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1.
In a field trial, different doses of five herbicides applied in autumn and late winder were compared for the control of barley grass (Hordeum leporium Link) in dryland Lucerne. Diuron at 1·1, 2·2, and 4·5 kg/ha and atrazine at 1·1 kg/ha were more effective in increasing Lucerne production than linuron at 4·5 kg/ha and various rates of dalapon and paraquat. Autumn application generally resulted in greater Lucerne production than late winter application. Most treatments reduced the amount of barley grass in the Lucerne. Diuron and atrazine also eliminated reduced the amount of barley grass in the Lucerne. Atrazine, diuron and linuron had a strong residual effect and reduced the density of subterranean clover and barley grass in the autumn following treatment.  相似文献   

2.
Summary. Comparative experimental results with dalapon-sodium and paraquat for the control of barley grass ( Hordeum leporinum Link) in lucene and subterranean clover pasture are reported. Sprays were applied 3–4 days after a simulated grazing.
At all rates tested (1–4 lb/ac), dalapon provided satisfactory control of, but did not eradicate, barley grass. Subterranean clover productivity was reduced substantially whether application was in May or July; lucerne growth was retarded by 4 lb/ac applied in July.
Paraquat applied at 0.06–0.25 lb/ac in May gave similar but somewhat less effective control than did dalapon. Some re-establishment of barley grass occurred as a result of late germinations following the May applications. Paraquat applied in July at 0.06 lb/ac gave unsatisfactory results, but at 0.12 and 0.25 lb/ac the control was comparable with that given by dalapon. Subterranean clover was damaged slightly by the May treatments but recovered quickly, after initial scorching, following applications in July. Lucerne was neither damaged nor retarded by paraquat.
The addition ofa wetting agent increased the efficacy of paraquat in controlling certain more tolerant annual grasses, but not barley grass.
Désherbage sélectif des pâtures ft des luzernes: lutte contre l'orge des lièvres  相似文献   

3.
G. P. ALLEN 《Weed Research》1965,5(3):237-251
Summary. Paraquat, dalapon and amitrole-T were compared in their ability to kill a long-established Agrostis/Lolium pasture in late July, late October and early April. Paraquat at 0.75, 1.5 and 3.0 lb/ac and dalapon at 10.6 and 15.0 lb/ac destroyed the sward most successfully but dalapon was not efficient at the April spraying. Amitrole-T at 4.0 lb/ac had the ability to cause the sward severe chlorosis and to kill most broadleaved species but failed to achieve a substantial kill of grass at the three dates. Paraquat was judged the most efficient chemical being non-residual and extremely rapid in action at all dates of application. Changes in botanical composition following chemical treatment are described. It is suggested that the composition of regrowth may be decided by choice of chemical and, in addition, influenced by the lime of application. Considerable reductions were achieved in the amount of Agrostis stolonifera recolonizing the plots after July application of all three chemicals but the autumn and spring treatments resulted in strong re-establishment by this species. A substantial increase of Lolium perenne resulted from July applications and this was most marked following the application of 5 lb/ac dalapon.  相似文献   

4.
Under normal systems of grassland management, most sown swards become invaded by weed grasses. This ingress is usually associated with a depletion in the size and number of the sown species. Selective herbicides can be used to combat this grass invasion and the results of two experiments are presented to show how low-dose dalapon in mid-July can be used for this purpose. When the sown grasses are too severely depleted, some method of introducing seed is required. A new one-pass technique is now being developed for establishing grass and clover seed into existing swards. After sowing, ways of increasing the clover content are being studied, based on the use of grass-suppressing herbicides in late winter. In one experiment several-fold increases in clover growth were recorded 5 months after applying carbetamide (2.8 kg/ha) and propyzamide (0.8 kg/ha).  相似文献   

5.
Summary. Studies on the physiological effects of dalapon in Cynodon dactylon (L.) Pers. were carried out. Field and glasshouse experiments showed that dalapon is freely translocated in the aerial organs and from these to the rhizomes. No transformation of the herbicide was detected during 72 h following application. In rhizomes as well as in stolons, dalapon caused growth inhibition and necrosis of buds while root growth was apparently not affected. This differential susceptibility was confirmed by culturing node explants in nutrient solution containing dalapon. Although dalapon killed aerial organs, most rhizomes were capable of recovery even when a high dose was applied. These results are discussed. Effets physiologiqius du dalapon sur Cynodon dactylon (L.) Pers.  相似文献   

6.
Changes in ihe species composition of a ryegrass pasture were examined over a 2 year period from a spring establishment. Seed of S23 perennial ryegrass was sown in main plots, eilher broadcast or drilled, at rates of 15, 25 or 35 kg/ha in a field experiment at Oxford. The whole area was oversown withfour weed grasses (Agrostis siolonifera.Holcus lanatus. Poa annua and P trivialis). Five cultural and three herbicide treatments were applied across the plots. These consisted of three levels of nitrogen (0. 50 and 100 kg N per ha), two companion species (Italian ryegrass and white clover) and 2.4-D, benazolin and methabenzihiazuron applications. Ten weeks after sowing, broad-leaved weeds accounted for nearly half the lotal dry-matter yield, except where controlled by the three herbicides. Grass yields were nol increased by herbicide treatment. The only cultural treatment checking broad-leaved weeds was ihe 35 kg/ha seeding rale. Seven months after sowing, the only treatment which had decreased the abundance of weed grasses was melhabenzthiazuron especially againsi A. stolonifera and Poa spp. Two years afler sowing, perennial ryegrass had only 34% ground cover and had been replaced largely by H. lanatus (38%), Poa spp, (15%) and A. stolonifera (7%), Where methabenzthiazuron had been used the ryegrass ground cover was 48%. with less P. trivialis and A. stolonifera. but H. lanatus was nol altered. White clover decreased H. lanatus cover. In two supplementary pot experiments, methabenzthiazuron sprayed pre-emergence damaged perennial ryegrass unless the seed was covered with at least 4 mm of soil. Only H. lanatmand F. rubra out of sixteen grasses were relatively resistant to methabenzihiazuron when applied at ihe tillering stage, confirming that this herbicide has potential for preventing the ingress of many unsown grasses in new leys.  相似文献   

7.
When dalapon and TCA are used for the management of aquatic weeds in irrigation distribution systems, they are often applied to established stands of Typha spp. and Phragmites australis in autumn or early winter, after draining water from the system. It has been assumed that the herbicides would dissipate from the sediments within 6 weeks, so that water supplies could be safely restored. In field experiments the decay of dalapon and TCA in sediments followed the classical pattern for a microbially mediated process, with a slow lag-phase, followed by a rapid phase of decline, but not to completion. Particularly for TCA, there was a final slow phase in which residues were sufficient to contaminate eluting water at concentrations much greater than the legally prescribed tolerance, even when the interval between herbicide treatment and water re-supply was more than 6 weeks. Although the overall pattern of dissipation in the sediment was similar for the two herbicides, concentrations of TCA were higher than those of dalapon in the elution water, probably reflecting differences in herbicide mobility and elution efficiency. Dye tracers were used in three field experiments to investigate the efficiency of herbicide elution and carryover of contaminated water when canals were filled to capacity, drained and refilled. Together with the rate of dissipation from sediments, canal topography and draining efficiency determined the safety of the elution process in removing surplus residues before re-supply of water for irrigation. In large-scale management operations, where the dissipation interval was only 17-19 days, the TCA was eluted from the sediment into flowing water in proportion to the square root of time, giving average concentrations over 3 days of discharge of more than 0.4gm?3. Ideally, the interval between spraying and water re-supply should be extended beyond 6 weeks. Alternatively, herbicide use should be restricted, or provision made for elution of surplus residues and disposal of contaminated water to waste, or onto tolerant crops or fallow land.  相似文献   

8.
Losses in grain yield prevented by controlling weeds were measured in 59 fields of (southern hemisphere) spring-sown wheat (Triticum aestivum L.) (cv, Otane) and 45 fields of spring-sown barley (Hordeum vulgare L.) (cv. Corniche) in five consecutive growing seasons from 1988/89 until 1992/93 in the Canterbury region of New Zealand. The losses were measured as the differences in yield between weeded and non-weeded plots located in randomly positioned pairs in the fields. In the first 2 years, the weeding was by push hoe in‘organically grown crops. For the last 3 years, the fields were under prophylactic herbicide regimens with nonweeded plots created by excluding commercial herbicide applications (made mostly in October for wheat and November for barley) with polyethylene sheets placed temporarily over the plots. For each season the distributions of yield losses were modelled using the normal distribution and probabilities of ‘breaking even’ on herbicide use derived by substituting cumulative probability density functions into a simple break-even model for herbicide use. The model assumed that herbicide application in the current crop has no flow-on economic effect for succeeding crops. The mean annual yield losses prevented by herbicide application were positively correlated with September and October rainfall for wheat and bailey respectively. As a consequence, the probabilities of breaking even on herbicide use increased with increasing spring rainfall. Using historical rainfall records, probabilities of breaking even were estimated for each of the 48 years from 1947 to 1994. Averaging over these years, the analysis revealed that at current grain prices prophylactic use of the commonly applied herbicides is likely to be uneconomic in 24% (95% confidence limits 6% and 50%) of fields of average-yielding Otane wheat and in 26% (95% confidence limits 1% and 91 %) of fields of average-yielding Corniche barley in Canterbury. It was concluded that there is potential for withholding herbicide treatments without jeopardizing profitability in these crops, particularly in seasons with low spring rainfall.  相似文献   

9.
Annual applications of the herbicides atrazine, simazine, linuron and diuron at 45 kg/ha were made to the same plots for 9 consecutive years from 1963 to 1971 in a peach (Prunus persica (L.) Batsch.) orchard located on sandy loam soil near Harrow, Ontario. Soil samples from these plots were collected in late October for the last 3 years (1969–1971) and trees were cut down in December, 1969. Herbicide residues were determined by bioassays based on the fresh and dry weight of oats (Avena sativa L.) and in one year results were confirmed by chemical analysis. Significant accumulation of herbicides was not observed. The maximum residue levels measured in October over the 3 years of sampling were 7′3 kg/ha for diuron, 3–8 kg/ha for linuron, 1–6 kg/ha for simazine and 04 kg/ha for atrazine in the top 15 cm of the soil profile. Simazine and atrazine showed a rapid decrease in amount after treatment but diuron and linuron were degraded more slowly. Measurable residues of all herbicides were confined to the upper 15 cm of the soil profile and the majority of herbicide remained in the 0–5-cm soil layer. Oats were planted in the orchard plots from 1972 to 1974 to follow the disappearance of the herbicides. All herbicides caused highly significant yield decreases in 1972, atrazine causing the least (38%) and diuron the greatest (86%) reductions. Diuron reduced the yield of oats in 1973 and caused a highly significant decrease in the weight of young oat plants in 1974.  相似文献   

10.
Invasive plants can seriously threaten biodiversity and ecosystem function. Thus, controlling the abundance and mitigating the deleterious effects of invasive plants is imperative. The effectiveness of removal methods could vary based on potential damage to non‐target species and on the ecological context of invasion. For example, species‐poor communities might benefit disproportionately from invasive removal because they tend to be more heavily invaded than species‐rich communities. In this study, we tested the efficacy of two common methods of invasive plant control, hand removal and 2,4‐D herbicide application, against the invasive forb, Galium verum. We further tested whether the community response to G. verum removal varied across communities that differed in native grass richness (one, three or six species) and composition. Grass diversity did not interact with G. verum removal to influence any response. Instead, hand removal and herbicide application each reduced G. verum stem density by >50% relative to controls. Furthermore, hand removal of G. verum increased species richness by 25% relative to controls and herbicide‐sprayed plots. Despite this benefit, hand removal is labour‐intensive and impractical for large areas. These results also suggest that applying herbicide may control G. verum spread without substantially reducing forb diversity in invaded tallgrass prairie. Thus, herbicide application may be most suitable for grasslands with low native forb diversity, especially in managed grasslands and pastures where maintaining native forb diversity is a lower priority than maintaining high grass productivity.  相似文献   

11.
Abstract

Two field experiments on chemical weed control in Faro 41 upland rice (Oryza sativa L.) variety were conducted at a rainforest site near the National Cereals Research Institute, Amakama Substation in 1989 and 1990. The herbicides tested were a coformulated mixture of pretilachlor and dimethametryne at 1.5, 2.0 and 2.5 kg a.i./ha, a co‐formulated mixture of piperophos and propanil applied at 3.16 and 3.95 kg a.i./ha, and Oxadiazon at 1.0 kg a.i./ha. Two hand weedings and a ‘no weeding’ treatment were included. The herbicides were applied 5 days after planting. All were safely selective to the crop. Most provided adequate weed control through 8–12 weeks after planting. Weeds controlled included Cynodon dactylon, Commelina benghalensis, Dlgitaria horizontalis, Eleusine indica, Panicum maximum and Pennisetum purpureum as grass weeds. The broadleaf weeds were Emilia sonchifolia, Ageratum conyzoides, Portulaca oleraceae, Richardia brasiliensis and Ipomoea Involuncrata. The sedges Mariscus alternifolius and Cyperus esculentus were encountered in the plots. Pretilachlordimethametryne at 2.5 kg a.i./ha had the best weeding score. Twoyear average grain yields of 1.7–2.6 t/ha were obtained from the herbicide treatments. With only 0.4 t/ha from the unweeded treatment, yield losses of more than 80% were recorded.  相似文献   

12.
Summary. Trials in 1959, 1960 and 1961 failed to show significant differences in yield between potatoes (Solanum tuberosum L.) of three varieties receiving from seven to nine separate tractnr cultivations and similar potatoes in which the weeds were well controlled by pre-emergence applications of a mixture of dinoseb(6.0 lb/ac)*and dalapon (2.5-5.0 lb/ac), With less effective herbicide treatments. including simazinc and 2,4-DES, there were significant reductions in yield.
Preliminary taint tests in 1959 on cooked tubers suggested that slight tainting might have been caused by one of the treatments, but tests on potato crisps made from the 1959 and 1960 crops were completely inconclusive. Tubers from all the treatments in the 1959 and 1960 trials sprouted normally in the spring after harvest.
Le désherbage des pommes de terre par des herbicides de pré-émergence  相似文献   

13.
Information on temporal and spatial variation in weed seedling populations within agricultural fields is very important for weed population assessment and management. Most of all, it allows a potential reduction in herbicide use, when post‐emergence herbicides are only applied to field sections with weed infestation levels higher than the economic weed threshold; a review of such work is provided. This paper presents a system for site‐specific weed control in sugarbeet (Beta vulgaris L.), maize (Zea mays L.), winter wheat (Triticum aestivum L.) and winter barley (Hordeum vulgare L.), including online weed detection using digital image analysis, computer‐based decision making and global positioning systems (GPS)‐controlled patch spraying. In a 4‐year study, herbicide use with this map‐based approach was reduced in winter cereals by 60% for herbicides against broad‐leaved weeds and 90% for grass weed herbicides. In sugarbeet and maize, average savings for grass weed herbicides were 78% in maize and 36% in sugarbeet. For herbicides against broad‐leaved weeds, 11% were saved in maize and 41% in sugarbeet.  相似文献   

14.
A national survey was conducted in Finland from 1982 to 1984 to determine the main weed species in spring cereals and the efficacy of herbicides on Finnish farms. The most common dicotyledonous weeds producing the highest biomass in spring cereals were Chenopodium album L., Galeopsis spp. L., Stellaria media (L.) Vill. and Lapsana communis L. The main grass weed was Elymus repens (L.) Gould. The average reduction of weed biomass by herbicide treatment was 75%. More reliable efficacy was obtained with herbicide mixtures than with MCPA alone.  相似文献   

15.
Abstract

Field experiments were conducted to determine the effectiveness of herbicides in controlling Rottboellia cochinchinensis (Lour.) W. D. Clayton and Cyperus rotundus L. in upland rice (Oryza sativa L.) at different moisture regimes as imposed by a line source sprinkler system. Preemergence application of pendimethalin [N‐(1‐ethylpropyl)‐3,4‐dimethyl‐2,6‐dinitrobenzenamine] was highly effective in controlling R. cochinchinensis irrespective of soil moisture after herbicide application. Bentazon [3‐(1‐methylethyl)‐(1H)‐2,1,3‐benzothiadiazin‐4(3H)‐one 2,2‐dioxide] and 2,4‐D [(2,4‐dichlorophenoxy)acetic acid] applied at postemergence effectively controlled C. rotundus when moisture supply was well above pan evaporation. These herbicides also had no adverse effect on rice stand and resulted in higher yield over the control. Water application rates above upland pan evaporation for a season‐long period was essential to obtain a high response to weed control either by herbicides or hand weeding. The data suggest that proper weed control by herbicides or hand weeding will not result in high upland rice grain yields if moisture level from rains fall below the critical level.  相似文献   

16.
Solatium karsensis Symon, an Australian native perennial, has become an important weed in irrigated summer crops in far western New South Wales. A screening trial of 14 herbicides showed that atrazine was the most effective treatment, though 2,4-D also suppressed S. karsensis in grain sorghum (Sorghum bicolor L. cv. Rico) for the duration of the crop. Grain sorghum yields were higher in plots treated with atrazine at 2–5 kg (a.i.) ha?1 than for any other herbicide treatment or the untreated control. Because the root system remained viable annual herbicide application would be necessary for the continued control of 5. karsensis.  相似文献   

17.
Weeds are a major constraint to increasing production of lentil (Lens culinaris Medik.) in Sudan, Field studies were conducted to determine the yield loss due to weeds, to identify the critical period of weed interference, to evaluate the activity of different herbicide mixtures in controlting weeds and their selectivity for lentil, and to evaluate different methods of weed control for developing an integrated weed management practice. At Rubatab. unrestricted weed growth accounted for up to 84% loss in yield. The critical period of weed control was between 2 and 4 weeks after sowing. However, a weeding regime experiment at Dongola, a cooler location with a longer growing season, indicated that the critical period was between 4 and 6 weeks after sowing. suggesting that the critical period might vary with the environmental conditions. The herbicides imazethapyr (0.05 kg a.i. ha-1), terbutryn (1.0 kg a.i. ha-1) and prometryn (1.0 kg a.i. ha-1), each in a tank mixture with pendimethalin (1.2 kg a.i. ha-1), were tolerated by lentil, controlled weeds effectively and significantly increased yields at Wad Hamid. Their efficacy in controlling weeds at Rubatab was low, however, because of the presence of Tephrosia apollinea (Del.) DC. and Melilotus indica (L.) All., which tolerated these herbicides. Efficacy was also reduced in heavier soils. One supplementary hand-weeding at 4 weeks after sowing enhanced the performance of these herbicides under such conditions. A tank mixture of oxyfluorfen (0.24 kg a.i. ha-1) with either terbutryn (1.0 kg a.i. ha-1) or prometryn (1.0 kg a.i. ha-1) also provided good weed control and increased yield of lentil at Wad Hamid. Application of a higher dose (1.5 kg a.i. ha-1) of terbutryn and prometryn caused phytotoxicity. Irrigation before seed-bed preparation reduced grass and broad-leaved weeds by 58% and 40% respectively, and gave a 30% increase in grain yield over no irrigation. Pre-emergence application of oxyfluorfen (0.24 kg a.i. ha-1) and a supplementary hand-weeding at 4 weeks after sowing gave excellent control of weeds and increased lentil yield by 57% over the weedy control. Thus, use of presowing irrigation, pre-emergence herbicide and one hand-weeding form an effective integrated package for controiling weeds in northern Sudan.  相似文献   

18.
We assessed the contributions of target site‐ and non‐target site‐based resistance to herbicides inhibiting acetyl‐coenzyme A carboxylase (ACC) in Alopecurus myosuroides (black grass). A total of 243 A. myosuroides populations collected across France were analysed using herbicide sensitivity bioassay (24 300 seedlings analysed) and ACC genotyping (13 188 seedlings analysed). Seedlings resistant to at least one ACC‐inhibiting herbicide were detected in 99.2% of the populations. Mutant, resistant ACC allele(s) were detected in 56.8% of the populations. Among the five resistant ACC alleles known in A. myosuroides, alleles containing an isoleucine‐to‐leucine substitution at codon 1781 were predominant (59.5% of the plants containing resistant ACC alleles). Comparison of the results from herbicide sensitivity bioassays with genotyping indicated that more than 75% of the plants resistant to ACC‐inhibiting herbicides in France would be resistant via increased herbicide metabolism. Analysis of herbicide application records suggested that in 15.9% of the populations studied, metabolism‐based resistance to ACC‐inhibiting herbicides was mostly selected for by herbicides with other modes of action. Our study revealed the importance of non‐target site‐based resistance in A. myosuroides. Using herbicides with alternative modes of action to control populations resistant to ACC‐inhibiting herbicides, the recommended management approach, may thus be jeopardised by the widespread occurrence of metabolism‐based resistance mechanisms conferring broad‐spectrum cross‐resistance.  相似文献   

19.
Two field experiments were carried out a year apart on the alkaloid poppy (Papaver somniferum) in 2012 and 2013 in north-west Hungary, to assess the efficacy of mesotrione and tembotrione herbicides for post-emergence weed control. Our experiments tested (1) a single application of mesotrione at 144 g active ingredient (a.i.) ha–1, (2) two separate applications of mesotrione at 144 g a.i. ha–1, (3) a single application of tembotrione at 88 g a.i. ha–1, (4) two separate applications of mesotrione at 88 g a.i. ha–1, and (5) the combination of a single application of mesotrione at 144 g a.i. ha–1 followed by a single application of tembotrione at 88 g a.i. ha–1. Both non-treated and hand-weeded plots were used as controls. Among the most important weeds, Chenopodium album was most successfully controlled in the majority of the test treatments, but Fallopia convolvulus and Polygonum aviculare tolerated each herbicide application in 2012, likely due to the dry weather conditions. Because of the botanical similarity to the crop, none of the treatments proved to be significant against Papaver rhoeas. One dosage of tembotrione alone never reduced the dry weights of the target weed species or weed numbers significantly. The cuticular wax layer of the opium poppy can provide a natural defence against these herbicides, but some temporary phytotoxic yellowish discoloration occurred after tembotrione treatments. Our results show that mesotrione in combination with tembotrione is the most effective treatment and should be employed in poppy cultivation.  相似文献   

20.
Barnyardgrass (Echinochloa crus-galli (L.) Beauv.), an annual species of the family Poaceae, is a major weed problem in rice-producing countries throughout the globe. Synthetic herbicides can effectively control this grass in rice paddies, but the development of resistant biotypes after the continuous use of the same active ingredients has led to low herbicide efficacy and yield losses. In this review, a summary of resistant-barnyardgrass cases in global rice production is reported based on data from the International Herbicide-Resistant Weed Database. The first case of resistant barnyardgrass in rice paddies was to the photosystem-II inhibitor propanil in the late 1980s. Eighty-five (85) out of 116 cases in the period from 1986 to 2022 refer to resistant barnyardgrass (E. crus-galli var. crus-galli, E. crus-galli var. formosensis and E. crus-galli var. zelayensis) in 16 countries. Barnyardgrass has been found resistant to acetolactate synthase (ALS) inhibitors (34 cases), acetyl-CoA carboxylase (ACCase) inhibitors (23 cases), photosystem-II inhibitors (11 cases), auxin mimics/cellulose biosynthesis inhibitors (9 cases), very long chain fatty acid inhibitors (6 cases), and microtubule assembly inhibitors (1 case). The majority of all resistance cases reported to the active ingredients penoxsulam, bispyribac-sodium, and imazamox (ALS inhibitors), cyhalofop-butyl and fenoxaprop-ethyl (ACCase inhibitors), propanil (photosystem-II inhibitors), and quinclorac (auxin mimics/cellulose biosynthesis inhibitors). Although target-site resistance with specific mutations has been identified, non-target site resistance mainly through herbicide detoxification is also of great concern increasing the chance of multiple herbicide resistance evolution. Rotation of herbicides should be adopted concerning the modes of action used as well as the application methods to mitigate resistance evolution of this weed in rice paddies.  相似文献   

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