Weed Science began its roots in Philippine soil in 1948 when the herbicide 2,4 D was introduced in the country. Pioneers in studying its effectiveness against lawn weeds were Renato Capinpin and Gerardo Ocfemia of the Department of Plant Pathology. During the chairmanship of Jose Velasco of the Botany Department in 1949, the first group of researchers on weeds and their control was formed: Marcos Vega, Jose Ona, Pedro Llera, Juliana Sierra and Santiago Obien.
Under the leadership of Marcos Vega- considered as the "father of Philippine Weed Science", Weed Science rose into prominence in the local agricultural scene. In was in the Department of Botany that prominent weed taxonomists like J.V. Pancho and Norma Aguilar did their various researches and publications on Philippine weeds. In 1969, the first book on weeds, Some Common Weeds in the Philippines by J.V. Pancho, M.R. Vega and D.L. Puckett was published.
With the creation of the College of Arts and Sciences in 1971, the Weed Science group was transferred to the College of Agriculture under the Weed Science Division of the Department of Agronomy. The first division head was Dr. Beatriz Mercado. The first PhD student in Weed Science, Kil-Ung Kim, graduated in 1974. Through the years, under the leadership of various division heads like Dr. Enrique Paller, Juliana Sierra-Manuel and Restituta Robles, the Weed Science division became the center-stage of scientific training of Weed Science students/scientists and likewise spawned other Weed Science groups in the country like for example, the NCPC and IRRI weed scientist groups.