reported to be useful for predicting shoot resistance, were performed, and plants were scored using a scale of disease severity. The average disease severity was calculated for each accession and was used to cluster the accession in five reaction classes. The screening revealed that sources of natural resistance to this fungus are limited. However, seedlings of seven accessions of different botanic groups displayed a resistant response to the stem inoculation, one cantaloup from Israel, one conomon accession from Korea, two wild agrestis and one acidulus from Africa, and two dudaim accessions from Middle East. The response of the F1 progenies varied from susceptibility to high resistance, the latter in progenies from the two agrestis wild types. These results suggest differences in the genetic basis of the resistance in the different selected sources. The resistant accessions are suggested to be screened under field conditions to confirm the level of resistance at adult plant stage and under stressful conditions.

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.

Instalou-se um experimento com manga 'Tommy Atkins' objetivando estudar a eficiência do índice de degradação de amido visando a sua utilização em nível de campo como mais uma alternativa para estimar a maturação dos frutos. A eficácia do método foi estabelecida pela sua correlação durante a maturação com o conteúdo de amido e com a coloração da casca, coloração da polpa, firmeza da polpa, pH, acidez total titulável, sólidos solúveis totais e açúcares redutores e não redutores. O ensaio foi instalado em delineamento inteiramente casualizado, composto por cinco tratamentos, com base na coloração da polpa e da casca. No caso da polpa: I - fruto verde; II - verde com traços de amarelo; III - mais verde que amarelo; IV - mais amarelo que verde; e V - traços de verde. Para a coloração da casca, adotou-se a mesma escala com variação de verde para vermelho. Utilizaram-se seis repetições por tratamento. Em geral, houve boa correlação entre o índice de degradação do amido e as outras variáveis estudadas, sendo que o índice de coloração da polpa apresentou melhor coeficiente de correlação. As análises de correlação indicam que o método pode ser utilizado pelo produtor.

In this work, a collection of 94 Macrophomina isolates obtained from roots of two weed species, Trianthema portulacastrum and Boerhavia diffusa, collected during surveys conducted during 2015 and 2016 in melon production fields in Northeastern Brazil, were characterized by using molecular techniques. Phylogenetic analysis of the EF1‐α gene allowed the identification of 32 isolates as M. phaseolina and 62 isolates as M. pseudophaseolina. Results of a pathogenicity test performed on melon seedlings of the cv. “Gladial” revealed that all M. phaseolina isolates inoculated were able to cause disease to melon seedlings, but only some M. pseudophaseolina isolates were able to infect them. This study represents the first report of M. pseudophaseolina in both T. portulacastrum and B. diffusa weeds, which are prevalent in the main Brazilian melon producing and exporting regions. Information about the biology and epidemiology of M. pseudophaseolina is scarce because of its recent description; thus, further research is needed for a better understanding of this fungus as a potentially emerging pathogen of melon and other crops.

RESUMOA utilização de métodos de inoculação constitui uma medida estratégica no estudo de resistência das cucurbitáceas. O objetivo deste trabalho foi avaliar dois métodos de inoculação de Rhizoctonia solani e Macrophomina phaseolina em meloeiro, visando o estudo de resistência. O experimento foi conduzido em casa de vegetação na Universidade Federal Rural do Semiárido, em Mossoró-RN, Brasil. Foram avaliados 05 acessos: A-09, A-16, A-18, A-22 e A-33 para R. solani e A-09, A-16, A-24, MR-1 e 'Olimpic' para M. phaseolina. Foram estudados os métodos areno-orgânico e palito de dente. Utilizou-se o delineamento inteiramente casualizado, com 5 repetições. Os isolados utilizados foram: Me 242, Me 243, Me 244 de R. Solani e I-248, I-249 e I-250 de M. phaseolina. Os acessos de meloeiro foram avaliados quanto à severidade da doença por uma escala de nota de 1 a 5. O método do palito de dente foi o mais eficiente em discriminar acessos de melão resistentes e suscetíveis e os isolados de R. solani e M. phaseolina quanto à virulência.