Converts carlactone to carlactonoic acid by catalyzing consecutive oxidations at C-19 to convert the C-19 methyl group into carboxylic acid (PubMed:25425668). Prefers 11R-carlactone to 11S-carlactone as substrate (PubMed:25425668). Acts downstream of CCD7/MAX3 and CCD8/MAX4 in strigolactone signaling pathway and may be implicated in synthesis of carotenoid-derived branch regulators. Acts as a positive regulator of the flavonoid pathway in the late vegetative stage plant. Strigolactones are hormones that inhibit tillering and shoot branching through the MAX-dependent pathway, contribute to the regulation of shoot architectural response to phosphate-limiting conditions and function as rhizosphere signal that stimulates hyphal branching of arbuscular mycorrhizal fungi and trigger seed germination of root parasitic weeds (PubMed:15737939, PubMed:16387852). Expressed in the vascular cylinder (including the pericycle) in roots, the cambial region of vascular bundles in inflorescence stems and the vascular junctions of axillary regions in leaves and flowers. Increased shoot branching. The branching phenotypes of the max1, ccd7/max3 and ccd8/max4 mutants can be rescued by exogenous treatment with the synthetic strigolactone analogs GR24 and 4BD. Belongs to the cytochrome P450 family.