Low-Volume Drone Spraying in an Apple Orchard: What Did the Tests Show?
One of the greatest challenges in modern fruit growing is implementing effective yet environmentally friendly plant protection. In its recent orchard test, ABZ Innovation evaluated the coverage and droplet formation of drone spraying in an apple orchard using widely used water-sensitive papers. For the purpose of the test, a deliberately low spray volume was applied to test the boundaries of the technology under extreme operational conditions.
Flight and Spraying Parameters
The spray pattern test was conducted using the ABZ Innovation L50 spraying drone. The settings applied during the trial were designed to maintain an optimal balance between aerial application efficiency and the appropriate droplet size range.
During the testing process, the drone application was intentionally carried out using water only, specifically stressing the system to evaluate the spray pattern under extreme conditions. It is important to emphasize that in practice—when applying plant protection products, biostimulants, or foliar fertilizers together with suitable adjuvants—the drift effect is significantly reduced due to altered droplet formation. Under real operational conditions, this results in a further improvement of both spray pattern and coverage.
Figure 1: The trial was conducted using the ABZ Innovation L50 spraying drone.
Flight operation team: ABZ Drone Ltd.
| Flight parameters | Value |
|---|---|
| Applied spray volume (Coverage) | 35 L/ha |
| Spacing | 8 m |
| Geschwindigkeit | 6 m/s |
| Tröpfchengröße | 262 μm (medium droplet size) |
| Altitude | 3 m |
Figure 2: Placement of water-sensitive papers in the orchard
Ergebnisse
To evaluate the penetration capability of the spray liquid, test papers were placed at various canopy levels, as well as on both the adaxial (upper) and abaxial (lower) leaf surfaces.
Figure 3: Spray pattern and coverage test with water-sensitive papers in an apple orchard
1. Upper Canopy Level
- Upper Surface (Adaxial): Highly dense, uniform droplet coverage is observed. Droplet distribution is excellent, providing good protection to the target surface.
- Lower Surface (Abaxial): Minimal to virtually zero droplet deposition occurs on the lower surface of the leaves, which is a natural consequence of the vertical, top-down airflow.
2. Middle Canopy Level (Outer/Lateral Canopy)
- Upper Surface (Adaxial): Good and uniform droplet distribution, with an adequate droplet density for the effective performance of fungicides and insecticides.
- Lower Surface (Abaxial): Minimal droplet coverage is present on the lower side.
3. Inner Canopy (Inner/Lower Branches)
- Upper Surface (Adaxial): Sparser, yet clearly visible droplet deposits appear. This proves that the downwash airflow generated by the drone is capable of pushing the spray liquid through denser foliage.
- Lower Surface (Abaxial): No significant coverage was detected on this surface.
Opportunities for Development and Optimization
Aerial application at a spray volume of 35 L/ha and a droplet size of 262 μm provides good coverage across the entire height of the canopy for products absorbed through the upper leaf surface. (For systemic products or fine atomization, even lower spray volumes may suffice for adequate efficacy.) However, for contact products, application efficacy cannot be guaranteed, as their optimal performance requires a higher level of surface coverage.
- Advantages: The drone’s downward airflow (downwash) effectively drives the active ingredient into the denser, inner parts of the canopy, ensuring optimal protection on the upper leaf surfaces for both contact and systemic products.
- Opportunities for Optimization: To achieve better coverage on the lower leaf surfaces—particularly where thorough coverage is essential for the effective control of specific pests or diseases—fine-tuning the flight speed (thereby increasing the spray volume) and adjusting the droplet size may be required.
Summary: The patterns on the water-sensitive papers demonstrated that even this minimal spray volume is capable of penetrating the inner canopy and reaching the lower leaf zones; at the same time, the potential for increasing droplet density became clearly evident.
IMPORTANT NOTICE: This experiment serves strictly as a baseline. In practical commercial applications, spraying configurations, flow rates, and other flight parameters must always be adjusted dynamically to adapt to specific crop vegetation and field layouts, microclimates, and ambient environmental conditions.
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