Acidification of the culture medium as a strategy to control endophytic contaminations in Prunus spp. rootstocks cultured in GreenTray TIS bioreactor

•Endophytic contaminations in in vitro cultures may produce high losses of plant material.•The GreenTray® TIS bioreactor was used to study the effect of a more acidic (pH 3) and a more basic (pH 7) pH than the commonly used for in vitro cultures (pH 5.7) in endophytes populations and micropropagation of RP-20 in vitro plantlets.•The culture of RP-20 plantlets at a pH 3 reduces endophytes populations without affecting in vitro micropropagation.•The acidification of the culture medium might substitute the addition of antibiotics to control endophytes in in vitro cultures.