I just read a news DJI is going to lauch a plant-protecting drone. Is it true?! Here is the link:DJI Plant-Protecting Drone Is On Coming Sale

I own a farm. And I want to know whether it's helpful for my farm. And how much is this drone?

Bad translation from Chinese.  DJI has developed an agricultural drone which can be used for crop spraying.  It's only good for a small area as it can only carry a small amount of liquid.  It's also very expensive at around $18,000.

Hello Frank, here is an introduction of  MG-1 http://www.dji.com/product/mg-1

Maybe the farms in China are the size of half a house lot, but that thing would be useless to any decent sized farm. Here in Australia we use Yamaha RC he;lis that are about one third the size of a real heli to do those sort of jobs.