Bacillus subtilis based-formulation for the control of postbloom fruit drop of citrus

Abstract

Postbloom fruit drop (PFD) caused by Colletotrichum acutatum affects flowers and causes early fruit drop in all commercial varieties of citrus. Biological control with the isolate ACB-69 of Bacillus subtilis has been considered as a potential method for controlling this disease. This study aimed to develop and optimize a B. subtilis based-formulation with a potential for large-scale applications and evaluate its effect on C. acutatum in vitro and in vivo. Bacillus subtilis based-formulations were developed using different carrier materials, and their ability to control PFD was evaluated. The results of the assays led to the selection of the B. subtilis based-formulation with talc + urea (0.02 %) and talc + ammonium molybdate (1 mM), which inhibited mycelial growth and germination of C. acutatum. Studies with detached citrus flowers showed that the formulations were effective in controlling the pathogen. In field conditions, talc + urea (0.02 %) provided 73 % asymptomatic citrus flowers and 56 % of the average number of effective fruit (ANEF), equating with fungicide treatment. On the contrary, non-treated trees had 8.8 % of asymptomatic citrus flowers and 0.83 % ANEF. The results suggest that B. subtilis based-formulations with talc as the carrier supplemented with a nitrogen source had a high potential for PFD control.

Interactions Among Plants, Insects, and Microbes: Elucidation of Inter-Organismal Chemical Communications in Agricultural Ecology

“…The floral microbiome is subject to conventional and biopesticide control measures: fungicides, antibiotics, and biocontrol products are applied to many flowering crops to prevent pathogen infection. , An understanding of the tritrophic interactions between flowering plants, the anthospheric microbiome, and floral visitors (both beneficial and detrimental) may lead to new or improved agricultural technologies. For example, microorganisms capable of emitting certain key volatile components not synthesized by plants may be developed and rapidly deployed to a wide variety of crops, without the need for genetic modification of the plants themselves.…”

Evaluation of Biological Plant Protection Products for Their Ability to Induce Olive Innate Immune Mechanisms and Control Colletotrichum acutatum, the Causal Agent of Olive Anthracnose

“…Bacillus amyloliquefaciens (former subtilis) is among the most well-studied biocontrol agents for the control of plant pathogens and post-harvest diseases [ 26 ]. It has also been studied in agricultural conditions in recent years with curative use [ 26 , 27 ]. It has been repeatedly observed that bacteria of the genus Bacillus achieve significant reduction in the mycelial growth of anthracnose-related pathogens [ 28 ], which is attributed to the metabolites they produce [ 26 ].…”