Progress 09/01/07 to 08/11/13
Outputs
Target Audience: Professional scientists in the field of weed science and soil science. Changes/Problems:
Nothing Reported
What opportunities for training and professional development has the project provided? Graduate student training and visiting scientist training on techniques that they would not normally be able to use or get training for. How have the results been disseminated to communities of interest? Results have been disseminated through scientific, peer-reviewed journal articles and oral or poster presentations. What do you plan to do during the next reporting period to accomplish the goals?
Nothing Reported
Impacts
What was accomplished under these goals?
The algae Botryococcus braunii, one of the potential renewable resources for production of liquid hydrocarbons, was used for testing the effect of selected herbicides on algal growth and hydrocarbon content. Twenty-two herbicides representing 14 modes of action were assayed. The photosystem II inhibitor diuron was the most toxic herbicide for algal growth, but hydrocarbon content increased from 34.9 to 42.4% of dry biomass in the presence of a 0.1mg/L concentration of diuron. The photosystem I inhibitor diquat was inhibitory to growth of B. braunii, but hydrocarbon content increased to 43.3% of dry biomass when treated with 5mg/L diquat. S-metalochlor, a mitosis inhibitor, reduced both algal growth and hydrocarbon content. Hydrocarbon content decreased to 16.4, 14.0 and 5.5% of dry biomass, respectively when treated with 0.1, 1, and 5mg/L S-metalochlor. The carotenoid biosynthesis inhibitor fluridone did not affect algal growth at 0.1mg/L, but decreased hydrocarbon content from 34.9 to 13.2%. The fatty acid and lipid biosynthesis inhibitor thiobencarb had no effect on algal growth or hydrocarbon content at 0.1mg/L, but it inhibited algal growth and decreased hydrocarbon content from 34.9 to 7.8% at 1mg/L. The oxidative phosphorylation uncoupler dinoterb at 0.1mg/L reduced algal biomass by 52.8% and decreased hydrocarbon content from 34.9 to 30.0%. Saflufenacil is a broadleaf herbicide for preplant burndown and pre-emergence applications in various crops. A study was established to evaluate the absorption and translocation of saflufenacil in hemp sesbania and imazethapyr in red rice as a function of their post-emergence interaction and light intensity. Imazethapyr plus saflufenacil provided a greater uptake (30%) and translocation (35%) of 14C-imazethapyr than imazethapyr alone. In the section above treated leaf (ATL), a higher percentage of the absorbed imazethapyr (23%) was quantified in the imazethapyr plus saflufenacil treatment after 168 h. Faster basipetal movement of imazethapyr was identified under higher light availability. Absorption of 14C-saflufenacil ranged from approximately 40 to 60% among herbicide and light intensity treatments. At 12 and 24 h after treatment (HAT) a greater percentage (15–20%) of the absorbed saflufenacil was quantified above the treated leaf at the two lower light intensities. Similar trends were observed for basipetal movement of saflufenacil. Saflufenacil enhanced absorption, overall translocation and acropetal movement of imazethapyr in the TX4 red rice. Basipetal movement of imazethapyr was faster under higher light intensities. Overall, imazethapyr improved absorption of saflufenacil in hemp sesbania plants. Reduction in light intensity resulted in greater translocation of saflufenacil, promoting acropetal and basipetal distribution at the two lower light intensity treatments. Saflufenacil is a new herbicide for broadleaf weed control in various crops. In rice, saflufenacil can be a prospective combination partner to complement the broadleaf weed control of herbicides such as imazethapyr. This study was established to evaluate 1) rice tolerance and 2) weed control of red rice (Oryza sativa L.) and hemp sesbania (Sesbania exaltata P. Mill.) to saflufenacil tank-mixed with imazethapyr. The experiment was conducted during 2009 and 2010 at the Texas A&M AgriLife Research and Extension Center located at Beaumont, TX. Treatments included a check, an imazethapyr treatment alone (70g a.i.ha−1 at the 1- to 2-leaf stage (EPOST) plus 70g a.i.ha−1 at the 4- to 6-leaf stage (LPOST)), and four saflufenacil doses (12.5, 18.75, 25, and 50g a.i.ha−1) applied at EPOST and LPOST. Imazethapyr treatment was applied to all saflufenacil treatments. Rice injury increased with doses of saflufenacil and injury up to 83% was observed at 7 DAA when 50gha−1 was applied EPOST. Subsequent evaluations indicated less injury over time demonstrating rice recovery from saflufenacil treatments. No injury was observed in the imazethapyr treatment alone. Rice plants seemed to recover faster from LPOST application injury than EPOST. Hemp sesbania control was ≥88% in all saflufenacil treatments in evaluations conducted before harvest indicating effective control throughout the growing season. Red rice control was 100% for all treated plots containing imazethapyr in both years. Therefore, imazethapyr control of red rice was not adversely affected by tank-mixing with saflufenacil. Although injury was significantly higher in the highest doses of saflufenacil, rice yield was not adversely altered by the herbicide treatments. In summary, rice was injured at the highest doses of saflufenacil, but injury did not reduce rice yield. Hemp sesbania was effectively controlled by saflufenacil (>90% on average). No antagonistic interactions between saflufenacil and imazethapyr were observed with red rice control. Saflufenacil appears to be an effective herbicide candidate for broadleaf control in rice. A simple and rapid method based on Solid Phase Extraction (SPE) coupled to HPLC-DAD was developed and validated for the analysis of fenoxaprop-P-ethyl and its degradation product fenoxaprop-P in water. The method was subsequently used for the determination of the dissipation rate of fenoxaprop-P-ethyl in tap and field water. Dissipation of fenoxaprop-P-ethyl was assessed under the presence and the absence of Gambusia affinis (mosquito fish). Three fish population densities (0, 5 and 10 fish per 15 L water) at two concentration ranges of fenoxaprop-P-ethyl (5 and 10 ìg/L) were tested. Samples were analyzed after 0, 24, 120, 240 and 360 h. Doses were designed to simulate those commonly found in surface water bodies in the north-eastern Greece. Mean recovery values of fenoxaprop- P-ethyl were higher than 81 % in the 0.05 to 5 ppb fortification range with respective RSDs lower than 18%. Fenoxaprop-P showed lower recoveries (65% to 84%) with RSDs lower than 22% due to its acidic nature and high background interference in the chromatographic analysis. The limits of quantification (LOQ) and limits of detection (LOD) were 0.05 and 0.01 ppb for fenoxaprop-P-ethyl and 0.1 and 0.05 for fenoxaprop-P, respectively. Both dissipation time of fenoxaprop-P-ethyl and formation of fenoxaprop-P were affected by pH values, and population densities of Gambusia affinis. Oilseed crops are being widely evaluated for potential biodiesel production. Seed meal (SM) remaining after extracting oil may have use as bioherbicides or organic fertilizers. Brassicaceae SM often contains glucosinolates that hydrolyze into biologically active compounds that may inhibit various pests. Jatropha curcas SM contains curcin, a phytoxin. A 14-day greenhouse study determined that Sinapis alba (white mustard), Brassica juncea (Indian mustard), Camelina sativa, and Jatropha curcas applied to soil at varying application rates [0, 0.5, 1.0, and 2.5% (w/w)] and incubation times (1, 7, and 14 d) prior to planting affected seed emergence and seedling survival of cotton [Gossypium hirsutum (L.)], sorghum [Sorghum bicolor (L.) Moench], johnsongrass (Sorghum halepense), and redroot pigweed (Amaranthus retroflexus). With each species, emergence and survival was most decreased by 2.5% SM application applied at 1 and 7 d incubations. White mustard SM incubated for 1 d applied at low and high rates had similar negative effects on johnsongrass seedlings. Redroot pigweed seedling survival was generally most decreased by all 2.5% SM applications. Based on significant effects determined by ANOVA, results suggested that the type, rate, and timing of SM application should be considered before land-applying SMs in cropping systems.
Publications
- Type:
Journal Articles
Status:
Published
Year Published:
2012
Citation:
Pythoglou, P., Z. Vryzas, C. Alexoudis, S.A. Senseman, and G. Vassiliou. 2012. Influence of biotic and abiotic factors on dissipation of fenoxaprop-P-ethyl in water. Fresenius Environ. Bull. 21(10A):3012-3017.
Camargo, E.R., S.A. Senseman, G.N. McCauley, and J.B. Guice. 2012. Rice tolerance to saflufenacil in clomazone weed control program. Crop Protect. 31:94-98.
Deng, L., S.A. Senseman, T.J. Gentry, D.A. Zuberer, T.L. Weiss, T.P. Devarenne, and E.R. Camargo. 2012. Effect of selected herbicides on growth and hydrocarbon content of Botryocuccus braunii (Race B). J. Industrial Crops and Products. 39:154-161.
Rothlisberger, K.L., F.M. Hons, T.J. Gentry, and S.A. Senseman. 2012. Oilseed meal effects on the emergence and survival of crop and weed species. Applied Environ. Soil Sci. Article ID 769357, doi:10.1155/2012/769357.
Camargo, E.R., S.A. Senseman, G.N. McCauley, S. Bowe, J. Harden, J. Guice. 2012. Interaction between saflufenacil and imazethapyr in red rice (Oryza ssp.) and hemp sesbania (Sesbania exaltata) as affected by light intensity. Pest Manag. Sci. 68:1010-1018.
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Progress 01/01/12 to 12/31/12
Outputs
OUTPUTS: Materials were disseminated by peer-reviewed publications, oral presentations and poster presentations. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Scientific community through scientific literature. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Oilseed crops are being widely evaluated for potential biodiesel production. Seed meal (SM) remaining after extracting oil may have use as bioherbicides or organic fertilizers. A 14-day greenhouse study determined that Sinapis alba, Brassica juncea, Camelina sativa, and Jatropha curcas applied to soil at varying application rates [0, 0.5, 1.0, and 2.5% (w/w)] and incubation times (1, 7, and 14 d) prior to planting affected seed emergence and seedling survival of cotton, sorghum, johnsongrass, and redroot pigweed. Redroot pigweed seedling survival was generally most decreased by all 2.5% SM applications. The algae Botryococcus braunii, one of the potential renewable resources for production of liquid hydrocarbons, was used for testing the effect of selected herbicides on algal growth and hydrocarbon content. The photosystem II inhibitor diuron was the most toxic herbicide for algal growth, but hydrocarbon content increased from 34.9 to 42.4% of dry biomass in the presence of a 0.1 mg/L concentration of diuron. The photosystem I inhibitor diquat was inhibitory to growth of B. braunii, but hydrocarbon content increased to 43.3% of dry biomass when treated with 5 mg/L diquat. S-metalochlor, a mitosis inhibitor, reduced both algal growth and hydrocarbon content. Hydrocarbon content decreased to 16.4, 14.0 and 5.5% of dry biomass, respectively when treated with 0.1, 1, and 5 mg/L S-metalochlor. The carotenoid biosynthesis inhibitor fluridone did not affect algal growth at 0.1 mg/L, but decreased hydrocarbon content from 34.9 to 13.2%. The fatty acid and lipid biosynthesis inhibitor thiobencarb had no effect on algal growth or hydrocarbon content at 0.1 mg/L, but it inhibited algal growth and decreased hydrocarbon content from 34.9 to 7.8% at 1 mg/L. The oxidative phosphorylation uncoupler dinoterb at 0.1 mg/L reduced algal biomass by 52.8% and decreased hydrocarbon content from 34.9 to 30.0%. These results will be useful for improving algal oil production while developing management systems to control invasive algal species in outdoor open pond systems ultimately keeping the oil producing algae pure.
Publications
- Deng, L., S.A. Senseman, T.J. Gentry, D.A. Zuberer, T.L. Weiss, T.P. Devarenne, and E.R. Camargo. 2012. Effect of selected herbicides on growth and hydrocarbon content of Botryocuccus braunii (Race B). J. Industrial Crops and Products. 39:154-161.
- Rothlisberger, K.L., F.M. Hons, T.J. Gentry, and S.A. Senseman. 2012. Oilseed meal effects on the emergence and survival of crop and weed species. Applied Environ. Soil Sci. Article ID 769357, doi:10.1155/2012/769357.
- Pythoglou, P., Z. Vryzas, C. Alexoudis, S.A. Senseman, and G. Vassiliou. 2012. Influence of biotic and abiotic factors on dissipation of fenoxaprop-P-ethyl in water. Fresenius Environ. Bull. (Accepted)
- Spiers, J.D., F.T. Davies, Jr., C. He, T.W. Starman, S.A. Finlayson, S.A. Senseman, and K.M. Heinz. 2011. Fertilization affects constitutive and wound-induced chemical defenses in Gerbera jamesonii. J. Environ. Hort. 29:180-184.
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Progress 01/01/11 to 12/31/11
Outputs
OUTPUTS: Saflufenacil is a new herbicide for broadleaf weed control in various crops. In rice, saflufenacil can be a prospective combination partner to complement the broadleaf weed control of herbicides such as imazethapyr. Studies were established to evaluate 1) rice tolerance and 2) weed control of red rice (Oryza sativa L.) and hemp sesbania (Sesbania exaltata P. Mill.) to saflufenacil tank-mixed with imazethapyr. The experiment was conducted during 2009 and 2010 at the Texas A&M AgriLife Research and Extension Center located at Beaumont, TX. Treatments included a check, an imazethapyr treatment alone (70 g a.i. per ha at the 1- to 2-leaf stage (EPOST) plus 70 g a.i. per ha at the 4- to 6-leaf stage (LPOST)), and four saflufenacil doses (12.5, 18.75, 25, and 50 g a.i. per ha) applied at EPOST and LPOST. Imazethapyr treatment was applied to all saflufenacil treatments. Rice injury increased with doses of saflufenacil and injury up to 83% was observed at 7 DAA when 50 g per ha was applied EPOST. Subsequent evaluations indicated less injury over time demonstrating rice recovery from saflufenacil treatments. No injury was observed in the imazethapyr treatment alone. Rice plants seemed to recover faster from LPOST application injury than EPOST. Hemp sesbania control was 88% in all saflufenacil treatments in evaluations conducted before harvest indicating effective control throughout the growing season. Red rice control was 100% for all treated plots containing imazethapyr in both years. Therefore, imazethapyr control of red rice was not adversely affected by tank-mixing with saflufenacil. Although injury was significantly higher in the highest doses of saflufenacil, rice yield was not adversely altered by the herbicide treatments. Research was conducted to evaluate 1) rice tolerance to saflufenacil applied preemergence (PRE) and postemergence (POST) and 2) the combination of saflufenacil and clomazone in light-textured soils. No injury from PRE application of saflufenacil was observed in 2009 and minimal injury for saflufenacil alone was observed in 2010. Injury as high as 68% was observed with combinations of 505 g per ha of clomazone applied PRE and 50 g per ha of saflufenacil applied POST in 2009 early evaluations. No interaction between clomazone and POST saflufenacil rates was observed in 2010. Due to strong hydrogen bonding interactions, thiourea has been shown to have a high affinity for anions such as inorganic phosphate. The interaction between phosphate and thiourea has been used to develop technologies that can detect and even remove phosphate from water. This research investigates the use of thiourea derivatized polymer flocculants for the sequestering of inorganic phosphate from water. A study described the development of a thiourea based monomer that was used to create a bi-functional polymer that flocculates suspended solid material as well as sorbs phosphate, removing both from water. PARTICIPANTS: Not relevant to this project. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Rice was injured at the highest doses of saflufenacil, but injury did not reduce rice yield. Hemp sesbania was effectively controlled by saflufenacil (>90% on average). No antagonistic interactions between saflufenacil and imazethapyr were observed with red rice control. Saflufenacil appears to be an effective herbicide candidate for broadleaf control in rice. Rice injury intensified with increasing rates of saflufenacil applied POST. However, rice recovered with time for herbicide treatments applied PRE and POST in both years. Consequently, rice yield was not affected by any of the saflufenacil rates applied either PRE or POST in a clomazone weed control program. A polymer removed more than 60% of the phosphate from a simulated wastewater sample. The addition of a thiourea trapping group to the polymer more than doubled the amount of phosphate removed from solution compared to control polymers.
Publications
- Camargo, E.R., S.A. Senseman, G.N. McCauley, and J.B. Guice. 2011. Rice response and weed control from tank-mix applications of saflufenacil and imazethapyr. Crop Protect. (Accepted)
- Camargo, E.R., S.A. Senseman, G.N. McCauley, and J.B. Guice. 2011. Rice tolerance to saflufenacil in clomazone weed control program. International J. Agron. (Accepted)
- Goebel, T.S., K.J. McInnes, S.A. Senseman, R.J. Lascano, L.S. Marchand, and T.A. Davis. 2011. Modifying polymer flocculants for the removal of inorganic phosphate from water. Tetrahedron Letters. 52:5241-5244.
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Progress 01/01/10 to 12/31/10
Outputs
OUTPUTS: Repeated applications may have a greater impact on the soil microbial community than a single application of glyphosate. Experiments were conducted to study the effect of one, two, three, four or five applications of glyphosate on soil microbial community composition and glyphosate mineralization and distribution of 14C residues in soil. The herbicides imazethapyr and imazapic, used in Clearfield rice, have high mobility and persistence in the soil, causing injury to non-resistant rice grown in rotation. These herbicides can leach and reach greater depths along the profile. This positioning can be a in-depth selectivity factor and partially explain the different results found in literature about carryover of imidazolines. To understand this effect, this study had the objective of to evaluate the effect of the positioning of the mixture of imazethapyr and imazapic (75g ai L-1 and 25g ai L-1) on the injury to non-resistant rice crop. Two experiments were carried out in soil with 15% clay and 1.2% organic matter in a greenhouse at the Universidade Federal de Pelotas, Pelotas, RS, Brazil. Experiment I consisted of a preliminary study to verify the location depth of the herbicide in the soil profile that causes injury to rice non-tolerant rice, and the herbicides has been allocated at depths of 0, 5, 10, 20, 30, 50 and 70 cm. Experiment II also consisted in the allocation of herbicide at depths in the soil profile of 3, 6, 9, 12, 15 and 18 cm. The present work aimed to evaluate plant injury caused by residues in the soil of the formulated mixture of imazethapyr and imazapic to a nontolerant genotype of rice (IRGA 417) drilled at 371 and 705 d after herbicide application (DAA). Outputs have been disseminated at both professional meetings in the form of posters or oral presentations. PARTICIPANTS: Training of graduate students was included with all reported published works. Also, included were collaborations with domestic and international scientists. Organizations included Texas A&M University, Texas AgriLife Research, Universidade Federal de Pelotas (Brazil) and Universidade Federal de Santa Maria (Brazil). TARGET AUDIENCES: Other professional scientists in the field of weed science and agronomy were the target audience of these activities. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Fatty acid methyl esters (FAMEs) common to gram-negative bacteria were present in higher concentrations following five applications relative to one, two, three or four applications both 7 and 14 days after application (DAA). Additionally, sequencing of 16S rRNA bacterial genes indicated that the abundance of the gram-negative Burkholderia spp. was increased following the application of glyphosate. The cumulative percentage 14C mineralized 14 DAA was reduced when glyphosate was applied 4 or 5 times relative to the amount of 14C mineralized following one, two or three applications. Incorporation of 14C residues into soil microbial biomass was greater following five glyphosate applications than following the first application 3 and 7 DAA. These studies suggest that the changes in the dissipation or distribution of glyphosate following repeated applications of glyphosate may be related to shifts in the soil microbial community composition. The variables were visual plant injury, plant shoot dry weight and plant height. The formulated mixture of imazethapyr + imazapic located near the soil surface cause injury to non resistant rice plants but when allocated at depths greater than 20 cm of the soil surface does not affect the development of non-resistant rice. Herbicide carryover reduced up to 55% of the grain yield of the IRGA 417 drilled at 371 DAA, and plant injury was still evident at 705 DAA but without grain yield reduction.
Publications
- Marchesan, E., F.M. dos Santos, M. Grohs, L.A. de Avila, S.L.O. Machado, S.A. Senseman, P.F.S. Massoni, and G.M.S. Sartori. 2010. Carryover of imazethapyr and imazapic to non-tolerant rice. Weed Technol. 24:6-10.
- Da Cas Bundt, A., L.A. de Avila, D. Agostinetto, M.A. Nohatto, K. Muller Souto, S.A. Senseman. 2010. Depth of placement of the herbicide imazethapyr+imazapic in soil profile on non-tolerant rice injury. Ciencia Rural 40:1867-1873.
- Lancaster, S.H., E. Hollister, S.A. Senseman, and T.L. Gentry. 2010. Effect of repeated glyphosate application on soil microbial community profile and function. Pest Manage. Sci. 66:59-64.
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Progress 01/01/09 to 12/31/09
Outputs
OUTPUTS: Repeated applications may have a greater impact on the soil microbial community than a single application of glyphosate. Experiments were conducted to study the effect of one, two, three, four or five applications of glyphosate on soil microbial community composition and glyphosate mineralization and distribution of 14 C residues in soil. Findings have been reported at the Southern Weed Science Society, Weed Science Society of America, and the Texas Plant Protection Association PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Not relevant to this project. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
Fatty acid methyl esters (FAMEs) common to gram-negative bacteria were present in higher concentrations following five applications relative to one, two, three or four applications both 7 and 14 days after application (DAA). Additionally, sequencing of 16S rRNA bacterial genes indicated that the abundance of the gram-negative Burkholderia spp. was increased following the application of glyphosate. The cumulative percentage 14 C mineralized 14 DAA was reduced when glyphosate was applied 4 or 5 times relative to the amount of 14C mineralized following one, two or three applications. Incorporation of 14C residues into soil microbial biomass was greater following five glyphosate applications than following the first application 3 and 7 DAA. These studies suggest that the changes in the dissipation or distribution of glyphosate following repeated applications of glyphosate may be related to shifts in the soil microbial community composition.
Publications
- Lancaster, S.H., E. Hollister, S.A. Senseman, and T.L. Gentry. 2009. Effect of repeated glyphosate application on soil microbial community profile and function. Pest Manage. Sci. Published online August, 2009.
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Progress 01/01/08 to 12/31/08
Outputs
OUTPUTS: Field studies were conducted to evaluate yellow nutsedge control and peanut yield when diclosulam and imazapic were applied at the rate recommended by the manufacturer (1x) and reduced (1/2x) rates in single and twin-row planting patterns. Research was conducted along the Texas Gulf Coast to determine trifloxysulfuron soil persistence and potential injury to corn, grain sorghum, rice, and soybeans. Experiments were conducted to evaluate sharppod morningglory control with postemergence herbicides used in cotton and to determine the influence of diuron on glyphosate efficacy. Laboratory studies were conducted to evaluate the effects of temperature and propanil on alligatorweed control with penoxsulam. Multiple crop protection pesticides are frequently applied as a tank-mixture for control of a variety of pests in cotton (Gossypium hirsutum). Studies were conducted over seven environments evaluating rice root growth inhibition (RGI) and foliar injury from penoxsulam at 30 and 60 g ai/ha and bispyribac-sodium at 30 g ai/ha applied to four- to five-leaf rice at three flood timings, 1, 7, and 14 d after herbicide treatment (DAT), for five rice cultivars, 'Bengal', 'Cypress', 'Wells', 'Cocodrie', and 'XP712'. All results were discussed at annual conferences during the active study period either at the American Chemical Society, the Southern Weed Science Society, the Weed Science Society of America, or the Texas Plant Protection Conference. PARTICIPANTS: Graduate Students - S.D. Willingham, B.A. Besler, M.A. Matocha, B.W. Minton, and G.L. Steele. All were responsible for putting out experiments and evaluations under guidance of the major professors and cooperators. Cooperators - J.M. Chandler (Texas AgriLife Research/TAMU), G.N. McCauley (Texas AgriLife Research), J. Richburg (Dow AgroSciences), R. Lassiter (Dow AgroSciences), R. Mann (Dow AgroSciences), W.J. Grichar (Texas AgriLife Research), T.A. Baughman (Texas AgriLife Extension), and R.G. Lemon (Texas AgriLife Extension). All individuals listed here provided technical expertise, experimental materials, equipment, and manpower to accomplish goals of the project. TARGET AUDIENCES: The target audience included the scientific community pertaining to weed science and producers of agronomic crops. Results were made available in presenation form at annual regional and national meetings and extended at field days to producers. PROJECT MODIFICATIONS: Not relevant to this project.
Impacts
To fully maximize yellow nutsedge control, the full rate of either imazapic or diclosulam should be applied to peanuts planted in a single or twin-row spacing. However, these treatments may not necessarily increase peanut yields. Trifloxysulfuron applied to cotton up to 20 g/ha the previous year should not cause phytotoxicity to corn, grain sorghum, rice, or soybeans when grown in rotation under soil and weather conditions similar to those in our studies. These results indicate that the combination of glyphosate with diuron improves aboveground sharppod morningglory desiccation, but limits glyphosate translocation. There is a strong potential for propanil to antagonize penoxsulam when applied to alligatorweed. Under the most severe antagonistic conditions (30 C) propanil applications following penoxsulam needed to be delayed 10 d to avoid antagonism. Greater absorption of radiolabeled trifloxysulfuron occurred in leaves 4 HAT treated with trifloxysulfuron tank-mixed with malathion compared to those treated with trifloxysulfuron alone at the 3-to 4-leaf stage. Translocation of trifloxysulfuron to plant tissue above and below the treated leaf was greater with the tank-mixture. However, increased foliar phytotoxicity (leaf burning) was observed 24 and 96 HAT with trifloxysulfuron tank-mixed with malathion compared to trifloxysulfuron applied alone. These studies suggest malathion could potentially reduce the rate of trifloxysulfuron metabolism in cotton. At 2 WAT, RGI for Cocodrie was higher following penoxsulam at 60 g/ha when compared with bispyribac-sodium. By 3 WAT, RGI was higher following penoxsulam at 60 g/ha when compared with penoxsulam at 30 g/ha for Cocodrie and greater than bispyribac-sodium and penoxsulam at 30 g/ha for Cypress. Foliar injury following penoxsulam at both rates was less than injury following bispyribac-sodium for all cultivars except XP712 at 1 WAT. XP712 resulted in <5% RGI and <6% foliar injury at each evaluation. Rice grain yield was not affected by herbicide treatment for any cultivar compared with the standard treatment of propanil plus quinclorac.
Publications
- Willingham, S.D., S.A. Senseman, G.N. McCauley, and J.M. Chandler. 2008. Effect of temperature and propanil on penoxsulam efficacy, absorption, and translocation, in alligatorweed (Alternanthera philoxeroides). Weed Sci. 56:780-784.
- Besler, B.A., W.J. Grichar, S.A. Senseman, T.A. Baughman, and R.G. Lemon. 2008. Effects of row pattern configurations and reduced (1/2x) and full rates (1x) of imazapic and diclosulam for control of yellow nutsedge (Cyperus esculentus) in peanut. Weed Technol. 22:558-562
- Matocha, M.A. B.W. Minton, and S.A. Senseman. 2008. The influence of malathion on trifloxysulfuron absorption and translocation in cotton. Cotton Sci. 12:48-52.
- Willingham, S., G.N. McCauley, S.A. Senseman, J.M. Chandler, J. Richburg, R. Lassiter, and R. Mann. 2008. Influence of flood interval and cultivar on rice (Oryza sativa) tolerance to penoxsulam. Weed Technol. 22:114-118.
- Matocha, M.A., B.W. Minton, and S.A. Senseman. 2008. Soil persistence of trifloxysulfuron in relation to corn (Zea mays), grain sorghum (Sorghum bicolor), rice (Oryza sativa), and soybeans (Glycine max). Weed Technol. 22:425-430.
- Steele, G.L., S.A. Senseman, A.S. Sciumbato, and J.M. Chandler. 2008. Diuron effects on the absorption and translocation of glyphosate in sharppod morningglory (Ipomoea cordatotriloba). Weed Technol. 22:414-419.
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: Activities included conducting and analyzing experiments, using the information for teaching purposes, and mentoring graduate students. The information was used to present at conferences including the Weed Science Society of America and the Southern Weed Science Society. Information was used as technology for individuals and student graduate programs.
PARTICIPANTS: Mark A. Matocha Bradford W. Minton Sarah H. Lancaster
TARGET AUDIENCES: Scientific community
Impacts
Accelerated solvent extraction (ASE) is a recently developed extraction technique that is more rapid and produces less waste than conventional liquid/liquid extraction methods. Optimal conditions for ASE of fluometuron from two Weswood clay loam soils were determined. Two solvents (acetonitrile and methanol), two temperatures (50 C and 100 C) and the number of static cycles (1, 2, and 3) were evaluated. The most efficient and reproducible extractions were obtained when using methanol combined with a 50 C extraction temperature and repeating the cycle 3 times. These experiments indicated that existing extraction methods for fluometuron can easily be adapted for ASE. Clomazone is an effective herbicide widely used for preemergence (PRE) grass control in rice. However, use of clomazone on sandy textured soils of the western Texas rice belt may cause serious rice injury. Two field experiments at three locations were conducted in 2002 and 2003 to determine the optimum rate
range that maximizes weed control and minimizes rice injury across a wide variety of soil textures and planting dates. At Beaumont, Eagle Lake, and Ganado, TX, PRE application of 0.34 kg ai/ha clomazone provided optimum weed control with minimal rice injury and maximum yield. Data suggests that clomazone is safe to use in rice on sandy textured soils. Injury may occur, however, rates suggested from this research can minimize injury and achieve excellent weed control. The surface runoff potential of trifloxysulfuron in Mississippi Delta cotton production systems has not been evaluated. The objectives of this study were to determine sorption/desorption coefficients for trifloxysulfuron; quantify foliar washoff of trifloxysulfuron applied to cotton at the fifth-leaf stage; and determine average edge-of-field concentrations and total mass losses of trifloxysulfuron when applied to cotton at the fifth-leaf stage and to bare soil. Sorption and desorption of trifloxysulfuron to Dundee silt
loam was described by the Freundlich equation. The Freundlich sorption and desorption coefficients were 1.15 and 1.22, respectively. Sorption data indicate that trifloxysulfuron is moderately sorbed to soil and will likely be transported primarily in the dissolved phase of surface runoff. Foliar washoff studies indicate that the amount of 14C-trifloxysulfuron available for washoff decreased logarithmically with time, and 91% of the applied trifloxysulfuron was available for washoff after 72 hr. Average edge-of-field concentrations of trifloxysulfuron were 0.8 ug/L and 1.3 ug/L for bare plots and cotton plots, respectively. Cumulative trifloxysulfuron losses from cotton plots were 0.21 g/ha while losses from bare plots were 0.13 g/ha. These values correspond to fractional losses of 2.7% for cotton plots and 1.7% for bare plots. Greater losses of trifloxysulfuron from cotton plots relative to bare plots is likely due to foliar washoff. Losses of trifloxysulfuron may be reduced if
applied when canopy closure is minimal.
Publications
- Lancaster, S.H. and S.A. Senseman. 2007. Accelerated solvent extraction of fluometuron from selected soils. J. Assoc. Offic. Anal. Chem. 90:1142-1145.
- Matocha, M.A. and S.A. Senseman. 2007. Trifloxysulfuron dissipation at selected pH levels and efficacy on Palmer amaranth (Amaranthus palmeri S. Wats). Weed Technol. 21:674-677.
- O Barr, J.H., G.N. McCauley, S.A. Senseman, R.W. Bovey, J.M. Chandler. 2007. Rice response (Oryza sativa) to clomazone as influenced by rate, soil characteristics, and planting date. Weed Technol. 21:199-205.
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Progress 01/01/06 to 12/31/06
Outputs
Research was conducted to evaluate the influence of glyphosate-based cotton pest management systems on soil microbial activity. Soils treated with glyphosate alone exhibited greater cumulative C mineralization 30 days after treatment than all other treatments, which were similar to the untreated control. The addition of Roundup WeatherMax reduced C mineralization in soils treated with fluometuron, aldicarb, or mefenoxam + PCNB formulations. A study was conducted to evaluate the absorption and translocation of foliar-applied 14C-trifloxysulfuron in Palmer amaranth and Texasweed at pH 5, 7, and 9 over a period of 4 to 72 h after treatment (HAT). Greater translocation of 14C-trifloxysulfuron was found in Texasweed when sprayed with the higher pH spray solutions. These data indicate that absorption and translocation of trifioxysulfuron in some weed species may be enhanced by increasing the pH of the spray solution by 2 pH units above the pKa. Laboratory studies were
conducted to determine the direct and indirect photolysis rates for imazethapyr and to evaluate the photolysis of imazethapyr in three rice paddy waters. Imazethapyr is susceptible to both direct and indirect photolysis reactions in water. A study was conducted to determine sorption/desorption coefficients for trifloxysulfuron; quantify foliar washoff of trifloxysulfuron applied to cotton at the fifth-leafstage; and determine average edge-of-field concentrations and total mass losses of trifloxysulfuron when applied to cotton at the fifth-leafstage and to bare soil. Sorption data indicate that trifloxysulfuron is moderately sorbed to soil and will likely be transported primarily in the dissolved phase of surface runoff. Foliar washoff studies indicate that 91% of the applied trifloxysulfuron was available for washoff after 72 hr. Greater losses of trifloxysulfuron from cotton plots relative to bare plots is likely due to foliar washoff. Losses of trifloxysulfuron may be reduced if
applied when canopy closure is minimal. A study was conducted to compare the mineralization of atrazine and metolachlor to their respective metabolites in VFS and cultivated soil. With the exception of total bacteria, propagule density of the microbial groups, endogenous soil enzymes, and microbial diversity were higher in the VFS soil. The potential for subsequent transport of atrazine and many of its metabolites may be greater in VFS soil compared to cultivated soil if reduced mineralization is not offset by increased sorption in the VFS. To determine the cause of the potential herbicide resistance, growth chamber studies were conducted to identify the presence and distribution of triasulfuron-resistant Italian ryegrass populations in Texas and to determine alternative herbicide management options for such populations. Varying levels of triasulfuron-resistance were found in samples from all 13 counties. Of the 48 Italian ryegrass ecotypes sampled, nine were categorized as
susceptible, 10 were slightly resistant, 17 were moderately resistant, and 12 were highly resistant to triasulfuron. In four selected ecotypes, triasulfuron resistant Italian ryegrass was cross-resistant to imazamox.
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies that minimize risk to applicators and consumers while keeping production practices optimized and food prices low.
Publications
- Tucker, K.P., G.D. Morgan, S.A. Senseman, T.D. Miller, and P.A. Baumann. 2006. Identification, distribution, and control of triasulfuron-resistant Italian ryegrass (Lolium multiflorum) in Central Texas. Weed Technol. 20:745-750.
- Matocha, M.A., L.J. Krutz, S.A. Senseman, K.N. Reddy, and C.H. Koger. 2006. Spray carrier pH effect on absorption and translocation of trifloxysulfuron in Palmer amaranth (Amaranthus palmeri) and Texasweed (Caperonia palustris). Weed Sci. 54:969-973.
- Matocha, M.A., L.J. Krutz, S.A. Senseman, K.N. Reddy, M.A. Locke, R.W. Steinreide, Jr. 2006. Foliar washoff potential and simulated surface runoff losses of trifloxysulfuron in cotton. J. Agric. Food Chem. 54:5498-5502.
- Lancaster, S.R., R.L. Haney, S.A. Senseman, J.M. Chandler, and F.M. Hons. 2006. Soil microbial activity is affected by glyphosate and pesticide programs for cotton (Gossypium hirsutum). J. Agric. Food Chem. 54:7221-7226.
- Krutz, L.J., T. Gentry, S.A. Senseman, I. Pepper, and D. Tierney. 2006. Mineralization of atrazine, metolachlor, and their respective metabolites in vegetated filter strip and cultivated soil. Pest. Manage. Sci. 62:505-514.
- Avila, L.A., J.H. Massey, S.A. Senseman, K.L. Armbrust, S.R. Lancaster, G.N. McCauley, and J.M. Chandler. 2006. Imazethapyr aqueous photolysis, reaction quantum yield, and hydroxyl radical rate constant. J. Agric. Food Chem. 54:2635-2639.
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Progress 01/01/05 to 12/31/05
Outputs
Field experiments were conducted to evaluate the effect of flood timing on red rice control with imazethapyr applied at different cultivated rice growth stages. Treatments included flood establishment at 1, 7, 14, and 21 d after postemergence (POST) herbicide treatment (DAT). Imazethapyr was applied preemergence at 70 g ai/ha followed by 70 g/ha POST when imidazolinone-tolerant rice cultivar 'CL-l6l' had three- to four-leaf stage (EPOST) or five-leaf stage (LPOST). Flood needed to be established within 14 DAT to achieve at least 95% red rice control when inazethapyr was applied EPOST. However, flood needed to be established within 7 DAT to provide at least 95% red rice control when imazethapyr was applied LPOST. Delaying the flood up to 21 DAT reduced rice grain yield for both application timings. Three red rice ecotypes (Oryza spp.), including LA 5, MS 5 and TX 4, were evaluated for acetolactate synthase resistance/tolerance to imazethapyr. The red rice ecotypes were
compared with a tolerant line (CL-121), a resistant line (CL-161) and a conventional rice variety (Cypress). Based on enzymatic activity, the mean I50 values were 1.5, 1.1, 1.5, 1.6, 20.8 and 590.6 uM imazethapyr, respectively, for LA 5, MS 5, TX 4, Cypress, CL-121 and CL-161. CL-161 was 32 times more resistant than CL-121 and at least 420 times more resistant than the average of the red rice ecotypes and Cypress. Results from the acetolactate synthase (ALS) assay showed that red rice ecotypes and Cypress had high susceptibility to imazethapyr when compared with the tolerant CL-121 and the resistant CL-16l. Measurable enzymatic tolerance to ALS-inhibiting herbicides has not yet developed in these red rice ecotypes. CGA-362622 has been registered for postemergence (POST) over-the-top or POST-directed application in cotton. Research was conducted to determine potential cotton phytotoxicity after POST application of CGA-362622 alone and with the insecticides acephate, dicrotophos,
azinphos methyl, oxarnyl, thiamethoxam, dimethoate, and malathion and to determine the response of four cotton cultivars to CGA-362622 applied alone, CGA-362622 applied with malathion injured cotton more than either pesticide applied alone, and yield was reduced in one of four locations when the pesticides were applied in mixture compared with nontreated cotton. Pyrithiobac or CGA-362622 mixed with malathion injured cotton similarly. The other insecticides tank mixed with CGA-362622 generally did not adversely affect cotton. The cotton cultivars 'Delta and Pine Land 50', 'Paymaster 1220', 'Paymaster 1220RR', and 'Stoneville 474' responded similarly to CGA362622 applied alone or with insecticides.
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies that minimize risk to applicators and consumers while keeping production practices optimized and food prices low.
Publications
- Minton, B.W., S.A. Senseman, J.T. Cothren, J.M. Chandler, and J.R. Wells. 2005. Cotton (Gossypium hirsutum L.) Response to CGA-362622 applied alone and in combination with selected insecticides. Weed Technol. 19:244-250.
- Avila, L.A., S.A. Senseman, G.N. McCauley, J.M. Chandler, and J.H. O'Barr. 2005. Effect of flood timing on red rice (Oryza spp.) control with imazethapyr applied at different rice stages. Weed Technol. 19:476-480.
- Avila, L.A., D.J. Lee, S.A. Senseman, G.N. McCauley, J.M. Chandler, and J. Tom Cothren. 2005. Acetolactate synthase (ALS) activity in red rice ecotypes (Oryza spp.) and imidazolinone tolerant/resistant rice cultivars (Oryza sativa) in response to imazethapyr. Pest. Manage. Sci. 61:171-178.
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Progress 01/01/04 to 12/31/04
Outputs
Experiments were conducted to determine the effect of soil characteristics and water potential on plant available clomazone and rice injury. A centrifugal double-tube technique was used to determine plant available concentration in soil solution (ACSS), total amount available in soil solution (TASS), and Kd values for clomazone on four soils at four water potentials. It appears that severe rice injury from clomazone on these soils could occur if TASS >110 ng/g and Kd < 1.1 ml/g. A study was conducted to compare TE, Minf, and Mas as among metolachlor, metolachlor oxanilic acid (OA) , and metolachlor ethanesulfonic acid (ESA) in buffalograss VFS. Runoff was applied as a point source up slope of a 1 X 3-m micro-watershed at a rate of 750 L/h. The point source was fortified at 0.12 ug/mL metolachlor, OA, and ESA. Results demonstrate that adsorption to the VFS grass, grass thatch, and/or soil surface is an important retention mechanism for metolachlor and metolachlor's
metabolites, especially under saturated conditions. Moreover, the Mas data indicate that metolachlor is preferentially retained by the VFS grass, grass thatch, and/or soil surface compared to its oxanilic and ethanesulfonic acid metabolites. Metolachlor, ESA, and OA adsorption and desorption parameters were compared between VFS and cultivated soil (CS). With the exception of a 1.7-fold increase in organic carbon content in the VFS, the evaluated chemical and physical properties of the soils were similar. Sorption coefficients for metolachlor were 88% higher in VFS than in CS. Relative to metolachlor, sorption coefficients for ESA and OA were at least 79% lower in both soils. Metolachlor desorption coefficients were 59% higher in the VFS than in the CS. Relative to metolachlor, desorption coefficients for ESA and OA were at least 66% lower in both soils. These data indicate that the mobility of ESA and OA will be greater than metolachlor in both soils. Field studies were conducted at
the Texas Agricultural Experiment Station using GR cotton, cv. DeltaPine 5690RR, to determine if application method and timing affect cotton fruit retention. Glyphosate at 1.12 kg ai/ha was precisely postdirected (PD), postdirected with 25% foliage coverage (PDFC), or applied over the top (OT) at the 8- or 18-leaf stage after an initial topical application of 1.12 kg/ha glyphosate at the 4-leaf stage. In one of the years of this study, 8 PD, 18 PDFC, and 18 OT reduced yield. In 1999 and 2000, 8 PDFC and 8 OT applications of glyphosate caused yield loss, mainly due to lower mean boll weight. Glyphosate applied topically at the 8-leaf stage also affected the Position 1 boll retention throughout the plant in both years. Glyphosate contact with leaves and stems should be avoided when applying glyphosate after the 4-leaf stage to prevent possible yield loss.
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies that minimize risk to applicators and consumers while keeping production practices optimized and food prices low.
Publications
- Krutz, L.J., S.A. Senseman, K.J. McInnes, D.W. Hoffman, and D.P. Tierney. 2004. Adsorption-desorption of metolachlor, metolachlor oxanilic acid, and metolachlor ethanesulfonic acid in vegetated filter strip and cultivated soil. J. Environ. Qual. 33:939-945.
- Viator, R., J.T. Cothren, and S.A. Senseman. 2004. The effect of glyphosate application timings and methods on glyphosate-resistant Gossypium hirsutum L. Weed Sci. 52:147-151.
- Lee, D.J., S.A. Senseman, J.H. O'Barr, J.M. Chandler, L.J. Krutz, G.N. McCauley, and Y.I. Kuk. 2004. Soil characteristics and water potential effects on plant available clomazone in rice (Oryza sativa). Weed Sci. 52:310-318.
- Krutz, L.J., S.A. Senseman, M.C. Dozier, D.W. Hoffman, and D.P. Tierney. 2004. Infiltration and adsorption of dissolved metolachlor, metolachlor oxanilic acid, and metolachlor ethanesulfonic acid by buffalograss [Buchloe dactyloides (Nutt. Engelm)]. Weed Sci. 52:166-171.
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Progress 01/01/03 to 12/31/03
Outputs
Adsorption and desorption of atrazine and its metabolites in vegetated filter strip (VFS) soil has not been evaluated, yet these data are needed to predict the transport of these compounds through the VFS. The predicted order of mobility in CS is hydroxyatrazine (HA)
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies that minimize risk to applicators and consumers while keeping production practices optimized and food prices low.
Publications
- Krutz, L.J., R.L. Haney, and S.A. Senseman. 2003. The effect of glyphosate on atrazine degradation in soil. Biol. Fertil. Soils. 38:115-118.
- Acosta, E., Y. Deng, G.N. White, J.B. Dixon, K.J. McInnes, S.A. Senseman, A.S. Frantzen, and E.E. Simanek. 2003. Dendritic surfactants showing evidence for frustrated intercalation: A new organoclay morphology. Chem. Materials 15:2903-2909.
- Senseman, S.A., T.C. Mueller, R.D. Wauchope, C. Clegg, R.W. Young, L.M. Southwick, M.B. Riley, H.A. Moye, J.A. Dumas, W. Mersie, J.D. Mattice, and R.B. Leidy. 2003. An interlaboratory comparison of extraction efficiency of pesticides from surface and laboratory water. J. Agric. Food Chem. 51:3748-3752.
- Cralle, H.T. T.B. Fojtasek, K.H. Carson, J.M. Chandler, T.D. Miller, S.A. Senseman, R.W. Bovey, and M.J. Stone. 2003. Wheat and Italian ryegrass (Lolium multiflorum) competition as affected by phosphorous nutrition. Weed Sci. 51:425-429.
- Lee, D.J., S.A. Senseman, A.S. Sciumbato, S.C. Jung, and L.J. Krutz. 2003. The effect of titanium dioxide alumina beads on the photocatalytic degradation of picloram in water. J. Agric. Food Chem. 51:2659-2664.
- Matocha, M.A., W.J. Grichar, S.A. Senseman, C.A. Gerngross, B.J. Brecke, W.K. Vencill. 2003. The persistence of imazapic in peanut (Arachis hypogaea) crop rotations. Weed Technol. 17:325-329.
- Krutz, L.J., S.A. Senseman, and A.S. Sciumbato. 2003. Solid-phase microextraction (SPME) for herbicide determination in environmental samples. J. Chromatogr. A. 999:103-121.
- Krutz, L.J., S.A. Senseman, K.J. McInnes, D.A. Zuberer, and D.P. Tierney. 2003. Adsorption and desorption of atrazine, desethylatrazine, deisopropylatrazine and hydroxyatrazine in vegetated filter strip and cultivated soil. J. Agric. Food Chem. 51:7379-7384.
- Krutz, L.J., S.A. Senseman, M.C. Dozier, D.W. Hoffman, and D.P. Tierney. 2003. Infiltration and adsorption of dissolved atrazine and atrazine metabolites in buffalograss filter strips. J. Environ. Qual. 32:2319-2324.
- Viator, R., S.A. Senseman, and J.T. Cothren. 2003. Reproductive Effects of glyphosate-resistant cotton (Gossypium hirsutum L.) to glyphosate. Weed Technol. 17:571-575.
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Progress 01/01/02 to 12/31/02
Outputs
Glyphosate applications have escalated with the Roundup-tolerant crop usage. Cumulative C mineralization and mineralization rate increased above background levels for all soils tested with addition of RU. Roundup Ultra was rapidly degraded by soil microbes despite soil type or organic matter content, even at high application rates, without adversely affecting microbial activity. Atrazine alone and atrazine plus glyphosate were added to soil to determine their effect on soil microbial activity as measured by C and N mineralization (Cmin, Nmin) and soil extractable atrazine wtihout the use of radiolabeled isotopes. Atrazine plus glyphosate stimulated microbial activity more than atrazine alone. Carbon mineralization was greatest during the first seven days of incubation after application while N mineralization was greatest during the 14-to 28-day period indicating a possible substrate shift from glyphosate to atrazine. These results show that Roundup Ultra stimulated
microbial activity while simultaneously inhibiting atrazine degradation. Laboratory experiments were conducted to determine and compare the adsorptive capacity of bermudagrass, a Weswood soil, and a Houston Black soil for atrazine and metolachlor to determine if the presence of one herbicide affects the adsorptive behavior of the other compound to these sorbents. Both Kd values for adsorption of atrazine (86.2) and metolachlor (131.5) to bermudagrass were greater than those of the two soils, Weswood (atrazine, 20.0 and metolachlor, 28.4) and Houston Black (atrazine, 35.8 and metolachlor, 33.5). Adsorption of atrazine to any of the sorbents was not affected by the presence of metolachlor. These data demonstrate that bermudagrass has a capacity to adsorb atrazine and metolachlor associated with surface runoff. Photocatalytic degradation of pesticides with titanium dioxide (TiO2) and other catalysts have shown promise as a potential water remediation method. The objective of this study
was to determine picloram degradation in water using various UV light sources and low pressure metal organic chemical vapor deposition (LPMOCVD) titanium dioxide alumina beads (TDABs) as a catalyst. A picloram test solution was introduced to the photoreactor inlet and recycled for 10 hr. Three ultraviolet light sources were compared for their photocatalytic capacity (UV-A, UV-B, and UV-C) both with and without TDABs. TDABs were added to the photoreactor at 1.8 g/cm3. The picloram degradation rate with UV-A and TDABs (t1/2 = 119.5 min) was greater than the degradation rate of UV-A alone (t1/2=2288 min). Picloram degradation was not enhanced by the presence of TDABs with either UV-B or UV-C. Rapid picloram degradation occurred with both UV-B and UV-C despite the presence of TDABs with mean half-lives ranging from 7 to 18 min.
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies that minimize risk to applicators and consumers while keeping production practices optimized and food prices low.
Publications
- Haney, R.L., S.A. Senseman, and F.M. Hons. 2002. Effect of glyphosate on microbial activity and biomass from selected soils. J. Environ. Qual. 31:730:735.
- Haney, R.L., S.A. Senseman, L.J. Krutz, and F.M. Hons. 2002. Soil carbon and nitrogen mineralization as affected by atrazine and glyphosate. Biol. Fert. Soils. 35:35-40.
- Rouche, A.R., R.W. Bovey, and S.A. Senseman. 2002. Water stress and triclopyr on clopyralid efficacy in honey mesquite. J. Range Mgmt. 55:266-269.
- Mattice, J.D., S.A. Senseman, and J.T. Walker. 2002. A portable extraction system for extracting water samples while traveling between collection sites. Bull. Environ. Contamin. Toxicol. 62:161-167.
- Mersie, W., C. Clegg, R.D. Wauchope, J.A. Dumas, R.B. Leidy, M.B. Riley, R.W. Young, J.D. Mattice, T.C. Mueller, and S.A. Senseman. 2002. Interlaboratory Comparison of Pesticide Recovery From Water Using Solid-Phase Extraction Disks. J. Assoc. Offic. Anal. Chem. (Accepted)
- Rosales-Robles, E., J.M. Chandler, H. Wu, S.A. Senseman, and J. Salinas-Garcia. 2002. Modeling rhizome johnsongrass development as influenced by temperature. Weed Sci. (Accepted)
- Dozier, M.C., S.A. Senseman, D.W. Hoffman, and P.A. Baumann. 2002. Adsorption of atrazine and metolachlor on bermudagrass (Cynodon dactylon L.) and two soils. Arch. Environ. Contamin. Toxicol. 43:292-295.
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Progress 01/01/01 to 12/31/01
Outputs
The quantity and frequency of Roundup Ultra (RU) applications have escalated with the advent of Roundup-tolerant crops. The objective of this study was to determine the impact of Roundup Ultra on soil microbial biomass and activity across a range of soils. The isopropylamine salt of glyphosate was applied in the form of RU at a rate of 234-ug active ingredient/g soil based on an assumed 2-mm glyphosate-soil interaction depth. Roundup Ultra significantly stimulated soil microbial activity as measured by C and N mineralization, as well as soil microbial biomass. Cumulative C mineralization as well as mineralization rate increased above background levels for all soils tested with addition of RU. The data strongly suggest that RU was the direct cause of the enhanced microbial activity. An increase in the C mineralization rate occurred the first day following RU addition and continued for 14 d. Roundup Ultra appeared to be rapidly degraded by soil microbes regardless of
soil type or organic matter content, even at high application rates, without adversely affecting microbial activity. Atrazine alone and atrazine plus glyphosate were added to soil to determine their effect on soil microbial activity as measured by C and N mineralization (Cmin, Nmin) and soil extractable atrazine. Atrazine alone was added to soils as the formulated product (Aatrex 4L) at a filed rate of 2X (94 mg/kg), 4X (188 mg/kg) and 6X (564 mg/kg) assuming a 2-mm soil penetration depth for glyphosate. Atrazine plus glyphosate stimulated microbial activit8 more than atrazine alone. During 56 days of incubation, mineralized C and N were highly correlated with the amounts of C and N mineralized above the controls and were highly correlated (R2=0.93 for Cmin and R2=0.97 for Nmin). Carbon mineralization was greatest during the first seven days of incubation after herbicide application while N mineralization was greatest during the 14-to 28-day period. These data indicate a possible
substrate shift from glyphosate to atrazine after several days of incubation. In another study, the isopropylamine salt of glyphosate was added at rates of 0, 43, 86, 129, 172, and 215 mg ai/kg soil based on an assumed 2-mm glyphosate-soil interaction depth. Soils were incubated for 4, 8, 12, 16, 20, 24, 28, and 32 d. Cumulative soil C mineralization and mineralization rates were higher in glyphosate treatments than the 0x and control treatments. A strong linear relationship (R2=0.99) between CO2-C evolved and glyphosate C added indicates microbial activity was enhanced by glyphosate. In the 0X treatment, 87% of the atrazine was degraded by 8 d. Soil amended with 1,2, 3, 4, and 5x rates of glyphosate degraded 77, 69, 60, 61, and 52% of the atrazine during the same period. Atrazine degradation approached 97% for all treatments after 12 d of incubation and differences among treatments were no longer observed. The percent atrazine remaining was inversely related to microbial activity.
Results form this study indicate that glyphosate enhances microbial activity while simultaneously inhibiting atrazine degradation.
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies that minimize risk to applicators and consumers while keeping production practices optimized and food prices low.
Publications
- Gerngross, C.A, W.J. Grichar, S.A. Senseman. 2001. Effects of diclosulam on potential crop rotations following peanut production in Texas. Proc. South. Weed Sci. Soc. 54:188.
- Grichar, W.J., C.A. Gerngross, R.L. Lemon, S.A. Senseman, B.A. Besler, and V.B. Langston. 2001. Interaction of peanut variety, diclosulam rate, and temperature on seed germination. Proc. South. Weed Sci. Soc. 54:200.
- Sciumbato, A.S., K.H. Carson, S.A. Senseman, and T.C. Mueller. 2001. Comparison of sample preservation methods for EPA method 525. Proc. South. Weed Sci. Soc. 54:208.
- Tucker, K.P., T.D. Miller, P.A. Baumann, and S.A. Senseman. 2001. Occurrence and management of ALS inhibitor resistant ryegrass (Lolium multiflorum). Proc. South. Weed Sci. Soc. 54:127.
- Gerngross, C.A., W.J. Grichar, and S.A. Senseman. 2001. Response of Georgia green peanut to postemergence herbicides under weed-free conditions. Proc. South. Weed Sci. Soc. 54:38.
- Vencill, W.K. and S.A. Senseman. 2001. Interaction of imidazolinone and sulfonamide herbicides on corn (Zea mays). Weed Sci. Soc. Ab. 41:83.
- Lopez, Y., O.D. Smith, W.L. Rooney, and S.A. Senseman. 2001. Genetic factors influencing high oleic acid content in Spanish market-type peanut cultivars. Crop Sci. 41:51-56.
- Mueller, T.C., S.A. Senseman, K.H. Carson, and A.S. Sciumbato. 2001. The effect of water sample pH adjustment on stability and recovery of triazine and chloroacetamide herbicides from water samples using Empore solid-phase extraction disks. J. Offic. Anal. Chem. 84:1070-1073.
- Jones, C.A., J.M. Chandler, J.E. Morrison, S.A. Senseman, and C.H. Tingle. 2001. Glufosinate combinations and row spacing for weed control in glufosinate-resistant corn (Zea mays). Weed Technol. 15:141-147.
- Mueller, T.C., S.A. Senseman, R.D. Wauchope, R.W. Young, L.M. Southwick, M.B. Riley, H.A. Moye, J.A. Dumas, W. Mersie, J.D. Mattice, and R.B. Leidy. 2001. Inter-laboratory comparison of solid-phase extraction disk recovery of atrazine, bromacil, chlorpyrifos, and metolachlor from water samples. Abst. Papers Amer. Chem. Soc. 61:24 AGRO
- Vencill, W.K. and S.A. Senseman. 2001. Interaction of imidazolinone and sulfonamide herbicides on corn (Zea mays). Weed Sci. Soc. Ab. 41:83.
- Krutz, L.J., R.L. Haney, and S.A. Senseman. 2001. The effect of glyphosate on atrazine degradation in soil. Proc. South. Weed Sci. Soc. 54:172.
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Progress 01/01/00 to 12/31/00
Outputs
Tank mixing pestcides and the use of prepackaged mixtures have become common agricultural practices. However, few studies evaluate pesticide degradation in multi-pesticide systems. A study was conducted to determine the effect of glyphosate application rates on soil microbial activity and atrazine degradation. A strong linear relationship between CO2-C evolved and glyphosate rates indicated that glyphosate was the direct cause of the enhanced microbial activity. Atrazine degradation was inversely related to glyphosate rates and microbial activity. CGA-362622 is a new sulfonylurea herbicide being developed by Syngenta for post-emergence weed control in cotton and sugarcane. Potential interactions of this compound with insecticides were possible and had not been previously studied. Increased foliar injury when CGA-362622 was applied with malathion, profenofos, or dimethioate and with pyrithiobac applied with malathion. There was no increase in cotton injury with the
tank-mixture of CGA-362622 with dicrotophos, azinphos-methyl, acephate, oxamyl, spinosad, pymetrozine, emamectin benzoate, or thiamethoxam compared to CGA-362622 applied alone. Seed cotton yield was not adversely affected by any treatment compared to the untreated control. Halosulfuron is a sulfonylurea herbicide used for broadleaf weed control in sorghum. Stunting of sorghum has been exhibited following treatment with halosulfuron. The objectives of this study were to determine the rate of halosulfuron uptake by sorghum, and the pattern of halosulfuron translocation in sorghum. Translocation of halosulfuron from the treated leaf was complete by 72 hours after treatment (hat). Greater than 98% of the absorbed halosulfuron remained in the treated leaf 240 hat. No statistical differences were found in the translocation of halosulfuron from the treated leaf to other plant parts. There was no translocation of the herbicide into the roots. Prosulfuron is a sulfonylurea herbicide applied
postemergence to control broadleaf weeds in grass crops including sorghum. Research was conducted to compare susceptibilities of different grain sorghum varieties to prosulfuron. The application of prosulfuron consistently reduced sorghum dry weights each year at both locations. However, there was no difference in prosulfuron tolerance among the sorghum varieties tested. Studies have been conducted to determine the effectiveness of grass filter strips in reducing off-target losses of pesticides, however, little work has been done to determine the adsorptive capacity of bermudagrass for pesticides. Therefore, the following objective were developed: 1) to determine and compare the adsorptive capacity of bermudagrass, a Weswood soil, and a Houston Black soil to atrazine and metolachlor and 2) to determine if the presence of one herbicide affects the adsorptive behavior of the other compound to these sorbents. Both Kd values associated with the adsorption of atrazine and metolachlor for
bermudagrass were significantly greater than the Kd values for Weswood and Houston Black soils.
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies tha tminimize risk to applicators and consumers while keeping produciton practices optimized and food prices low.
Publications
- Krutz, L.J., S.A. Senseman, and R.L. Haney. 2000. Effect of glyphosate on atrazine degradation. Agron. Abs. 92:407.
- Dozier, M.C., S.A. Senseman, D.W. Hoffman, and P.A. Baumann. 2000. Adsorption of atrazine and metolachlor on bermudagrass (Cynodon dactylon) and two soils. Weed Sci. Soc. Ab. 40:89.
- Mueller, T.C., S.A. Senseman, D. Wauchope, R. Young, L. Southwick, M. Riley, A. Moye, R. Montalvo-Zapata, W. Mersie, J. Mattice, and R. Leidy. 2000. Empore disks to concentrate herbicide residues from water samples: An inter-laboratory comparison. Weed Sci. Soc. Ab. 40:334.
- Haney, R.L., S.A. Senseman, A.S. Sciumbato, and F.M. Hons. 2000. The effect of glyphosate on atrazine degradation and soil microbial activity. Weed Sci. Soc. Ab. 40:337.
- Dozier, M.C., S.A. Senseman, and D.W. Hoffman. 2000. Adsorption of atrazine and metolachlor on bermudagrass and two soils. Proc. South. Weed Sci. Soc. 53:212.
- Sciumbato, A.S., S.A. Senseman, W.L. Rooney, E.P. Prostko, C.H. Tingle, and J.M. Chandler. 2000. Sorghum variety tolerance to postermergence applications of prosulfuron. Proc. South. Weed Sci. Soc. 53:214.
- Sciumbato, A.S., S.A. Senseman, and R.W. Bovey. 2000. Diflufenzopyr absorption and translocation in velvetleaf (Abutilon theophrasti). Proc. South. Weed Sci. Soc. 53:142.
- Carpenter, A.C., S.A. Senseman, and H.T. Cralle. 2000. Halosulfuron uptake and translocation in sorghum. Proc. South. Weed Sci. Soc. 53:146.
- Minton, B.W., J.W. Wells, and S.A. Senseman. 2000. Potential interaction of CGA-362622 applied with cotton insecticides. Proc. South. Weed Sci. Soc. 53:26.
- Mueller, T.C., S.A. Senseman, R.D. Wauchope, C. Clegg, R.W. Young, L.M. Southwick, M.B. Riley, H.A. Moye, J.A. Dumas, W. Mersie, J.D. Mattice, and R.B. Leidy. 2000. An inter- laboratory comparison of Empore solid-phase extraction disk recovery of atrazine, bromacil, chlorpyrifos and metolachlor from water samples. J. Offic. Anal. Chem. (Accepted).
- Senseman, S.A. and M.L. Ketchersid. 2000. Evaluation of co-solvents with supercritical fluid extraction of atrazine from soil. Arch. Environ. Contamin. Toxicol. 38:263-267.
- Haney, R.L., S.A. Senseman, F.M. Hons and D.A. Zuberer. 2000. The effect of glyphosate on soil microbial activity and biomass. Weed Sci. 48:89-93.
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Progress 01/01/99 to 12/31/99
Outputs
Supercritical fluid extraction (SFE) using CO2 and solid-phase extraction (SPE) are two technologies that are alternatives to Soxhlet and liquid/liquid extraction (LLE). This research compared SFE and SPE extraction of imazapic and imazethapyr from three soils. Recovery of the herbicides using a SFE-CO2 method was approximately 80% for Poth and Tremona soils and 60% when extracted from Ships soil with high clay content and high pH. SPE recovery of both herbicides averaged 78% and was not statistically different between soils. Combining SPE disks with a SPE cartridge cleanup procedure provided a faster filtration with cleaner filtrate compared with using SPE C-18 cartridges by themselves. Halosulfuron is a sulfonylurea herbicide used postemergence in corn, sorghum, and sugarcane production for the control of numerous broadleaf weeds and Cyperus species. Studies were done to determine the connection of sorghum injury to the relative soil adsorption and desorption of
halosulfuron. There was a positive relationship between organic matter content and halosulfuron adsorption. Desorption of halosulfuron was directly related to clay content. Sorghum injury would be least likely to occur on soils with high organic matter. The use of auxin-like herbicides for postemergence control of broadleaf weeds in cereal crops and rangeland has been popular since the 1940 s. Soon after their introduction, off-target movement to susceptible broadleaf crops became a concern. Greenhouse studies were conducted to develop a method of quantifying growth regulator herbicide off target movement and plant injury attributed to volatility. It was determined that this method provided herbicide volatility rates based on plant injury that were consistent with rates and injury from the rate-response curve. The increasing use of Roundup-Ready crops has sparked concern regarding the environmental impact of the herbicide glyphosate. Although glyphosate is not directly applied to
soil, a significant concentration of material may reach the soil surface during application. Studies investigated the impact of glyphosate on soil microbial activity as measured by C and N mineralization. CO2 evolution increased as glyphosate rate increased. Glyphosate significantly stimulated microbial activity as measured by C and N mineralization. These data suggest that glyphosate was the source of increased microbial activity. A series of experiments were conducted to determine the effectiveness of bermudagrass filter strips-in removing atrazine and metolachlor from surface runoff. Results from the TAMUF micro-watershed exhibited no significant difference in % total herbicide load retained by either the bermudagrass or soil plots when the compounds were applied alone or together as a tank-mix. The soil column study revealed that a significantly greater amount of runoff leached through the soil columns covered in bermudagrass compared with bare soil columns. Finally, it was
determined that bermudagrass had relatively high Kd's for both compounds that were significantly greater for the bermudagrass verses the Weswood soil.
Impacts
Results from this work enable us to understand the impact of agrochemicals on the environmentally sensitive areas that include surface water, ground water, non-target plant species, microbial populations and human exposure. The ultimate goal is to understand the processes well enough to design pest control strategies that minimize risk to applicators and consumers while keeping production practices optimized and food prices low.
Publications
- Pace, P.F., H.T. Cralle, J.T. Cothren, and S.A. Senseman. 1999. Photosynthate and dry matter partitioning in short- and long-season cotton cultivars. Crop Sci. 39:1065-1069.
- Bovey, R.W., J. Dahlberg, S.A. Senseman, F.R. Miller, and P. Madera-Torres. 1999. The effect of glufosinate on desiccation and germination of grain sorghum. Agron. J. 91:373-376.
- Senseman, S.A., M.C. Dozier, D.W. Hoffman, J.E. Wolfe III, and K.N. Potter. 1999. Grass filter strip removal of atrazine and metolachlor from simulated runoff under saturated conditions. Abst. Papers Amer. Chem. Soc. 217:71 AGRO.
- Dozier, M.C., S.A. Senseman, D.W. Hoffman, J.E. Wolfe III. 1999. Effectiveness of bermudagrass (Cynodon dactylon) filter strips in herbicide removal from simulated surface runoff. Weed Sci. Soc. Ab. 39:106.
- Sciumbato, A.S., J.M. Chandler, and S.A. Senseman. 1999. Quantitation of growth regulator drift and plant injury. Proc. South. Weed Sci. Soc. 52:209.
- Carpenter, A.C., S.A. Senseman, and H.T. Cralle. 1999. Adsorption-desorption of halosulfuron on selected Texas soils. Proc. South. Weed Sci. Soc. 52:211.
- Haney, R.L., S.A. Senseman, F.M. Hons, and D.A. Zuberer. 1999. Effects of glyphosate on soil microbial activity. Proc. South. Weed Sci. Soc. 52:215.
- Dozier, M.C., S.A. Senseman, D.w. Hoffman, J.E. Wolfe, III, and K.N. Potter. 1999. Effectiveness on bermudagrass (Cynodon dactylon) filter strips in herbicide removal from simulated surface runoff. Proc. South. Weed Sci. Soc. 52:224.
- Weber, J.B., S.A. Senseman, W.W. Witt, J.W. Wilcut, E.P. Webster, W. Vencill, R.E. Talbert, C. Smith, D.R. Shaw, T.F. Peeper, T.Mueller, D.K. Miler, B.J. Brecke, and M. Barrett. 1999. Soil binding values for herbicides need to be standardized. Proc. South. Weed Sci. Soc. 52:199.
- Carson, K.H., H.T. Cralle, J.M. Chandler, T.D. Miller, R.W. Bovey, S.A. Senseman, and M.J. Stone. 1999. Wheat (Triticum aestivum) and Italian ryegrass (Lolium multiflorum) growth and interaction during continuously watered and drought conditions. Weed Sci. 47:440-445.
- Rosales-Robles, E., J.M. Chandler, S.A. Senseman, and E.P. Prostko. 1999. Influence of growth stage and herbicide rate on postemergence johnsongrass (Sorghum halepense) control. Weed Tech. 13:525-529.
- Rosales-Robles, E., J.M. Chandler, S.A. Senseman, and E.P. Prostko. 1999. Integrated johnsongrass (Sorghum halepense) management in cotton (Gossypium hirsutum) with reduced rates of clethodim and cultivation. Cotton Sci. 3:27-99.
- Rosales-Robles, E., J.M. Chandler, S.A. Senseman, and E.P. Prostko. 1999. Integrated johnsongrass (Sorghum halepense) management in field corn (Zea mays) with reduced rates of nicosulfuron and cultivation. Weed Tech. 13:367-373.
- Howe, J.A., Y.H. Choi, R.H. Loeppert, L.C. Wei, S.A. Senseman, and A.S.R. Juo. 1999. Qualitative and quantitative determination of phytosiderophores by high performance liquid chromatography. J. Chromatogr. 841:155-164.
- Pace, P.F., S.A. Senseman, H.T. Cralle, and M.L. Ketchersid. 1999. Supercritical fluid extraction and solid-phase extraction of AC 263,222 and imazethapyr from three Texas soils. Arch. Environ. Contamin. Toxicol. 37:440-444.
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Progress 01/01/98 to 12/31/98
Outputs
BAS 654 is a member of the semicarbazone herbicide family and inhibits polar auxin transport. The combination of BAS 654 and dicamba was more phytotoxic than either alone but the effects appeared to be more additive than synergistic to velvetleaf, field bindweed, honey mesquite and cotton. The effect of pretreatment with BAS 654 was more pronounced that when BAS 654 was applied simultaneously with or after dicamba. Supercritical fluid extraction (SFE) CO2 of two imidazolinone herbicides was studied. The most effective co-solvent for SFE of AC 263,222 and imazethapyr from three soils was the 82% acetonitrile/18% acetic acid. AC 263,222 and imazethapyr recovery was significantly lower in the soil that contained the highest amount of clay and had the highest pH. SFE recovery of both herbicides averaged 81, 59, and 80% for Poth, Ships, and Tremona soils, respectively. Solid-phase extraction (SPE) recovery of both herbicides was not statistically different in any of the
soils and ranged from 75 to 81%. Adsorption studies with prosulfuron are completed. Soils with lower percent organic carbon and higher pH are more likely to demonstrate injury to sorghum due to lower adsorption and higher chemical availability. A study was designed to determine the effectiveness of grass filter strips in reducing off-site losses of atrazine and metolachlor. Sheet runoff flowed across the grass filter strip plot more uniformly and at a faster rate than the bare-soil plots. Approximately twice as much runoff volume was collected on the grass plots compared with the bare-soil plots. The grass filter strip plots intercepted and reduced atrazine concentrations by 20% but had no significant effect on metolachlor concentrations.
Impacts
(N/A)
Publications
- Dozier, M.C., S.A. Senseman, D.H. Hoffman, and K.N. Potter. 1998. Effectiveness of grass filter strips in herbicide removal from simulated runoff. Ninth International Congress of Pesticide Chemistry. London, UK. Abstract No. 6C-030.
- Hoffman, D.W., J.E. Wolfe, S.A. Senseman, and K.N. Potter. 1998. Effectiveness of grass filter strips to reduce atrazine in simulated runoff. Ninth International Congress of Pesticide Chemistry. London, UK. Abstract No. 6C-029.
- Pace, P.F., S.A. Senseman, H.T. Cralle, and M.L. Ketchersid. 1998. Supercritical fluid extraction of imidazolinone herbicides from Texas soils. Proc. South. Weed Sci. 51:249.
- Ketchersid, M.L. and S.A. Senseman. 1998. Response of velvetleaf, field bindweed and mesquite to BAS 654 and dicamba. Proc. South. Weed Sci. 51:258.
- McFadin, J.L. and S.A. Senseman. 1998. Prosulfuron adsorption/desorption in selected soils. Proc. South. Weed Sci. 51:227.
- Dozier, M.C., S.A. Senseman, D.W. Hoffman, J.E. Wolfe III, and K.N. Potter. 1998. The removal of atrazine and metolachlor from simulated field runoff by grass filter strips. Proc. South. Weed Sci. 51:230.
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Progress 01/01/97 to 12/31/97
Outputs
Adsorption of prosulfuron to four Texas soils was studied by applying radiolabeled and technical-grade prosulfuron to the soils at concentrations of 0, 33.5, 67, 134, and 268 ug/kg with a 1:10 sorbent to solution ratio. Adsorption isotherms were constructed using the Freundlich model and the relative affinity (Kf) was calculated for each soil. Ships clay did not adsorb prosulfuron enough to present a statistically significant relationship between adsorption and solution concentration. The order of increasing adsorption of the other soils and their Kf values were: Houston Black clay (0.967 mL/g) < Bernard clay loam (1.64 mL/g) < Acuff Estacado sandy clay loam (1.99 mL/g). Of the soils tested, Houston Black clay and Ships clay were more likely to demonstrate significant sorghum injury. Metolachlor and atrazine runoff plots have been established on bermudagrass to determine the effect of this grass as a filter in reducing herbicide contaminated runoff. Runoff containing
metolachlor alone, atrazine alone, and metolachlor + atrazine have been applied to bare soil and compared with runoff moving across grass filter strips. The grass filters were more effective at removing the atrazine and metolachlor in the first 30 minutes of each run. A saturation point was reached with respect to removal of the herbicides after the initial 30-minute period. Herbicides applied in a tank mix were retained less than the herbicides applied alone suggesting competition for available adsorption sites. Simultaneous extraction of clomazone and trifluralin from a Lufkin fine sandy loam soil was effectively achieved by supercritical fluid extraction (SFE) using a Dionex 703 SFE system with oven temperature of 65 C, restrictor temperature of 125 C, and 5% molar volume of acetone added as a co-solvent mixed with the supercritical CO2.
Impacts
(N/A)
Publications
- McFadin, J.L. and Senseman, S.A. 1997. Adsorption/desorption of prosulfuron on selected soils. Proc. South. Weed Sci. 50:191.
- Dozier, M.D., Hoffman, D.H., Senseman, S.A., Potter, K.N., and Wolfe, J.E., III. 1997. The removal of atrazine and metolachlor from simulated field runoff by grass filter strips. Proc. South. Weed Sci. 50:190.
- Ketchersid, M.L., Senseman, S.A., and Dotray, P.A. 1997. Persistence of trifluralin and clomazone after early PPI application. Proc. South. Weed Sci. 50:192.
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Progress 01/01/96 to 12/30/96
Outputs
Experiments are ongoing related to prosulfuron injury to sorghum by determining adsorption to various soils in the sorghum-growing region of Texas. Five soils are being evaluated with respect to adsorption and desorption. The soils studied appear to demonstrate an S-shape adsorption isotherm and limited adsorption of prosulfuron. Results of desorption and plant uptake studies will be combined with adsorption data to determine the source of inconsistent herbicide injury. Supercritical fluid extraction (SFE) of atrazine, trifluralin, clomazone, and norflurazon from various Texas soils has demonstrated favorable results. This technology has obvious limitations but demonstrates consistent recovery (>80%) of the above compounds. Metolachlor and atrazine runoff plots have been established on bermudagrass to determine the effect of this grass as a filter in reducing herbicide contaminated runoff. Runoff containing metolachlor alone, atrazine alone, and metolachlor + atrazine
have been applied to bare soil and compared with runoff moving across grass filter strips.
Impacts
(N/A)
Publications
- SENSEMAN, S. A., LAVY, T.L. and DANIEL, T.C. 1996. Ground water monitoring for pesticides at selected mixing/loading sites in Arkansas. Environ. Sci. Tech. (Inpress).
- SENSEMAN, S.A., LAVY, T. L., GBUR, E.E. and SKULMAN, B.W. 1996. Trace level pesticide detections in surface water at selected sites in Arkansas. Environ. Sci. Tech. (In press).
- LAVY, T.L.,MATTICE, J.D., MASSEY, J.H., SKULMAN, B.W., SENSEMAN, S.A., GBUR, E. E., JR. and BARRETT, M.R. 1996. Long-term in-situ leaching and degradation of six herbicides aged in subsoils. J. Environ. Qual. 25:1268-1279.
- SENSEMAN, S.A. and KETCHERSID, M.L. 1996. Evaluation of co-solvents in supercritical fluid extraction of atrazine from selected soils. Proc. South. Weed Sci. Soc. 49:210.
- BRAUN, J.C., CHANDLER, J. M., SENSEMAN, S.A. and SMITH, H.R. 1996. Peak for postemergence weed control in grain sorghum. Proc. South. Weed Sci. Soc. 49:34.
- MCFADIN, J.L. and SENSEMAN, S.A. 1996. Adsorption/desorption of prosulfuron on selected soils. Texas Plant Protection Conf. 8:32.
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