Impact of pesticides in properties of Bradyrhizobium spp. and in the symbiotic performance with soybean

The Challenge of Combining High Yields with Environmentally Friendly Bioproducts: A Review on the Compatibility of Pesticides with Microbial Inoculants

“…Another interesting observation in the study by Rodrigues et al [25] was the changes in colony morphology, smaller with the increase of the exposure to the pesticide. However, regular colonies were recovered after the bacteria were grown under optimal conditions, indicating an adaptive mechanism to the stressful conditions when exposed to the pesticides.…”

“…For example, in a study by Gomes et al [102], although fungicides (carbendazin + thiram) did not affect nodulation, plants had lower number of pods per plant, grains per plant, and yield. Intriguingly, in two field experiments performed with soybean in Brazil, seed treatment with Standak ® Top affected the total N accumulated in the grains of plants relying on both BNF and N fertilizer, indicating the negative impact of the pesticide on N metabolism [25]. In another study, a decrease in both protein and oleic acid contents was observed in soybean inoculated and treated with mefenoxan + fludioxonil [103].…”

“…In another study, Gomes et al [102] observed no effects on nodulation when seeds were inoculated with B. japonicum SEMIA 5079 + B. diazoefficiens SEMIA 5080 and treated with carbendazin + thiram. More recently, when the compatibility of B. japonicum SEMIA 5079 and B. elkanii SEMIA 587 was verified with Standak ® Top, composed of a mixture of two fungicides and one insecticide (piraclostrobin, thiophanatemethyl, and fipronil), the effects were also more drastic for B. elkanii [25]. Altogether, indications are that B. elkanii is less tolerant to fungicides than B. japonicum or B. diazoefficiens.…”

“…However, the damage to microbial inoculants increases with the number of combined chemicals. As previously mentioned, Standak ® Top, one of the most used for treatments of seeds in several countries, especially for soybean, is composed of two fungicides and one insecticide; it affects the survival of B. japonicum and, especially, B. elkanii cells, with a drastic decrease verified after 7 days of contact [25]. It is worth mentioning that pre-inoculated soybean seeds have been in contact with Standak ® Top for up to 90 days, often resulting in zero recoveries of rhizobial cells from seeds [126].…”

Mixture compatibility of Anticarsia gemmatalis nucleopolyhedrovirus (AgMNPV) with pesticides used in soybean

“…In addition to the tank mix of synthetic and biological products, the mix also occurs in seed treatments. The treatment of soybean seed with Bradyrhizobium spp mixed with fungicides pyraclostrobin and thiophanate-methyl and the insecticide fipronil, caused a decrease in the efficiency of the bacteria immediately and over time (RODRIGUES et al, 2020). The use of Thichoderma spp combined with the fungicide Fludioxonil to treat soybean seed, caused an increase in crop production (ZANDONÁ et al, 2019).…”