Unmanned aerial vehicle remote sensing to delineate cotton root rot

Authors: WANG, TIANYI - Texas A&M University; THOMASSON, ALEX - Texas A&M University; Yang, Chenghai; ISAKEIT, THOMAS - Texas A&M University; NICHOLS, ROBERT - Cotton, Inc; COLLETT, RYAN - Texas A&M University; HAN, XIONGZHE - Texas A&M University; BAGNALL, CODY - Texas A&M University

Submitted to: Journal of Applied Remote Sensing (JARS)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2020
Publication Date: 11/30/2020
Citation: Wang, T., Thomasson, A., Yang, C., Isakeit, T., Nichols, R.L., Collett, R.M., Han, X., Bagnall, C. 2020. Unmanned aerial vehicle remote sensing to delineate cotton root rot. Journal of Applied Remote Sensing (JARS). 14(3):034522-1. https://doi.org/10.1117/1.jrs.14.034522.
DOI: https://doi.org/10.1117/1.jrs.14.034522

Interpretive Summary: Cotton root rot is a persistent and destructive soil-borne fungal disease that needs to be treated every year with the Topguard fungicide. Airborne imagery from manned aircraft has been used to map the disease and create prescription maps for site-specific application of the fungicide to minimize its usage. In this study, an unmanned aerial vehicle (UAV) was used to collect high-resolution images in a field known to be infested with this disease. A prescription map was created from the UAV-based imagery for fungicide application. Results showed that the prescription map reduced the fungicide use by 88% with a decrease of root rot infestation by 90%. The results and methods from this study will be useful as an alternative tool for cotton root rot management as more and more producers have access to UAVs for aerial imaging.

Technical Abstract: Cotton root rot (CRR) is a persistent soil-borne fungal disease that is devastating to cotton crops in certain fields, predominantly in Texas. Research has shown that CRR can be prevented or mitigated by applying fungicide during planting, but fungicide application is expensive. The potentially infected area within a field has been shown to be consistent, so it is possible to apply the fungicide only at locations where CRR exists, thus minimizing the amount of fungicide applied across the field. Previous studies have shown that remote sensing from manned aircraft is an effective means of delineating CRR-infested field areas. In 2015, an unmanned aerial vehicle (UAV) was used to collect high-resolution remote-sensing images in a field known to be infected with CRR. A method was developed to produce a prescription map from these data, and in 2017 fungicide was applied based on a prescription map derived from the 2015 image data. The results showed that the prescription map reduced the fungicide applied by 88.3%, with a reduction in CRR area of 90% compared to 2015. A simple economic model suggested that it is generally better to treat an entire CRR-infested field rather than leaving it untreated, and application based on a prescription map becomes preferable as the size of the farm and the yield increase while the CRR infestation level and the number of fields on the farm decrease.