Proof of concept study: a novel mobile in-canopy imaging system for detecting symptoms of fungal diseases in cereals

To recognize species-specific symptoms of plant diseases automatically, a near surface imaging at a sub-millimeter scale is necessary. Current investigations relate to an inspection of the upper visible crop parts using camera imaging from above the canopy. The paper presents primarily results using a sensor system, which is operating inside the canopy to monitor the vertical health status of winter wheat. This in-canopy sensor is also inspecting lower, invisible crop parts. With this technology a spatial and temporal precise crop protection—a future spraying of only the infected field parts would be possible. A commercially available camera with an NIR filter was attached to a vertical rod. To protect the camera while moving through the crop, it was installed inside a tube. This tube guaranteed a constant distance to the crop tissue so that it did not cover the camera lens. The mobile device was flexibly mounted on the back, three-point linkage of a tractor. In this first use example, the sensor was operated inside the crop canopy to inspect the lower leaves and directly at the canopy surface to inspect the upper leaves and the ears. In the images of the leaves inside the canopy, symptoms of tan spot (anamorph Drechslera tritici-repentis (Died.) Shoemaker) were clearly visible at flowering. When the camera was operated at the canopy level, black ears (caused by black point/kernel smudge/black head molds) were visible at milk ripeness.