Goosegrass is a problematic weed of golf courses, sports fields, and residential lawns that decreases playability and aesthetic quality of turf. With the recent banning of MSMA in sports fields and intensive restrictions in golf and sod production, turfgrass managers are seeking alternatives for postemergence goosegrass control and how to utilize currently labeled goosegrass control products more effectively. Studies were conducted to investigate a suspected-resistant (SR) goosegrass accession in Richmond, VA and characterize the resistance mechanism if present. The SR accession showed a hypersensitive response to oxadiazon treatment and reached maximum electrolyte leakage quicker than the susceptible (S) accession, but had significantly lower electrolyte leakage indicating less tissue damage and suggesting there is a physiological resistance mechanism within the SR accession. In absorption and translocation studies, percent oxadiazon absorption and translocation was not significantly affected by goosegrass biotype. Roots of both the S and resistant (R) biotypes contained over 95% of total detected oxadiazon, while the plant tissue above the treated foliage only contained small quantities. These results suggest that absorption or translocation is not the mechanism conferring oxadiazon resistance in the goosegrass biotype from Richmond, VA. Greenhouse and field trials were conducted to determine the lowest rate at which topramezone, with or without the addition of triclopyr, controls goosegrass while maintaining commercially-acceptable bermudagrass quality. In field trials, topramezone rate did not significantly affect goosegrass cover at 56 and 70 days after initial treatment (DAIT). All treatments reduced goosegrass cover below 3 and 7% with and without the addition of triclopyr, respectively at 70 DAIT. A significant herbicide effect on bermudagrass cultivar showed higher injury from topramezone within three weeks of application, but injury persisted longer from treatments containing triclopyr. Bermudagrass cultivars completely recovered by 4 weeks after treatment (WAT) from all treatments. Greenhouse trials were conducted to determine if goosegrass growth stage affects efficacy of nine postemergent herbicides or programs documented to have goosegrass activity. As goosegrass growth stage increased from four- to five-leaf to greater than eight-tiller stage, goosegrass control and biomass reduction decreased among all of the herbicides except topramezone and MSMA plus metribuzin at 4 and 8 WAT. These data suggest that one application of sulfentrazone is only effective for seedling stage (pre-tiller) goosegrass control; foramsulfuron, topramezone, and metribuzin suppress all growth stages of goosegrass; and diclofop, sulfentrazone plus metribuzin, fenoxaprop, and metamifop control up to three-tiller stage goosegrass. / Ph. D.

Made available in DSpace on 2014-06-11T19:30:24Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-02-23Bitstream added on 2014-06-13T20:20:53Z : No. of bitstreams: 1 cardoso_la_dr_botfca.pdf: 589722 bytes, checksum: 199f3a851af1d40ea61eaa7ce630f683 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Este trabalho teve como objetivo avaliar a seletividade do herbicida topramezone aplicado de forma isolado e em mistura com tebuthiuron, em pós-emergência inicial sobre dez variedades de cana-de-açúcar em condição de cana-planta. O experimento foi conduzido na Fazenda Experimental Lageado, pertencente a FCA/UNESP – Botucatu/SP. Os tratamentos utilizados foram: topramezone + Dash (70 g ha-1 + 0,25% v/v-1); topramezone + tebuthiuron + Dash (70 + 1000 g ha-1 + 0,25% v/v-1); topramezone + tebuthiuron + Dash (100 + 1000 g ha-1 + 0,25% v/v-1) e ametryn + tebuthiuron (1500 + 1000 g ha-1), aplicados aos 35 DAP (dias após o plantio), além de uma testemunha sem aplicação. O delineamento experimental utilizado foi o de blocos casualizados em parcelas subdivididas com quatro repetições. As dez variedades utilizadas foram: SP 83 2847, SP 80 3280, RB 85 5453, SP 80 1842, SP 89 1115, RB 86 7515, PO 8862, RB 85 5156, SP 80 1816 e SP 81 3250. Para aplicação dos herbicidas, utilizou-se um pulverizador costal, pressurizado a CO2 e equipado com barra de aplicação com seis pontas Teejet XR 110 02VS, e um volume de aplicação foi de 200 L ha-1. As avaliações visuais de fitotoxicidade foram realizadas aos 7, 14, 28 e 35 dias após a aplicação (DAA), sendo que aos 28, 64 e 300 DAA dos herbicidas foram determinados os números de perfilhos por metro e aos 28 e 64 DAA determinou-se a altura média de 15 plantas nas duas linhas centrais da parcela. Ao final do estudo foram determinados os parâmetros tecnológicos como pol, fibra e brix e, os parâmetros produtivos como o comprimento, diâmetro e peso dos colmos e a produção de açúcar por parcela. A formulação isolada de topramezone seguida de suas misturas com tebuthiuron proporcionaram inicialmente severos sintomas visuais de injúrias às plantas... / The objective of this experiment was to evaluate the selectivity topramezone herbicide alone, and in a mixture with tebuthiuron. The herbicides were applied after sprouting to ten varieties of sugar cane on condition of first crop. This research was carried out on the Experimental field from São Paulo State University in Botucatu/SP city. The treatments were: topramezone + Dash (70 g ha-1 + 0.25% v/v-1); topramezone + tebuthiuron + Dash (70 + 1000 g ha-1 + 0.25% v/v-1); topramezone + tebuthiuron + Dash (100 + 1000 g ha-1 + 0.25% v/v-1) and ametryne + tebuthiuron (1500 + 1000 g ha-1) applied 30 DAP (days after planting). Treatments were organized in a randomized complete block split plot with 4 replications for each treatment. Ten varieties utilized in this study: SP 83 2847, SP 80 3280, RB 85 5453, SP 80 1842, SP 89 1115, RB 86 7515, PO 8862, RB 85 5156, SP 80 1816, and SP 81 3250. The herbicides treatments were applied using a CO2 pressurized backpack sprayer at 2.0 bar. The boom was equipped with six TeeJet XR 110 02VS flat fan nozzles, delivering a volume of 200 L ha-1. Visual fitotoxicity evaluations were taken 7, 14, 28, and 35 DAA (days after application). At 28, 64, and 300 DAA the number of tillers per meter were determined, and at 28 and 64 DAA average plant height was determined from 15 plants in two central lines of each plot. At the end of the study, technological parameters such as pol, fiber, and brix were determined. At this same stage, productive parameters such as length, diameter, stalk weight, and sugar production per plot were also determined. The formulation of topramezone alone followed its mixtures with tebuthiuron initially provided severe visual injury to the sugar cane plants, however the plants of all varieties tested had a total visual injury recovery... (Complete abstract click electronic access below)

Resumo: Este trabalho teve como objetivo avaliar a seletividade do herbicida topramezone aplicado de forma isolado e em mistura com tebuthiuron, em pós-emergência inicial sobre dez variedades de cana-de-açúcar em condição de cana-planta. O experimento foi conduzido na Fazenda Experimental Lageado, pertencente a FCA/UNESP - Botucatu/SP. Os tratamentos utilizados foram: topramezone + Dash (70 g ha-1 + 0,25% v/v-1); topramezone + tebuthiuron + Dash (70 + 1000 g ha-1 + 0,25% v/v-1); topramezone + tebuthiuron + Dash (100 + 1000 g ha-1 + 0,25% v/v-1) e ametryn + tebuthiuron (1500 + 1000 g ha-1), aplicados aos 35 DAP (dias após o plantio), além de uma testemunha sem aplicação. O delineamento experimental utilizado foi o de blocos casualizados em parcelas subdivididas com quatro repetições. As dez variedades utilizadas foram: SP 83 2847, SP 80 3280, RB 85 5453, SP 80 1842, SP 89 1115, RB 86 7515, PO 8862, RB 85 5156, SP 80 1816 e SP 81 3250. Para aplicação dos herbicidas, utilizou-se um pulverizador costal, pressurizado a CO2 e equipado com barra de aplicação com seis pontas Teejet XR 110 02VS, e um volume de aplicação foi de 200 L ha-1. As avaliações visuais de fitotoxicidade foram realizadas aos 7, 14, 28 e 35 dias após a aplicação (DAA), sendo que aos 28, 64 e 300 DAA dos herbicidas foram determinados os números de perfilhos por metro e aos 28 e 64 DAA determinou-se a altura média de 15 plantas nas duas linhas centrais da parcela. Ao final do estudo foram determinados os parâmetros tecnológicos como pol, fibra e brix e, os parâmetros produtivos como o comprimento, diâmetro e peso dos colmos e a produção de açúcar por parcela. A formulação isolada de topramezone seguida de suas misturas com tebuthiuron proporcionaram inicialmente severos sintomas visuais de injúrias às plantas... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract : The objective of this experiment was to evaluate the selectivity topramezone herbicide alone, and in a mixture with tebuthiuron. The herbicides were applied after sprouting to ten varieties of sugar cane on condition of first crop. This research was carried out on the Experimental field from São Paulo State University in Botucatu/SP city. The treatments were: topramezone + Dash (70 g ha-1 + 0.25% v/v-1); topramezone + tebuthiuron + Dash (70 + 1000 g ha-1 + 0.25% v/v-1); topramezone + tebuthiuron + Dash (100 + 1000 g ha-1 + 0.25% v/v-1) and ametryne + tebuthiuron (1500 + 1000 g ha-1) applied 30 DAP (days after planting). Treatments were organized in a randomized complete block split plot with 4 replications for each treatment. Ten varieties utilized in this study: SP 83 2847, SP 80 3280, RB 85 5453, SP 80 1842, SP 89 1115, RB 86 7515, PO 8862, RB 85 5156, SP 80 1816, and SP 81 3250. The herbicides treatments were applied using a CO2 pressurized backpack sprayer at 2.0 bar. The boom was equipped with six TeeJet XR 110 02VS flat fan nozzles, delivering a volume of 200 L ha-1. Visual fitotoxicity evaluations were taken 7, 14, 28, and 35 DAA (days after application). At 28, 64, and 300 DAA the number of tillers per meter were determined, and at 28 and 64 DAA average plant height was determined from 15 plants in two central lines of each plot. At the end of the study, technological parameters such as pol, fiber, and brix were determined. At this same stage, productive parameters such as length, diameter, stalk weight, and sugar production per plot were also determined. The formulation of topramezone alone followed its mixtures with tebuthiuron initially provided severe visual injury to the sugar cane plants, however the plants of all varieties tested had a total visual injury recovery... (Complete abstract click electronic access below) / Orientador: Dagoberto Martins / Coorientador: Rogerio Peres Soratto / Banca: Carlos Alexandre Costa Cruscicol / Banca: Neumarcio Vilanova da Costa / Banca: Fernando Tadeu de Carvalho / Doutor

Goosegrass [Eleusine indica (L.) Gaertn.] and smooth crabgrass [Digitaria ischaemum (Schreb.) Schreb. ex Muhl.] are problematic weeds in bermudagrass and creeping bentgrass turf. Increased incidences of herbicide resistant weed populations and severe use restrictions on formerly available herbicides have increased need for selective, postemergence control options for these weeds in creeping bentgrass and bermudagrass turf. This weed management exigency has led turf managers to utilize less effective, more expensive, and more injurious options to manage goosegrass and smooth crabgrass. Although potentially injurious, topramezone can control these weeds, especially goosegrass, at low doses. Low-dose topramezone may also improve bermudagrass and creeping bentgrass response. An initial investigation of three 4-hydroxyphenylpyruvate dioxygenase (HPPD) inhibiting herbicides in different turf types showed that Kentucky bluegrass, perennial ryegrass, and tall fescue were highly tolerant to topramezone, while creeping bentgrass and bermudagrass could tolerate topramezone doses that may control grassy weeds. Further investigation suggested that frequent, low-dose topramezone applications or metribuzin admixtures could enhance weed control and may conserve turfgrass quality. A novel mixture of topramezone at 3.7 g ae ha-1 and metribuzin at 210 g ai ha-1 controlled goosegrass effectively and reduced bermudagrass foliar bleaching associated with topramezone 10-fold compared to higher doses of topramezone alone in 19 field and 2 greenhouse trials. In an attempt to further enhance bermudagrass tolerance to topramezone, post-treatment irrigation was applied at various timings. When bermudagrass turf was irrigated with 0.25-cm water at 15 or 30 minutes after herbicide treatment, bermudagrass injury was reduced to acceptable levels when following low-dose topramezone plus metribuzin but not when following high-dose topramezone alone. Goosegrass control was reduced significantly by post-treatment irrigation in all cases, while irrigation reduced goosegrass control by low-dose topramezone plus metribuzin to below-commercially-acceptable levels. Novel, low-dose, frequent application programs containing topramezone or siduron were developed for season-long crabgrass or goosegrass control on creeping bentgrass greens. Greens-height creeping bentgrass quality was preserved following five biweekly treatments of siduron at rates between 3,400 to 13,500 g ai ha-1 and topramezone at 3.1 g ha-1. Siduron programs controlled smooth crabgrass and suppressed goosegrass while topramezone programs controlled goosegrass and suppressed smooth crabgrass. In laboratory and controlled-environment experiments, goosegrass absorbed three times more 14C than bermudagrass within 48 hours of 14C-topramezone treatment. Bermudagrass also metabolized topramezone twice as fast as goosegrass. Metribuzin admixture reduced absorption by 25% in both species. When herbicides were placed exclusively on soil, foliage, or soil plus foliage, topramezone controlled goosegrass only when applied to foliage and phytotoxicity of both bermudagrass and goosegrass was greater from topramezone than from metribuzin. Metribuzin was shown to reduce 21-d cumulative clipping weight and tiller production of both species while topramezone caused foliar discoloration to newly emerging leaves and shoots with only marginal clipping weight reduction. These data suggest that selectivity between bermudagrass and goosegrass is largely due to differential absorption and metabolism that reduces bermudagrass exposure to topramezone. Post-treatment irrigation likely reduces topramezone rate load with a concomitant effect on plant phytotoxicity of both species. Metribuzin admixture decreases white discoloration of bermudagrass by decreased topramezone absorption rate and eliminating new foliar growth that is more susceptible to discoloration by topramezone. / Doctor of Philosophy / Goosegrass and smooth crabgrass are problematic weeds in bermudagrass and creeping bentgrass turf. Increased incidences of herbicide resistant weed populations and severe use restrictions on formerly available herbicides have increased need for selective, postemergence control options for these weeds in creeping bentgrass and bermudagrass turf. Although potentially injurious, topramezone (Pylex™) can control these weeds, especially goosegrass, at low doses. Low-dose Pylex™ may also improve bermudagrass and creeping bentgrass response. An initial investigation evaluating tembotrione (Laudis®), Pylex™, and mesotrione (Tenacity®) in different turfgrass species showed that Kentucky bluegrass, perennial ryegrass, and tall fescue were highly tolerant to Pylex™ at rates ranging from 0.75 to 2.25 fl. oz./A, while creeping bentgrass and bermudagrass were low to moderately tolerant to Pylex™. Further investigation suggested that frequent, low-dose (less than 0.25 fl. oz./A) Pylex™ applications or metribuzin (Sencor®) admixtures could enhance weed control and may conserve turfgrass quality. A novel mixture of Pylex™ at 0.15 fl. oz./A and Sencor® at 4 oz. wt./A controlled goosegrass effectively and reduced bermudagrass injury to near acceptable levels and significantly less than Pylex™ applied alone at 0.25 fl. oz/A. In an attempt to further enhance bermudagrass tolerance to Pylex™, post-treatment irrigation was applied at different timings. When bermudagrass turf was irrigated at 15 or 30 minutes after herbicide treatment, bermudagrass injury was reduced to acceptable levels when following Pylex™ at 0.25 fl. oz./A plus Sencor® at 4 oz but not when following Pylex™ applied alone at 0.5 fl. oz./A. Goosegrass control was reduced significantly by post-treatment irrigation in all cases, while irrigation reduced goosegrass control by low-dose Pylex™ plus Sencor® to below-commercially-acceptable levels. Novel, low-dose, frequent application programs containing Pylex™ or siduron (Tupersan®) were developed for season-long crabgrass or goosegrass control in creeping bentgrass greens. Greens-height creeping bentgrass quality was preserved following five biweekly treatments of Tupersan® at rates between 6 and 24 lb./A and Pylex™ at 0.125 fl. oz./A. Tupersan® programs controlled smooth crabgrass and suppressed goosegrass while Pylex™ programs controlled goosegrass and suppressed smooth crabgrass. The data from these studies indicate that utilizing low-dose Pylex™ in combination with Sencor® can impart acceptable bermudagrass safety while also controlling goosegrass effectively. For creeping bentgrass greens, the low-dose, frequent application of Tupersan® is the safest legal option for golf course superintendents to control smooth crabgrass effectively, while having some ability to suppress goosegrass.