Survival of Macrophomina phaseolina sclerotia in nitrogen amended soils
Filho, E.S.; Dhingra, O.D.
Phytopathologische Zeitschrift 97(2): 136-143
The effect of N at 1, 3, 5 or 7 mg/g of soil, supplied as NaNO3 (NO3-N) or (NH4)2SO4 (NH4-N), on the survival of phytopathogenic M. phaseolina sclerotia was studied in 2 soils. The sandy clay loam and sandy loam soils were infested with 640 sclerotia/g of soil. The population of M. phaseolina declined gradually and significantly in both soils supplied with N from any source or at any concentration. In sandy clay loam soil the population dropped to 2-10 propagules if supplied with 3, 5 or 7 mg N/g of soil from either source. The major drop occurred 30-40 days after N amendment. In sandy loam soil the population dropped to 2 or 100 propagules if amended with 7 or 5 mg NH4-N/g of soil, respectively, but remained at 250 or 460 propagules/g of soil if N source was NO3. In both soils, NH3-N incited more rapid and drastic decline in population than NO3-N.