Rates Of Simazine Research Articles

Enhanced simazine herbicide degradation by optimized fluoride concentrations in TiO2 nanotubes growth

The performance of simazine degradation using TiO2 nanotubes is strongly influenced by the morphology and structure of the nanotubes. TiO2 nanotubes were synthesized from pristine titanium foil in EG/NH4F/KOH solution using anodic oxidation technique. This study investigates the effect of fluoride concentration in the electrolytes on the efficiency of Simazine photodegradation. We found that the optimum NH4F concentration was 0.5 wt% resulted in 57.4% degradation rate of simazine after 240 min of UV illumination. The result was attributed to the well separated, ordered and uniform structure of TiO2 nanotubes. Having the optimum fluoride concentration in electrolyte is crucial as the photodegradation performance depends on the crystal structure, surface morphology, and phase stability of the TiO2 nanotubes.

Improving Soil Simazine Dissipation Through an Organic Amendment Inoculated with Trametes versicolor

The aim of this research was to investigate the effect of applying sewage sludge combined with wheat crop residue as an organic amendment on the dissipation rate of simazine spiked at 2 and 20 mg kg−1 in an Andisol soil from southern Chile. Changes in some soil enzymes related to soil quality were measured by spectrophotometry, simazine dissipation rates were measured by gas chromatography, and biomass production in the contaminated soil was evaluated. Results of this study indicated that application of the organic amendment inoculated with Trametes versicolor enabled a decrease in negative effects of the herbicide on soil enzymatic activities and a reduction in final concentrations of simazine (~ 80% at both doses). The simazine half-life time was reduced from 14 to 10 days and from 36 to 15 days for doses of 2 and 20 mg kg−1, respectively. These findings prove that the combined strategy of biostimulation and bioaugmentation using these residues can be effectively used to reduce residue pesticides in soils, mainly by increasing the microbiological activity, thus improving simazine dissipation in an Andisol soil.

Seedling Centipedegrass Response to Mesotrione Plus Simazine Mixtures

Centipedegrass (Eremochloa ophiuroides) is a low-maintenance, warm-season grass common throughout the southern United States. Slow establishment and growth rate of seeded centipedegrass often allows for increased weed competition, yet weed control options are limited. Tank-mixing simazine with mesotrione has been reported to improve weed control because of synergistic modes of action. A 2-year field trial was conducted to evaluate centipedegrass response to mesotrione and simazine applications applied 2 weeks after emergence. Mesotrione (0.25 lb/acre) did not reduce centipedegrass cover at any rating when applied alone. All rates of simazine, alone and tank-mixed with mesotrione, resulted in decreased centipedegrass cover 7 days after treatment (DAT). However, simazine alone at 0.25 lb/acre did not reduce turf cover 14, 28, and 49 DAT, and simazine at 0.25 lb/acre tank-mixed with mesotrione at 0.25 lb/acre did not reduce turf cover 28 and 49 DAT. Results indicate that newly established centipedegrass is vulnerable to cover reduction because of simazine and simazine plus mesotrione tank-mixture. Mesotrione and mesotrione tank-mixed with low rates of simazine is a viable option for newly seeded centipedegrass weed control; however, turf cover may be delayed.

Relating Simazine Performance to Irrigation Management1

Although water is crucial to the performance of preemergence herbicides, pesticide performance has rarely been related to irrigation management. This 2-yr study investigated the effect that amount of irrigation water applied had on activity of simazine. Three rates of simazine at 0, 1.12, and 2.24 kg/ha were applied to a 3-yr-old nectarine orchard that was irrigated with microsprinklers. The performance of simazine was compared between irrigation treatments initially targeted to provide water at 110 (efficient) and 175% (overwatered) of crop water requirements. Simazine effectiveness was based on the survival of oat and cucumber plants that were seeded at 0, 14, 28, 56, and 84 d after herbicide application. A longer time interval to 50% survival indicated prolonged herbicidal activity. Results were consistent between years in that simazine's performance was consistently greater in efficient irrigation treatments. The greatest increases were measured at the higher simazine application rate (2.24 kg/ha); overall averages for the length of time to reach 50% survival for cucumber were 50 and 23 d and for oats were 55 and 15 d for efficient and overwatered irrigation treatments, respectively. Use of an efficient irrigation management technique could have enhanced simazine's performance through a decreased leaching of residues from the weed root zone or less chemical or biological degradation (or both). Adoption of efficient irrigation management has been identified as a best management practice to mitigate leaching of pesticide residues to groundwater in coarse soils in California. This study indicates that efficient irrigation improves simazine performance and that both factors, pesticide application and irrigation management, should be considered when developing a weed management system.Nomenclature: Simazine; cucumber, Cucumis sativus L.; nectarine, Prunus persica L.; oat, Avena sativa L.Additional index words: Bioassay, groundwater contamination, herbicide performance, irrigation efficiency.Abbreviations: ELISA, enzyme-linked immunosorbant assay; ETo, evapotranspiration.

Movement of simazine in runoff water and weed control from citrus orchard as affected by reduced rate of herbicide application.

Simazine (6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine) and diuron (N'-(3,4-dichlorophenyl)-N,N-dimethylurea) are applied as pre-emergence herbicides to control weeds in over 45,000 hectare of citrus in the San Joaquin Valley of California. Growers usually apply 2.0 kg active ingredient (ai) ha(-1) simazine and 2.0 kg ai ha(-1) diuron together in the fall and winter seasons. Surface water and groundwater contamination, ecological, and health damage have led to increased regulatory attention and a search for changes in current weed management practices. Reduced application rate of simazine on runoff losses generated by simulated rainfall was studied in experiment 1. Treatments included a control without herbicide application and application of herbicides at 0.5, 1.0, 1.25 and 2.0 kg ai ha(-1). Three generated runoff events were produced using simulated rainfall with 540 l water. For each simulated rainfall event, the simazine concentration in runoff water was greatest at the first volumetric sampling interval, decreasing gradually in subsequent samples. Simazine concentration in runoff water for the three runoff events was undetectable for the control treatment. For the first simulated rainfall event, simazine concentrations in runoff water averaged 0.55, 1.07, 1.27, and 2.12 mg l(-1) for treatments receiving 0.5, 1.0, 1.25 and 2.0 kg ai ha(-1) herbicide application, respectively; simazine concentration in runoff water from the second event one week later averaged 0.16, 0.27, 0.36, and 0.58 kg ai ha(-1) and two weeks later the concentration was reduced to 0.05, 0.10, 0.14 and 0.22 mg l(-1), respectively. Total simazine mass recovered in runoff water from the three simulated rainfall events was estimated approximately 13.8, 26.3, 32.3 and 53.8 g ha(-1) for the treatments receiving herbicide application at 0.5, 1.0, 1.25 and 2.0 kg ai ha(-1), respectively. Field evaluation of weed density showed that pre-emergence herbicides applied at reduced rates (1.0 and 1.25 kg ai ha(-1)) were as effective as the standard rate (2.0 kg ai ha(-1)) for weed control in experiment 2.

Triazine Resistance in a Biotype of Wild Radish (Raphanus raphanistrum) in Australia1

This study documents the first case of triazine resistance in wild radish and the resistance mechanism involved. The high survival (57 to 97%) of the resistant (R) biotype progeny plants treated at a rate four times higher than the commonly recommended rate of simazine or atrazine clearly established that the R biotype plants were resistant to triazines. All the plants of the susceptible (S) biotype plants were killed when treated at half the commonly recommended rate of atrazine (0.5 kg/ha) or simazine (0.25 kg/ha). The dry weight of the S biotype was reduced by 89 to 96% at the commonly recommended rate of atrazine or simazine, while the dry weight of the R biotype plants was reduced by only 36 to 54% even when treated at a rate four times higher than the commonly recommended rate of atrazine or simazine. The growth-reduction–ratio values indicated that the R biotype progeny plants were 105 and 159 times more resistant to atrazine and simazine, respectively, than the S biotype plants. Leaf chlorophyll fluorescence yield was reduced by 97% in the S biotype 24 h after application of triazine compared with only 9% reduction in the R biotype, indicating that the resistance mechanism involved is target-site based. The R biotype was effectively controlled by herbicides of different modes of action.Nomenclature: Atrazine; simazine; triazine; wild radish, Raphanus raphanistrum L. #3 RAPRA.Additional index words: Dry weight, leaf chlorophyll fluorescence.Abbreviations: ALS, acetolactate synthase; DAE, days after emergence; GR50 ratio, the ratio of the herbicide rate required to inhibit the growth of resistant biotype progeny plants by 50% to the rate required to inhibit the growth of S biotype plants by 50%; PS II, photosystem II; R, resistant (biotype); S, susceptible (biotype); SE, standard error; TT, triazine tolerant; WA, Western Australia.

PERSISTENCE OF ATRAZINE, METRIBUZIN AND SIMAZINE HERBICIDES IN TWO SOILS

An oat bioassay was conducted in pots under greenhouse conditions to determine the persistence of atrazine, metribuzin and simazine herbicides in soils of the southeast of Buenos Aires Province, Argentina. Atrazine rates of 0, 0.58, 1.16 and 2.32 mug g-1 of active ingredient (a.i.), metribuzin rates of 0, 0.14, 0.28 and 0.56 mug g-1 of a.i., and simazine rates of 0, 0.72, 1.45 and 2.9 mug g-1 of a.i. dry soil weight were applied to pots containing soils from Balcarce and San Cayetano sites. Organic matter (OM) content and pH of Balcarce soil were 5.5% and 5.8%, while for San Cayetano soil were 2.9% and 6.7%, respectively. Relative dry weight (RDW) of oat shoots was calculated as percentage of control. Considering a 20% RDW reduction of oat shoots, persistences of recommended rates for the region were: atrazine (1.16 mug g-1 of a.i.), 78 and 130 days after treatment (DAT) for Balcarce and San Cayetano soil, respectively; metribuzin (0.28 mug-1 of a.i.), 63 and 77 DAT for Balcarce and San Cayetano soil, respectively; simazine (1.45 mug g-1 of a.i.), 81 and 156 DAT for Balcarce and San Cayetano soil, respectively. Results show that persistence of atrazine, metribuzin and simazine in soil increased with high rates, low OM content and high pH.

Herbicides for Gentians

Gentians are a small but expanding flower crop in New Zealand. Few herbicide recommendations are available for gentians. A range of pre-emergence herbicides were tested, with application in August when the buds on the crown were still dormant. Established crops appeared to tolerate herbicides better than newly planted crops. Herbicide mixtures with low rates of simazine or terbuthylazine combined with low rates of alachlor or diuron gave good weed control without damage to an established crop. Post-emergence application of haloxyfop at 0.25 kg/ha gave good control of summer grasses and did not damage the crop.

Influence of cultivar and season on the response of Trifolium subterraneum to simazine

The tolerance of 6 cultivars of Trifolium subterraneum (subterranean clover) to simazine applied at 0.63 and 1.25 kg a.i./ha was determined under weedfree conditions in the field by measuring herbage and seed yields. Large herbage yield losses occurred as a result of the simazine in spring in the 2 years of the experiments. In 1989, spring herbage yield losses of the cultivars at the 0.63 and 1.25 kg/ha simazine rates averaged 56 and 82%, respectively. In 1990 the spring herbage yield losses were 27 and 51%. Significant variation in tolerance was observed between cultivars in both years, with Trikkala being the most tolerant and Karridale the most susceptible cultivar. Rate of herbicide had the greatest effect on herbage yield, with cultivar having a smaller effect. In 1989, with relatively favourable spring conditions, clover seed yields were depressed by simazine, but in 1990 when drier conditions prevailed during flowering and seed set, seed yields were unaffected or slightly increased by simazine in all cultivars except the early-flowering cultivar Dalkeith. Seed yields of simazine-treated swards were 196-1480 kg/ha in 1989 and 359-686 kg/ha in 1990. The seed yield response in 1990 suggests that herbicides which retard growth in winter help to conserve soil water and, therefore, may benefit seed filling later in the season. The presence of Lolium rigidum at spraying did not reduce the effect of the herbicide on clover herbage yield and had no effect on seed set. Although simazine may reduce herbage yields and, in some cases, seed yields, its use may be justified for the control of annual grasses when other factors such as disease control, pasture quality, and level of weed competition are considered.

Herbaceous weed control in young conifer plantations with formulations of nitrogen and simazine

Weed control and 2nd-year survival and growth of newly planted Douglas-fir (Pseudotsugamenziesii (Mirb.) Franco) and noble fir (Abiesprocera Rehd.) seedlings were measured after application of herbicide and fertilizer in a replicated complete factorial experiment with four levels of simazine (0, 2.2, 4.4, 8.8 kg/ha), three levels of nitrogen (0, 110, 220 kg/ha), two types of nitrogen (urea prill; urea + trimamino-s-triazine (TST) prill), and two kinds of formulations (cogranular prill of simazine + nitrogen; nitrogen prill followed by liquid simazine). For the first growing season, total weed and grass control increased with increasing simazine rates. Total weed control was better when urea + TST, rather than urea alone, was applied in conjunction with simazine. Formulation and nitrogen rate were not significant. After plot treatment with 1.1 kg/ha of liquid hexazinone at the beginning of the second growing season, Douglas-fir survival decreased as rate of urea alone increased; survival decreased with little or no weed control and remained constant or increased with good weed control as rate of urea + TST increased. Noble fir height and diameter and Douglas-fir diameter declined with poor weed control but increased at least to the levels of untreated seedlings with good weed control. Noble fir diameter responded positively to added nitrogen. Although simazine may be toxic to 1st-year conifers, this study suggests that more complete weed control in conjunction with fertilization may benefit young conifer plantations.

Simazine rates and mixtures for poplar and willow cuttings

Simazine rates and mixtures for poplar and willow cuttings

Dynamics of Microbial Population in Soil as Influenced by Simazine and Ecological Factors

Simazine, even at normal rates of application, showed toxicity to bacteria fungi. It was less toxic to actinomycetes, since toxicity up to 20 ppm of the herbicide was not observed. On the contrary, the normal rate of simazine stimulated both Azotobacter and actinomycetes population. The interaction of simazine with soil ecological factors, such as temperature, moisture, pH, and organic matter, affected soil microbial population differently. Simazine was relatively less toxic to bacteria under acidic and alkaline conditions of soil; they were not affected at 15 degrees C. Actinomycetes were comparatively not adversely affected even with 200 ppm of simazine under high soil moisture regime. The stimulatory effect of simazine on Azotobacter was also confirmed under different ecological conditions. The incorporation of 2 per cent of organic matter in soil mitigated the toxicity of simazine in respect to soil fungi. Simazine also appeared to be less toxic to soil fungi at lower temperatures, under acidic and alkaline conditions of soil, as well as under high moisture regime.

Effect of simazine, lindane and ceresan on soil respiration and nitrification rates

The effect of three pesticidesviz, simazine, lindane and ceresan upto 100-fold of field application was studied on organic matter mineralization as well as on nitrification rates in Delhi alluvial soil. The normal rate of simazine (2 ppm) did not influence CO2 evolution but higher concentrations suppressed it. Lindane and ceresan inhibited CO2 production from soil by normal concentrations but the same CO2 production was enhanced in berseem roots treated soil upto 10 ppm of ceresan. The nitrification of ammonium sulphate in soil due to these pesticides was impaired significantly for varying periods. The inhibitory effect of higher concentrations was marked only upto 3 weeks, subsequently the rate of nitrification was restored. Among the nitrifiers, Nitrobacter were more susceptible as compared to Nitrosomonas.

Nitrogen Use in Winter Wheat in Response to Systematic Pesticides1

AbstractVarious pesticides exhibit plant growth regulating activity and have increased crop yields or altered concentrations of various constituents. Our purpose was to test the effect of commercially available pesticides on winter wheat (Triticum aestivum L.) with regard to N use, protein concentration, and dry matter production. Growth chamber‐grown wheat seedlings were supplied 2.5 or 10.0 mM nitrate‐N concentrations in nutrient solutions at each of two temperature regimes. Pesticides added to different pots were 0.5 mM concentrations of simazine [2‐chloro‐4, 6‐bis (ethylamino)‐S‐triazine] or dyrene [2,4‐dichloro‐6‐(0‐chloroanilo‐s‐triazine], and 25 mM concentrations of disulfoton [0, 0‐diethyl S‐(2‐(ethylthio) ethyl) phosphorodithioate] or guthion [0, 0‐dimethyl S‐(4‐oxo‐1,2,3‐benzotriazin‐3 (4H)‐ylmethyl phosphorodithioate]. Simazine increased nitrate reductase activity and nitrate concentration, and decreased glutamine synthetase activity. The same four materials were sprayed on field plots at 0.1 or 1.1 kg/ha at one of four growth stages. No autumn treatment affected yield or protein content of forage. Lower simazine rates applied at anthesis and higher simazine rates applied at all three spring growth stages decreased grain yields. Simazine treatments that decreased grain yields, and guthion applied during autumn increased grain protein concentration. The other treatments had no effect on protein or yield. Simazine applied during anthesis decreased grain test weights significantly. Decreased grain yields and increased grain protein concentrations probably resulted from detrimental effects of simazine on photosynthate accumulation and absence of a direct effect on N assimilation when foliar‐applied. Decreased grain test weights apparently resulted from floret sterility and undeveloped grains.

Susceptibility of Alfalfa Cultivars to Triazine Herbicides1

AbstractWhile simazine [2‐chloro‐4,5‐bis(ethylamine)‐s‐triazine] has been used for several years to control perennial broadleaf weeds in alfalfa (Medicago sativa L.), it occasionally fails to provide adequate weed control, or causes crop injury. Other triazine herbicides have been shown to provide more reliable weed control but also may injure the crop. Consequently, this study was conducted to determine which triazine herbicide was least injurious to alfalfa and if alfalfa cultivars differed in their susceptibilities to the herbicides. Included in the study were five alfalfa cultivars and the herbicides atrazine [2‐chloro‐4‐(ethylamino)‐6‐(isopropylamino)‐s‐triazine], cyanazine [2‐chloro‐4‐ (1‐cyano‐1‐methylethylamino)‐6‐ethylamino‐s‐triazine], secbumeton (2‐sec‐butylamino‐4‐ethylamino‐6‐methxy‐s‐triazine) and simazine.The cultivars were established on silt loam (Typic Argin‐doll Fine‐Silty Mixed Mesic) and loamy sand (Typic Udipsament Sandy‐Mixed) soils. Results of tests conducted on both soils indicated that the ‘Vernal,’ ‘Saranac,’ and ‘Iroquois’ cultivars had the greatest yield potential under Wisconsin conditions, but when expressed as a percentage of yield in untreated plots, the ‘Tempo’ cultivar was injured least by the herbicides. The ‘DuPuits’ cultivar, while initially responding to the triazine herbicides much like the other cultivars, exhibited greater injury after overwintering. Initial injury to the Vernal cultivar on the silt loam soil was greatest from atrazine, secbumeton, and cyanazine, but recovery was nearly complete by the spring following treatment. On the loamy sand soil, however, atrazine and high rates of simazine produced the greatest initial injury, and injury to the Vernal cultivar persisted through the following spring.

Three Year Effects of Herbaceous Weed Control in a Sycamore Plantation

Screening studies initiated in 1969 to determine the effectiveness and selectivity of herbicides for herbaceous weed control during the first growing season in American sycamore (Plantanus occidentalis L.) plantations indicated that simazine [2-chloro-4,6-bis(ethylamino)-s-triazine], atrazine [2-chloro-4-(ethylamino)-6- (isopropylamino)-s-triazine], and dalapon (2,2-dichloropropionic acid) had the desired properties at economically feasible use rates. To further evaluate these herbicides and ametryne [2-(ethylamino)-4-(isopropylamino)-6-(methylthio)-s-triazine], permanent plots were established in a sycamore plantation in 1970. Weed control obtained from a single herbicide application in the spring after planting seedlings in the winter has resulted in increased height, diameter, and volume growth of the sycamore for at least three growing seasons. No serious phytotoxicity on the crop species was noted with application rates from 4.5 to 9.0 kg/ha of the s-triazines alone or from 5.6 kg/ha of dalapon in combination with the lower rate of simazine and atrazine.

RESPONSE OF WEEDS AND SEVERAL SHELTERBELT TREE AND SHRUB SPECIES TO GRANULAR SIMAZINE

Granular simazine (2-chloro-4,6-bis(ethylamino)-s-triazine), at 3.36, 6.72, and 10.08 kg/ha, was applied to new transplants of Caragana arborescens Lam., Cotoneaster acutifolia Turcz., Crataegus sp., Fraxinus pennsylvanica Marsh. var. subintegerrima (Vahl.) Fern., Hippophae rhamnoides L., Lonicera tatarica L., Malus baccata (L.) Borkh., Picea glauca (Moench) Voss, Picea pungens Engelm., Pinus sylvestris L., Populus deltoides Marsh., Populus × Northwest (Hort.), Prunus padus L. var. commutata Dipp., Prunus virginiana L. var. melanocarpa (A. Nels.) Sarg., Rosa rugosa Thunb. cult Hansa, Salix acutifolia Willd., Salix pentandra L., Shepherdia argentea Nutt., Sorbus americana Marsh., Syringa villosa Vahl., Ulmus americana L., and Ulmus pumila L. Simazine at 6.72 kg/ha gave 68% control of annual weeds and this was sufficient for the adequate growth of most of the tree and shrub species in this test. None of the species showed visible injury symptoms at any of the simazine rates tested, but the growth of some was reduced at the high simazine rate.

Chemical Control of Weeds in Transplanted Ground Covers1

Abstract Nine herbicides were evaluated for their efficacy and safety in new plantings of pachysandra, English ivy, myrtle, and ajuga. Sprays of diphenamid, norea, simazine and trifluralin or granules of amiben and EPTC effectively controlled grasses and selected broadleaved weeds in two growing seasons. English ivy and pachysandra displayed excellent tolerance to all of the herbicides at the rates tested, although there was some injury observed from the 2× rate of simazine in 1969. Ajuga and myrtle exhibited a much wider range in susceptibility to the various herbicides. Preplant applications of trifluralin or post-transplant applications of norea gave good weed control and did not injure ajuga at two rates of application. Myrtle displayed adequate tolerance to both diphenamid and granular EPTC.

Moisture and the Use of Simazine on Prunus1

Abstract Weed competition reduced the growth of young peach and plum rootstoeks. Heavy sprinkler irrigation increased the phytotoxicity of simazine to young Prunus rootstoeks. Recovery from severe foliar injury occurred during the season and normal growth resulted at the lower rates of simazine. No detrimental residual effect on tree growth was noted during the following season.

EFFECTS OF DILUTE SPRAYS OF SIMAZINE ON SPRING WHEAT

In 1967, 18 spring wheat varieties (Triticum aestivum L. em Thell.) were grown in the field at Bozeman, Montana, and sprayed on three dates with low rates of 2-chloro-4,6-bis (ethylamino) -s-triazine (simazine).The simazine treatments significantly affected both yield and percent protein. Yields decreased as rate of simazine increased and as wheat plants were more mature when treated. The May 16 and June 16 simazine treatments resulted in grain protein about 2% higher than the control, but this increase was accompanied by a corresponding decrease in yield of grain.A highly significant r value of 0.77 between grain protein and the grain to straw ratio suggests that grain protein is heavily dependent on total foliage production.