp conditions leaves wheelings, and wheelings on a gradient concentrate water. Over successive seasons that becomes soil movement downhill, which on a steep site is exactly what the grower is trying to avoid.
A drone removes both problems at once — not because it is clever, but because it never touches the ground.
What went in the tank
This was a nutrition programme, not a crop protection one. That distinction matters more than it sounds, so here is exactly what went on:
YaraVita Bud Builder FL — a compound liquid fertiliser carrying nitrogen and phosphorus alongside boron, zinc, calcium and magnesium.
FMC Copper Fertiliser — a formulated copper fertiliser, 256 g/l copper, for correcting copper deficiency. Vines on the shallow, leached soils common across South Devon are among the crops most prone to it.
Sulphur-Biotic — a 700 g/l sulphur suspension, applied to prevent or correct sulphur deficiency.
Zodiac — a biostimulant built on cold-pressed Ascophyllum nodosum seaweed and vegetal protein hydrolysate, used to support the vine's own stress response.
Every one of those is a UK fertiliser or biostimulant. None is a plant protection product. We don't apply plant protection products from the air, because there is currently no commercial authorisation in the UK that allows it — a point we would rather state plainly than leave a grower to wonder about.
Application rate was 150 litres per hectare.
How we ran it
We flew the block in mid-August with the XAG P100 Pro, working an evening slot. Evening suits foliar nutrition: the thermals have gone, the wind has usually dropped, and the leaf takes up product better than it does in the heat of the afternoon.
The aircraft held an RTK correction link to its base station throughout, which is what makes flying rows at 1.5-metre spacing on a gradient a controlled operation rather than an interesting one. On tight rows the drone has to hold its line to within a fraction of the row width while the ground beneath it is dropping away; without centimetre-level positioning, that isn't a job worth attempting. Obstacle avoidance handled the vines and the posts without intervention.
Flight time came in at fifteen to twenty minutes per hectare at that rate. The mixing and setup either side of the flying is close to fixed — it takes much the same time whether the block is one hectare or ten, which is the real reason drone application makes most sense once there is a proper day's work on the ground.
The job was notified in advance to the MOD's low-flying deconfliction desk at Swanwick and added to their CADS system before the aircraft flew — a step we take on every job in the South West, because military low-flying training routes cross a good deal of Devon at exactly the heights an agricultural drone works at. A written risk assessment went to the client several days ahead, alongside the job brief.
How it went
Smoothly, which on a thirty-degree slope is the whole point. The RTK link held, the obstacle avoidance did its job around the vines, and the block was covered in a single evening visit.
No wheelings. No compaction on wet ground. No one driving a loaded sprayer across a side slope at the end of a long day.
If your vines are on a slope
Steep and awkward ground is where drone application makes the clearest case for itself — not as a replacement for everything a sprayer does, but as the option for the blocks where the sprayer is the limiting factor.
If you farm vines on a gradient in Devon or Cornwall and want to know whether a drone pass would work on your rows, get in touch and we'll come and look at it. See our full range of agriculture services here.
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