Premature Field Collapse in Spring Potatoes: Does Alternaria solani Bear the Blame?

Abstract In recent years, a new phenomenon known locally as “premature field collapse” has become a serious concern for potato growers in the spring growing season in the northwestern Negev region of Israel. The progress of the syndrome is rapid, and entire fields may collapse within 10 to 20 days, causing significant yield losses. The symptoms observed on infected plants resemble those of early blight caused by Alternaria solani . This pathogen typically poses a threat to autumn crops but is usually harmless to spring plantings, making this occurrence particularly unusual. This study aimed to characterize the syndrome, examine whether A. solani is the causal agent, and investigate possible physiological and environmental factors contributing to this phenomenon. We hypothesized that shifts within the A. solani population to a more aggressive isolate or an isolate better adapted to the spring season had occurred. In line with our initial hypothesis, we conducted extensive field and laboratory analyses to compare A. solani isolates from autumn and spring crops regarding their response to temperature, fungicides, and virulence on various Solanaceae hosts. While no evidence was found to support the involvement of other pathogens or a distinct A. solani population, our findings highlight the need for further research into the role of external triggers, such as nutrient deficiencies or environmental stressors, in exacerbating plant susceptibility. Understanding these factors is essential for developing effective management strategies to mitigate yield losses and sustain potato production in this critical agricultural region.