ABSTRACT. Cowpea (Vigna unguiculata) crops produce a poor yield in northeastern Brazil compared to the other regions. The goal of this study was to assess the effects of irrigated cropping systems and sowing seasons on cowpea yield and profitability in Vitória da Conquista, Bahia, Brazil. Field studies were performed in four experiments during the rainy and dry seasons during 2016/2017 and 2017/2018, which denoted harvests 1, 2, 3, and 4, respectively. A randomized block design was used for each experiment with four replicates and the following treatments for cropping systems: (1) manual weeding; (2) liming and manual weeding; (3) liming and phosphorus (P) fertilization at sowing, nitrogen (N) and potassium (K) topdressing fertilization, and chemical weed control; (4) liming and P fertilization at sowing, K topdressing fertilization, rhizobia inoculation, and chemical weed control; (5) liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control; and (6) seed pretreatment with cobalt (Co) and molybdenum (Mo), liming and P fertilization at sowing, N and K topdressing fertilization, rhizobia inoculation, and chemical weed control. The technology added to cropping systems increased the number of pods per plant, pod length, seeds per pod, and 100-seed weight, irrespective of the rainy or dry sowing season. Economic analysis, in turn, showed that the technology decreased the total operating cost despite increasing the cost of mechanical operations, inputs, and materials because of the replacement of manual weeding by chemical weed control. However, these costs were not influenced by the sowing seasons. We concluded that technologically enhanced cropping systems, especially systems 4 and 6, improved grain yield and provided greater profitability, which translated into improved economic benefits for farmers. Conversely, the sowing season influenced profitability, which was higher for dry season harvests, when there was less product offered and prices became higher.

Abstract Potato scab is one of the main diseases affecting potato tubers during their development, causing great commercial damage to farmers. The use of some antagonistic microorganisms has been shown as a viable alternative to phytosanitary control of several crops. However, this work aimed to verify in vitro effects of microorganisms antagonistic against phytopathogenic Streptomyces sp. and in vivo treatment of scab in potato tubers. Trichoderma longibrachiatum; Trichoderma harzianum; Pochonia clamydosporia; Bacillus subtilis (except for in vivo test); Bacillus subtilis + Trichoderma longibrachiatum, and Bacillus subtilis + Enterococcus faecium were tested for in vitro growth inhibition of Streptomyces via microorganism radial pairing test, with both volatile and non-volatile metabolites. In parallel, the antagonistic microorganisms were tested in vivo in protected environments by cultivating potato plants in pots with soil contaminated with Streptomyces sp., then evaluating the number of injured tubers, injured area, severity index, production losses and the frequency of tubers by lesion type. The results indicate major in vitro inhibition of Streptomyces sp. by Trichoderma longibrachiatum, Trichoderma harzianum, and Bacillus subtilis + Enterococcus faecium under the antagonism (48 - 80%) and antibiosis tests, as well as a major reduction of tuber lesions size (34 - 60%), severity index, and production losses in the in vivo test.

Resumo O objetivo desta pesquisa foi avaliar a toxicidade de doses do herbicida oxyfluorfen aplicado em pré-emergência via água de irrigação na implantação da cultura do eucalipto, clone VCC865 (híbrido de Eucalyptus urophylla x Eucalyptus grandis), além de sua eficácia no controle de plantas daninhas. O experimento foi conduzido em condições de campo, em delineamento experimental em blocos casualizados, com quatro repetições, em esquema fatorial 5 x 2 x 2, sendo cinco doses do herbicida oxyfluorfen (0; 360; 720; 1080 e 1440 g i.a. ha-1), dois modos de aplicação (sobre a planta e sobre o solo) e dois volumes da água de irrigação (5 e 10 litros). Os tratamentos foram aplicados manualmente 15 dias após o plantio das mudas com auxílio de um regador. Foram realizadas avaliações de porcentagem visual de intoxicação, altura de plantas, diâmetro do coleto, número de folhas, área foliar total, massa seca da parte aérea, teor relativo de clorofila, condutância estomática, concentração interna de CO2, taxa fotossintética e taxa de transpiração. As plantas daninhas presentes na área útil do entorno das covas de plantio foram identificadas e quantificadas, para determinação da densidade de plantas na área amostrada por tratamento. Foram identificadas na área de implantação do eucalipto 27 espécies de plantas daninhas, pertencentes a 23 gêneros e 11 famílias botânicas, com maior ocorrência de Chenopodium carinatum, Blainvillea biaristata e Urochloa decumbens. O oxyfluorfen na água de irrigação, independente da forma de aplicação e o volume de água de irrigação, mostrou-se seletivo à cultura nas doses avaliadas, promovendo nas maiores doses (1080 e 1440 g i.a. ha-1) eficiente controle em pré-emergência das plantas daninhas e aumento no crescimento inicial do eucalipto, principalmente no número de folhas, área foliar e acúmulo de massa seca da parte aérea.

Abstract This research aimed to evaluate the toxicity of oxyfluorfen doses applied in pre-emergence via irrigation water in the implantation of eucalyptus crop, clone VCC865 (hybrid Eucalyptus urophylla x Eucalyptus grandis), in addition to its effectiveness in weed control. The experiment was conducted under field conditions, in experimental design in randomized block, with four replications, in a 5 x 2 x 2 factorial scheme: five doses of oxyfluorfen herbicide (0, 360, 720, 1080 and 1440 g a.i. ha-1), two forms of application (on the plant and on the soil) and two volumes of irrigation water (5 and 10 L). The treatments were applied manually 15 days after planting the seedlings using a watering can. Eucalyptus intoxication percentage, plant height, collar diameter, leaf number, leaf area, shoot dry mass, relative chlorophyll content, stomatal conductance, internal CO2 concentration, photosynthetic rate and respiration rate were evaluated. Weeds present in the useful area of the planting holes were identified and quantified to determine plant density in the sampled area by treatment. In the area of implantation of the eucalyptus, 27 species of weeds were identified, belonging to 23 genera and 11 botanical families, with greater occurrence of Chenopodium carinatum, Blainvillea biaristata and Urochloa decumbens. The oxyfluorfen in the irrigation water, regardless of the application form and the volume of irrigation water volume, was selective for the crop at the doses evaluated. The highest doses (1080 and 1440 g a.i. ha-1) effectively controlled pre-emergence of weed growth, which increased initial growth of the eucalyptus plants, mainly in the leaf number, leaf area and accumulation of shoot dry mass.

Neste trabalho avaliou-se o levantamento fitossociológico e determinaram-se os períodos críticos de competição com a cultura da mandioca, submetida ou não à adubação NPK. Para tanto, as plantas infestantes foram colhidas a cada 35 dias, até os 525 dias após a plantação da mandioca, por meio do lançamento aleatório de um quadrado de ferro vazado de 0,5 x 0,5 m (0,25 m²) na área útil das parcelas com e sem adubação. As plantas no interior do quadrado foram cortadas rente ao solo, contadas e identificadas por espécie. Sida rhombifolia, Brachiaria plantaginea e Cynodon dactylon apresentaram os maiores índices de frequência relativa (FR), densidade relativa (DR), abundância relativa (AR) e índice de valor de importância (IVI). Posteriormente, os dados de produtividade de raízes tuberosas foram ajustados ao modelo de regressão não linear sigmoidal de Boltzmann, para determinação dos períodos críticos de competição: período anterior à interferência (PAI), período total de prevenção à interferência PTPI e período crítico de prevenção à interferência (PCPI). A adubação fornecida à cultura da mandioca influenciou a determinação de diferentes índices fitossociológicos e períodos críticos de competição.

The objective of this study was to evaluate the phytosociological survey and determine the critical periods of weeds competition with the cassava crop, submitted or not to NPK fertilization. Therefore, the weeds were collected every 35 days, until 525 days after cassava planting, through the random release of a cast iron square 0.5 m x 0.5 m (0.25 m²) in plots with and without fertilization. The plants inside the square were cut close to the ground, counted and identified by species. Sida rhombifolia, Brachiaria plantaginea and Cynodon dactylon showed the highest FR, DR, AR and IVI. Subsequently, the yield data of storage roots were adjusted to non-linear regression model sigmoidal Boltzmann to determine the critical periods of competition: PAI, TPIC and PCPI. The fertilizer supplied to cassava crop contributed to the determination of different phytosociological indices and critical periods of competition.

O objetivo foi estudar a seletividade de inseticidas aos inimigos naturais na cultura do algodão (Gossypium hirsutum L.r. latifoliumHurtch), cultivar DeltaOpal, no município de Malhada (BA) e conhecer a fauna benéfica associada. O trabalho foi conduzido na safra 2010/2011, com delineamento experimental em blocos ao acaso, com seis tratamentos e quatro repetições, sendo os tratamentos: (1) Fipronil 200 SC (0,38 L.ha-1); (2) Alfacipermetrina 100 SC (0,30 L.ha-1); (3) Lufenuron 50 CE (0,30 L.ha-1); (4) Imidacloprid 200 SC (0,30 L.ha-1); (5) Paration Metil 600 CE (1,00 L.ha-1); e (6) Testemunha (água). A aplicação dos produtos foi feita 80 dias após a emergência, com avaliações um dia antes da aplicação e 1, 7 e 14 dias após a aplicação (DAA) por meio do pano de batida e armadilha Moericke. Em laboratório, os insetos foram triados, contados e identificados em famílias. A toxicidade dos produtos varia em função do grupo do inimigo natural. A Imidacloprida é seletiva às aranhas, sendo os demais inseticidas medianamente tóxicos (Alfacipermetrina e Paration Metil: 1º e 14º DAA; Lufenuron: 14º DAA) ou tóxicos (Fipronil e Alfacipermetrina: 7º DAA). Fipronil (1º DAA), Alfacipermetrina (7º DAA) e Paration Metil (14º DAA) são medianamente tóxicos aos adultos de joaninhas. Os inseticidas estudados são tóxicos às larvas de joaninhas, com mais impacto até os sete dias após a aplicação, com exceção do Paration Metil, classificado como inócuo até esse período. Registra-se a ocorrência de 13 famílias de aranhas e 18 famílias de hymenópteros parasitoides em agroecossistema de algodão na região de Malhada (BA).

The aim of this work was study the selectivity of insecticides in favor of natural enemies in cotton (Gossypium hirsutum latifolium Hurtch Lr), DeltaOpal cultivar, in the city of Malhada (BA), and to know the associated beneficial fauna. The study was conducted at the agricultural year of 2010/2011. The design was conducted in randomized blocks with six treatments and four replications. The treatments were: (1) Fipronil 200 SC (0.38 L.ha-1); (2) Alphacypermethrin 100 SC (0.30 L.ha-1), (3) Lufenuron 50 EC (0.30 L.ha-1), (4) Imidacloprid 200 SC (0.30 L.ha-1), (5) Methyl parathion 600 EC (1.00 L.ha-1), and (6) control (water). The product was applied 80 days after emergence, and the evaluations were performed one day before application and 1, 7 and 14 days after application (DAA). The samples were taken using the sampling method beating cloth and Moericke traps. Natural enemies were brought to the laboratory for sorting, counting and identification by family. The toxicity of the products ranged according to the group of natural enemies. Imidacloprid is selective to the spiders and insecticides are moderately toxic (Methyl Parathion and Alphacypermethrin: 1 and 14th DAA; Lufenuron: 14th DAA) or toxic (Fipronil and Alphacypermethrin: 7thDAA). Fipronil (1 DAA), Alphacypermethrin (7th DAA) and Methyl Parathion (14th DAA) are moderately toxic to adult ladybirds. The analyzed insecticides are toxic to the larvae of ladybirds, with more impact until seven days after the application, with the exception of Methyl Parathion classified, as innocuous until this period. The occurrence of 13 families of spiders and 18 families of parasitic Hymenoptera is registered in cotton agroecosystems in the region of Malhada, in the state of Bahia.