Fusarium rot of melon, caused by species of the genus Fusarium, has become an important postharvest disease for many Brazilian producers. Due to the delayed onset of symptoms, this disease is often only detected when fruits arrive at the importing country, thus generating economic loss for the exportation of the fruit. This study was developed with the aim of investigating which Fusarium species cause fruit rot in melon and to evaluate any differences in aggressiveness and development of symptoms. Species were identified through phylogenetic analysis of two loci and morphological markers. The 28 isolates obtained from diseased melon fruits of different commercial cultivars were identified as Fusarium falciforme (FSSC), F. sulawesiense, F. pernambucanum (FIESC), and F. kalimantanense (FOSC). Three isolates belong to a new phylogenetic lineage within the F. fujikuroi species complex (FFSC). All isolates were tested for pathogenicity, and first symptoms of rot in Canary melon were observed 2 days after inoculation. Isolates of F. falciforme and F. sulawesiense were shown to be more aggressive. Our results extend information on Fusarium species that cause fruit rot in melon and support the development of management strategies, as there is currently no efficient control for this disease. To our knowledge, this is the first report of the occurrence of species of the FSSC, FOSC, and FFSC from muskmelon fruits in Brazil.

RESUMO A podridão-do-colo do meloeiro, causada por Fusarium solani (Mart.). e a murcha do Sclerotium, causada pelo patógeno Sclerotium rolfsii Sacc., são importantes doenças que acometem o meloeiro. Metodologias adequadas de inoculação destes patógenos nas culturas são de grande importância para diversos estudos envolvendo o controle destas doenças, como a resistência de acessos de meloeiro. Desta forma, este trabalho teve como objetivo determinar métodos de inoculação de F. solani e S. rolfsii em meloeiro, com intuito de verificar uma metodologia de inoculação adequada e eficiente para estudos com os referidos patógenos. Dois experimentos foram conduzidos em casa de vegetação. No primeiro experimento estudou-se 4 métodos de inoculação para F. solani em 5 acessos de meloeiro. O segundo, testou-se 5 métodos de inoculação para S. rolfsii em 4 acessos da mesma cultura. O delineamento experimental foi em blocos casualizados com 5 repetições. Os métodos de inoculação utilizados foram: inoculação com palito de dente colonizado com estruturas do patógeno, discos de BDA com estruturas do fungo, infestação do solo com arroz colonizado com estruturas do fungo e infestação do solo com milho colonizado com estruturas do fungo. Para o S. rolfsii foi acrescentado o método dos escleródios. Em ambos os experimentos foram utilizadas sementes de melão das cultivares Iracema, Olimpic, A-16, A-50 e A-15, exceto A-15 para o fungo S. rolfsii. Utilizou-se a macro SAS F1_LD_F1 para realizar a análise de variância. Para o patógeno F. solani, as metodologias do palito e arroz infestado foram as mais eficientes. Já o método do arroz infestado foi o mais eficiente para o fungo S. rolfsii.

Sanitary and quality of seeds of three native species (Aroeira, Jucá, and Mofumbo) from the Caatinga biome, Brazil, and different control methods of microorganisms in seeds were evaluated. We used 500 seeds of each species, 100 for each treatment: control, superficial disinfestation, Enzimatic II, Captana and Mancozebe. Seeds were distributed in Petri dishes containing potato-dextrose-agar culture medium and stored in incubator type Biochemical Oxygen Demand at 28 ± 2 °C for five days. For germination tests, 100 seeds were arranged in germitest paper previously sterilized and moistened with sterilized distilled water, and incubated for 19 (mofumbo), 20 (jucá), and 25 (aroeira) days in incubators at 28 ± 2 °C. Aspergillus flavus, A. niger, A. ochraceus, Lasiodiplodia sp., Penicillium sp. and Rhizopus sp. are associated with the studied seeds. Captana reduced the incidence of Aspergillus and Penicillium in the seeds, being the most efficient in controlling the microfauna associated with these seeds. Enzimatic II also proved to be an efficient control for Aspergillus spp. There was no interference of the tested products on seed germination.

Brazil is one of the largest melon (Cucumis melo) producers in the world and most of the production is exported to international markets. Currently, over 15% of the Brazilian melon shipments are lost during export transportation due to Fusarium fruit rot, which is jeopardizing the livelihood of the Brazilian melon producers. Herein, we focused on understanding the aggressivity of five different species of Fusarium causing fruit rot on the main types of melon produced in Brazil. We also investigated the correlation between pathogenicity and fruit quality. Experiments were performed under a completely randomized experimental design, in a 5x8 factorial scheme, using two methodologies for inoculation: deposition of discs of culture media containing fungal structures and deposition of spore suspensions in needle-punctured lesions. The fungal species used were Fusarium falciforme, F. sulawesiense, F. pernambucanum, F. kalimantanense, and Fusarium sp. Fruits of two hybrids from four types of melons, Canary (Goldex and Gold Mine), Piel de Sapo (Grand Prix and Flecha Verde), Galia (McLaren and DRG3228), and Cantaloupe (SV1044 and Bonsai), were used. Disease severity was assessed by measuring the lesions, disease severity index, fruit firmness, and degrees Brix of fruits. The five Fusarium spp. caused rot in the fruits of all melon hybrids studied and the aggressivity of those fungal species varied with the type/hybrid of melon fruits studied. Fruits of the hybrids McLaren and Bonsai presented the largest lesions among all melon hybrids, and hybrids of Canary type (Gold Mine and Goldex) were the most tolerant to rot caused by the Fusarium species investigated. Furthermore, the greater the severity of Fusarium fruit rot, the lower the pulp firmness of the melon fruits but degrees Brix did not correlate with the onset of the disease.

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