C-DRONE GUIDE · 21 SEPTEMBER 2026
Quercy melon and drones: mapping vigour and irrigation under IGP rules, price
Quercy melon — an IGP since 2004, grown on about 513 hectares shared by roughly a hundred growers across the Lot and Tarn-et-Garonne départements — sold into a tight market in 2026: national volumes were up, yet prices, over several weeks, no longer covered production costs in the basin. On a crop bound by specifications setting a minimum weight and sugar content, where irrigation directly governs fruit quality and the harvest window plays out over just a few weeks, spotting a struggling zone before it compromises an entire row changes the equation. Here is what aerial drone mapping concretely brings, and what it never replaces.
Published on 21 September 2026, reviewed on 21 September 2026 — regulations in force as of September 2026.
Quercy melon IGP: a sector of small plots between the Lot and Tarn-et-Garonne
Quercy melon first earned product conformity certification in 1996, before securing protected geographical indication status on 24 June 2004. Its production zone covers parts of the Lot and Tarn-et-Garonne départements — around Lalbenque, Castelnau-Montratier and Montcuq on the Lot side, Caussade, Lauzerte, Montpezat-de-Quercy, Moissac and Montauban on the Tarn-et-Garonne side — plus a fringe of neighbouring Lot-et-Garonne. The sector covers roughly 513 hectares shared by close to 90 growers (2025 figure), for an annual harvest of around 10,000 to 12,000 tonnes depending on the year, at an average yield of about 20 tonnes per hectare — modest-sized holdings, often just a few hectares each.
The IGP specifications are precise: a minimum weight of 450 grams, a sugar content of at least 11° Brix, a stalk under 2 cm, and sale within six working days of harvest. That regularity requirement made the 2026 season particularly tricky: national melon production was up around 3% on 2025 (roughly 340,000 tonnes), yet in Tarn-et-Garonne, local agricultural press reported, over several weeks, sale prices that no longer covered production costs. Against that backdrop of squeezed margins, any data point that limits the risk of losing part of the harvest or overspending on irrigation carries immediate value.
What multispectral mapping documents on a melon plot
A multispectral flight produces a vigour index (NDVI and related indices) that reveals a localised drop in foliage vitality before it is visible from the row: an early disease focus, a deficiency, a localised drip-line fault, or compaction of the calcareous soils typical of the Quercy causses. The principle is documented by a field study conducted in Florida and Georgia and published in 2019 in Plant Disease by Kalischuk, Paret, Freeman and co-authors: combining a drone-derived NDVI index with a stress index made spotting gummy stem blight foci (Stagonosporopsis cucurbitacearum) in watermelon faster and more systematic than a conventional plot walk-through (see the study on Google Scholar). No equivalent study has been published specifically on melon (Cucumis melo); watermelon, another cucurbit exposed to the same pathogen and grown in a very similar way, is the best available parallel. Our guide comparing a multispectral camera against a standard RGB camera covers the sensors and indices involved.
The second lever concerns irrigation: Quercy melon, grown on often free-draining calcareous soils, depends on regular watering to reach the minimum sugar content required by the IGP specifications without the fruit splitting late in the cycle. A drone-mounted thermal camera reveals canopy temperature differences that betray water stress before any visible wilting, using a method transposable from vineyards — detailed in our guide on crop water stress with a thermal drone. Choosing the flight window remains decisive: our guide on the thermography measurement window covers the time-of-day and weather conditions that make a thermal map usable.
The honesty clause: a vigour anomaly is not a plant-health diagnosis
The honesty clause. The Kalischuk et al. study shows that combined NDVI/stress scouting speeds up finding gummy stem blight foci in watermelon at the scale of a field monitored over time — it says nothing about a single flight's ability to deliver a diagnosis, and it concerns a neighbouring cucurbit rather than melon itself. On a Quercy melon plot, a vigour drop picked up by drone points to a zone to check, never an identified cause: the same spectral signature can betray Fusarium wilt (Fusarium oxysporum f. sp. melonis, which causes a sudden and irreversible collapse of the plant), gummy stem blight, powdery mildew (Podosphaera xanthii), or simply a water deficit or nutrient shortfall with no pathogen involved at all.
Yet the decision that follows differs radically depending on the cause: a confirmed Fusarium wilt calls for pulling the infected plant and lengthening the crop rotation on that plot for future seasons — a heavy decision never made on an NDVI map alone; powdery mildew is treated with a targeted fungicide, with no extreme urgency; a simple water deficit is corrected by adjusting irrigation. That distinction remains entirely a matter of ground verification by the grower, their cooperative or their technical adviser — the drone speeds up finding where to look first across a holding of several hectares split into small plots, never determining what is found there. Our guide on industrial tomato and drone vigour mapping documents the same early-detection principle on an entirely different crop, pathogen and basin.
Who commissions this service, and 2026 prices
Demand comes from the Melon du Quercy interprofessional syndicate, cooperatives and individual growers operating under the IGP, and the chambers of agriculture of the Lot and Tarn-et-Garonne supporting the sector. The terrain of the Quercy causses and the Tarn plain presents few obstacles to flight; the point to check before any campaign remains the proximity of an aerodrome — in Montauban, LFDB aerodrome on the city's north-eastern edge, plus the no-fly grounds of the 17th parachute engineer regiment, require a systematic check. The Géoportail drone zone map remains the first reflex before any campaign; our regional guide on drone missions in Occitanie covers the whole airspace picture. Missions around Caussade, Moissac and Montauban are handled from Montauban.
Ranges observed in France in 2026, excluding VAT:
| Service | Observed price (excl. VAT) |
| Multispectral flight, vigour spotting (up to 5 hectares) | €280 to €480 |
| Additional pass per extra 5 hectare block | €80 to €130 |
| Thermal water-stress mapping (up to 8 hectares) | €320 to €550 |
| Combined seasonal monitoring (3 passes, vigour + irrigation) | €650 to €1,050 |
These figures cover the flight and delivery of a usable map within 24 to 48 hours; they do not include the fungicide treatment decision or diagnosing the exact cause of an anomaly, which remain the responsibility of the grower, their cooperative or their technical adviser. Since IGP holdings are often small, a campaign pooled by the cooperative or syndicate across several neighbouring plots noticeably reduces the cost per hectare. Request a quote stating the area, the number of plots and the period targeted: during fruit set for early disease-focus spotting, close to harvest for water-stress mapping.