Preventative treatments in nursery with different biocontrol agents and potassium phosphite salt to control Fusarium wilt agents of lettuce and rocket

This study was carried out to test, in artificially infested soil under greenhouse, the effectiveness of different biocontrol agents (Bacillus spp., mixtures of Trichoderma sp., Glomus spp. + B. megaterium + Trichoderma complex) and potassium phosphite applied as preventative treatments against Fusarium wilt of lettuce caused by Fusarium oxysporum f. sp. lactucae and rocket F. oxysporum f. sp. raphani. The results obtained provide evidence of the capability of commercial BCAs to reduce lettuce and rocket Fusarium wilt by 42 and 47%, respectively, under high disease pressure, when applied four times, starting from the nursery. The phosphite-based products have generally caused a consistent disease control of F. oxysporum f. sp. lactucae, 61-69%, and of F. oxysporum f. sp. raphani, 54-65%, and have shown statistically similar results to those of azoxystrobin, which has been used as a reference (59-65% efficacy), with a significant effect on the yield. Results have been validated in a commercial farm in soil naturally infested by F. oxysporum f. sp. lactucae. Although the Fusarium wilt control shown by such products was not complete under experimental conditions, their contribution to disease management could be interesting, because they can be used to complement other control measures.