‘It’s not about the drone, but about what you want to measure’

Detection systems are not yet widely used in horticulture. Drones have the potential to change all that. Recently, Erik Pekkeriet, a researcher at Wageningen UR is experiencing a newfound interest in detection systems. „That’s great. But the first question shouldn’t be what can a drone be used for but what do I want to measure?”

What makes drones so popular?
„Drones are by far the most flexible logistical carriers. You can control them very accurately. One thing is for sure: drones won’t hit any posts or bars when flying in a greenhouse. But there are also some disadvantages. For some applications, it will be more convenient to use the existing infrastructure, for example, a platform along a tubular rail.”

What will be impossible for drones?
„Drones won’t be able to carry artificial light, for example. And that’s what you need when monitoring photosynthesis or diseases within the plants. The lamp and the battery are very heavy. You can use available sunlight to photograph the condition of the crop, but consistent lighting is preferable to obtain a better image. In a greenhouse, you’ll find many construction elements that affect the light.”

Shouldn’t a bigger drone be able to carry more weight?
„Yes, but a big drone will move a lot of air above the crop. The plants will fall over. It has to be a small drone. Outside, this limitation doesn’t exist. There, you’ll be able to fly the drone higher, and there won’t be any greenhouse-construction elements to cast a shadow.”

What can a drone be used for?
„You can use a drone to take pictures and to measure crop growth. Right now, I believe that this is the best achievement we can expect. It will be too much to ask for to have them detect diseases or measure photosynthesis. To do this, the drone has to carry a light source. By the way, the first question shouldn’t be ’what can a drone be used for?’ but ’what do I want to measure?’ I’d like to see the order of those questions reversed.”

What are we going to measure in the future?
„In the future, we will monitor each plant individually. We can’t just continue to inspect the greenhouse visually. If we want to take new steps towards growing a vital product without full-field crop protection, then we will have to switch to precision horticulture. Every intervention with chemical products involves a decrease in production. Therefore, we need to intervene on a local level. You can only make this happen if you inspect each plant on its own.”

You have been working on precision horticulture for a long time. Has this been used in practice already?
„Not yet. It’s very difficult to turn this into a viable business case. For example, it’s unknown how much extra production it will generate. That’s because the production isn’t measured at the moment.”

But growers do know their production numbers?
„Yes, they know their average yield per square meter. And that’s the problem. I would like to know about each plant’s harvest. Why does one plant has a better yield than the other? Is that because of a disease? Or because of a lack of fertilisation? When you know the cause, then you can make changes.”

Joef Sleegers