ABSTRACT
Sclerotia of Sclerotinia sclerotiorum, a fungal pathogen of soybean, may be affected by herbicides used in the pre-planting management or even in post-emergence applications. The objective of the present study was to verify the action of the herbicides glyphosate, glufosinate ammonium and dicamba on mycelial growth and carpogenic germination of sclerotia and Sclerotinia sclerotiorum. The PDA culture medium was supplemented with concentrations of 10, 100, 1000 and 10000 ppm herbicides, receiving inoculation of fungal mycelium in Petri dishes. The diameter of the mycelium growth was measured daily. The carpogenic germination of sclerotia was analyzed with the deposition of ten sclerotia on the ground surface which was sterilized, arranged in plastic boxes and sprayed with solutions at concentrations of 1, 10, 100, 1000 and 10000 ppm herbicides. Evaluations were carried out at 30, 40 and 50 days after incubation by counting the number of stipes and apothecia. Glufosinate ammonium caused the greatest mycelial growth inhibition on S. sclerotiorum, which was above 40% even at the lowest concentration. The speed of mycelial growth was also lower from 10 ppm glufosinate. While for the control sample there was differentiation of stipes into apothecia, sclerotia treated with the herbicides showed a high number of stipes and a low number of apothecia. Changes in morphology, such as deformation on the edges of the apothecia disks, changes in coloration and stunted aspect, were also observed in sclerotia treated with herbicides. The herbicides glyphosate, glufosinate ammonium and dicamba alter the development of S. sclerotiorum sclerotia and may have an inhibitory action on the fungus.
Keywords
sclerotia; glyphosate; glufosinate ammonium; dicamba
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