Seven years of white mold biocontrol product’s performance efficacy on Sclerotinia sclerotiorum carpogenic germination in Brazil: A meta-analysis

Abstract

Biocontrol is a plausible strategy to be considered on the management of white mold but the efficacy is not always the same. Therefore, the identification of the sources of such variable performance fosters a fine-tune product recommendation to achieve the highest performance. Based on seven soybean crop seasons, 59 uniform field trials were conducted throughout Brazil to assess the performance of Sclerotinia sclerotiorum sclerotia parasitism under different temperature and rainfall regimes. Hence, we carried out a meta-analysis to evaluate the effect of three treatment classes (Trichoderma-, Bacillus-, and a Mixed combination of both organisms) on the reduction of S. sclerotiorum sclerotia carpogenic germination (mean difference; MD) according to a multilevel network model (59 trials, k = 340). Throughout trials included in the meta-analysis, biocontrol reduced carpogenic germination ca. 70 % of times, with fitted MD¯ values of − 10.6 for Bacillus, −8.6 for Trichoderma, and − 7.0 for Mixed Bacillus and Trichoderma groups. Separate network models were then fitted to determine the influence of average monthly temperature (AMT) and average monthly rainfall (AMR) under three classes (low, moderate, and high) for each variable on the carpogenic germination. Overall, interactions of treatments and low or moderate AMT and AMR were significant (p < 0.1). Temperatures above 27 °C and precipitation higher than 250 mm have not contributed to the reduction in carpogenic germination regardless of the considered active ingredient. Hence, biocontrol product́s reduce carpogenic germination in ca. 9 % and dominant weather conditions. These relationships are important factors involved in sclerotia colonization and therefore, high temperatures and rainfall should not be indicated for the product’s application for best BCAs performance.