Herbicide injury in crops: Symptomology and resource building for agricultural extension

Herbicides play a critical role in modern agriculture by managing weed populations and maintaining crop productivity. However, off-target herbicide exposure can result in crop injury that is difficult to distinguish from symptoms caused by abiotic stressors like nutrient deficiency or drought. This study aimed to (1) evaluate herbicide injury symptoms across major Oklahoma crops under greenhouse and field conditions, and (2) contribute to a photographic resource for agricultural extension. Crops including wheat, canola, corn, cotton, sorghum, and camelina were treated with common herbicides such as Metribuzin, Aggressor®, Beyond®, Glyphosate, Dicamba, and 2,4-D. Injury symptoms were rated over a three-week period using standardized scoring scales and photographic documentation. Results from greenhouse trials showed that symptom onset and severity varied widely by crop and herbicide, with Camelina being highly sensitive to both Metribuzin and Beyond®, and Roundup Ready® canola showing full resistance to Glyphosate. Field data generally mirrored these trends but revealed more gradual symptom development, likely due to environmental variability. CoAXium® wheat demonstrated consistent resilience to Aggressor®, while Showdown wheat experienced more severe injury. The combined greenhouse and field findings highlight the value of integrating both experimental settings to better understand crop-herbicide interactions. Ultimately, this research provides foundational data for future efforts to develop an accessible herbicide injury photo database for use in agricultural extension and crop management decision-making.