In vitro antifungal/fungistatic activity of manganese phosphite against soybean soil-borne pathogens

Soybean root and stem rots caused by soil-borne pathogens are diseases commonly found in soybean fields, and one of the most important causes of crop losses. In the present study, the mycelial sensitivity of Fusarium virguliforme, F. tucumaniae, Sclerotin ia sclerotiorum and Macrophomina phaseolina was evaluated on potato dextrose agar media (25 mL) supplemented with different concen trations of manganese phosphite (MnPhi) diluted in water (0, 25, 37.5, 50, 100, 200, 300, 400, 500, 800 and 1000 µg/mL). Mycelial growth sensitivity was analyzed using logarithmic linear regression analysis. The MnPhi concentration needed to inhibit 50% of the my celial growth (IC50) ranged from 105 µg/mL (Fusarium spp.) to 409 µg/mL (M. phaseolina). Sclerotia were completely inhibited at 500 µg/mL. The results of our study represent the first report on the di rect in vitro fungicidal/fungistatic action of MnPhi against fungi that are causal agents of soil-borne diseases.