Pre-emergence herbicides, especially PPO inhibitors and photosynthetic inhibitors (metribuzin), can injure seedlings, particularly when cool temperatures coincide with rain soon after emergence. Spotty necrosis can occur when rain splashes droplets of residue herbicide from the soil onto emerged seedlings. The fungicide seed treatment fluopyram (ILeVO©; Bayer CropScience) can cause yellow-brown discoloration on cotyledons termed the ‘halo effect’, but is not common on the trifoliate leaves. Environmental conditions and genetics may impact severity of the halo effect from fluopyram.
In many cases pre-emergence herbicide injury will not harm plants to the point of effecting yield. Similarly, fluopyram halo effect has not been shown to impact yield negatively.
Pre-emergence herbicides Fluopyram fungicide 
