In order to study a plant disease, one needs to know the symptomatic manifests, morphology and biology of the pathogen that causes mutual relations between the host plant and the pathogen, and the influence exerted by environmental conditions. In the fight against plant diseases, preventive measures are mainly used. These sought to determine the degree of impairment in nature pests of the acorn crop emergence percentage and seedling development in the first year of vegetation under the influence of prophylactic or curative treatments applied at sowing. using some new fungicides. To control these pathogens fungicides series of new generations were tested. Tests were made in several forest nurseries using acorn of several origins and several species of the genus Quercus. Acorns were treated before sowing and the effect of these treatments in health and seedling emergence percentage obtained was observed.