Texas A&M University College Station, Texas, United States
Abstract Text: Fusarium oxysporum f. sp. vasinfectum race 4 (Fov4) is a cause of Fusarium wilt in cotton that differs from other races because it can infect cotton without the presence of a coinfecting nematode; it has been a focal point for research because of the threat it poses to cotton lint and seed production. In the context of the disease triangle, while there has been substantial research on host-pathogen interactions, less has concerned the environmental conditions that mediate pathogenesis.Fov’s capacity to persist in the soil as a saprotroph makes environmental conditions in the off season an important contributor to inoculum density variation at the start of the subsequent growing season, when cotton is most susceptible to Fusarium wilt. I present evidence that thermal and chemical conditions affect inoculum density of Fov. For Fov from the High Plains of Texas, temperatures at certain times of year were associated with inoculum density variation, with higher influence of temperatures during spring and fall than during summer. We investigated the chemical and climatological conditions that are conducive to Fov4 growth and pathogenesis.Fov4 inoculum in the soil was quantified using qPCR and related to thermal and chemical conditions at the plot level.This work advances niche modeling related to pathogenesis, describing the conditions under which the pathogen grows in the soil and the separate conditions that enable infection and disease, and scaffolding niche modeling of other pathogens. Understanding the ecology of this pathogen is critical for sustainable management.
