Why is the plywood tray outlet free from fumigation?

Let me talk about what is plywood, because my language ability is limited, I am afraid that I can't express myself better, or you can't understand what I mean. Please allow me to use the introduction on Baidu Encyclopedia: plywood is rotated by wood Cut into veneers or sliced ​​into thin wood by wood. Here we can see that the thin wood avoids the presence of aphids. The adhesive has both anti-virus and anti-adhesive properties. It can be fumigated without disinfection and then glued with adhesive. The three-layer or multi-layered plate-like material is usually made of odd-numbered veneers and the fiber directions of the adjacent veneers are vertically glued to each other. It means that the plywood generally consists of three layers and five layers. Or the nine-layer board is glued, of course, their sheet thickness will also become thicker with the addition of the number of layers;