ABSTRACT The objective of this study was to assess seed health and the effect of plant extracts on Fusarium oxysporum f. sp. vasinfectum mycelial growth and sporulation, plant pathogen reduction in seeds and fusariosis control in okra seedlings. Health was assessed by the Blotter Test, after immersing the seeds in natural extracts and plating. To verify the mycelial growth of the plant pathogen, the extracts were incorporated in PDA culture medium and the pathogen was added and assessed, including the spore count. In the greenhouse, the seeds were immersed in the extracts, sown and at 15 days they were sprayed with extracts, at 21 days inoculated with the pathogen and disease severity on the seedlings was assessed 7 days later. There were higher incidences of Fusarium sp. and Rhizopus stolonifer in the seeds of the cultivars Valença and Santa Cruz 47. The extracts that resulted in lower pathogen incidence was basil, in cv. Valença and cinnamon and neem, in cv. Santa Cruz 47. The neem treatment presented the best inhibition percentage and the lowest sporulation mean in mycelial growth of the pathogen. Neem presented higher disease incidence control in the seedlings of cv. Valença and basil on the seedlings of cv. Santa Cruz 47.

Abstract Essential oils have been widely studied because they are natural sources of substances that have antimicrobial properties. In fruit growing, especially in mango crop, anthracnose (Colletotrichum gloeosporioides) is considered the main disease because it causes series of damages in the fruit production chain and, in this sense, essential oils can be an option in this disease control. The objective of this study was to evaluate the effect of essential oils obtained from the leaves of Chá-de-moça (Pectis brevipedunculata) and Melosa (Dizygostemon riparius) in the in vitro and in vivo control of the C. gloeosporioides fungus, in seedlings and mango fruits. The in vitro bioassays were performed by testing the effect of different concentrations of essential oils (0, 1, 2, 3 and 4 µl/mL) on the reduction of mycelial growth of the C. gloeosporioides fungus. Additionally, the anthracnose control in mango seedlings (Tommy Atkins, Constantina, Comum and Rosa cultivars) was evaluated by foliar application of essential oils at 4 µl/mL concentration. Disease control in fruits of the same mango cultivars was evaluated at 3 µl/mL concentration of essential oils. The evaluation was carried out by measuring the average diameter of the colonies, for the in vitro treatment, and the lesions for the in vivo treatments, in two diametrically opposite directions. There was a decrease in the fungus mycelial growth in all tested concentrations. There was a decrease in the disease severity from the sixth day after the oils application in Tommy Atkins cultivar seedlings, when treated with both essential oils at 4 µl/mL concentration. As for preventive treatments with fruits, it was observed that all cultivars achieved a reduction in severity from 54.83% at 3 µl/mL concentration with the use of both essential oils. Given the results obtained, it was observed that the essential oils P. brevipedunculata and D. riparius can be a viable alternative in the anthracnose control in mango culture.

Resumo Os óleos essenciais têm sido largamente estudados por serem fontes naturais de substâncias que possuem propriedades antimicrobianas. Na fruticultura, especialmente na cultura de manga, a antracnose (Colletotrichum gloeosporioides) é consideradaa principal doença por causar uma série de prejuízos na cadeia produtiva dos frutos, e,nesse sentido,os óleos essenciais podem ser uma opção no controle desta doença. O objetivodeste trabalho foi avaliar o efeito dos óleos essenciais obtidos das folhas de Chá-de-moça (Pectis brevipedunculata) e Melosa (Dizygostemon riparius) no controle in vitro e in vivo do fungo C. gloeosporioides, em mudas e frutos de mangueira. Os bioensaios in vitro foram realizados testando-se o efeito de diferentes concentrações dos óleos essenciais (0; 1;2; 3 e 4 µl/mL) sob a redução do crescimento micelial do fungo C. gloeosporioides.Adicionalmente, avaliou-se o controle da antracnose em mudas de manga (cultivares Tommy Atkins,Constantina, Comum e Rosa), pela aplicação foliar dos óleos essenciais, na concentração de 4 µl/mL. O controle da doença em frutos das mesmas cultivares de manga foi avaliado naconcentração de 3 µl/mL dos óleos essenciais. A avaliação foi feita pela mensuração dodiâmetro médio das colônias, para o tratamento in vitro, e das lesões, para ostratamentos in vivo, em dois sentidos diametralmente opostos. Houve diminuição do crescimento micelial do fungo em todas as concentrações testadas. Observou-se diminuição na severidade dadoença a partir do sexto dia após aplicação dos óleos nas mudas de cultivar Tommy, quandotratada com ambos os óleos essenciais, na concentração de 4 µl/mL. Já para os tratamentospreventivos com frutos, foi observado que todas as cultivares obtiveram redução daseveridade a partir de 54,83%, na concentração de 3 µl/mL, com uso de ambos os óleos essenciais.Diante dos resultados obtidos, foi observado que os óleos essenciais P. brevipedunculata e D. ripariuspodem ser uma alternativa viável no controle de antracnose na cultura de manga.