One of the actual and demanded problems of contemporary precision agriculture is the determination of the state of agricultural plants. An accurate prediction of plant status during the growing period is necessary for the efficient use of fertilizers, low yields and high quality products. A method of this problem solution is based on the analysis of the optical characteristics of the plants on digital images. In this paper the method of color analysis of plants with aerial photos is considered. All calculations of the experiment were carried out using the language R.