Pesticide Application Documentation

We product oat and barley products and we occasionally apply insecticide to the grain to kill off injurious insects. My question is aside from our documentation (dilution rates and application rates) do we need to be able to trace the product we treated to the finished product? For instance if we treat a truckload of barley into a bin and then bag that product, do I need to be able to trace which bags that product went into? 

Yes; if there was ever a simulated or true recall in the finished product related to the process of applying insecticide to the grain then you would have a traceability gap if you weren't performing this documentation step.