Soil solarization and biosolarization for controlling crown and root rot disease complex of greenhouse tomato under hysteretic soil conditions

Tzenko D. Vatchev

Abstract: This study revealed the effectiveness of pre-plant soil solarization and biosolarization against the crown and root rot disease complex of greenhouse tomatoes in soils “locked in” by hysteretic performance as a result of multiple applications of broad-spectrum disinfestation methods, which are non-selective to indigenous soil microbial communities. Greenhouse pot experiments were conducted using naturally infested soil containing the principal pathogen, Fusarium oxysporum f.sp. radicis-lycopersici and associated species, including Colletotrichum coccodes, Fusarium solani, Pyrenochaeta lycopersici, Rhizoctonia solani AG 4 and AG 6, Sclerotinia sclerotiorum, Pythium spp., and Phytophthora spp. Soil was collected from a tomato production glasshouse with a long history of disease, where annual chemical soil fumigation or heat steaming had ceased to have a positive effect on plant health or yields. Soil was filled into transparent polyethylene bags, either with or without incorporation, at different rates of fresh tomato residues cut into pieces 2-4 cm in length. The bags were left open (untreated controls) or tightly closed and exposed to the sun for 7 to 30 days. Treated and untreated soils were transferred to plastic pots, along with tomato plants. Ideals were cultivated for 75 days. Thirty-day solarization reduced the severity of crown and root rot by 40.9%. Biosolarization with the addition of tomato-crop residues at a maximum rate of 100 g L-1 soil, followed by 30-day solarization, provided the highest level of disease control – 52.5%. The incorporation of fresh tomato crop residues without subsequent solar heating had no disease-modifying effect or led to an increase in disease symptoms. No follow-up disease-suppressive effect was observed during a second cropping cycle in the same soils. However, both ecologically benign methods have demonstrated that they can break the tendency of the boomerang effect and overcome the condition of hysteresis in soil ecosystems subjected to pulse disturbances by drastic, pathogen-eradicating treatments.

Keywords: associated pathogens; buffering capacity; complex etiology; hysteresis; resilience; soil disinfestation

Citation: Vatchev, Tz. D. (2025). Soil solarization and biosolarization for controlling crown and root rot disease complex of greenhouse tomato under hysteretic soil conditions. Bulg. J. Agric. Sci., 31(5), 873–886

Date published: 2025-10-28