BB 4 - Gina vs. Bika

The Gemara understands that it is more likely that the custom will be to build a wall in regards to a גינה - a vegetable garden or fruit orchard - than a בקעה - a field meant to grow grains. The question is, Why?

נ"ל בע"ה that the understanding is that the whole reason that we would build a wall is to prevent מראית עין - the Evil eye. That being the case, it is more likely for someone to look jealously at a field that is immediately ready for consumption - the vegetable garden or fruit orchard - as opposed to a field of grains that require many steps of processing before the produce can be consumed.