No abstract

Bacterial wilt limits tomato production and resistant rootstocks could be important for the integrated management of the disease. Since there is an interaction between local bacterial strains and tomato genotype, this study aimed to evaluate 14 tomato rootstocks to bacterial wilt in the Mata mesoregion of Pernambuco state, Brazil. The rootstocks reaction to two sequevars of Ralstonia solanacearum and two of R. pseudosolanacearum was evaluated in four experiments carried out in the greenhouse using the completely randomized experimental design, with four replications composed of four plants each. Seven genotypes were selected to evaluate the reaction to bacterial wilt as rootstocks grafting in tomato plants ‘Tomini F1’ in a production area with disease history in the Chã Grande municipality, using randomized block design with four plants per treatment in each block. In the field experiment, disease symptoms were not observed in the grafted plants in ‘Guardião’, ‘Woodstock’, and ‘Yoshimatsu’. Regarding all experiments, ‘Guardião’ and ‘Muralha’ showed the best resistance levels and could be used in the integrated management of bacterial wilt and studied in plant breeding programs.

No abstract

Onion’s (Allium cepa) slippery skin caused by Burkholderia gladioli pv. alliicola is one of the bacterial diseases that stand out in producing regions of the Brazilian Northeast. Given the importance and potential threat of this disease, and the absence of resistant varieties, the aim of this study was to evaluate the reaction of onion genotypes to slippery skin and to analyze the tolerance stability of the most promising genotypes to different strains of the bacteria. Nine strains of B. gladioli pv. alliicola were artificially inoculated in onion bulbs cv. Baia Periforme and the three most aggressive strains (CCRMBG39, CCRMBG172 and CCRMBG212) were selected to evaluate the tolerance to the disease. Fifty-eight onion genotypes were challenged with the most aggressive strain (CCRMBG39) and 34 genotypes were considered as tolerant, with a disease severity varying from 9.79 to 13.42 mm. The fifteen most promising genotypes and the most susceptible genotype were selected to study the stability of tolerance using the three selected strains. The genotypes F2 (EHCEB 20151030 x EHCEB 20133015), Cascuda T5, Crioula Mercosul, Juporanga, EHCEB 20111036, Cascuda T6 and EHCEB 20142028 remained tolerant to the disease when inoculated with the three strains, with a disease severity ranging from 9.13 to 14.19 mm. In view of these results, we conclude that these genotypes can be used as potential sources of tolerance to onion slippery skin.

A cana-de-açúcar é uma das principais fontes de açúcar, álcool, aguardente além de ser usada para geração de eletricidade e também como ração animal. Dentre os patógenos que parasitam a cultura se destacam os nematoides. Para se adotar medidas eficazes no manejo dos fitonematoides é imprescindível considerar não apenas a espécie do patógeno, mas também o quanto deste está presente na área. Os levantamentos populacionais são importantes para identificação da comunidade nematológica presente na área, e determinação da distribuição desses patógenos numa determinada localidade. O objetivo do trabalho foi avaliar a flutuação populacional de fitonematoides ao longo de nove anos de manejo da cultura em áreas do Rio Grande do Norte, Alagoas e Pernambuco com o cultivo das seguintes variedades de cana-de-açúcar RB813804, RB867515, RB92579, SP791011 e SP813250 entre os anos de 2009 a 2018. Foi observado que as populações de Pratylenchus e Meloidogyne aumentou ao decorrer dos anos avaliados, sendo que nos anos de 2017 verificou-se as maiores populações para Pratylenchus e 2009 para Meloidogyne registrando-se a ocorrência de Meloidogyne e Pratylenchus em todas as variedades avaliadas, as maiores densidades do nematoide das galhas foi observada nas variedades RB813804, e SP791011 e menores nas variedades RB867515 RB92579. Com relação a Pratylenchus observou-se que RB867515, SP813250, apresentaram as maiores densidades de Pratylenchus enquanto que a SP791011 apresentou as menores densidades populacionais. No decorrer dos anos avaliados as populações dos nematoides aumentaram, isso se deve principalmente o fato das variedades cultivadas serem suscetíveis; outro fator que contribuiu foram os solos de textura arenosa que predominam nas usinas avaliadas facilitando o aumento da densidade populacional dos nematoides.