ABSTRACT Tomato is an important economic crop due to its consumption and production worldwide. However, like other crops, it is susceptible to pathogens, being necessary agrochemicals to prevent diseases and improve the production of fruits. Among the sustainable alternatives to crop production, microbial inoculants are used as biofungicide and biostimulants for plant development. Thus, this work aimed to evaluate the biocontrol potential of seven Trichoderma spp. isolates (T1, T2, T3, T4, T15, T17, and T19) against tomato pathogens in vitro experiments, and their potential to improve tomato growth. The Trichoderma spp. antagonism was investigated against Alternaria sp. 003/09, Botrytis sp. 006/13, Fusarium sp. 007/09, and Stemphylium sp. A73. Dual culture, volatile, and diffusible compounds activity tests showed that all new Trichoderma spp. tested could reduce the mycelial growth of all tested pathogens, highlighting T15 and T17 isolates. Seed and soil inoculation revealed very contrasting results: Trichoderma sp. T17 showed a beneficial effect when inoculated in soil, reducing the percentage of yellowish leaves, and increasing dry weight and stem diameter. Inoculation of Trichoderma sp. T17 in the seed increases hypocotyl and radicle lengths, and the seed vigor index. Finally, the strains studied present the potential to be used to develop biocontrol products.

Resumo O objetivo deste trabalho foi avaliar o efeito do óleo essencial de Eucalyptus staigeriana sobre o crescimento micelial e a germinação de conídios de Colletotrichum gloeosporioides e Greeneria uvicola em uvas, assim como o seu potencial para o controle de podridões no período pós-colheita e o seu efeito nas propriedades organolépticas das uvas. O óleo essencial (OE) apresentou atividade antifúngica in vitro contra ambos os patógenos, com efeito fungicida sobre o crescimento micelial e sobre a germinação de conídios, nas concentrações de 1,0 e 0,5 μL mL−1, respectivamente. Os compostos voláteis do OE exibiram efeito fungistático sobre o crescimento micelial de C. gloeosporioides e efeito fungicida sobre G. uvicola. Na pós-colheita, o OE reduziu a incidência da podridão-madura em até 75 e 86%, nos tratamentos preventivos e curativos, respectivamente, e a incidência da podridão-amarga em até 54% no tratamento curativo. Como o OE não influencia significativamente as propriedades sensoriais das uvas, não afeta a intenção de consumo para uvas tratadas com o OE. O OE de E. staigeriana é eficiente para o controle in vitro de ambos os patógenos; além disso, também é eficiente no controle da incidência de podridões fúngicas no período pós-colheita, principalmente no tratamento curativo.

Abstract The objective of this work was evaluate the effect of Eucalyptus staigeriana essential oil on Colletotrichum gloeosporioides and Greeneria uvicola mycelial growth and conidia germination on grapes, as well as its potential for the control of postharvest rot diseases and its effect on the organoleptic properties of grapes. The essential oil (EO) showed in vitro antifungal activity against both pathogens, with fungicidal effect on mycelial growth and on conidia germination at the concentrations of 1.0 and 0.5 μL mL−1, respectively. The EO volatile compounds had a fungistatic effect on the mycelial growth of C. gloeosporioides and a fungicidal effect on G uvicola. At postharvest, the EO reduced the incidence of ripe rot up to 75% and 86% in the preventive and curative treatments, respectively, and the incidence of bitter rot up to 54% in the curative treatment. Since the EO does not affect significantly grape sensory properties, it does not affect the consumption intention of grapes treated with the EO. The EO of E. staigeriana is efficient in the in vitro control of both pathogens; moreover, it is also efficient in the control of the incidence of postharvest fungal rot diseases, mainly in the curative treatment.

Abstract Alternaria alternata causes leaf spot and black rot diseases in leaves and grapes of grapevines, respectively, and leads to huge economic losses in table grapes production. As natural antifungal agents, essential oils (EOs), which are generally recognized as safe substances, shows strong antifungal activity against fungal phytopathogens. The aim of this study was to determine the chemical composition of Eucalyptus staigeriana EO and its in vitro and in vivo effects against A. alternata. The major compounds of E. staigeriana EO were citral (34.32%, of which 21.83% geranial and 12.49% neral), limonene (20.60%) and 1,8-cineole (12.33%). E. staigeriana EO exhibited the highest inhibitory activity on mycelial growth and conidial germination at 1 µL mL-1. Moreover, the EO was able to reduce the incidence and severity of leaf spot disease in leaves and black rot disease in table grapes caused by A. alternata. These results represent a possible alternative to reduce the use of synthetic molecules for the control of diseases in postharvest of table grapes and in vineyard.

Abstract Fusarium wilt is a fungal disease that causes economic losses to viticulture, whose causal agent Fusarium sp. has been associated with the decline and death of young vines. This work had the objective of evaluating the antagonistic potential of Bacillus subtilis F62 against F. oxysporum in vitro and in vivo, as well as the growth promotion in the grapevine rootstock SO4. In the in vitro assay, the antagonism by diffusible and volatile compounds of B. subtilis F62 and the inhibition of conidial germination of four Fusarium sp. isolates were evaluated. In the in vivo assay, cuttings and micropropagated plants of SO4 were submitted to four treatments: control, Bac (B. subtilis F62 inoculation), Fus (F. oxysporum inoculation) and Bac + Fus. We observed that inhibition of mycelial growth occurred mainly by diffusible compounds. B. subtilis F62 had a positive effect on the growth promotion and in the biocontrol of F. oxysporum, reducing the frequency of pathogen re-isolation in cuttings (18.1%) and in micropropagated plants (52.4%). These results demonstrate the ability of B. subtilis F62 to upgrade plant development and assist in controlling of the Fusarium wilt in the grapevine rootstock SO4.

Vários compostos naturais voláteis produzidos pelo metabolismo secundário de plantas têm demonstrado ação antimicrobiana comprovada, permitindo a sua utilização no controle de fitopatógenos. Apresentam também, baixo impacto ambiental em comparação aos pesticidas convencionais. Os óleos essenciais apresentam esses compostos que podem ser encontrados em várias espécies de plantas, tais como Lippia alba (Mill.) N.E. Brown (Verbenaceae). Óleos essenciais de quatro quimiotipos de L. alba, caracterizados por seus compostos majoritários, cânfora, citral, linalol e cânfora/1,8-cineol, foram testados contra o fitopatógeno Alternaria solani Sorauer (Pleosporaceae), que causa pinta preta em tomates e é responsável por grandes perdas econômicas na produção. A ação antifúngica dos óleos essenciais foi testada in vitro utilizando meio de cultura batata dextrose ágar (BDA) nas concentrações 0,1, 0,5, 1,0, 1,5 e 2,0 µL mL-1 dos óleos essenciais. O quimiotipo que apresentou o melhor desempenho foi citral, mostrando inibição significativa em comparação aos outros a partir da concentração 0,5 µL mL-1. O óleo essencial do quimiotipo linalol foi eficiente a partir da concentração 1,5 µL mL-1. Porém, o quimiotipo cânfora não apresentou ação contra o fitopatógeno. Além disso, os óleos essenciais não tiveram nenhum efeito notável sobre a germinação e crescimento de tomate. Em conclusão, estes óleos essenciais apresentaram ação fungicida contra A. solani.

Several volatile natural compounds produced by plant secondary metabolism have been proven to present antimicrobial action, enabling their use in phytopathogen control. They also present low environmental impact when compared to conventional pesticides. Essential oils contain these compounds and can be found in several plant species, such as Lippia alba (Mill.) N.E. Brown (Verbenaceae). Essential oils of four chemotypes of L. alba, characterized by their major compounds, namely camphor, citral, linalool and camphor/1,8-cineole, were tested against the phytopathogen Alternaria solani Sorauer (Pleosporaceae), which causes early blight on tomatoes and is responsible for great economic losses regarding production. Essential oils antifungal action was tested in vitro using potato dextrose agar medium with essential oil concentrations at 0.1, 0.5, 1.0, 1.5 and 2.0 µL mL-1. The chemotype that had the best performance was citral, showing significant inhibition compared to the others, starting at the 0.5 µL mL-1 concentration. The essential oil belonging to the linalool chemotype was efficient starting at the 1.5 µL mL-1 concentration. Conversely, the camphor chemotype did not show any action against the phytopathogen. Moreover, the essential oils had no remarkable effect on tomato germination and growth. In conclusion, these essential oils presented fungicidal action against A. solani.

The genus Mikania ranks high in the list of best-selling natural products in the world. Its main distribution is in South America, but some species are found in Asia, North America and Africa. It is used for treating fever, rheumatism, colds and respiratory diseases, as well as snake bites and scorpion stings, due to its broad spectrum of action. There are approximately 430 species of this genus and only 12% have been studied, highlighting their chemical and pharmacological diversity. The main chemical groups are: coumarins and derivatives, sesquiterpenes, sesquiterpenes lactones, diterpenes, phytosterols/terpenoids and flavonoids. This review aims to supply useful references for scientists interested in natural products and the search for new compounds, from over the 300 already described for the genus.