Efficacy of sugarcane pyroligneous extract in suppressing carpogenic germination of Sclerotinia sclerotiorum

ABSTRACT

White mold, caused by the fungus Sclerotinia sclerotiorum, is a disease of agronomic importance that affects crops such as soybeans and beans. Considered an aggressive pathogen, it causes symptoms in different parts of the plant, and its control is difficult due to the formation of resistance structures called sclerotia, which allow it to survive in the soil for long periods. The objective of the present study was to evaluate the effectiveness of different concentrations of pyroligneous extract (PE) from sugar cane in suppressing the carpogenic germination of S. sclerotiorum in vitro. The concentrations tested were 0; 1,000; 2,000; 3,000; 4,000 and 5,000 ppm. The extract was incorporated into water agar medium and poured into gerbox boxes with 20 sclerotia. The total number of sclerotia with emission of stipes and apothecia, the total number of sclerotia with emission of stipes and the total number of sclerotia with apothecia were quantified. There was a significant difference in carpogenic germination between the treatments evaluated. Increasing concentrations of sugarcane PE negatively affected the carpogenic germination of sclerotia, the number of stipes per sclerotium and the number of apothecia formed per sclerotium. It was found that sugarcane PE did not inhibit the formation of stipes, but made it difficult to differentiate them into apothecium, especially at the concentration of 5,000 ppm. Sugarcane PE at concentrations of 4,000 and 5,000 ppm promoted reduction in the percentage of germinated sclerotia, as well as in the number of apothecia per sclerotium.

Keywords
white mold; pyroligneous acid; sclerotia