Grapes and drones – a perfect match?
Talking about drones, we mainly refer to unmaned air vehicles (UAVs), those remote controlled flying vehicles that became popular due to improved handling and affordable prices in recent years. Thanks to more clear regulations and information, the anxiety that comes with every new technology meanwhile lost ground to enthusiasm. The stunning photo and video footage shot by UAVs doesn’t seem to lose its fascination.
Vineyards are a perfect scenery for such beautiful aerial views. Maybe that’s why the idea to use drones to ease vineyard work popped up so often during the last years. Numerous press releases about specialized vineyard drones were given out by startups and research institutes. Or maybe it’s because many vineyards are not accessible for large machines and thereby predestined for something that doesn’t stick to the ground. At a winegrower fair we visited recently, drones were getting a lot of attention as well, far more than any other high-tech solution presented. Still, only few vineyards are regularly visited by drones until today. But why? And will this change? To shed some light on these questions, let’s have a look at the possible use cases and hurdles to overcome.
Besides the pretty obvious and most common use for drones – creating landscape pictures or movies for marketing purposes – the two major use cases that drones can deliver for winegrowers are application of plant protection and remote sensing.
Application of plant protection
Especially at rather inaccessible vineyards, drones can be faster than any tractor or human. Current agriculture drones like the Agras MG-1  can carry about 10 to 15 litres of fluid, are very precise and can automatically keep their flying height above the crops at the right level to effectively apply the plant protection. Handling is easy: On leading-edge UAV models the flight route and amount of fluid can easily be set on a smartphone-like user interface on the remote control. A steep slope vintage of several hundred square meters could be sprayed within 10 minutes from a secure distance.
While this is already technically possible today, there are also several impediments that drone manufacturers still need to overcome. First of all, the high costs of agricultural drones: An investment of 10-15 thousand Euros converts to several hundred hours of manual spraying. Next, aviation and pesticides control authorities also have a say. In many countries an allowance to fly large UAVs is needed, so the drone itself will not be the only matter of expense. Other countries, like Germany, also have restrictions on where to use aircrafts for spraying (steep slope vintage) and require every vehicle to run through a rather long approval process . Lastly, the battery capacity is quite limited, so either the speed advantage is eaten up by the time and effort for recharging or a large number of expensive spare batteries is needed. Using fuel instead of electricity to increase the flight time just strengthens the barriers of initial costs and administrative barriers. Nevertheless, agricultural drone manufacturers and resellers are exploring every option to make their technology suitable for vineyards. Some of them focus on building very specific larger drones with an increased capacity , some try to find a way of getting permissions and user guidelines ready for existing drones . Given the rapid innovation during the last years, it’s just a matter of time until authorizations are given, flying permits might get irrelevant (because software takes care of the steering) and the technology will get more perfomant and less pricy. Especially for winery cooperatives, rural communities or service companies UAVs might soon deliver a rapid return on invest. We expect the number of related service offerings to rise quickly within the next years, not least as multiple use cases could be combined.
Remote Sensing / Analyzing crops
Any plant absorbs or reflects (infra-) red light depending on its growing power and general condition. Multispectral cameras or NDVI filters for standard cameras, which can see up to 30 times more of the light bandwidth than a human, mounted on a drone  can collect that information within seconds of a flyover. This information would be extremely time consuming and difficult to be gathered and charted by humans. It gives informative details about the vegetation status and temperature of different areas within a vineyard. Knowing where the vines are underdevloped or excessively growing and where the hot and cool areas are can assist both, immediate and long term decisions. Adjusting fertilization and irrigation for specific areas or finding and fixing an irrigation pipe burst is for sure something that helps saving costs and improving the grape quality within the current season. But sometimes, vegetation differences are difficult to remedy, mainly when they result out of the soil properties. In this case the knowledge helps to seperate vineyards into clusters, treat them differently and make use of each of the clusters advantages; so called precision viticulture. Most winegrowers use vegetation mapping to keep the grape quality consistent, others even produce different wines out of different clusters, although growing the same grape variety. 
Smaller camera-drones are much more common and affordable than agricultural drones, much lighter and more enduring. Accordingly, the time and performance drawbacks mentioned for heavier load-carrying drones do not apply. In some countries even the strong regulations do not apply for more lightweight drones. Most mountable cameras have a pretty high resolution, so the drones can capture large areas with a single flight high above the vineyard. Plus, a drone and an according NDVI filter for a camera can be purchased for about €1000. A more advanced and precise multispectral camera like the Parrot Sequoia+  is more expensive, about €3200. But as drone rentals or flying services with available equipment in this category are pretty common, a purchase is often not necessary.
Compared to spraying with UAVs, remote sensing is much more doable these days and as indicated a few wineries are using this technology today exist. Still, for most winegrowers, flying or route-mapping a drone and interpreting the resulting vegetation maps requires some training. While automatic analysis of such drone data is already under development, the costs for such software solutions will most likely only pay off for large wineries, cooperatives and service companies.
Winegrowers searching for issues with inconsistent grape quality or soil differences, interested in precision viticulture, more accurate information or technology in general can give remoting sensing via drones a try today, simply by hiring a service company for a few hours or by renting a drone.
With increasing popularity and enhancing technology both use cases will ideally merge, so the condition of single vines can get measured and purposeful enhanced at the same time. The influence on the profitability of winegrowing and the positive impact on the environment, are things that even sceptics will appreciate.
Sources & Further Readings
 DJI Technology Co., Ltd (2018)
 Bundesamt für Justiz (2018). (German)
 Agronator (2018).
 droneparts.de (2018) (German)
 Drone U on YouTube
 Deutscher Weinbauverband e.V. on YouTube (partly German/French)
 Parrot Drones SAS (2018)