The soft rot caused by Pectobacterium carotovorum subsp. carotovorum (Pcc) may occur in Chinese cabbage (Brassica pekinensis) plantations presenting till 67% of incidence. In this research we evaluated the Pcc sensibility to bactericides in vitro, the effect of Mycoshield® at 3.0 and 1.5 g L-1, and yeasts at 10(8) cel/mL-1 to control the disease in greenhouse and field. Plants were sprayed with Mycoshield® (oxitetracycline 20%) and yeasts (Rh1 and Rh2 (Rhodotorula spp.) and Sc1 (Saccharomyces cerevisae)) seven days after transplant and inoculated with the isolate Pcc120 seven days and 12 h after treatment, respectively. In all experiments disease epidemiological components were evaluated. In vitro 40 Pcc isolates were resistant to copper sulfate and sensitive to oxitetracycline, streptomycin, oxitetracycline + streptomycin and oxitetracycline + copper sulfate all at 0.2 g L-1. Six Pcc isolates were more inhibited by Mycoshield® than by Agri-Micina® (oxitetracycline 1.5% + streptomycin 15%) both at 3.0 g L-1, but there was no inhibition by Kasumin® (Kasugamicin 2%) (2.0 mL L-1). In greenhouse Mycoshield® at 3.0 g L-1 reduced disease severity and disease index up to 47.4 and 19.0%. The yeast Sc1 reduced disease severity and area under the disease progress curve (AUDPC) up to 27.6 and 39.3% respectively, while Rh1 reduced AUDPC up to 33.5%. In field Mycoshield® reduced the disease index (14.4%) severity (15.5%) and AUDPC (28.9%), while Rh1 reduced disease index by 8.8% and Sc1 reduced the AUDPC by 15.7%. In conclusion Mycoshield® and yeasts showed low efficiency for controlling soft-rot of Chinese cabbage in field.
Brassica pekinensis; Pectobacterium carotovorum subsp. carotovorum; Saccharomyces cerevisiae; Rhodotorula sp.; oxitetracycline; streptomycin
