Synthetic fungicides have been the main control of phytopathogenic fungi. However, they cause harm to humans, animals, and the environment, as well as generating resistance in phytopathogenic fungi. In the last few decades, the use of microorganisms as biocontrol agents of phytopathogenic fungi has been an alternative to synthetic fungicide application. Actinomycetes isolated from terrestrial, marine, wetland, saline, and endophyte environments have been used for phytopathogenic fungus biocontrol. At present, there is a need for searching new secondary compounds and metabolites of different isolation sources of actinomycetes; however, little information is available on those isolated from other environments as biocontrol agents in agriculture. Therefore, the objective of this review is to compare the antifungal activity and the main mechanisms of action in actinomycetes isolated from different environments and to describe recent achievements of their application in agriculture. Although actinomycetes have potential as biocontrol agents of phytopathogenic fungi, few studies of actinomycetes are available of those from marine, saline, and wetland environments, which have equal or greater potential as biocontrol agents than isolates of actinomycetes from terrestrial environments.

In this work, the efficiency of chitosan as a biocontrol agent against Fusarium solani on tomato plants was determined and the antifungal activity and the induction of defence enzymes were evaluated. Treatments were carried out with different concentrations of chitosan (1, 2 and 3 g L⁻¹) combined with a synthetic fungicide (carbendazim). The results showed that all chitosan treatments significantly inhibited the mycelial growth and biomass of F. solani, with the most effective results obtained with the 3 g L⁻¹ treatment. Scanning electron microscopy revealed that chitosan causes severe structural damage to F. solani, including cell lysis and the deformation of mycelium and spores. In addition, plants treated with chitosan showed significant improvements in height, stem diameter, root dry biomass and root length compared to those treated with synthetic fungicide and the control (no chitosan application). Enzyme assays showed that chitosan significantly increased superoxide dismutase, catalase, peroxidase and phenylalanine ammonia-lyase activity, indicating an increased defensive response. These results suggest that chitosan is a viable and less toxic alternative for the management of disease caused by F. solani in tomato plants, promoting both plant health and growth.

Fusarium spp. damages the roots of crops, its control is with synthetic fungicides, however, marine actinomycetes can be an option to the use of agrochemicals. The objective of this work was the identification and morphological characterization of marine actinomycetes as antagonists to Fusarium solani (Mart.) Sacc. Fusarium spp. was isolated from diseased tomato plants and mangrove sediment actinomycetes, both identified through taxonomic keys and molecular techniques. Eight isolates of Fusarium spp. were obtained, H8 being the most virulent and it was identified as F. solani. Thirty actinomycetes were isolated, of which only four inhibited the phytopathogen, being A19 the one that inhibited the fungus by 70% and was identified as Streptomyces sp. Marine actinomycetes may be an option for disease management in plants of agricultural interest.

Using microorganisms as biocontrol agents of phytopathogens has been an alternative to synthetic fungicides. Actinomycetes isolated from soil and plants have reduced diseases caused by phytopathogens; however, microorganisms from marine environments may be an option as biocontrol agents. The tomato crop possesses an important economic impact worldwide, being Mexico the main exporter. Several species of Fusarium cause damage to tomato crops and are controlled with synthetic fungicides. The objective of this work was to determine the effect of marine actinomycetes as biocontrol on Fusarium solani in tomato plants. Four strains of marine actinomycetes (A20, A19, A18, and A15) and one terrestrial actinomycete (ED48) were used. The actinomycetes strains used, produced siderophores. The greatest inhibition of mycelial growth of F. solani due to iron competition was obtained by strain A19 with 74.28%. Only two actinomycetes showed antifungal activity by VOCs (A19 and A18), strain A19 showed the highest antagonistic activity with PICR of 76.75%. Actinomycetes treatments showed significant differences with synthetic fungicide application in growth, disease severity (SE), and disease incidence (DI) variables. The application of marine actinomycete (A19) on plants infested with F. solani increased the levels of enzyme activity (SOD, POD, CAT, and PAL) versus plants in that only F. solani and distilled water (control) were applied. Actinomycetes of marine origin are an option as biocontrol agents for F. solani.

Synthetic fungicides have experienced a significant increase in recent years, necessitating the search for more sustainable and environmentally friendly alternatives. In this regard, chitosan has emerged as an option to reduce reliance on these products. This study evaluated the effect of chitosan as a biocontrol agent against Fusarium oxysporum in tomato fruits. A fully randomized experimental design incorporating 6 treatments was employed, consisting of four chitosan treatments (0.5, 1, 2, and 3 g L^-1), a negative control involving the application of a synthetic fungicide, and a positive control inoculated with F. oxysporum. Samples were taken from infected tomato fruits. The F4 isolate of Fusarium sp. was identified as F. oxysporum, and demonstrated the highest level of virulence. Among the four chitosan treatments, the 3 g L^-1 treatment showed the highest a percentage of mycelial growth inhibition (PMGI) at 79.92% and the greatest reduction in biomass at 0.65 g, which did not differ significantly from the synthetic fungicide. Regarding disease severity and incidence, there were significant variations among each of the chitosan treatments, with the highest results obtained with the 2 and 3 g L^-1 treatments. All chitosan treatments reduced disease severity in tomato fruits. Applying chitosan on fruits of the tomato plant presents an alternative for diminishing reliance on synthetic fungicides.

Los abonos orgánicos aportan materia orgánica, nutrimentos y microorganismos, lo cual favorece la fertilidad del suelo y la nutrición de las plantas. El objetivo del trabajo fue determinar el efecto del humus de lombriz y el jacinto de agua sobre el crecimiento y desarrollo de plantas de pepino, en un diseño completamente al azar con cuatro repeticiones, las cuales se sometieron a la aplicación de los abonos humus de lombriz y jacinto de agua. Se midió altura de la planta, número de frutos, largo del fruto, diámetro del fruto, peso del fruto y el rendimiento. Los resultados mostraron que la aplicación del humus de lombriz más el jacinto de agua incrementaron las variables altura de la planta, largo del fruto y peso del fruto en el pepino respecto al control, con diferencias significativa el rendimiento agrícola alcanzando 1.61 t/ha. El efecto bioestimulante de estos bioabonos permitió un mejor desarrollo del cultivo del pepino.