Halo of yellow around cotyledons

You may have observed canola with a yellow halo around the outside edge of cotyledons. If this happens when growing conditions are optimal and there hasn’t been frost, seed treatment is the likely cause. When the plant is growing very fast, translocation of seed treatment into the plant is also very fast. This can result in an occasional yellowing of the margins of the cotyledons. It does not affect plant health or efficacy of the product.