Columnar cacti are an essential resource in arid and semi-arid forests. Although they do not provide direct economic benefits, they are vital for maintaining the ecological balance of flora and fauna in desert ecosystems. Over the past 20 years, necrotic disease has been observed in the southern part of the peninsula, leading to a decline in wild cactus populations. To assess the infectious nature of the disease associated with cactus necrosis syndrome (CNS), a study was conducted to identify the fungal pathogens involved and to measure the spread and severity of CNS. Disease intensity was determined by estimating the incidence, severity, and dispersion index. The suspected pathogenic fungi were studied based on symptoms, dispersion patterns, morphological features, and PCR analysis using general and specific primers. To evaluate the pathogenicity and severity of the isolated fungi, experimental inoculations were performed on two-month-old cardon cacti. Results showed that at least four fungi (Phoma spp., Nigrospora sphaerica, Chaetomium spp., Coniochaeta spp., and Alternaria alternata) may be associated with CNS, with responses varying depending on whether infections are mixed or straightforward. Common symptoms included canker and pustules, with prevalence rates of 78.87% and 85.3%, respectively. An increase in incidence of 9.89% was noted compared to 2019 (74.83%) and 2020 (84.72%). The average severity rate for all observed symptoms was 55.21%. These findings identify the causal agents involved in necrotic diseases, which could influence the severity and progression of NCS in BCS and southern Baja California. However, additional research is needed to determine if other fungal agents are involved and to clarify their roles in pathogenicity. Moreover, the phytosanitary status of the fungal communities associated with wild cacti remains unexplored. These findings are valuable for advancing research on the pathometry and epidemiology of this important forest resource in Mexico and around the world.