Banca de DEFESA: JULIANE FERREIRA PINTO

Biofumigation with fresh poultry litter for the control of clubroot:

Brassica oleracea; Eruca sativa; Plasmodiophora brassicae; organic residues; biofumigation.

Biofumigation is a strategy used as an alternative to chemical fumigants in the control of
diseases caused by soilborne pathogens. It is based on the incorporation of organic residues
and the release of compounds with suppressive activity. This study aimed to evaluate the
effect of five doses of fresh poultry litter (FPL) and two post-incorporation management
practices, maintaining the pots open or sealed, on the intensity of clubroot and on the
development of cauliflower (cv. Vigo F1) and arugula (cv. Rococó). The experiment was
conducted in a greenhouse using 25-L pots, in a randomized block design, arranged in a 2 × 5
× 2 factorial scheme: soil inoculated or non-inoculated with resting spores of Plasmodiophora
brassicae (density); application and incorporation of five doses of FPL (doses in g L⁻¹); and
maintenance of the pots open or sealed for 28 days, with four replications. The application of
FPL promoted changes in soil chemical attributes, with an increase in pH and nutrient
availability, especially under sealed conditions. In sealed pots, a suppressive effect on
spontaneous plants was observed, with a significant linear reduction in plant density, fresh
mass, and dry mass as FPL doses increased. In cauliflower, treatments did not significantly
affect growth and yield variables, indicating the absence of phytotoxic effects from FPL
application or pot sealing. However, in inoculated pots, a progressive reduction in disease
incidence and severity was observed with increasing doses. In open pots, the highest
incidence (75%) and severity occurred in the absence of FPL, with disease suppression
observed only at the highest dose (2.14 g L⁻¹). In sealed pots, incidence was 25% at doses of
0.0, 0.27, 0.54, 1.07, and 2.14 g L⁻¹, and reached 0% from the dose of 1.07 g L⁻¹ onward. In
arugula, increasing FPL doses significantly increased fresh mass and the volume of healthy
roots, regardless of inoculation or management, and contributed to the reduction of disease
intensity, especially under sealed pot conditions. It is concluded that fresh poultry litter has
biofumigant potential for reducing losses caused by clubroot, in addition to providing
nutritional effects and promoting improved plant development.