Terumot & ma'aserot in an open-air pavilion and from a crate

Question

Shalom, on a farm there is a wooden open-air pavilion where meals are served, and salads are prepared from produce picked in the field. When vegetables are brought there, is there an obligation to separate tithes (ma‘aserot)? Additionally, if vegetables are placed in a small crate before being brought into the packing house, may one take from the crate and eat without separating tithes? All the best.