ZAP FFS #2, the control, and Soilweb.com Product B had the highest rhizosphere yeast and mold levels, from 4.5 to 5.1 x 104 CFU/gdw, but Vitazyme had nearly as high levels: 4.1 x 104 CFU/gdw. On the other hand, Vitazyme had by far the highest rhizospheric active fungal biomass of 61.5 ug/gram; the next highest level was 50.6 for Super Bio, and all other values are considerably less. These results show that Vitazyme performed the best of all eleven treatments in this California grape root zone microorganism stimulation study.