The doctoral program in Plant and Soil Science requires 60 semester hours of graduate coursework beyond the baccalaureate degree and 12 dissertation hours, totaling 72 hours. Doctoral students can follow a track in crop protection, crop science, fibers and biopolymers, horticulture, and soil science. The track should be chosen at the time of the preliminary examination. If the preliminary examination for admission to doctoral studies reveals weaknesses in the student's subject matter background, the student may be required to take remedial courses designated by the graduate faculty of the department. The student's advisory committee will make recommendations concerning language requirements and basic work in other sciences. A Ph.D. candidate in the department is required to take written and oral comprehensive qualifying examinations prepared and conducted by the graduate committee. The purpose of these examinations is to determine whether or not a candidate possesses a depth of knowledge in the track they are following, a breadth of knowledge in supporting areas, understanding of the scientific method, and the ability to communicate knowledge in an organized and scholarly manner.