Advancements in phenotyping of WOSR infected by Sclerotinia

Abstract: Sclerotinia stem rot is a serious threat to oilseed rape worldwide. The aim of this
study was to use the unmanned aerial vehicle to point the sites of the field that are heavily
infected with Sclerotinia sclerotiorum. To achieve this goal the field experiment was done over two years with 16 cultivars of winter oilseed rape artificially inoculated with the isolate Sc4 originating from oilseed rape in Poland. Several inoculation methods were used and the
inoculum had a form of infected petals, confetti, wheat grains, toothpicks and homogenised
mycelium. The biometrical measurements were done using inoculated and control plants, with the latter not treated with the pathogen. The Parrot Bluegrass drone equipped with a Parrot Sequoia multispectral camera with an RGB sensor and four spectral channels was used. The images were spectrally calibrated using gray plate calibration images with known spectral properties, and orthophotos were made in Pix4D software. The orthophotomaps were created for each date using photos from photogrammetric measurements, and the spectral indices NDVI and CHL RE were calculated for each plot. The results of the experiments showed that UAVs can successfully point out the sites at oilseed rape fields with the symptoms of Sclerotinia stem rot.