Abstract

Potato pink rot, caused by tuber infections with Phytophthora erythroseptica, is an important soil-borne disease that can lead to major losses. Environmental conditions that favour disease include warm, wet and poorly structured soils. Under in vitro growth conditions, studies with a range of Phytophthora species including P. erythroseptica, have shown that a brief cold shock treatment of 8-10°C can stimulate zoospore production and release. This study aimed to determine the effect of in situ-applied cold shock treatments on infection and disease. Inoculated potato plants were exposed to rapid root zone cooling through application of ice water to achieve a soil temperature of ~8-10 °C, at selected growth stages (tuber initiation, early bulking, and tuber maturation). Soil temperatures were continuously logged at tuber depth. Destructive assessments and qPCR analyses were performed to determine disease incidence, severity, and quantify pathogen levels. Preliminary results showed higher infection and greater disease incidence in cold-shocked plants than in non-shocked controls under the same moisture condition, indicating that short cooling events do favour pathogen activation and infection. Outcomes will support an event-based risk framework that combines cold events with soil moisture to improve pink rot prediction and guide mitigation around forecast cold periods. The study advances soil borne disease epidemiology by linking transient root zone cooling with symptom onset and disease progression.