Seletividade de herbicidas à grama batatais e sua relação com as características anatômicas foliares / Herbicide selectivity to batatais grass and its relation to the leaf anatomical characteristics

Objetivou-se avaliar a seletividade de herbicidas aplicados em pós-emergência sobre Paspalum notatum e relacioná-la com os caracteres da anatomia foliar. Os herbicidas(g ha-1) testados foram: bentazon (720), nicosulfuron (50), halosulfuron (112,5), oxadiazon (875) e 2,4-D (698) e um tratamento controlesem herbicidas. A fitointoxicação foi avaliada dos 7 aos 35 dias após a aplicação dos herbicidas (DAA). Para a análise anatômica foliar coletou-Se folhas aos 35 DAA. Avaliou-se a % fitointoxicação, a altura e a massa seca da gramapela análise de variância pelo teste Fepelo teste de Tukey a 5%. Os valores dos caracteres anatômicos foram submetidos ao teste de análise de agrupamento. Os herbicidas bentazon, nicosulfuron, halosulfuron, oxadiazon e 2,4-D causaram injúrias (máximo de 0,5, 33,0, 17,5, 27,25 e 3,5%, respectivamente) dissiparam-se até os 35 DAA, exceto os sintomas causados pelo nicosulfuron que nesse período de avaliação ainda apresentava 29% de injúria. Apenas o2,4-D não afetou a altura de plantas. Não foram observadas diferenças entre os tratamentos quantoàmassa seca das plantas.A Análise de Agrupamento resultou na formação de dois grupos distintos, sendo que o primeiro grupo formou-se pelo tratamento controle, bentazon, halosulfuron e 2,4-D; o segundo grupo pelo nicosulfuron e oxadiazon. Nas plantas tratadas com nicosulfuron observou-se redução na % de parênquima, aumento na espessura da folha e na porcentagem de feixes vasculares; já com o oxadiazon observou-se redução da espessura da folha e na porcentagem de feixes vasculares e aumentou a epiderme abaxial e a % da bainha do feixe na região da asa. As porcentagens da epiderme adaxial e abaxial, da bainha do feixe, do feixe vascular e do parênquima conferiram a seletividade dessa espécie aos herbicidas testados. Os herbicidas que constituíram o segundo grupo foram os menos seletivos à espécie.(AU)

The objective of this study was to evaluate the selectivity of herbicides applied in post-emergence on Paspalum notatum L. and to relate it to the characters of the leaf anatomy. The herbicides (g ha-1) tested were: bentazon (720), nicosulfuron (50), halosulfuron (112.5), oxadiazon (875) and 2.4-D (698) and a control treatment without herbicides. The phytotoxicity was evaluated from 7 to 35 days after herbicide application (DAA). Leaf anatomy was collected at 35 DAA. The percent phytotoxification, height and dry mass of the grass were evaluated by analysis of variance by the F test and by the Tukey test at 5%. The values of the anatomical characters were submitted to the cluster analysis test. The herbicides bentazon, nicosulfuron, halosulfuron, oxadiazon and 2,4-D caused injuries (maximum of 0.5, 33.0, 17.5, 27.25 and 3.5%, respectively) and dissipated up to 35 DAA, except the symptoms caused by nicosulfuron, which in this evaluation period still presented 29% of injury. Only 2.4-D did not affect plant height. No differences were observed between the treatments regarding the dry mass of the plants. The cluster analysis test resulted in the formation of two distinct groups, the first group being formed by the control treatment, bentazon, halosulfuron and 2,4-D; the second group by nicosulfuron and oxadiazon. In plants treated with nicosulfuron, there was a reduction in parenchyma%, increase in leaf thickness and percentage of vascular bundles; with oxadiazon, a reduction in leaf thickness and in the percentage of vascular bundles was observed and the abaxial epidermis and % of the sheath of the bundle in the wing region were increased. The percentages of adaxial and abaxial epidermis, bundle sheath, vascular bundle and parenchyma confer the selectivity of this species to the tested herbicides. The herbicides that constituted the second group were the least selective to the species.(AU)

Seletividade de herbicidas à grama batatais e sua relação com as características anatômicas foliares / Herbicide selectivity to batatais grass and its relation to the leaf anatomical characteristics

Objetivou-se avaliar a seletividade de herbicidas aplicados em pós-emergência sobre Paspalum notatum e relacioná-la com os caracteres da anatomia foliar. Os herbicidas(g ha-1) testados foram: bentazon (720), nicosulfuron (50), halosulfuron (112,5), oxadiazon (875) e 2,4-D (698) e um tratamento controlesem herbicidas. A fitointoxicação foi avaliada dos 7 aos 35 dias após a aplicação dos herbicidas (DAA). Para a análise anatômica foliar coletou-Se folhas aos 35 DAA. Avaliou-se a % fitointoxicação, a altura e a massa seca da gramapela análise de variância pelo teste Fepelo teste de Tukey a 5%. Os valores dos caracteres anatômicos foram submetidos ao teste de análise de agrupamento. Os herbicidas bentazon, nicosulfuron, halosulfuron, oxadiazon e 2,4-D causaram injúrias (máximo de 0,5, 33,0, 17,5, 27,25 e 3,5%, respectivamente) dissiparam-se até os 35 DAA, exceto os sintomas causados pelo nicosulfuron que nesse período de avaliação ainda apresentava 29% de injúria. Apenas o2,4-D não afetou a altura de plantas. Não foram observadas diferenças entre os tratamentos quantoàmassa seca das plantas.A Análise de Agrupamento resultou na formação de dois grupos distintos, sendo que o primeiro grupo formou-se pelo tratamento controle, bentazon, halosulfuron e 2,4-D; o segundo grupo pelo nicosulfuron e oxadiazon. Nas plantas tratadas com nicosulfuron observou-se redução na % de parênquima, aumento na espessura da folha e na porcentagem de feixes vasculares; já com o oxadiazon observou-se redução da espessura da folha e na porcentagem de feixes vasculares e aumentou a epiderme abaxial e a % da bainha do feixe na região da asa. As porcentagens da epiderme adaxial e abaxial, da bainha do feixe, do feixe vascular e do parênquima conferiram a seletividade dessa espécie aos herbicidas testados. Os herbicidas que constituíram o segundo grupo foram os menos seletivos à espécie.

The objective of this study was to evaluate the selectivity of herbicides applied in post-emergence on Paspalum notatum L. and to relate it to the characters of the leaf anatomy. The herbicides (g ha-1) tested were: bentazon (720), nicosulfuron (50), halosulfuron (112.5), oxadiazon (875) and 2.4-D (698) and a control treatment without herbicides. The phytotoxicity was evaluated from 7 to 35 days after herbicide application (DAA). Leaf anatomy was collected at 35 DAA. The percent phytotoxification, height and dry mass of the grass were evaluated by analysis of variance by the F test and by the Tukey test at 5%. The values of the anatomical characters were submitted to the cluster analysis test. The herbicides bentazon, nicosulfuron, halosulfuron, oxadiazon and 2,4-D caused injuries (maximum of 0.5, 33.0, 17.5, 27.25 and 3.5%, respectively) and dissipated up to 35 DAA, except the symptoms caused by nicosulfuron, which in this evaluation period still presented 29% of injury. Only 2.4-D did not affect plant height. No differences were observed between the treatments regarding the dry mass of the plants. The cluster analysis test resulted in the formation of two distinct groups, the first group being formed by the control treatment, bentazon, halosulfuron and 2,4-D; the second group by nicosulfuron and oxadiazon. In plants treated with nicosulfuron, there was a reduction in parenchyma%, increase in leaf thickness and percentage of vascular bundles; with oxadiazon, a reduction in leaf thickness and in the percentage of vascular bundles was observed and the abaxial epidermis and % of the sheath of the bundle in the wing region were increased. The percentages of adaxial and abaxial epidermis, bundle sheath, vascular bundle and parenchyma confer the selectivity of this species to the tested herbicides. The herbicides that constituted the second group were the least selective to the species.

Optimization of spray deposition and Tetranychus urticae control with air assisted and electrostatic sprayer

Improved spray deposition can be attained by electrostatically charging spray droplets, which increases the attraction of droplets to plants and decreases operator exposure to pesticide and losses to the environment. However, this technique alone is not sufficient to achieve desirable penetration of the spray solution into the crop canopy; thus, air assistance can be added to the electrostatic spraying to further improve spray deposition. This study was conducted to compare different spraying technologies on spray deposition and two-spotted spider mite control in cut chrysanthemum. Treatments included in the study were: conventional TJ 8003 double flat fan nozzles, conventional TXVK-3 hollow cone nozzles, semi-stationary motorized jet launched spray with electrostatic spray system (ESS) and air assistance (AA), and semi-stationary motorized jet launched spray with AA only (no ESS). To evaluate the effect of these spraying technologies on the control of two-spotted spider mite, a control treatment was included that did not receive an acaricide application. The AA spraying technology, with or without ESS, optimized spray deposition and provided satisfactory two-spotted spider mite control up to 4 days after application.

Optimization of spray deposition and Tetranychus urticae control with air assisted and electrostatic sprayer

Improved spray deposition can be attained by electrostatically charging spray droplets, which increases the attraction of droplets to plants and decreases operator exposure to pesticide and losses to the environment. However, this technique alone is not sufficient to achieve desirable penetration of the spray solution into the crop canopy; thus, air assistance can be added to the electrostatic spraying to further improve spray deposition. This study was conducted to compare different spraying technologies on spray deposition and two-spotted spider mite control in cut chrysanthemum. Treatments included in the study were: conventional TJ 8003 double flat fan nozzles, conventional TXVK-3 hollow cone nozzles, semi-stationary motorized jet launched spray with electrostatic spray system (ESS) and air assistance (AA), and semi-stationary motorized jet launched spray with AA only (no ESS). To evaluate the effect of these spraying technologies on the control of two-spotted spider mite, a control treatment was included that did not receive an acaricide application. The AA spraying technology, with or without ESS, optimized spray deposition and provided satisfactory two-spotted spider mite control up to 4 days after application.(AU)

Interferência de Brachiaria Ruziziensis sobre plantas daninhas em sistema de consórcio com milho / Interference of Brachiaria Ruziziensis on the weeds in intercropping with corn crop

Com relação às forrageiras tropicais, a espécie Brachiaria ruziziensis destaca-se pela grande aceitabilidade pelos bovinos quando comparada às demais espécies do gênero Brachiaria, além de excelente habilidade para competir com plantas daninhas. Com isso, o estudo objetivou avaliar os efeitos de densidades de Brachiaria ruziziensis no consórcio com a cultura do milho, em relação ao controle e desenvolvimento de plantas daninhas no sistema de integração lavoura-pecuária. O experimento foi realizado durante o período de dezembro/2007 a maio/2008, em área experimental pertencente à Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba ­ SP. Os tratamentos foram constituídos, em arranjo fatorial, pela combinação de quatro densidades de Brachiaria ruziziensis (0, 10, 15 e 20 kg ha-1) e três espécies de plantas daninhas (Ipomoea grandifolia, Digitaria horizontalis e Cenchrus echinatus), em cultivo consorciado com milho. As avaliações realizadas foram: a infestação das espécies daninhas (densidade de plantas m-2), a fitomassa seca (g planta-1) e a área foliar (cm2 planta-1). Constatou-se que Brachiaria ruziziensis reduziu a infestação de todas as plantas daninhas avaliadas. Verificou-se, ainda, que as espécies Digitaria horizontalis e Ipomoea grandifolia foram as plantas daninhas de mais difícil controle.

Regarding tropical forage plants, the specie Brachiaria ruziziensis are prominence for to be most acceptable for cattle when compared with others Brachiaria species, besides the excellent competitive ability with weeds. Then, this study aimed to evaluate the effects of Brachiaria ruziziensis density in intercropping with corn crop, about weeds control and weeds development in the crop-cattle integration system. The experiment was realized during the period between December/2007 to May/2008, in the experimental area of Escola Superior de Agricultura "Luiz de Queiroz", Piracicaba ­ SP. The treatment was composed in a factorial arrangement, by combination of four Brachiaria ruziziensis density (0, 10, 15 and 20 kg ha-1) and three weed species ((Ipomoea grandifolia, Digitaria horizontalis e Cenchrus echinatus), in intercropping with corn crop. The evaluations realized were: weed infestation (density m-2), the dry biomass (g plant-1) and leaf area (cm2 plant-1). It was noted that Brachiaria ruziziensis reduced the all of weeds infestation evaluated. Also, it was checked that Digitaria horizontalis and Ipomoea grandifolia were the weeds with most difficult control.