Soil solarization and control of Phytophthora spp. in citrus nursery

AbstractSolarization technology utilizes the solar radiation to kill soil-borne pests, diseases, and weeds in an environmentally and eco-friendly way Phytophthora spp. play a major role in causing seedling mortality in citrus nurseries. Although chemical applications can effectively manage the disease, excessive use often leads to the development of pathogen resistance. A field experiment was conducted to evaluate the effect of soil solarization alone and in combination with bioagent Trichoderma harzianum on the control of Phytophthora spp., in addition to growth performance of Rough lemon (Citrus jambhiri) seedlings. Soil solarization was carried out during the hot summer for 45- days (15April to 30 May) using 100-micron UV-stabilized polyethylene sheets, which resulted in a significant increase in soil temperature at both 5 cm and 10 cm depths. The maximum temperature recorded at 5 cm depth was 52°C, which was 10–11°C higher than the non-solarized control. Soil samples collected before and after solarization revealed a substantial reduction in the population of Phytophthora spp. across all solarized plots. Moreover, most annual and perennial weeds were effectively controlled by solarization. Soil solarization followed by the addition of T. harzianum mixed with farmyard manure (FYM) significantly reduced seedling mortality (7.60%) and enhanced plant growth, with mean height and girth reaching 55.40 cm and 2.58 cm, respectively. The results suggested that soil solarization combined with T. harzianum is an effective, eco-friendly and economical alternative to chemical control for managing Phytophthora-induced mortality in citrus nurseries.