As short as i know, Rural Marketing is buy and sell activities by marketer or supplier to encourage rural people. Rural has two way process, rural to urban and urban to rural.
For example, rural to urban: agricultural products, milk, livestock products, etc. Rural people sell products to urban market. Second, urban for rural: gasoline, electronics, etc.
Normally, rural marketing doesn't need effort to graphic design, branding or even advertising. They usually do their business by trust.