Dr. Orillo's researches in plant pathology helped pave the way to minimizing losses suffered by crop producers attributable to plant diseases. Noteworthy of his scientific publications are on coffee rust, blight affecting kenaf and leaf spot of maize caused by Helminthosporium maydis.

In recognition of his outstanding contributions to Philippine agriculture, Dr. Orillo received the Distinguished Alumnus award given by the UP College of Agriculture in 1974. He is also a member of several professional and learned societies namely: Botanical Society of America, American Association for the Advancement of Science and the American Phytopathological Society.