sentences:  The limitation of this parasite as a biocontrol agent is that it requires that some of the pathogen be present to act as a host for its growth.In plant species and cultivars with little or no powdery mildew resistance, the small amount of pathogen growth may cause an unacceptable amount of damage before "A. quisqualis" can control the fungus.To prevent hypervirulent strains from arising and spreading rapidly due to monoculture, cultivar mixtures are commonly employed in mango plantations.