Abstract: Utilizes machine vision to thin fields, for example by selectively spraying plants with enough fertilizer to kill the plants, for example to maintain a minimum distance between plants or to enable remaining plants to grow in a pattern, for example two dimension diamond pattern. The use of fertilizer to kill plants has the benefit of fertilizing the field, i.e., the remaining plants not to be killed, at the same time. This unexpected result which occurs in the thinning and simultaneous fertilizing of a field is based the discovery that immature plants are more sensitive to fertilizer than mature plants. The system and method eliminates the need for harmful chemicals and mechanical thinners and may be retrofitted onto existing spray systems and platforms, thus eliminating herbicides and thinning machinery.