High-Throughput UAV Hyperspectral Remote Sensing Pinpoints Bacterial Leaf Streak Resistance in Wheat

Bacterial leaf streak (BLS), caused by Xanthomonas translucens pv. undulosa, has become an intermittent yet economically significant disease of wheat in the Upper Midwest during the last decade. Because chemical and cultural controls remain ineffective, breeders rely on developing resistant varieties, yet visual ratings in inoculated nurseries are labor-intensive, subjective, and time-consuming. To accelerate this process, we combined unmanned-aerial-vehicle hyperspectral imaging (UAV-HSI) with a carefully tuned chemometric workflow that delivers rapid, objective estimates of disease severity. Principal component analysis cleanly separated BLS, leaf rust, and Fusarium head blight, with the first component explaining 97.76% of the spectral variance, demonstrating in-field pathogen discrimination. Pre-processing of the hyperspectral cubes, followed by robust Partial Least Squares (RPLS) regression, improved model reliability by managing outliers and heteroscedastic noise. Four variable-selection strategies—Variable Importance in Projection (VIP), Interval PLS (iPLS), Recursive Weighted PLS (rPLS), and Genetic Algorithm (GA)—were evaluated; rPLS provided the best balance between parsimony and accuracy, trimming the predictor set from 244 to 29 bands. Informative wavelengths clustered in the near-infrared and red-edge regions, which are linked to chlorophyll loss and canopy water stress. The best model, RPLS with optimal preprocessing and variable selection based on the rPLS method, showed high predictive accuracy, achieving a cross-validated R2 of 0.823 and cross-validated RMSE of 7.452, demonstrating its effectiveness for detecting and quantifying BLS. We also explored the spectral overlap with Sentinel-2 bands, showing how UAV-derived maps can nest within satellite mosaics to link plot-level scouting to landscape-scale surveillance. Together, these results lay a practical foundation for breeders to speed the selection of resistant lines and for agronomists to monitor BLS dynamics across multiple spatial scales

Health status of free-ranging ring-necked pheasant chicks (Phasianus colchicus) in North-Western Germany.

Being a typical ground-breeding bird of the agricultural landscape in Germany, the pheasant has experienced a strong and persistent population decline with a hitherto unexplained cause. Contributing factors to the ongoing negative trend, such as the effects of pesticides, diseases, predation, increase in traffic and reduced fallow periods, are currently being controversially discussed. In the present study, 62 free-ranging pheasant chicks were caught within a two-year period in three federal states of Germany; Lower Saxony, North Rhine-Westphalia and Schleswig-Holstein. The pheasant chicks were divided into three age groups to detect differences in their development and physical constitution. In addition, pathomorphological, parasitological, virological, bacteriological and toxicological investigations were performed. The younger chicks were emaciated, while the older chicks were of moderate to good nutritional status. However, the latter age group was limited to a maximum of three chicks per hen, while the youngest age class comprised up to ten chicks. The majority of chicks suffered from dermatitis of the periocular and caudal region of the head (57-94%) of unknown origin. In addition, intestinal enteritis (100%), pneumonia (26%), hepatitis (24%), perineuritis (6%), tracheitis (24%), muscle degeneration (1%) and myositis (1%) were found. In 78% of the cases, various Mycoplasma spp. were isolated. Mycoplasma gallisepticum (MG) was not detected using an MG-specific PCR. Parasitic infections included Philopteridae (55%), Coccidia (48%), Heterakis/Ascaridia spp. (8%) and Syngamus trachea (13%). A total of 8% of the chicks were Avian metapneumovirus (AMPV) positive using RT-PCR, 16% positive for infectious bronchitis virus (IBV) using RT-PCR, and 2% positive for haemorrhagic enteritis virus (HEV) using PCR. All samples tested for avian encephalomyelitis virus (AEV), infectious bursal disease virus (IBDV) or infectious laryngotracheitis virus (ILTV) were negative. The pool samples of the ten chicks were negative for all acid, alkaline-free and derivative substances, while two out of three samples tested were positive for the herbicide glyphosate. Pheasant chick deaths may often have been triggered by poor nutritional status, probably in association with inflammatory changes in various tissues and organs as well as bacterial and parasitic pathogens. Theses impacts may have played a major role in the decline in pheasant populations