ABSTRACT. Bacterial leaf streak caused by Xanthomonas vasicola pv. vasculorum is an emerging disease for corn production around the world. However, information on management of this disease is still limited. This study aimed to determine the in vitro sensibility of X. vasicola pv. vasculorum to different chemicals and to evaluate the control of bacterial leaf streak on corn under greenhouse conditions. In vitro tests were carried out with kasugamycin, copper sulfate, copper oxychloride, copper hydroxide, cuprous oxide, bioactive copper, mancozeb, chlorothalonil, methyl thiophanate, and tebuconazole at the dosages of 1, 5, 10, 20, 50, 100, 200, and 400 μg mL−1. Four strains of X. vasicola pv. vasculorum were included in the study. The minimal inhibitory concentration for kasugamycin ranged from 50 to 200 μg mL-1, whereas to the inorganic copper compounds varied from 5 to 50 μg mL-1 and to the bioactive copper was 100 μg mL-1. Further, mancozeb and tebuconazole inhibited the bacterial growth at the dosage ranging from 5 to 20 μg mL-1 and 50 to 400 μg mL-1, respectively, depending on the X. vasicola pv. vasculorum strain. Chlorothalonil and methyl thiophanate did not inhibit the growth of the bacterium at any tested concentration. The control of bacterial leaf streak under greenhouse conditions was investigated on corn plants of the cultivar IPR 164 at the V3 phenological vegetative stage, sprayed with kasugamycin (3 mL L-1), copper oxychloride (1.5 mL L-1), bioactive copper (1 mL L-1), mancozeb (2 g L-1), tebuconazole (1 mL L-1), and chlorothalonil (2 mL L-1). The corn plants were inoculated with a 108 CFU mL-1 suspension of the RL1 strain of X. vasicola pv. vasculorum. Only copper oxychloride significantly reduced disease severity. However, this copper compound caused phytotoxicity to the corn plants at the tested concentration.

O uso de porta-enxertos resistentes poderá ser um método promissor para o controle do nematoide Meloidogyne enterolobiiem plantios comerciais de goiaba, em caso de compatibilidade de enxertia. O presente trabalho teve como objetivo avaliar o pegamento via enxertia por garfagem de topo em fenda cheia, entre a goiabeira e acessos de araçazeiros resistentes a M. enterolobii. Os tratamentos foram constituídos pelos porta-enxertos utilizados, araçazeiros (três acessos de Psidium cattleyanum) e a goiabeira. O delineamento estatístico adotado foi em blocos casualizados (DBC), com quatro tratamentos, cinco repetições, e oito plantas por parcela. Após a enxertia, foi avaliada a percentagem de pegamento dos enxertos. As mudas produzidas foram plantadas no campo e avaliadas quanto ao crescimento inicial das diferentes combinações. Constatou-se pegamento de enxertia entre a goiabeira 'Paluma' e os porta-enxertos de goiabeira e araçazeiros dos acessos 115 e 117, ocorrendo uma taxa de pegamento de 63, 32 e 29%, respectivamente. No campo, os araçazeiros utilizados como porta-enxertos induziram menor desenvolvimento de copa e resultaram em morte de plantas. A incompatibilidade entre a goiabeira 'Paluma' e o porta-enxerto P. cattleyanumfoi confirmada um ano após plantio no campo.

The use of resistant rootstocks could be a promising method to control nematodeMeloidogyne enterolobiiin commercial plantations of guava. The present study aimed to evaluate the success of grafting guava as a scion on accessions of cattley guava as rootstocks resistant to M. enterolobii.The treatments consisted of the rootstocks cattley guava plants (three accessions of Psidium cattleyanum) and common guava (control). In the apical wedge grafting method, scion of Paluma cultivated variety was used. The experiment was arranged in a randomized block design with four treatments and five replicates, and eight plants per plot. The saplings produced as described before were planted in the field where the initial growth of the different combinations were evaluated. Graft success was observed for the control (common guava) and for accessions 115 and 117 of cattley guava plants, with success rates of 63, 32 and 29%, respectively. In the field, the cattley guava used as rootstocks hampered Paluma canopy development and caused death of plants. Incompatibility of P. cattleyanumas rootstocks for P. guajavaPaluma was confirmed one year after cultivation in field.

Este trabalho teve por objetivo estimar parâmetros genéticos relacionados à produção de frutos em um dialelo de pimenta (Capsicum baccatum var. pendulum). Foram avaliados cinco genitores de pimenta (UENF 1616, UENF 1624, UENF 1629, UENF 1639 e UENF 1732) e seus respectivos híbridos F1, a partir de um dialelo completo, sem recíprocos. O experimento foi conduzido em cultivo protegido (politúnel), na área de convênio UENF/PESAGRO-RIO, Campos dos Goytacazes, no período de julho a dezembro de 2009. O delineamento experimental foi em blocos casualizados, com três repetições e nove plantas por parcela. Avaliaram-se as seguintes características agronômicas: diâmetro da copa (DC), altura de planta (ALTP), dias para a frutificação (DF), número de frutos por planta (NFP), peso médio do fruto (PMF), massa seca do fruto (MSF); teor de massa seca (TMS), comprimento do fruto (CF), diâmetro do fruto (DIAM), espessura da polpa (ESP), teor de sólidos solúveis totais (TSS) e produção por planta (PROD). Somente as características PMF, MSF e PROD tiveram ausência de significância nos três testes de suficiência do modelo aditivo-dominante, indicando haver homogeneidade entre as variâncias e covariâncias e, consequentemente, ausência de epistasia no controle destas características. Para PMF e MSF, os efeitos gênicos aditivos foram os mais importantes. Por sua vez, na expressão de PROD o efeito de dominância foi o mais importante. Verificou-se dominância parcial para PMF e MSF e sobredominância para PROD. Os genitores UENF 1616 e UENF 1629 foram os que tiveram as maiores concentrações de alelos favóraveis para as três características em estudo.

This work aimed to estimate genetic parameters related to the fruits production in a chilli pepper diallel (Capsicum baccatum var. pendulum). Five chilli pepper genitors were evaluated (UENF 1616, UENF 1624, UENF 1629, UENF 1639 and UENF 1732) and its respective hybrids F1, from a complete diallel without reciprocals. The experiment was carried out in a greenhouse covered with plastic film located in area from the consortium UENF/PESAGRO-RIO, Campos dos Goytacazes, RJ, from July/2009 to December/2009, in a randomized block design with three repetitions and nine plants by plot. The following agronomic traits were evaluated: canopy diameter (CD); plant height (PH); days for fruiting (DF); number of fruits by plant (NFP); fruit average-weight (FAW); fruit dry mass (FDM); dry matter (DM); fruit length (FL); fruit diameter (FD); fruit wall thickness (PT); total soluble solids (TSS); and yield per plant (PROD). Only the FAW, FDM and PROD had absence of significance concerning the three tests of sufficiency for the additive dominant model, indicating that there is homogeneity among the variances and co-variances and, consequently, lack of epistasis in the control of character. For the FAW and FDM traits, the additive genetic effects were the most important ones. Nevertheless, in the PROD the dominance effect was the most important. It was verified a partial dominance for FAW and FDM, and an over-dominance for PROD. The genitors UENF 1616 and UENF 1629 were the ones which had larger concentrations of favorable alleles for the three characteristics under study.