The effects of biological control agents, potassium phosphite and calcium oxide on race 1 of Fusarium oxysporum f. sp. lactucae of lettuce in closed soilless cultivation systems

Abstract

AbstractEighteen trials were carried out in a closed soilless system to evaluate the effectiveness of different strains of experimental non‐pathogenic Fusarium oxysporum and Fusarium solani, commercial biocontrol agents (Streptomyces griseoviridis, Bacillus subtilis and Beauveria bassiana), as well as products based on calcium oxide (CaO) and potassium phosphite on race 1 of Fusarium oxysporum f. sp. lactucae, the causal agent of the Fusarium wilt of lettuce. The treatments were applied to lettuce seedlings, which had been grown for 2 days in a peat medium before being artificially inoculated with the pathogen, and were repeated five times at 7‐day intervals. The experimental non‐pathogenic F. oxysporum MSA35 and FC3 strains provided a greater disease severity reduction (54%–83% efficacy) than the commercial B. subtilis (29%–31% efficacy), S. griseoviridis (22%–52% efficacy) and B. bassiana (39%–63% efficacy) formulations. The highest fresh weight value was provided by the non‐pathogenic F. oxysporum MSA35 and FC3 strains, thereby generally reflecting the observed disease reduction. Calcium oxide and potassium phosphite generally resulted in disease protection, but a great variability in efficacy was observed. The obtained results showed good possibilities for the non‐pathogenic Fusarium oxysporum strain against the pathogen in soilless systems.