Bioactive management alternatives for Sclerotinia minor Jagger in lettuce (Lactuca sativa).

Resumen

Objective: To determine the effect of biological control agents and plant extracts on the sclerotia of Sclerotinia minor through in vitro and in vivo trials.

Design/Methodology/Approach: Through in vitro and in vivo trials, analyses were performed on sclerotia treated with bioactive products, including the percentage of germination, parasitic colonization, disease incidence, and fresh plant weight.

Results: Trichoderma harzianum completely inhibited the growth of S. minor in vitro through mycoparasitism and enzymatic degradation. In vivo, it reduced disease incidence to 20% and resulted in a lower percentage of germination and sclerotia produced post-trial, whereas the control treatments reached 100% infection. Sclerotial germination only occurred in the presence of the host plant. Trichoderma maintained a stable population in the soil (10⁴ CFU/g), demonstrating high persistence. In contrast, Bacillus spp. showed lower efficacy, with high percentages of sclerotial germination (92.5-97.5%). Organic matter slightly increased disease incidence by creating favorable conditions for the pathogen.

Limitations/Implications: Due to the biology of the pathogen, it is necessary to determine more precisely the biological interactions occurring in the plant rhizosphere to better understand the action of the biological agents.

Findings/Conclusions: Trichoderma harzianum establishes itself as a viable alternative for the management of S. minor in lettuce, reducing sclerotia viability through mycoparasitism and competition. Its implementation allows for a reduction in the dependence on synthetic fungicides and contributes to more sustainable production, minimizing the development of fungicide resistance.