The spraying of herbicides in crops has become the main form of weed control. Although it means unexpected effects on non-target plants resulted by spraying drift. Thus, improvements in application techniques, as the best selection of spray nozzles and adjuvant, are essential to avoid environmental contamination and economic losses. On this work, we evaluate how much adjuvant associated with nozzles can reduce the spray drift. The nozzles used at experiment were air induction flat tip, hollow cone and twinjet and the spray liquids, which were composed of herbicide glyphosate and phosphatidylcholine + propionic acid adjuvant. Measurements were made at wind tunnel and droplet sizer, at laser diffraction method. The models of nozzles influence in droplet size characteristics and in occurrence of spray drift. The use of adjuvants reduces the spray drift only combined with the twinjet nozzle, while for the other models the adjuvant did not reduce the global spray drift at significant levels. The adjuvant reduced the spray drift until 39%, while the nozzles model reduced until 74%. Both techniques when combined were able to reduce until 80%. The model of nozzle has the biggest result on drift mitigation and the use of adjuvants can increase the drift mitigation specially with nozzles that produces smallest droplets.
Bacillus thuringiensis (Bt) is the main bacterium used in the formulation of bioinsecticides because it produces toxins and spores that are toxic to several orders of insects. The efficacy of Bt bioinsecticide is influenced by the quality of its application. The association with other crop protection products, such as adjuvants, can affect the physical and chemical parameters of the mixture. This study evaluated the physical and chemical parameters, volume median diameter (VMD), uniformity coefficient of droplets (SPAN), percentage of volume in drift droplets (%V <100 µm), contact angle, surface tension, potential of hydrogen (pH) and electrical conductivity (E.C.) of Bt bioinsecticides in concentrated suspension (SC), and wettable powder (WP) formulations associated with adjuvants. The largest droplet diameter and smallest values of drift droplets were found in the WP formulation with lower drift potential. The addition of mineral oil and surfactant to the mixtures of bioinsecticide reduced contact angle values and surface tension of the droplets, resulting in greater spreading of droplets in leaves. The addition of lecithin and propionic-acid-based adjuvants lowered the pH in both formulations. The adjuvants used in this study affected the physical and chemical characteristics of the mixtures, improving or impairing the quality of Bt bioinsecticide applications.
ABSTRACT:This research aimed to determine the optimal size of guava fruits to be bagged, and to evaluate the efficiency of different bagging at the control of fruits flies, as well as their correlation with the fruit quality. The work was conducted in a commercial guava orchard of Paluma variety at the municipality of Crato, in Cariri region, Ceará, Brazil, from October 2011 until April 2012. Popcorn bags, parchment paper bags, newspaper bags, micropierced plastic bags, TNT and the control were tested in four groups of fruits diameters: first group (2.0 to 3.0 cm), second group (3.1 to 4.0 cm), third group (4.1 to 5.0 cm) and fourth group (5.1 to 6.0 cm). Fruits were collected when they became mature and after each collect they were transferred to the Laboratory of Entomology of the Federal University of Cariri in order to evaluate the fruit flies attacks and the physicochemical parameters of the fruits. Bagging the guava is effective to avoid attacks from fruit flies, regardless of the type of bag used. Moreover, one can recommend bagging the guava with diameter less than 2 cm. Fruits were heavier, larger in length and with better Brix degrees when bagged in newspaper bags, with diameters ranging from 4.1 to 5.0 cm. On the other hand, to obtain fruits with larger diameters, one can recommend bagging the fruits with 5.1 to 6.0 cm in diameter. KEYWORDS: mechanical control; orchading; frugivorous flies;Psidium guajava. RESUMO: Com o objetivo de determinar o tamanho ideal dosfrutos para serem ensacados e avaliar a eficiência de diferentes ensacamentos no controle de moscas-das-frutas, bem como sua correlação com a qualidade das goiabas do Cariri cearense, realizou-se esta pesquisa no Crato, Ceará, no período de 13 de outubro de 2011 a 16 de abril de 2012 em um pomar comercial de goiaba da variedade Paluma. Foram avaliados sacos de pipoca, papel manteiga, jornal, plástico microperfurado, TNT e a testemunha; e quatro grupos de diâmetro dos frutos: 1º grupo (2,0 a 3,0 cm), 2º grupo (3,1 a 4,0 cm), 3º grupo (4,1 a 5,0 cm) e 4º grupo (5,1 a 6,0 cm). Os frutos foram colhidos à medida que atingiam a maturação e após cada colheita eram levados ao Laboratório de Entomologia da Universidade Federal do Cariri, Campus do Crato, para avaliar o ataque das moscas-das-frutas e os parâmetros físico-químicos dos frutos. O ensacamento dos frutos é eficiente no controle das moscas-das-frutas independente do tipo de saco utilizado, recomendando-se ensacar quando as goiabas estiverem com diâmetro igual ou inferior a 2,0 cm. O jornal favorece o aumento do peso, comprimento e ºBrix quando os frutos são ensacados com diâme-tros de 4,1 a 5,0 cm. Já para obter frutos com maiores diâmetros, recomenda-se ensacar com 5,1 a 6,0 cm de diâmetro. PALAVRAS-CHAVE: INTRODUÇÃOAs moscas-das-frutas (Anastrepha spp e Ceratitis capitata) são as principais pragas para os pomares de goiaba (Psidium guajava L.) (Manica et al., 2000). Suas larvas se alimentam da polpa do fruto, o que acarreta baixa produção, tornando-o impróprio para o consumo in natura e sem...
Spodoptera frugiperda is a pest of economic importance for several crops with resistance reports to Bt crops and pesticides. Eco-friendly Bt biopesticides may be an alternative to chemical insecticides due to their selectivity and specificity. However, the efficacy of Bt biopesticides may be influenced by the association with other chemicals, such as adjuvants. This study evaluated the compatibility and toxicity of Bt biopesticides mixed with adjuvants for the control of S. frugiperda. The treatments included the association of Dipel SC and Dipel PM with adjuvants. Compatibility tests were used to evaluate the Bt mixture. Bt suspensions obtained from mixtures of Bt and adjuvants at 106 and 3 × 108 spores/mL−1 were used to evaluate S. frugiperda mortality and distilled water was used as the control. The addition of the adjuvant LI increased growth and sporulation, indicating compatibility with Bt biopesticides. The other adjuvants were toxic to reducing Bt growth and sporulation. Only the mixture of Bt with LI and Bt alone was effective to S. frugiperda. The addition of adjuvants to Bt biopesticide affect the Bt sporulation, growth and mortality.
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