'arboricultural' is formed in English from the noun 'arboriculture' plus the adjectival suffix '-al'; 'arboriculture' itself is built from Latin elements 'arbor' meaning 'tree' and 'cultura' meaning 'cultivation'.

'arboriculture' was coined in Modern English (influenced by Modern Latin 'arboricultura'); 'arboricultural' developed later by adding '-al' to create an adjective meaning 'relating to arboriculture'.

Originally the root elements referred specifically to 'tree' and 'cultivation'; over time the compound came to denote the organized practice and science of tree cultivation, and the adjective now means 'relating to that practice'.