Compatibility of azoxystrobin and cyproconazole on plant growth-promoting microorganisms

Avoiding the toxicity effect of chemical fungicides on rhizobacteria is a sustainable alternative for agroecosystem management. Rhizobacteria, whose bioprotective and plant growth-promoter potential have been reported in the literature, lack studies on their performance in integrated management with pesticides. Thus, this study aimed to evaluate the effects of azoxystrobin + cyproconazole on the growth of Bacillus subtilis, Streptomyces seoulensis, and Bradyrhizobium japonicum. Three independent experiments were set up, i.e., one for each microorganism, and carried out in a completely randomized design in a factorial scheme (3 x 6), with three doses (recommended by the manufacturer, half, and twice) and six periods of evaluations (48, 96, 144, 192, 240, and 288 hours), with three replications. Growth inhibition rings were evaluated. Azoxystrobin + cyproconazole at all tested doses is compatible with B. subtilis. The use of azoxystrobin + cyproconazole affected the growth of B. japonicum and S. seoulensis, which were sensitive to all its doses until 288 hours after inoculation.