Effect of microorganisms on degradation of fluopyram and tebuconazole in laboratory and field studies

Abstract

Nowadays, chemical pesticides are the most widespread measure used to control crop pests and diseases. However, their negative side effects prompted the researchers to search for alternative options that were safer for the environment and people. Pesticide biodegradation by microorganisms seems to be the most reasonable alternative. The aim of the laboratory studies was to assess the influence of Bacillus subtilis and Trichoderma harzianum, used separately and combined together, on fluopyram and tebuconazole degradation. In field studies, the degradation of fluopyram and tebuconazole after the application of the biological preparation in apples was investigated. The results from the laboratory studies show that the greatest decomposition of fluopyram and tebuconazole was observed in tests with T. harzianum in a range of 74.3–81.5% and 44.5–49.2%, respectively. The effectiveness of fluopyram degradation by B. subtilis was 7.5%, while tebuconazole inhibited bacterial cell growth and no degradation was observed. The mixture of microorganisms affected the degradation of fluopyram in a range of 8.3–24.1% and tebuconazole in a range of 6.1–23.3%. The results from the field studies show that degradation increased from 3.1 to 30.8% for fluopyram and from 0.4 to 14.3% for tebuconazole when compared to control samples. The first-order kinetics models were used to simulate the residue dissipation in apples. For the determination of pesticide residues, the QuEChERS method for apple sample preparation was performed, followed by GC–MS/MS technique. Immediately after the treatments, the maximum residue level (MRL) values for tebuconazole were exceeded, and it was equal to 100.7% MRL for the Red Jonaprince variety and 132.3% MRL for the Gala variety. Thus, preharvest time is recommended to obtain apples in which the concentration of pesticides is below the MRL and which can be recognized as safe for humans.

Multiple Assays on Non-Target Organisms to Determine the Risk of Acute Environmental Toxicity in Tebuconazole-Based Fungicides Widely Used in the Black Sea Coastal Area

“…Among other species, they analyzed 13 strains of Bacillus, and found only three capable of degrading Tebuconazole. Other reports [ 74 ] have shown that on the contrary, the growth of B. subtilis is inhibited by Tebuconazole; these results are similar to our observations.…”

Dual RNA sequencing during Trichoderma harzianum–Phytophthora capsici interaction reveals multiple biological processes involved in the inhibition and highlights the cell wall as a potential target

“…On the other hand, certain microorganisms possess the ability to degrade the fungicides applied to plants and can weaken the protection effects provided by these agrochemicals. 64 Thus, clarification of the interplay between biocontrol microorganisms and fungicides is of considerable significance. In the present study, findings were made that the presence of T. harzianum T-22 could increase the inhibitory effect of carboxylic acid amide fungicides on P. capsici, indicating that fungicide degradation should not be a concern when combining T. harzianum T-22 and mandipropamid/dimethomorph in agricultural systems.…”