negatively regulates negative regulation of developmental process biological regulation appressorium formation regulation of appressorium formation negative regulation of appressorium formation GO:0075019 biological_process negative regulation of appressorium formation on or near host Any process that stops, prevents, or reduces the frequency, rate or extent of symbiont appressorium formation. Note that this term should not be used to annotate gene products of the host. It should only be used to annotate those gene products from the symbiont involved in this process.