Efficacy of Biological Products in Managing Root Pathogens in Melons

Biological control represents a sustainable alternative that can be used to reduce the impacts of soilborne diseases in melon cultivation, which are major constraints to productivity. This study evaluated the effectiveness of four biological products formulated with Bacillus and Trichoderma species in suppressing symptoms caused by root pathogens in melon crops, including Fusarium spp., Macrophomina phaseolina, Monosporascus cannonballus, and Rhizoctonia solani. Two greenhouse experiments were conducted to simulate successive crop cycles using two naturally infested soils (A and B). Bombardeiro/Lastro, Quality®, TrichobiolMax, and TrichonemateMax were applied using two management strategies: (1) a tray application 8 days after sowing (DAS) + four pot applications at 7-day intervals, totaling five applications, and (2) a tray application 8 DAS + two pot applications at 14-day intervals, totaling three applications. The yellow melon cultivar ‘Goldex’ was used in the experiments. Forty-five days after transplanting, the treatments showed statistically significant differences compared to the positive control (naturally infested soil without products), both in disease incidence and severity and in plant growth parameters. In Soil A, three applications of Quality® and TrichobiolMax resulted in 50% and 60% disease incidences, respectively. In Soil B, five applications of Lastro and TrichobiolMax led to 60% of plants showing disease symptoms. These products also reduced disease severity in both soils, and TrichonemateMax showed potential for nematode control. Additionally, these products resulted in a 21% reduction in the frequency of Fusarium spp. in Soil A. These findings are valuable for developing sustainable practices in melon cultivation, promoting more efficient and environmentally sound management of root diseases.