Spray job gone horribly wrong. What spray was used?

Long story short. Spray company was hired to spray for weevil. Next day hay started to turn and burn. No smell to it. Questions, what should I ask for compensation from spray company and what would you guess as to what was used? They are being good at taking responsibility for the killed field and have no idea what has happened. Waiting for results back from samples taken. Had some grass and dandelions that it didn’t touch. Thanks.

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Spray job gone horribly wrong. What spray was used?