Disease Cycle and Epidemiology

Macrophomina phaseolina survives in the soil and crop residue as microsclerotia. These microsclerotia served as the primary source of inoculum. Microsclerotia are formed from aggregates of hyphal cells joined by a melanin material with 50 to 200 individual cells composing an individual microsclerotia. Under favorable conditions, hyphae germinate from the microsclerotia and infect the roots of the host plant. Hyphae initially invade the cortical tissue of host plant and then through the xylem colonizing the vascular tissue. Finally gray-black mycelia and sclerotia are produced in the vascular tissue that plugs the vessels. Diseased plants may wilt and prematurely die with senesced leaves remaining attached to petioles. Hot, dry weather promotes infection and disease development to most of the plant species.