Sunflower protection by drone

Why a drone once the rows close

Once sunflower is taller than 1 to 1.5 m, a tractor sprayer breaks stems and permanently flattens about 5 to 6% of the crop in its wheel tracks. The drone avoids this: it flies 3 m above the heads, and the strong downdraught from the rotors drives the droplets down to the lower leaves, so the product covers the whole canopy.

The drone needs only 15 to 20 litres of water per hectare, against 150 to 400 litres for a tractor. On grouped fields we can do about 20 ha an hour, roughly twice a tractor's daily output. It can also work after rain: only the road to the field needs to dry, and if you have tarmac access, we work the same day.

For comparison, contract tractor spraying costs about RSD 2,000 per cadastral jutro (around €30 per hectare), and that price does not count the yield lost to trampling. Our drone price is €20 to €25. The full calculation is on the drone or tractor page.

Sunflower diseases: spraying at flowering

The diseases that cost sunflower the most yield are Phomopsis stem canker, Sclerotinia white rot and grey mould. The best window for fungicide is from bud stage (when the bud appears at the top of the stem) to the end of flowering. For Phomopsis the crop is most susceptible during and just after flowering, and advisory services (such as PSS Sombor) recommend controlling grey mould in the same window.

We set the exact spray day by combining PIS warnings (the Plant Protection Forecasting and Warning Service) with the state of your field. You choose the product and rate with your agronomist, and Nikola then mixes it precisely in our tank at the field.

Trial results support the drone at this stage. In a 2024 field trial (Șerban et al.), two fungicide treatments by drone at only 10 litres of water per hectare reached 94% efficacy, while one treatment at 200 litres per hectare, the volume a tractor sprayer uses, gave only 58%.

Sunflower desiccation: when and how

Desiccation of sunflower (drying the crop chemically) gives even ripening and an earlier harvest. It is done once the seed reaches physiological maturity, usually 25 to 40 days after flowering. Your agronomist sets the exact moment from the seed moisture for your hybrid.

Sunflower carries a lot of green material (leaves, stem and head often stay green after the seed is ripe), so harvesting without desiccation causes real problems: the combine's sieves clog, wet debris gets into the seed, and the crop arrives at the buyer with high moisture and extra drying costs.

The right seed moisture for desiccation is 25 to 45%, and hybrids can differ by up to 10 percentage points. Timing matters: desiccating too early cuts yield and thousand-seed weight, while desiccating too late no longer shortens the wait for harvest. Done correctly at temperatures above 20 °C, harvest can start 7 to 14 days earlier. Cooler weather or rain slows the drying down (Đukić et al., 2007).

When desiccation is done by tractor, the sprayer booms break plants in two rows: by the same study's calculation, 7% of plants are flattened and the actual yield loss is about 3.5%. By drone, that loss disappears. To protect neighbouring crops from drift, we work in winds of up to 3 to 5 m/s.

Full details of the service: desiccation by drone. More on timing and method: sunflower desiccation: when and how it is done.

Pre- and post-emergence spraying of sunflower

Pre-emergence spraying (soil-applied herbicides after sowing, before the crop emerges) is still a job for the tractor. The sprayer can run very low and soak the soil and weed seeds with a large volume of water. In conventional sunflower hybrids it is also the only line of defence against broadleaf weeds. After emergence, all hybrids can be treated against Johnson grass and other grass weeds, but broadleaf weeds can be controlled with herbicides only in tolerant IMI and SU hybrids, by the third leaf pair at the latest (following the manufacturers' recommendations, such as Galenika Fitofarmacija or ADAMA).

We apply these herbicides by drone only when long spells of rain keep the tractor off the field, and only if the nearby fields carry the same crop.

More on weed types and herbicides: pre- and post-emergence spraying of sunflower.

Sunflower treatment calendar

These stages are standard practice, but the exact day is always set by PIS warnings and your agronomist.

How much sunflower desiccation by drone costs

Sunflower desiccation costs €25 per hectare up to 20 ha, €22 from 20 to 100 ha and €20 over 100 ha. The same prices apply to fungicide treatments and foliar feeding. You supply the product and the water. Travel within 50 km of Opovo is free; beyond that we charge €1 for every extra kilometre (one way, per visit).

Worked example (a new client's first order): 35 ha of sunflower near Alibunar, 61 km from Opovo.

• 35 ha × €22 = €770
• First hectare free: −€22
• Travel: €11 (11 km over 50 km × €1)
• Total to pay: €759

If we do three treatments on the same field in a season (for example foliar feeding, fungicide and desiccation), you get 5% off; a package of five or more treatments gets 10% off. Clients with a package get priority when booking, and you pay after each treatment. We take fields under 10 ha only within 20 km of Opovo. More details in the price list.