Otto S.H. Reinecke, an expert on deciduous fruit, was the son of Johann Samuel Gotlieb Reinecke, accountant, and his wife Christina Johanna Georgina, born Herbert. He attended the Secondary School in Middelburg, Transvaal Colony, and passed the matriculation examination of the University of the Cape of Good Hope in 1907. The next year he was selected by the government of the Transvaal Colony as one of a small group of matriculants who were to study agriculture overseas. He was sent to the Ontario Agricultural College (associated with the University of Toronto) in Guelph, Ontario, Canada, where he obtained the degree Bachelor of Science in Agriculture (BSA) in 1912. Upon his return to South Africa he worked as a horticulturalist at the agricultural schools at Elsenburg, near Stellenbosch, and Cedara, near Howick, KwaZulu-Natal. In April 1918 he was appointed as the first professor of pomology in the Faculty of Agriculture at the University of Stellenbosch, a position he held until his retirement in 1961. During this long period he visited many of the fruit producing countries of the world. He was an excellent lecturer, also a part-time farmer, and was popular with the farming community.
Reinecke made several significant contributions to the development of the deciduous fruit industry in the Western Cape and strove to place it on a scientific basis. His research on the pruning of fruit trees, published as 'Die snoei van blaarwisselende vrugtebome' (The pruning of deciduous fruit trees) in the Annale van die Universiteit Stellenbosch (Afdeling A, 1928, Vol. 6(4), 31p) established that moderate pruning gives a better yield than hard pruning and caused a revolution in the pruning of young trees. His studies on the cross-fertilisation of fruit trees led to his being awarded the degree Doctor of Science (DSc) by the University of South Africa in 1930, for a thesis entitled Field and laboratory studies of the pollination requirements of varieties of deciduous fruit trees grown in South Africa (Stellenbosch University, College of Agriculture, Science Bulletin No. 90, 1930).
Reinecke also instituted a systematic search for a suitable yellow clingstone peach variety for canning. This search eventually led to the identification of a suitable peach tree at Kakamas, along the Orange River, by one of his former students, A.D. Collins. Material for the propagation of this tree, which was later named Kakamas, was sent to Reinecke in 1933. The resulting trees were planted at Elsenburg for further study. The variety proved well-suited to the climate of the Western Cape, while its fruit was excellent for canning. Seedlings were distributed to nurserymen in 1938. The Kakamas peach subsequently became one of the best canning peaches in the world.
Other research by Reinecke was published in 'The relation of seed formation to fruit development of the pear' (South African Journal of Science, 1930, Vol. 27, pp. 303-309), 'Dieback of fruit trees in Western Cape Province' (Department of Agriculture, Bulletin No. 97, 1931), and 'A semi-evergreen form of Lombardy poplar' (with C.L. Wicht; Journal of the South African Forestry Association, 1942, Vol. 9, pp. 19-22).
Reinecke was married in Cape Town, on 13 April 1922, to Iris Kathleen Bam, a teacher, with whom he had a son and two daughters.