O presente trabalho buscou uma alternativa de solução para o problema através da mistura, no tanque, dos agroquímicos mefluidide e bentazon, aplicada apó s a emergência total da cultura e das plantas infestantes. As doses dos componentes usados no experimento em kg/ha, foram, para o mefluidide, 0,000 - 0,144 - 0,288 e 0,480 e, para o bentazon, 0,000 - 0576 - 0,864 e 1,152 combinadas entre si. O delineamento estatístico foi o de blocos ao acaso. No momento da aplicação a soja iniciava o seu terceiro trifólio e as principais plantas daninhas presentes no experimento, carurú (Amaranthus spp), carrapicho-de-carneiro (Acanthospermum hispidum DC), guanxuma (Sida spp), quenopólio (Chenopodium album L.) , da classe das dicotiledôneas, e capim-marmelada (Brachiaria plantaginea (Link) Hitcl), capimpé-de-galinha (Eleusine indica (L.) Gaertm), da classe das monocotiledôneas, estavam em diferentes estádios de desenvolvimento. Os resultados obtidos confirmaram a ação definida dos componentes na calda, mefluidide, sobre o grupo das monocotiledôneas e bentazon sobre o grupo das dicotiledôneas. Misturados, entretanto, a adição de um melhorou a atividade do outro sobre o grupo de plantas que controla. Sintomas fitotóxicos somente foram observados nos tratamentos com mefluidide solitário. Os tratamentos, quanto à produção, não diferiram estatisticamente da testemunha capinada. No controle total das plantas infestantes as misturas não di fe riram estatis ticamente entre si. A extensão numérica no controle de dicotiledôneas, bem como a interação estatística entre os compostos indica a existência de ação sinérgica da mistura.

The tankmix of mefluidide and bentazon offers a possibility for solution of the mixed weed population in soybean crop. The mefluidide rates applied in the experiment were 0.000 - 0.144 - 0.288 - 0.480 kg i.a./ha, and for bentazon 0.000 - 0.576 - 0.864 - 1.152 isolated or mixed in a randomized blocks design experiment. At spraying time soybean were at the leaves stage and the predominant weeds were Amaranthus sp., Acanthospermum hispidum, Sida sp., Chenopodium album, Brachiaria plantaginea, Digitaria sanguinalis, Eleusine indica. The tankmixed spray showed a wide herbicide activity, more effective than the control of any of the herbicides applied alone due to a sinergistic action.

O efeito de EPTC (S-etildipropiltiolcarbamato) sobre o desenvolvimento e a absorção de macronutrientes até o florescimento e os seus teores nas sementes e vagens, na colheita, foi estudado em dois experimentos de campo com a cultura do feijão, var. Carioca. O EPTC foi aplicado em pré-plantio com incorporação nas doses de 0, 1, 2, 4, 8 e 16 kg/ha em dois experimentos em solos argiloso e barrento. A avaliação da ação do herbicida sobre o desenvolvimento da cultura se fez pela obtenção de pesos de matéria seca de folhas, caules e vagens, durante o ciclo e número de plantas e produção de sementes na colheita. No início do florescimento foram analisados os teores de N, P, K, Ca, Mg e S em folhas e caules e, na colheita, em vagens e sementes. O EPTC, nas doses de 1, 2 ou 4 kg/ha não afetou o desenvolvimento da cultura, não alterou o teor de nutrientes em folhas ou caules, no início do florescimento, nem o teor nos grãos ou vagens, na colheita. Também não alterou a população de plantas ou a produção de grãos. As doses de 8 e 16 kg/ha de EPTC causaram redução de crescimento, de absorção de nutrientes, número de plantas por área e produção de sementes. O ciclo da cultura foi alongado. Os teores de nutrientes foram mais elevados, em geral, nas folhas, caules e vagens. Com essas doses ocorreu maior acúmulo de K nas vagens na colheita. Nenhuma das doses de EPTC, em qualquer dos experimentos, causou alteração nos teores de macronutrientes nas sementes.

The effect of EPTC, on growth and the macronutrient content in leaves and stems, at flowering set, and in seeds and pods, at harvest, in common beans CV. Carioca was studied. The EPTC was applied pre-plant incorporated at the dosages of 0, 1, 2, 4, 8 and 16 kg/ha in two experiments on clay and loamy soils. The influence of the herbicide on the crop growth was evaluated by means of fresh and dry matter weights of leaves, stems and pods at different periods of the crop cycle and by the stand and seed production. In both experiments the concentration of N, P, K. Ca, Mg and S were analysed in leaves and stems at the flowering set. The content of the same nutrients in seeds and pods were determined at harvest. Rates of 1, 2 or 4 kg/ha of EPTC did not affect the crop growth or the nutrient content in leaves, stems, seeds or pods. Rates of 8 and 16 kg / ha reduced the plant growth, nutrient absorption, stand and yield, but the nutrient concentration was enhanced in leaves, stems and pods. With these rates of EPTC the K content in pods was signifficantly higher. None of the applied rates of EPTC caused changes in the macronutrients concentration in the seeds at harvest.

O controle de plantas daninhas e a tolerância de gladíolos, cultivares Spick and Span e White Friendship, a tratamentos herbicidas foi estudado em um experimento de campo em solo areno-argiloso. Foram aplicados os herbicidas trifluralin e EPTC em pré-plantio com incorporação e chloroxuron, DCPA, diphenamid, pendimethalin e diuron em pré -emergência. Houve maior incidência de gramíneas que foram controladas por todos os herbicidas, exceto chloroxuron, sendo o controle pelo EPTC de 83% e pelos demais, acima de 90%. Para as dicotiledóneas, o controle foi na seguinte ordem decrescente: pendimethalin, chloroxuron, diuron, trifluralin, EPTC, DCPA e diphenamid. O EPTC afetou a germinação de bulbos, causando, também, retenção de crescimento e atraso no ciclo. No florescimento, as hastes florais foram colhidas, medidas e pesadas, verificando-se redução significativa de peso de matéria fresca com o tratamento EPTC para o cultivar Spick and Span, e com trifluralin, EPTC, chloroxuron e pendimetha lin para o White Friendship.

The weed control by herbicides and their effects on gladioli was evaluated on a field experiment on sandy-loam soil on CV Spick and Span and White Friendship. Trifluralin and EPTC were applied pre-plant incorporated and chloroxuron, DCPA, diphenamid, pendim et halin and diuron in pre-emergence. Grass species were predominant in the area and were controled by all herbicides except chloroxuron. Control by EPTC was of 83% and over 90% by all others. The broadleaves were controled in the following decrescent order: pendimethalin, chloroxuron, diuron , trifluralin, EPTC, DCPA and diphenamid. Only EPTC affected the sprouting of bulbs, causing also growth retention and delaying of flower set. The flowers stems were cut off a the opening of the first flower, measured and weighted. EPTC caused significant reduction in weight of CV Spick and Span and trifluralin , EPTC, chloroxuron and pendimethalin of CV White Friendship.

Três experimentos de campo foram instalados em solos com diferentes texturas, aplicando - se o herbicida EPTC, nas doses de 0, 1, 2, 4, 8 e 16 kg/ha, para verificar o seu efeito sobre a nodulação natural em feijão. Os nódulos foram amostrados no início do florescimento, sendo contados e obtendo-se o peso da matéria seca. As produções de sementes foram obtidas no final do ciclo. Em nenhum dos experimentos verificou -se diferença significativa no número ou no peso de nódulos para qualquer das doses aplicadas . Apenas em um dos experimentos houve redução sig - nificativa da produção de grãos com a aplicação das doses de 8 e 16 kg/ha de EPTC.

Three field experiments were performed on different soils, with application of EPTC at 0, 1, 2, 4, 8, and 16 kg/ha, to study its effect on natural nodulation of common bean. The nodules were sampled at flowering, counted and their dry matter weight was obtained. The seed production was obtained at har - vest. differences among number or weight of nodules due to any of the EPTC applied rates. In only one there was a significant reduction of yield due to the rates of 8 and 16 kg/ha of EPTC.

Foi estudada a taxa de lixiviação dos herbicidas trifluralin. atrazine e bromacil em três la. tossolos de texturas diferentes, utilizando-se as doses normais de uso de cada um. Foram utilizadas colunas não deformadas de cada solo e, após a percolação de precipitação simulada de 110 ou 220 mm, semearam-se capim-arroz (Echinochloa cruz-galli (L.) Beauv.) e alface (Lactuca sativa L. var. La Chaume) longitudinalmente nas metades de cada uma. A lixiviação dos herbicidas foi avaliada aos 21 e 33 dias após a semeação. Com indicação dada pelo capim-arroz verificou-se que o trifluralin apresentou lixiviação pequena em quantidade e extensão no perfil, sendo semelhante nos três solos. No solo argiloso e areno-argiloso, com 110 ou 220 mm de chuva, o bromacil apresentou lixiviação bem maior que o atrazine. O bioensaio indicou que as concentrações de bromacil e de atrazine decresciam com a profundidade do perfil. As taxas de lixiviação dos herbicidas foram, de modo geral, proporcionais à sua solubilidade.

The leaching rate of trifluralin, atrazine and bromacil in three latossols, with different textures, applying normal dosages of each. was studied. Intact columns of each soil were used and simula ted precip itations of 110 or 220 mm of water, Echinochloa cruz-galli L. Beauv. and Lactuca sativa cv. La Chaume were sown lenghtwise in the two halves of each colum. The leaching rate of the herbic ides was evaluated 21 and 23 days after seedling. With the indication given by E. cruz_galli it was verified that trifluralin showed very little leaching in the soil prof ile, and was similar in the three soils. In the clay and sandy-clay soils with 110 or 220 mm of rain, bromacil showed higher leaching rate than atrazine. In the loamy soil both herbicides showed simila r leaching due to the presence of caulinite, with has a low adsorbing capacity for atrazine. The bio-assay indicated that the bromacil and atrazine concentrations diminished with the profile depth. In general the leaching rates of the hebicides were proporcional to their solubilities.

Foram instalados no Centro Experimental de Campinas e na Estação Experimental de Tietê, nos anos agrícolas de 1970/71 a 1972/73, ensaios para avaliar o efeito da competição de plantas daninhas com o algodoeiro. Em 1970/71 foram estudados oito trata-mentos com seis. repetições: competição durante 10, 20, 30, 60, 90 e 120 dias após a emergência do algodoeiro e dois tratamentos testemunhas, sendo um sempre no limpo e outro sempre com mato. Os tratamentos foram mantidos no limpo após a respectiva primeira capina. Baseado nos resultados obtidos, foram estudados, nos anos agrícolas de 1971/72 e 1972/73, nove tratamentos, com cinco repetições: sempre. no limpo, capinas aos 10, 20, 30 e 40 dias após a emergência do algodoeiro. Após as capinas o algodoeiro foi mantido livre de competição. Os tratamentos restantes foram: capinas até os 10, 20, 30 ou 40 dias. As parcelas apresentavam quatro linhas lie cinco metros de comprimento. Em cada tratamento determinaram-se o número e o peso de matéria fresca e seca das plantas daninhas, ao final do respectivo período de competição, bem como a produção do algodão e as características econômicas de porcentagem de fibra, peso de um capulho, peso de 100 sementes, comprimento de fibra, uniformidade de comprimento, índice Micronaire, índice Pressley e maturidade. Os resultados mostraram que houve menor produção de algodão quando, após o período de 20 dias sem mato, mantiveram-se em competição o algodoeiro e plantas dani-nhas. Não houve efeito estatístico significativo na produção quando se manteve o algodoeiro até 40 dias sem a competição de plantas daninhas, embora esse tratamento tenha provocado uma queda de 30% de produção. Houve efeito negativo das plantas daninhas, pelo menos em um dos locais estudados, ou em um dos anos estudados, nas seguintes características: porcentagem de fibra, peso de um capulho, peso de 100 sementes, índice Micronaire, uniformidade de comprimento e índice Pressley.

The effect of weed competition on cotton (Gossypium hirsutum L.) was evaluated in the Centro Experimental de Campinas and the Estação Experimental de Tietê during the 1970/71, 1971/72 and 1972/73 agricultural seasons. In the first season, competition periods of 10, 20, 30, 40, 60, 90 or 120 days, after emergence were studied, compared to checks always either with or without weeds. In the next seasons, competition was studied during the first 10, 20, 30 or 40 days after emergence, or after these periods, until harvest, maintained previously weed free for these different periods and afterwards competition was allowed until harvest. The experimental plots had four rows of five meters, distributed in randomized blocks with five or six replications. For evaluation of the competition effects the following parameters were considered: number, fresh and dry weights of weeds, after each competition period; fiber percentage, boll and seed weight, cotton yield, fiber length uniformity, Micronaire, Pressley and maturity, at harvest. The results showed a lower yield of cotton when the competition period was longer than 20 days after emergence. When the crop was maintained weed free for the first 30 to 40 days yield was similar to the completely weed free treatment. Competition periods of 90 days or longer determined negative effect on yield. In some cases a negative effect of weed competition was observed on fiber percentage, boll and seed weight, Micronaire, fiber uniformity and Pressley.

Os autores estudam a bacia hidrográfica da barragem "Monjolinho". notadamente a velocidade de assoreamento. São descritas as características físicas da bacia, baseadas no levantamento planialtimétrico da área. Descrevem também, o tipo de solo e a cobertura vegetal encontrados no local, bem como as alterações ocorridas na bacia de inundação e no talude de montante do atêrro, após período de 7 anos de funcionamento do açude.

In this paper the authors present the study of the "Monjolinho" earth dam watershed with particular reference of its silting problem. The physical characteristics of the watershed, based on a plane - altimetric survey, are presented. A description of the soil type, vegetative cover, as well as of the changes that took place in the reservoir flood and in the upstream side slope after 7 years of use is given.

Neste trabalho é apresentado, em detalhes, o projeto para à construção de uma barragem de terra, na qual foi empregada, com bons resultados, a impermeabilização do núcleo central por meio do hidróxido de sódio em solução a 3%. A impermeabilidade foi determinada durante a fase da construção, em amostras de solo de estrutura não deformada. Após a conclusão da reprêsa êsse efeito foi avaliado determinando-se a posição assumida pela linha de saturação, no interior do atêrro. Acham-se descritas, também, as técnicas usadas para a impermeabilização do núcleo e para a determinação da linha de saturação.

The purpose of this paper is to present a detailed project that may be helpful to others undertaking the building of an earth dam. Results obtained in an impermeable earth dam are presented; the impermeability was attained by sodium hydroxide treatment of its central core; the effect on the impermeability of the dam was determined from undisturbed samples collected during and after the construction period. The position reached by the saturation line in the external slope was determined in order to evaluate the effect of the treatment on the impermeability of the dam.

Trichoderma sp. grown in liquid medium produced a substance which has caused up to 90% reduction in the infection capacity of the tobacco mosaic virus, measured in number of local lesions on Nicotiana glutinosa half leaf inoculations. Under the present experiments the fungus has been grown in liquid medium and the filtrates used in inactivation tests on the virus. From the fact that the liquid filtrate showed inactivation power after only two days of culture it is concluded that the inactivation is of the nature of a secretion of the fungus into the liquid medium. The inactivation proceeded within 2 minutes after mixture of the culture extract with the virus, no better results were obtained if the mixtures allowed to stand for a longer period of time. If cultures were grown in the light in the laboratory the inactivation power decreased after the second day as was found by Weindling (8), for the effect on Rhizoctonia sp. If grown in the dark the inactivator continues to increase in concentrations for at least 22 days. In the dark no spores formation could be observed. Physiological activity associated with spores formation may be the reason for the loss of inactivator in day light grown cultures where spores start to be formed after the second day of growth. Extraction of the inactivator with chloroform was attempted according to Weindling's method. The inactivator could never be completely extracted since the treated filtrate kept showing inactivation on tobacco mosaic virus. This suggests that the inactivator for the virus may be a different from the one found by Weindling against Rhizoctonia sp. By ultracentrifugation at 35,000 r.p.m. no inactivator could be obtained from the filtrate. Using Takahashi's acetone method a whitish precipitate could be obtained which showed an inactivation of tobacco mosaic virus.

A type of leaf-roll has been noticed for many years in commercial tobacco plantings in the State of S. Paulo. Leaf-roll plants were supposed to be affected by a virus disease, but repeated attempts to transmit it by grafting, juice inoculation and by insect vectors failed consistently. Later studies showed that the leaf-roll condition is due to genetic factors and that probably more than a pair of recessive genes are involved in its transmission. Even after the genetic nature of the leaf-roll condition was definitely established, attempts were made to induce the leaf-roll condition in plants genetically normal by several methods : 1. Spraying their leaves with the juice from leaf-roll plants ; 2. Approach-grafting a leaf-roll scion onto a normal plant and vice-versa, following with defoliation, cutting back or shading of the normal graft component. This was done to stimulate translocation of the phloem contents from the leaf-roll scion or stock into the normal stock or scion respectively. It was thought that if leaf-roll were due to the genetically controlled production of a hormone-like substance, these treatments might induce the leaf-roll condition in plants genetically normal. The results, however, have been negative.

Observations were made with tobacco plants which, after being naturally infected in the field by the virus of "vira-cabeça", a disease identical to spotted wilt (3), not only resisted to it, but exhibited complete recovery. Several trials were carried out in order to ascertain the following points : 1) whether the recovery means a greater degree of individual constitutional resistance ; 2) whether it represents an acquired immunity or ; 3) whether it is just of pure accidental nature. Plants showing recovery were selfed and seeds collected from them sown in separate rows. The same procedure was always applied with the new recovered plants. Thus, strains of plants were obtained representing several succeeding generations of recovered plants. In 1940-41 recovery progenies were planted at two different transplanting periods. During the next season 1941-42 these progenies, which represented already one more generation in comparison with those of 1940-41, were planted in two districts where the average occurrence of "vira-cabeça" was different. The percentages of "vira-cabeça", observed in all trials, were submitted to statistical analysis, comparing the errors obtained for difference of districts, transplanting time, varieties and progenies representing several generations of recovered plants. Comparing the calculated errors it was found that the greatest effect in the occurrence of ' Vira-cabeça" observed should be attributed to different transplanting times or different districts. The selection of recovered plants showed no influence in lowering the incidence of * vira-cabeça" : hence the impossibility of getting types of tobacco resistant to "vira-cabeça" through selection of recovered plants. Plants were observed in the field that after the first recovery exhibited symptoms of the disease, and then completely recovered from it again. This is in accordance with the results of Smith (11) in the reinoculation of tobacco plants after recovery from spotted wilt and of Costa (4) who reinoculated "vira-cabeça" - recovered tobacco plants with it. Therefore, as far as our knowledge is concerned districts should be selected where the disease does not appear very frequently; transplanting periods should be chosen, tc guarantee the lowest possible incidence of the disease.

A giant type of tobacco, Nicotiana tabacum L., spontaneously appeared in a tobacco culture at the Central Experiment Station, Campinas, during the agricultural year 1938-39. Cuttings from three of those plants were grown to maturity and seeds were secured from 18 of them. All the seed reproduced the giant type.

Forty-five plants including an hybrid of N. tabacum L. x N. glutinosa L., were tested as to the susceptibility to "vira-cabeça". Of all the plants tested Nicotiana paniculata L. proved to be the best for the study of local lesions, these being very clear-cut 4 days post-inoculation. Petunia sp., Nicandra physaloides Gaertn., Nicotiana glutinosa L., come next as good indicator plants also.