Effect of integrating fungicide and biocontrol foliar sprays on maize grain yield and fumonisin content

Abstract: The adoption of biocontrol is low in maize production although its synergistic action with fungicides on the grain content of fumonisin is reported. The objective of this work was evaluate the potential effect of Bacillus sp. (BIOUFLA2) and Streptomyces araujoniae (BIOUFLA1) combined or not with fungicide (azoxystrobin + ciproconazol) on grain yield, Fusarium verticillioides, incidence and total fumonisin content. Maize plants were sprayed two times, at the phenological stages V9 and R1 with water, BIOUFLA1, BIOUFLA2, fungicide alone or in different combinations two by two. All plants were inoculated with F. verticillioides. Upon harvest, treatments were evaluated for total yield, F. verticillioides grain contamination (blotter test) and total fumonisin (B1 and B2) contents. The treatment combination fungicide at V9-V10 combined to S. araujoniae at R1 resulted in increased yield in three out of the four field trials, while all the other treatment combinations resulted in increased yield in two out of the four trials. All treatment combinations less the two sprays of fungicide reduced F. verticillioides incidence in grains compared to the water control. None of the treatments contributed to the reduction on the fumonisin content compared to the control but the two sprays of fungicides or S. araujoniae and the combination S.araujoniae (V9-V10) + Fungicide (R1) resulted in higher mycotoxin contents compared to the control. The use of the fungicide at V9 followed by S. araujoniae (R1) resulted in more consistent yield increases, reduced grain contamination by F. verticillioides and did not increase the fumonisin content compared to the control.