Sphynolactone-7 (SPL-7) is an active site-targeting, highly potent and selective strigolactone receptor ShHTL7 agonist (YLG competitive binding IC50 = 310 nM/ShHTL7, 1.2 µM/ShHTL8, >7.0 µM/ShHTL2-6, ShHTL9-11, AtD14) that acts as a seeds germination stimulant with femtomolar- and picomolar-level potency, respectively, toward the parasitic plants Striga hermonthica ecotypes and Orobanche minor, while exhibiting no Arabidopsis-stimulatory efficacy.