Evaluation of two Bacillus sp. strains as an alternative to chemical fungicides for controlling Botrytis cinerea in roses destined for preservation

Abstract

This study evaluated the efficacy of Bacillus subtilis and Bacillus amyloliquefaciens as biocontrol agents against Botrytis cinerea in rose crops destined for preservation in Cayambe, Ecuador. A randomized complete block design was used with nine treatments: six biological (three concentrations of each species) and three chemical treatments. The incidence and severity of the pathogen were evaluated weekly, along with economic indicators such as the cost-benefit ratio (CBR) and net benefit (NB). The biological treatment B1D3 (B. subtilis 1×10¹² CFU/ml) demonstrated the highest effectiveness, reducing incidence to 21.7% and severity to 7.61%, significantly outperforming the chemical treatments Q1, Q2, and Q3, whose values ranged between 24.2%-30.8% for incidence and 9.25%-10.80% for severity. Economically, B1D3 also stood out, achieving a CBR 10% higher and an NB approximately 40% greater than the closest chemical treatment (Q2). In contrast, lower-concentration biological treatments, such as B2D1 (B. amyloliquefaciens 1×10⁶ CFU/ml), were less effective, with incidences of 40.4% and severities of 21.6%. These results position B1D3 as a sustainable and economically viable alternative to traditional chemical fungicides, reinforcing its utility for integrated management of B. cinerea. This study supports the use of Bacillus as an effective and cost-efficient strategy that enhances the sustainability of floriculture while reducing the environmental impact associated with synthetic chemical use.