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1.
Invasive knotweeds (Reynoutria spp.) pose an ongoing challenge for weed management programs worldwide, requiring years of persistent treatment. In this study, we tested efficacy of diquat applied as foliar spray early in the growing season for short-term suppression, and for potential to boost long-term control when applied sequentially with a mid-season treatment of imazapyr. We evaluated responses of knotweeds (R. japonica, R. × bohemica, and R. sachelinensis) treated with one of three diquat concentrations (0.25%, 0.50%, or 1.0%, v/v), using multiple metrics to capture changes in aboveground plant density and abundance. Canopy cover and biomass were significantly reduced by all diquat concentrations and resembled pre-treatment conditions at 8WAT, reflecting the shift toward reduced stem heights in treated compared with untreated plots. Stem counts at 8WAT, however, did not differ in response to diquat treatments. Sequentially applied early-season diquat and mid-season imazapyr treatments reduced canopy cover (66%–82%), biomass (65%–91%), and stem density (57%–79%) when evaluated 1 year after treatment; reductions were greatest in plots treated with medium and high diquat concentrations, suggesting that diquat treatments may have an additive effect. Overall, our study establishes rates of diquat to reduce biomass of invasive knotweed, and supports additional testing to assess improvement in long-term control when used sequentially with a systemic herbicide. 相似文献
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R. S. L. JEATER 《Weed Research》1964,4(2):133-141
Summary. In Malayan rubber plantations where the weed flora was dominated by grasses paraquat was superior to diquat as a herbicide. At the rates needed to give satisfactory grass weed control paraquat also gave an adequate control of broad-leaved weeds.
The rate of paraquat needed varied between 0.75 and 1.25 lb/ac depending on the weed flora and the growth stage of the rubber trees. In young rubber 1.0–1.25 lb/ac gave 8–10 weeks' control, but in mature rubber there was only 20% recovery 6 months after an application of 0.75 lb/ac. Where weed regrowth was very rapid after the initial spray, as in the case of Paspalum conjugation in young rubber, a second application some 2–3 weeks after the first was an advantage. The volume of water in which it was applied was not critical.
Rain falling soon after application did not reduce the herbicidal activity of paraquat. Paraquat did not injure rubber trees providing it was not sprayed onto green tissue and this feature combined with its inactivation by soil made it safe to use from a very early stage in the growth of the rubber trees.
L'évaluation du paraquat et du diquat pour la lutte contre les mauvaises herbes dans les plantations de caoutchouc 相似文献
The rate of paraquat needed varied between 0.75 and 1.25 lb/ac depending on the weed flora and the growth stage of the rubber trees. In young rubber 1.0–1.25 lb/ac gave 8–10 weeks' control, but in mature rubber there was only 20% recovery 6 months after an application of 0.75 lb/ac. Where weed regrowth was very rapid after the initial spray, as in the case of Paspalum conjugation in young rubber, a second application some 2–3 weeks after the first was an advantage. The volume of water in which it was applied was not critical.
Rain falling soon after application did not reduce the herbicidal activity of paraquat. Paraquat did not injure rubber trees providing it was not sprayed onto green tissue and this feature combined with its inactivation by soil made it safe to use from a very early stage in the growth of the rubber trees.
L'évaluation du paraquat et du diquat pour la lutte contre les mauvaises herbes dans les plantations de caoutchouc 相似文献
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敌草快的水解动力学研究 总被引：2，自引：1，他引：2
研究了敌草快于25℃下在去离子水、河水和地下水3种水体不同pH值(pH 5、7、9)条件下的水解动力学以及pH为9时不同温度(10、25、35℃)条件下的水解行为。结果表明,敌草快的水解动力学属于一级反应,且其在去离子水中的水解速率与其在河水和地下水中的相似;敌草快在酸性和中性条件下比较稳定,不易水解,而在碱性条件下水解较快;温度升高有利于水解反应,水解活化能为25.89 kJ/mol,活化熵为-191.81 J/mol·K,温度效应系数为1.52。 相似文献
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We conducted a glasshouse study to examine effects of hydrology on the growth and physiology of Lygodium microphyllum (Old World climbing fern), an invasive exotic that is rapidly colonising forested wetlands in Florida, USA. We assessed the fern's growth and physiological responses to three hydrological treatments – flood, drought and field capacity. To further explore the physiology of the treatment responses of L. microphyllum , we also sprayed each plant with gibberellic acid, paclobutrazol (gibberellin inhibitor) or a water control solution (at a rate of 5 mL three times per week) using a 3 × 3 factorial design. Flooding reduced relative growth rate by 55%, whereas periodic exposure of ferns to a soil water potential of −1 MPa did not affect growth or physiology. Flooding led to substantial decreases in specific leaf area and area-based rates of pinna photosynthesis, resulting in a 64% lower rate of photosynthesis per unit pinna mass. Application of growth regulators had no effect on fern growth, morphology or physiology. Even though flooding substantially reduced growth, L. microphyllum still showed a positive relative growth rate after >2 months of inundated soils. This apparent hydrological plasticity is likely a contributing factor to the introduced fern's widespread establishment across a range of plant communities within the Florida Everglades ecosystem. Short-term manipulation of site hydrology does not appear to be an effective management option. Consequently, this has considerable implications for the Everglades, which is undergoing a 30-year system-wide hydrological restoration. 相似文献
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The effect of the herbicides di-allate, diquat, diuron, paraquat, tri-allate and trifluralin, at a range of application rates from 0.5 to 32 times that recommended by the manufacturers, on vesicular-arbuscular (V-A) endophyte spore abundance in the soil and on infection of wheat roots was investigated in field and glasshouse experiments. Paraquat and diquat had no measurable effect on V-A endophyte spore abundance. There was a slight trend to lower V-A endophyte spore numbers at high rates of application of di-allate and tri-allate but no trend for the other chemicals. Infection intensity (% root length infected) declined at high rates of di-allate and led to lower mycorrhizal root weights. The phosphorus content of the shoots was also reduced by di-allate. High doses of di-allate, diuron, tri-allate and trifluralin reduced most parameters of plant growth more than mycorrhizal parameters. It is therefore concluded that at normal application rates these chemicals are unlikely to affect adversely endomycorrhiza formation or function. 相似文献
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卫星RNA作为黄瓜花叶病毒的生防因子——Ⅲ.含有卫星RNA的黄瓜花叶病毒S51的某些生物学特性的研究 总被引：2，自引：0，他引：2
1982~1983年比较了含有卫星RNA的黄瓜花叶病毒(CMV)S51和CMV分离物的寄主范围、症状反应和蚜虫传染的特性。对属于8科25种以蔬菜为主的植物的接种和回接实验证明:S51比CMV的寄主范围窄得多,只侵染茄科、葫芦科和藜科中的10种植物,CMV侵染6科的20种植物。S51除在西葫芦的部分植株上有花叶症状外,均无症状;而CMV能引起重花叶、畸形和坏死等症状。桃蚜对S51的传染效率比CMV低,潜育期延长2~6天。 相似文献
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Optimizing diquat efficacy with the use of adjuvants may broaden the spectrum of weed control, but relevant research towards this direction is limited. Field and greenhouse experiments were conducted to evaluate the effect of diquat applied alone and with six commercial adjuvants (surfactants and oil-based adjuvants) on various weed species. Diquat effect was evaluated in two field experiments on natural populations of common lambsquarters (Chenopodium album L.), prostrate knotweed (Polygonum aviculare L.) and burning nettle (Urtica urens L.) along with two greenhouse trials on rigid ryegrass (Lolium rigidum L.). In field or greenhouse experiments, all the adjuvants significantly increased the control of C. album, P. aviculare, and L. rigidum, from 48, 42 and 7%, up to 82, 74 and 67%, respectively, in terms of fresh weight reduction, but to a different extent for each adjuvant. U. urens was totally (100%) controlled in terms of visual estimation either with diquat or with diquat plus any adjuvant. The differences in the effect of diquat applied with adjuvants mainly depended on the weed species examined and they were not proportional to the surface tension reduction of the spray solution caused by the adjuvants. Overall, the surfactants and the oil-based adjuvants examined in this study considerably enhanced the effect of diquat; this can broaden the spectrum of weed control against broadleaf and grass weeds in orchards and non-crop areas. The results are discussed in relation with the classification of the adjuvants. 相似文献
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Aim of our study was to exploit the relation between deposit structure at the microscale and the uptake and biological efficacy of herbicides. For this purpose, we analysed the relevance of the deposit structure of diquat dibromide, as affected by surfactants, on the spatially resolved chlorophyll fluorescence (ChlF) and the desiccation of the leaves. The present study is a sequential work to our studies with the systemic compound glyphosate. On that basis, we hypothesized here that larger deposits of diquat are negatively related to the bio-efficacy of the compound. By using selected ethoxylated rapeseed oil adjuvants (RSO 5, RSO 10, RSO 30, RSO 60) we influenced the deposit properties of diquat dibromide droplet residue on the leaves of easy-to-wet Viola arvensis and the difficult-to-wet Chenopodium album species. With the spatially-resolved pulse amplitude modulated (PAM) ChlF technique we demonstrated the effect of diquat on the physiology of the tissue. As shown, the RSO surfactants did not affect the area of diquat residue on the easy-to-wet leaves of V. arvensis; this trend is similar to those observed for ChlF and the herbicide desiccation potential. In contrary, on C. album, decreased deposit area of diquat droplet was associated with increased effect on ChlF parameters and increased desiccation potential of the herbicide, thus explaining its higher foliar uptake. 相似文献
12.
苏门白酒草Conyza sumatrensis是中国华南地区常见的阔叶杂草,在果园和非耕地常造成严重危害。本研究采用整株剂量反应法,明确了采自广东省广州市的苏门白酒草疑似抗性种群 (GZ-R) 对草甘膦、百草枯和敌草快的抗性水平,比对了GZ-R种群和采自广东省清远市的敏感对照种群 (QY-S) 的草甘膦靶标酶基因EPSPS2片段的差异,并测定了灭草松、氯氟吡氧乙酸等5种茎叶处理剂对不同叶龄苏门白酒草的室内防除效果。结果表明:GZ-R种群对草甘膦和百草枯分别产生了中等水平和高水平抗性,并已对敌草快产生交互抗性,3种药剂对GZ-R种群的LD50值分别是对QY-S种群LD50值的7.2、72.3和6.6倍;与QY-S种群相比,GZ-R种群的EPSPS2基因106位由脯氨酸突变为苏氨酸。在灭草松、氯氟吡氧乙酸或2甲4氯钠推荐剂量下,于4~5叶期施药,苏门白酒草死亡率均为100%,但于6~7叶期和10~12叶期施药,苏门白酒草死亡率显著下降至44.4%~91.7%;而在草铵膦或苯嘧磺草胺推荐剂量下,不同叶龄期施药苏门白酒草的死亡率均为100%,因此在植株生长早期可使用草铵膦和苯嘧磺草胺防除已对草甘膦和百草枯等除草剂产生抗性的苏门白酒草。 相似文献
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Botryosphaeria canker of Cistus ladanifer 总被引：1，自引：0，他引：1
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R. C. BRIAN 《Weed Research》1966,6(4):292-303
Summary. In a number of plant species, the biological activity of diquat and paraquat was increased by an increase in environmental humidity. This improved activity resulted from an increase in both uptake and movement.
High humidity was more effective after treatment than before it, and durations of 8 hr or more were required to produce the maximum effect. When periods of low humidity of up to 16 hr were interposed between treatment and high humidity, there was no significant effect on the activity of diquat in darkened tomato or sugar beet.
The increase in activity occurred both in the dark and in the light, and it is therefore concluded that humidity does not exert its effect by modifying the degree of stomatal opening.
Experiments were carried out with wheat using two air humidities combined with different soil moisture contents, ranging from saturated down to only 30% of water-holding capacity. Greatest movement occurred where high air humidity was combined with low soil moisture, and least where low air humidity was combined with high soil moisture. It is concluded that diquat and paraquat would be most effective in the field when sprayed under dry soil conditions in late afternoon or evening when increased humidity (and darkness) can follow soon after treatment.
Les sels quatemaires de bipyridylium
Effet de l'humidité atmosphérique et de l'humidité du sol sur l'absorption et la migration du diquat et du paraquat dans les plantes 相似文献
High humidity was more effective after treatment than before it, and durations of 8 hr or more were required to produce the maximum effect. When periods of low humidity of up to 16 hr were interposed between treatment and high humidity, there was no significant effect on the activity of diquat in darkened tomato or sugar beet.
The increase in activity occurred both in the dark and in the light, and it is therefore concluded that humidity does not exert its effect by modifying the degree of stomatal opening.
Experiments were carried out with wheat using two air humidities combined with different soil moisture contents, ranging from saturated down to only 30% of water-holding capacity. Greatest movement occurred where high air humidity was combined with low soil moisture, and least where low air humidity was combined with high soil moisture. It is concluded that diquat and paraquat would be most effective in the field when sprayed under dry soil conditions in late afternoon or evening when increased humidity (and darkness) can follow soon after treatment.
Les sels quatemaires de bipyridylium
Effet de l'humidité atmosphérique et de l'humidité du sol sur l'absorption et la migration du diquat et du paraquat dans les plantes 相似文献
15.
Glyphosate ? ? Mention of irademark or proprietary product does not constitute a gtiarantee or warranty oC the product by the U.S. Department of Agriculture and does nut imply its approval to the exclusion of other products thai may also be suitable.
was sprayed at 0009–1·12 kg a.i. ha?1 on the foliage of large potted glasshouse-grown Canada thistle [Cirsium arvense (L.) Scop.], which had extensive, well-developed roots. Increasing the glyphosate rate progressively reduced the total number of visible adventitious root buds plus emerged secondary shoots per plant proportionately more than root biomass, 10 days after treatment. Cortical tissue of thickened propagative roots became soft, water-soaked, darkened, and some regions decomposed, exposing strands of vascular tissue. Lateral roots completely decomposed. When thickened roots were segmented to stimulate secondary shoot emergence from root buds 10 days after foliar treatment, Fewer secondary shoots emerged than expected from the number of visible adventitious root buds present on both control and herbicide-treated plants. Increasing the rate of glyphosate also reduced the regrowth potential of root buds proportionately more than root biomass. Regrowth potential was measured as the number of emerged secondary shoots 35 days after segmenting unearthed roots from plants that had been sprayed 10 days earlier. When foliar-applied at 0·28 kg ha?1, glyphosate decreased the regrowth potential of root buds to zero in 2 and 3 days, as measured by secondary shoot dry weight and number, respectively, even though root fresh weight was unchanged 3 days after foliar treatment. These dose-response and time-course experiments demonstrate that glyphosate did not reduce root biomass as much as it decreased root bud numbers and secondary shoot regrowth potential from root buds. 相似文献
was sprayed at 0009–1·12 kg a.i. ha?1 on the foliage of large potted glasshouse-grown Canada thistle [Cirsium arvense (L.) Scop.], which had extensive, well-developed roots. Increasing the glyphosate rate progressively reduced the total number of visible adventitious root buds plus emerged secondary shoots per plant proportionately more than root biomass, 10 days after treatment. Cortical tissue of thickened propagative roots became soft, water-soaked, darkened, and some regions decomposed, exposing strands of vascular tissue. Lateral roots completely decomposed. When thickened roots were segmented to stimulate secondary shoot emergence from root buds 10 days after foliar treatment, Fewer secondary shoots emerged than expected from the number of visible adventitious root buds present on both control and herbicide-treated plants. Increasing the rate of glyphosate also reduced the regrowth potential of root buds proportionately more than root biomass. Regrowth potential was measured as the number of emerged secondary shoots 35 days after segmenting unearthed roots from plants that had been sprayed 10 days earlier. When foliar-applied at 0·28 kg ha?1, glyphosate decreased the regrowth potential of root buds to zero in 2 and 3 days, as measured by secondary shoot dry weight and number, respectively, even though root fresh weight was unchanged 3 days after foliar treatment. These dose-response and time-course experiments demonstrate that glyphosate did not reduce root biomass as much as it decreased root bud numbers and secondary shoot regrowth potential from root buds. 相似文献
16.
Leakage of electrolytes from leaf discs of treated Phaseolus Vulgaris L. plants was the main criterion used to study the effect of several chemicals on the permeability of leaf-cell membranes. Paraquat, diquat, dinoseb and oxyfluorfen (2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(Trifluoromethyl) benzene) increased leaf-cell membrane permeability after exposure for 12 h or less. An‘aromatic’oil caused a large increase in permeability at 2–5 min after treatment. Increases in electrolyte release were also correlated with release of soluble amino acids from the leaf discs but the former method was the more sensitive. Increase in cell membrane permeability was always associated with injury symptoms such as appearance of necrotic areas in leaves. Chlorpropham, linuron, sodium azide, glyphosate and 2,4-D at 10?3M, as well as 1% X-77 surfactant and a non-phytotoxic isoparaffinic oil did not alter leaf-cell permeability at 12 h after treatment. Light was necessary for paraquat and oxyfluorfen to alter leaf cell permeability. Paraquat and oxyfluorfen caused a greater increase in leaf-cell permeability of a soybean mutant with yellow leaves as compared with the normal green leaves. With oxyfluorfen this difference in permeability was greater than with paraquat, and was associated with the appearance of severe necrotic injury symptoms in the yellow mutant; paraquat caused no injury symptoms. 相似文献
17.
G. R. FISH 《Weed Research》1966,6(4):350-358
Summary. A bay in Lake Rotoiti was completely cleared of a heavy infestation of Lagarosiphon major by means of diquat at a concentration of 05 ppm. Weed kill was alow and there was no reduction of dissolved oxygen in the area, probably because of the cool weather at the time (April). Considerable numbers of planktonic algae developed, but after a few months it was apparent that herbicide treatment had caused an exchange of Lagarosiphon for a less massive growth of Nilelta species. Some of the changes in bio-logical production were measured and an explanation of the observed plant succession is offered.
Quelques effets de la destruction des mausaises herbes aquatiques dans le lac Rotoiti, en Nouvelle-Zélande 相似文献
Quelques effets de la destruction des mausaises herbes aquatiques dans le lac Rotoiti, en Nouvelle-Zélande 相似文献
18.
Pitch canker, caused by the fungus Fusarium circinatum , is a disease affecting many pine tree species. In California, Pinus radiata (Monterey pine) is the principal pine host affected by pitch canker. This investigation into factors affecting infection frequency by F. circinatum of P. radiata examined the influence of: (i) wound size; (ii) relative humidity; (iii) time of inoculation; (iv) inoculum density; and (v) wound age. Wounded branches sustained significantly more infections when large-diameter (1·6 mm) rather than small-diameter (0·5 mm) wounds were made. Infection frequencies tended to be higher at 100% RH than at ambient humidity, although these differences were not statistically significant. Infection frequencies were significantly higher on branches inoculated after 17·00 h than on branches inoculated before noon. Infection frequencies were significantly higher for wounded branches spray-inoculated with 5 × 107 rather than 1 × 107 spores mL−1 . Infection frequencies of pruning wounds declined as wounds aged. 相似文献
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Glyphosate at 2 kg/ha was more effective in reducing regrowth of purple nutsedge (Cyperus rotundus L.) scapes at 90% than at 50% relative humidity (r.h.), and more effective at ?2 bars than at ?11 bars of plant water potential. Regrowth of treated plants subjected to water potentials of ?1 to ?8 bars was reduced 54–60% while at ?11 bars growth inhibition was only 34%. A time interval of as little as 8 h between application and excision was sufficient to give 47% reduction in regrowth at 90% r.h. None of the treated plants, except those clipped immediately after application, produced new shoots from the basal bulb, while all the untreated control plants produced one or more new shoots. Experiments using 14C-glyphosate substantiated these results. Three times more 14C-label was translocated into the underground parts of nutsedge at 90% than at 50% r.h. Twice as much translocated at ?2 bars than at ?11 bars of water potential. 相似文献