PJB-1979-22
Relation of sclerotial inoculum density and soil moisture to infection of field crops by macrophomina phaseolina
A. HAKEEM
SHEIKH AND A. GHAFFAR
Abstract
The effect of sclerotial density of v at
various soil moisture levels on disease incidence in black gram, guar, okra and cotton was investigated. Infection percentage increased linearly with the increase in inoculum density of sclerotia in
soil but varied inversely in relation to soil moisture regime. Infection percentage was consistently higher
at 30 days compared to that at 15 days of experimental period. The susceptibility to Macrophomina infection varied in the test species. Whereas a scelrotial density of 5/g of soil gave 50% infection in black gram,
20 sclerotia/g of soil were required for okra , guar and 40 for cotton at
25% water holding capacity (W.H.C) Inoculum density of up
to 40 sclerotia /g soil coupled with high soil moisture (100% W.H.C) did not produce more than 50% infection.
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