This page provides information on the cactus dieback that was recently (2021) discovered on cactus (Opuntia littoralis) at a nursery in San Pasqual Valley and one restoration site sourced with the nursery cactus in Bandy Canyon. Recent findings from the Department of Plant Pathology, UC Davis pathogenicity tests show that the most frequent fungal species on the diseased cactus are a variety of Alternaria species. The plant pathology lab will next conduct greenhouse experiments to evaluate the effect of environmental factors such as humidity and water availability on disease severity. Information from this study will be used to develop best management practices for land mangers.