In order to determine the effects of crop rotation in the inoculum potential of fungi Phytophthora parasitic variety nicotinae in Ferrallitic red soils at the Tobacco Experimental Station La Sabana in San Antonio de los Baños, it was carried out a study about crop rotation from 1981-1987.Plots enclosed by zinc slides and inoculated uniformly with the fungi were used in the first year and replant in order to multiplication the pathogen.

The species used in the rotation crops were: tobacco variety Burley 21, Colocasia esculent, velvet bean and fallow in rotation ranging from 1 to 4 years.
Its was found that with one and two years of rotation the reduction of inoculum potential was minimal, with three years the reduction was appreciable and with four years of rotation, the reduction of inoculum was notable.