Fungicides in maize production under tropical conditions reduce losses from foliar diseases, but only a few reduce ear rot incidence or mycotoxin contamination in kernels. Biocontrol agents (BCAs) may reduce postharvest losses but their efficacy has not been demonstrated in field conditions. Here, we evaluated the use of bacterial isolates in tandem with fungicides on Fusarium verticillioides incidence and fumonisin content. After an early screening, Bacillus subtilis and Streptomyces araujoniae isolates were used in field trials. Maize plants were sprayed twice: at the end of the vegetative stage (V9) and at the beginning of the reproductive stage (R1). Sprays were made by applying water, B. subtilis strain BIOUFLA2, S. araujoniae strain ASBV‐1T, or fungicide (cyproconazole + azoxystrobin) in different combinations, totalling nine treatments. Ten days later, all maize ears were inoculated with F. verticillioides. Plants were assessed for foliar diseases, grain yield, F. verticillioides incidence and fumonisin content in kernels. The treatment with two fungicide sprays reduced most of the foliar diseases but not F. verticillioides incidence in kernels. Twice‐sprayed B. subtilis and S. araujoniae reduced F. verticillioides, but did not protect leaves against other pathogens. All treatments encompassing a fungicide followed by one of the BCAs reduced F. verticillioides incidence compared to control. Twice‐sprayed fungicide increased fumonisin by 50% compared to water control, while fungicide followed by B. subtilis decreased the fumonisin content by 40%. Replacing the second chemical spray with S. araujoniae did not reduce the fumonisin content but provided a higher yield than a twice‐sprayed fungicide. Exclusive use of chemical fungicides may not ensure higher grain quality and yield, but the integration with B. subtilis BIOUFLA2 can accomplish both.
The taxonomic position of 26 filamentous actinobacteria isolated from a hyper-arid Atacama Desert soil and 2 from an arid Australian composite soil was established using a polyphasic approach. All of the isolates gave the diagnostic amplification product using 16S rRNA oligonucleotide primers specific for the genus Amycolatopsis. Representative isolates had chemotaxonomic and morphological properties typical of members of the genus Amycolatopsis. 16S rRNA gene analyses showed that all of the isolates belong to the Amycolatopsis methanolica 16S rRNA gene clade. The Atacama Desert isolates were assigned to one or other of two recognised species, namely Amycolatopsis ruanii and Amycolatopsis thermalba, based on 16S rRNA gene sequence, DNA:DNA relatedness and phenotypic data; emended descriptions are given for these species. In contrast, the two strains from the arid Australian composite soil, isolates GY024(T) and GY142, formed a distinct branch at the periphery of the A. methanolica 16S rRNA phyletic line, a taxon that was supported by all of the tree-making algorithms and by a 100 % bootstrap value. These strains shared a high degree of DNA:DNA relatedness and have many phenotypic properties in common, some of which distinguished them from all of the constituent species classified in the A. methanolica 16S rRNA clade. Isolates GY024(T) and GY142 merit recognition as a new species within the A. methanolica group of thermophilic strains. The name proposed for the new species is Amycolatopsis deserti sp. nov.; the type strain is GY024(T) (=NCIMB 14972(T) = NRRL B-65266(T)).
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.