You only want to apply expensive fungicide when there is a fungus problem. That means someone needs to go out to the field and check - at least today. You don't want to harvest until the corn is dry, someone needs to check the progress of drying before - today the farmer hand harvest a few cobs of corn from various parts of the field to check. There are lots of other things the farmer is checking that we don't have sensors for - we could but they would be too expensive.