Evaluating the Potential for Aerial Imagery to Detect Weedy rice in California Rice Fields, 2019


Whitney Brim-DeForest, farm advisor, UCCE, Sutter, Yuba, Placer, and Sacramento counties

In July 2018, researchers conducted a preliminary study to determine whether aerial drones with cameras attached could be used to help identify weedy rice in California rice fields.

Results did not show much difference with observations at the field level. Yet there is a pressing need to improve the accuracy of mapping weedy rice populations. Concurrently, efforts are underway to develop a drone with the capacity to target and spray individual weedy rice populations. Without a map, the spray drone will be less useful.

In 2018 and 2019, researchers used two cameras (a red-green-blue and a multispectral) attached to drones in the field. One field was flown over in 2018, and two fields were flown over in 2019. Also, in 2019, researchers adjusted the camera angle to see whether a side angle might result in better visual contrast.

In a greenhouse, they employed a more sensitive hyperspectral sensor to determine whether this approach might result in better detection of weedy rice. Unfortunately, there was little difference observed in the samples from the greenhouse. Field testing in both 2018 and 2019 with a fixed-wing drone also did not detect a significant difference between conventional rice and weedy rice (or sprangletop and watergrass).

Further data analysis will be conducted using the images collected in 2018 and 2019.