The subject matter of the invention is a hydroxyapatite carrier, corresponding to the formula: Ca(10-x)Mx(PO4)(6-y)(CO3)y(OH)2 in which: M is chosen from Cu, Mg, Zn, Pb, Cd, Ba, K, Mn, Mo, Fe, Ag, B, Se or a combination of at least two of such elements; —x is comprised between 0 and 2, preferably between 0 and 1, more preferably between 0 and 0.8, even more preferably between 0.02 and 0.05; —y is comprised between 0 and 2, preferably between 0 and 1, more preferably between 0.002 and 0.030, The hydroxyapatite is a carrier of a bioactive substance chosen among a metal ion selected from Cu, Zn, S, Mn, Mg, K, Fe, B, Mo, Se and/or an extract of vegetal origin. The bioactive substances are active in the treatment of vascular diseases of plants, in particular: grapevine yellows (caused by grapevine phytoplasma), bacterial canker in kiwifruit (caused by Pseudomonas syringae), olive quick decline syndrome (caused by Xylella fastidiosa) and Citrus bacterial canker disease (caused by Xanthomonas axonopodis).
