Adaptability of Phytophthora capsici Resistant Bell Pepper Cultivars in Southern Georgia

Abstract

Phytophthora capsici (PCap), which causes Phytophthora root rot, is the most destructive soilborne pathogen for bell pepper (Capsicum annuum L.) production in Georgia, USA. Extensive host range, persistence of inoculum in the soil, and lack of effective chemical control methods make this disease particularly difficult to manage. Resistant cultivars offer a practical solution to manage PCap in affected bell pepper fields. However, most commercial cultivars resistant to PCap are predominantly grown in the northeastern United States. This research aimed to screen commercial bell pepper cultivars for resistance to PCap, marketable yield, fruit size distribution, and overall adaptability for production within the largest growing areas in southern Georgia. Field trials were conducted during Spring 2022 and 2023 in commercial growers’ fields with a known history of PCap infestation to evaluate PCap-resistant bell pepper cultivars across four trials conducted in the three counties (Colquitt, Echols, and Lowndes) responsible for ∼78% of bell pepper production in Georgia. Eleven cultivars were evaluated: nine that claimed PCap resistance and two widely grown PCap susceptible cultivars included for comparison. Phytophthora root rot incidence was very low in these research trials. However, there were significant differences in total yields, marketable yields, fruit size, and unmarketable yields. On the basis of marketable yields for jumbo, extra large, and large-sized fruit, we recommend the PCap-resistant cultivars PS 0994-1819, Paladin, and Mercer for fresh market bell pepper growers. Furthermore, ‘Revolution’ is recommended for processor growers due to higher jumbo-sized fruit yields and lower quality and higher pancaking for the spring season in southern Georgia, USA. Newer cultivars Tarpon and Nitro have a more desirable disease-resistance package; however, ‘Nitro’ had small-sized fruit, and ‘Tarpon’ tended to have lower total yields than current commercial standards.