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1.
Broadcast sprays of several herbicides were applied at different times of the year at several sites in Hawkes Bay, Canterbury and Otago. For good thistle control, date of application was more important than types of herbicide. In Hawkes Bay, applications made in April, May and June tended to be the most effective. Under slightly cooler Canterbury conditions, April, September and October were the best application dates. In the Otago trials, spring emergence of thistle seedlings meant that the most consistent results came from September or October applications. At all sites, applications made in July or August were relatively ineffective, probably because of low winter temperatures and slow thistle growth rates. MCPA (potassium salt) at 1·0 kg ha?1 was the standard herbicide used in all experiments. MCPA at 0·5 kg ha?1, MCPB (sodium salt) at 0·5 and 1·0 kg ha?1 and 2,4-D at 0·5 kg ha?1 did not kill as many thistles as MCPA at 1·0 kg ha?1. MCPA at 1·5 kg ha?1 and MCPB (butyl) ester + clopyralid at 0·5 + 0·015 or 1·0+0·03 kg ha?1 gave consistently better control than MCPA at 1·0 kg ha?1 2,4-D at 1·0 or 1·5 kg ha?1, MCPB at 1·5 or 2·0 kg ha?1, and MCPA + MCPB at 0·33 + 1·0 or 0·67 + 0·5 kg ha?1 gave results very similar to MCPA at 1 kg ha?1. Thistle control varied between sites and years. Some of the variation may have been due to different proportions of first and second year thistles present at spraying, and to variation in genetically determined herbicide susceptibility. Chemical control of thistles was short term only, because of dormant seeds in the soil.  相似文献   

2.
Some aspects of the action of fluazifop-butyl on the chlorophyll content, chloroplast functioning and chloroplast ultrastructure of Elymus repens are reported. Over a period of 0–12 days after spraying with 0.25 or 1.0 kg ha?1 of the herbicide, chlorophyll a and b contents of this susceptible plant decreased, progressing from the youngest to the more mature leaves. Newly formed tillers and the youngest expanding leaves exhibited a more severe type of chlorosis and were often found to be devoid of chlorophyll. A similar progressive decline of the chlorophyll content was observed in an experiment where leaf segments were floated in fluazifop-butyl. Evidence of a rapid and significant alteration of the normal chlorophyll fluorescence of E. repens leaves treated with fluazifopbutyl was obtained. The herbicide, at a concentration range of 0.25–1.0 μg μ1?1, caused a significant loss of the fast fluorescence rise, fluorescence yield and, after 24 h, caused a total abolition of the fluorescence decay (PS decas). These results are discussed. Ultrastructural damage to chloroplasts was seen within 24 h after treatment with fluazifop-butyl. This damage ranged from a partial to total disruption of the outer chloroplast envelope and a disorganization of the internal thylakoid system. Such Ultrastructural effects on chloroplasts were found to intensify up to about 6–7 days after spraying, by which time nearly all chloroplasts in tissue sections were affected to some degree.  相似文献   

3.
Pre-harvest application of glyphosate in barley at 1·44 and 0·72 kg ha?1 was compared with post-harvest application at 1·44 kg ha?1 at six sites in south-east Scotland, three sprayed in 1980 and three in 1981. Both levels of pre-harvest application gave consistent 95–99% control of A. repens compared with 0–76% control from post-harvest application. Yields of crops grown in 1981 were significantly increased after all the 1980 pre-harvest treatments and after one post-harvest treatment. No significant depressions in grain germination were recorded from the lower rate of pre-harvest application but one significant depression was recorded from the higher rate. Combine harvesting throughput at a given grain loss level was significantly improved by pre-harvest application and moisture content of grain at harvest was significantly reduced by up to 2·5%. Wheeling losses from pre-harvest spraying ranged from 1 to 5%. Crop yield increases in the year after spraying compensated for herbicide and application costs plus any yield losses through tractor wheelings.  相似文献   

4.
Field and glasshouse experiments were conducted from 1995 through 1996 to evaluate application timing of asulam (methyl sulfanilylcarbamate) for torpedograss (Panicum repens L.) control in relation to plant age in sugarcane. Above‐ground shoots of torpedograss were completely controlled with asulam at 2–4 kg active ingredient (a.i.) ha?1 applied 60 or 80 days after planting (DAP) in artificially infested pots. But some newly developed rhizome buds survived after asulam application resulting in 1–25 and 76–100% or more regrowth in 60 and 80 DAP‐applied pots, respectively. Whereas the herbicide at 2–4 kg a.i. ha?1 applied within 60 DAP completely controlled above‐ground shoots, applied 80 DAP at 2 kg a.i. ha?1 it did not completely control the weed in the artificially infested field. Regrowth levels were 1–25 and 76–100% or more in 60 and 80 DAP‐applied plots, respectively. Asulam at 2–3 kg a.i. ha?1 applied 20, 40, 60 or 80 DAP in a naturally infested field completely controlled above‐ground shoots and regrowth levels were 76–100 or more, 51–75, 1–25 and 26–50% in these same DAP applied plots, respectively. The herbicide applied at 4 kg a.i. ha?1 caused chlorosis on younger sugarcane leaves (one‐leaf stage), but when applied at 2–3 kg a.i. ha?1, no injury symptoms were shown. The herbicide at 2–4 kg a.i. ha?1 applied within 60 DAP resulted in remarkably higher yield and shoot biomass of sugarcane than that applied 80 DAP. This study suggested that asulam at 2–3 kg a.i. ha?1 should be applied 60 days after planting for the maximum control of torpedograss regrowth and better yield of sugarcane. This study also indicated that torpedograss cannot be completely controlled with a single application of asulam in a naturally infested field because of rhizome fragmentation by cross plowing and distribution of rhizomes into different soil layers that require different times to emerge. The shoots emerging after asulam application could not be controlled. Another study is required to determine the interval between sequential applications of asulam for better control of torpedograss in a naturally infested field.  相似文献   

5.
Various control strategies for Achillea millefolium L. (yarrow) were investigated in a dense stand of the weed at Lincoln College in 1977–1978. In early spring plots were either rotary cultivated or left undisturbed. In late spring, plots of both previous treatments were either left undisturbed, rotary cultivated or sprayed with glyphosate at 1·5 kg ha?1. The whole experiment was rotary cultivated twice 1 week later and sown with Hordeum vulgure L. cv. Zephyr (barley) at 144 kg seed ha?1. MCPA + dicamba at 0·9+0·15 kg ha?1 was applied to half of each plot when the second node was detectable (Zadok 32). Rotary cultivation and glyphosate both substantially reduced the regrowth of A. millefolium but glyphosate reduced regrowth by a greater proportion when applied to undisturbed plants than when applied to plants regenerating after cultivation. Both gave a more than 95% reduction compared to the control (rotary cultivation only at sowing time) in the amount of A. millefolium present in the barley stubble in the autumn. MCPA + dicamba caused seedling mortality but did not affect the numbers of primary shoots from rhizome fragments. The grain yield of the barley increased from 2·91 t ha?1 when A. millefolium was not controlled to 4·23 t ha?1 with good control. The barley yield appeared to be restricted by competition from regenerating A. millefolium and by a nitrogen deficiency induced in some regimes by nitrogen immobilization in decaying rhizomes.  相似文献   

6.
Field experiments at Lacombe on a Ponoka loam soil (9·6% organic matter) during 1982 and 1983 investigated the tolerance of spring wheat (Triticum aestivum L.) cv. Neepawa in a weed free situation to trifluralin applied at 0·0–3·0 kg ai ha?1 in the autumn or spring and incorporated to a depth of 10 cm. Rates of trifluralin above 1·0 kg ai ha?1 applied in the autumn or spring reduced the percent stand of wheat compared to an untreated control. Two weeks after emergence the crop showed 37 or 47% injury indicated by delayed growth, following application at 1·0 kg ai ha?1 in the autumn or spring, respectively. The wheat recovered throughout the course of the growing season. At harvest, trifluralin applied in the autumn or spring at rates below 1·0 kg ai ha?1 caused a yield increase while higher rates caused a yield decrease compared to the untreated control. Spring application caused a greater yield loss than autumn application. The tolerance of spring wheat to trifluralin at rates required for weed control (1·1 kg ai ha?1 or higher) on this soil type is marginal.  相似文献   

7.
Fluazifop-butyl, haloxyfop and sethoxydim with adjuvant oil were applied for three successive growing seasons to established strawberries infested with Elymus repens. The weed was virtually eradicated by three applications of haloxyfop (0.8 kg a.e. ha?1) in successive years. A similar effect was given by five applications of haloxyfop (0.4 kg a.e. ha?1) and fluazifop-butyl (1.6 kg AI ha?1) in three growing seasons. Lower rates of haloxyfop and fluazifop-butyl, and a high rate of sethoxydim (1.6 kg AI ha?1) applied five times were less effective, the ground cover of E. repens shoots not being reduced by the end of the experiment although weight of living rhizome was only 10-30% of that on untreated plots. Fruit yields on treated plots generally reflected the level of E. repens control, but there was some evidence of crop phytotoxicity from herbicide treatments. During the experiment E. repens untreated plots increased from about 30-100% ground cover and reduced yield 13, 28 and 68% in successive years compared with weed-free plots.  相似文献   

8.
We have studied the synergistic action of deltamethrin and prochloraz in bees in laboratory experiments that allowed us to express dosages in terms of field rates (g ha?1). It was established that, used alone, deltamethrin at 0·125 g ha?1 and prochloraz at 25 g ha?1 did not produce mortalities different from that of the control during 96 h of observation. Sprayed as a mixture of these doses, deltamethrin and prochloraz produced 67·5% corrected mortality within 24 h and 74·1% corrected mortality within 50 h. Sequential treatments of deltamethrin and prochloraz spaced by a 0·8-day interval reduced the synergistic action of both molecules. At 50 h, the lethal effects were 27·5% corrected mortality for the treatment of deltamethrin followed by prochloraz and 23·8% corrected mortality for the treatment of prochloraz followed by deltamethrin. Results are discussed in terms of mode of action and sub-lethal effects.  相似文献   

9.
Ammonium-containing fertilizers such as granular limestone ammonium nitrate (LAN) and liquid ammonium nitrate (AN) proved to be most effective in stimulating germination and emergence of wild oat in sandy and loamy soil. In pot experiments, rates as low as 25 kg N ha?1, significantly increased seedling emergence of wild oat. In sandy soil percentage emergence increased with increasing levels of LAN-fertilizer up to 125 kg N ha?1 which gave 76·1 % emergence after 60 days. In control pots where no nitrogen was applied, only 21·6% of seeds planted emerged after 60 days, In loamy soil, as for AN in both soil types, high levels of LAN initially delayed seedling emergence. This negative effect disappeared approximately 15 days after seeding, resulting in no significant difference in emergence of wild oat where 25 to 125 kg N ha?1 was applied as LAN or AN. All these rates, however, increased seedling emergence between 25 and 35% compared to the no-nitrogen treatments. Since the same rate of ammonia gas is not equally effective in breaking dormancy of semi- and deeply dormant wild oat seed, results of these experiments are not necessarily applicable to wild oat seeds differing in dormancy status.  相似文献   

10.
Control of Avena fatua (L.) (wild oat) with diclofop methyl applied at 0·7 kg ha?1 at the two-leaf stage and difenzoquat at 0·84 kg ha?1 at the four-leaf stage in wheat (Triticum aestivum L.) under field conditions was good and not affected when either of these herbicides was mixed with 3,6-dichloropicolinic acid as the monoethanolamine salt at 0·14, 0·20 or 0·30 kg ha?1. In the glasshouse, mixtures containing 3,6-dichloropicolinic acid at rates as high as 0·6 kg ha?1 also did not affect control of A. fatua. When barban at 0·35 kg ha?1, or flamprop methyl at 0·56 kg ha?1 was mixed with similar rates of 3,6-dichloropicolinic acid and applied at the two-leaf and four-leaf stage of A. fatua respectively, a reduction in control of A. fatua (antagonism) occurred under both field and glasshouse conditions. The herbicides for control of A. fatua did not influence the fresh weight suppression of C. arvense shoots obtained in the glasshouse with 3,6-dichloropico-colinic acid at 0·3 kg ha?1. Early tolerance of wheat (cv. Neepawa) was acceptable with all mixtures. Wheat yields with diclofop methyl or difenzoquat alone or in mixture with 3,6-dichloropicolinic acid were increased over the yields from the A. fatua-infested control.  相似文献   

11.
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   

12.
Pre-emergence activity of pendimethalin on propanil-resistant jungle rice (Echinochloa colona) was demonstrated in glasshouse trials. Both susceptible and resistant populations, collected from Costa Rica, were controlled by 1·25 kg ha-1, the usual application rate used in the field where Rottboellia cochinchinensis is also a problem. When applied post-emergence, propanil performance was improved by the addition of low doses of pendimethalin to the herbicide mixture. A propanil-resistant selection was controlled by 0·23 kg ha-1 pendi-methalin+0·54 kg ha-1 propanil at the one-to-two leaf stage, and 0·23 kg ha-1 pendimethalin+1·08 kg propanil at the three-to-four leaf stage compared to 1·08 kg and 2·16 kg ha-1 respectively when propanil was applied alone. This suggests that pendimethalin improves post-emergence control in the field compared to the standard propanil treatment and can provide residual pre-emergence control of late-germinating individuals, so reducing the propanil selection pressure. For effective jungle rice control, growers apply propanil (3·84 kg ha-1) at 10 and 20 days after planting (DAP) followed by one application of fenoxaprop-P-ethyl (0·045 kg ha-1) at 35 DAP. Field experiments, conducted in dry-seeded upland rice in southern Costa Rica, demonstrated that under high jungle-rice population pressure, one application of pendimethalin at 1·5 kg ha-1 provided an effective replacement for propanil, resulting in reduced weed-control costs. ©1997 SCI  相似文献   

13.
Growth inhibition of pot-grown Elymus repens (L.) Gould by fluazifop-butyl was occasionally enhanced by pre-treatment with ethephon. Studies with 14C-labelled fluazifop-butyl showed that ethephon increased the accumulation of 14C in basal buds and proximal parts of the rhizome system. This potential modification in the distribution of fluazifop-butyl within E. repens rhizomes may have reduced regeneration and recovery of the E. repens, particularly from the basal buds, although there was no increase in the proportion of 14C translocated into the rhizome. Also, ethephon not only activated the sinks in the rhizome but in the foliage of E. repens as well, and could initiate buds without sinks. The effects of ethephon on fluazifop-butyl phototoxicity were irregular in their occurrence and degree, and possible reasons for this are discussed. Effets depré-traitements à I'étéphon sur la réponse de Elymus repens au fluazifop-butyl Lors d'expériences en pots, des pré-traitements & 1'étéphon augmentaient occasionnellement 1'inhibition de croissance d'Elymus repens (L.) Gould traité au fluazifop-butyl. Des etudes avec du fluazifop-butyl marqué au 14C ont montré que l'éléphon augmentait l'accumulation de 14Cdans les bourgeons de la base et dans les parties proximales des rhizomes. Bien que la proportion de 14C transportée dans le rhizome ne soit pas accrue, cette modification de la distribution du fluazifop-butyl à l'intérieur des rhizomes d'E. repens pourrait limiter la régénération et la reprise de croissance, en particulier à partir des bourgeons de la base. En outre, l'étéphon activait des puits métaboliques non seulement dans le rhizome mais aussi dans le feuillage d'E. repens et pouvait initier des bourgeons qui ne se comportaient pas comme des puits métaboliques. Tant 1'existence que 1'intensité des effets de 1'étéphon sur la phytotoxicité du fluazifop-butyl étaient irréguliers et les raisons possibles en sont discutées. Wirkung einer Vorbehandlung mit Ethephon auf die Reaktion von Elymus repens (L.) Gould auf Fluazifop-butyl In Gewächshausversuchen war die Wuchshem-mung von Elymus repens durch Fluazifop-butyl gelegentlich durch eine Vorbehandlung mil Ethephon verstärkt. Untersuchungen mil 14C-Fluazifop-butyl ergaben, daß Ethephon die Ak-kumulation von 14C in basalen Knospen und proximalen Teilen des Rhizoms förderte. Die so mögliche Veränderung der Verteilung von Fluazifop-butyl in den Quecke-Rhizomen kann zu der reduzierten Regeneration der Pflanzen geführt haben, vor allem aus den basalen Knospen, obwohl insgesamt keine groBere 14C-Menge im Rhizom gefunden wurde. Ethephon aktivierte nicht nur die Sinks im Rhizom, son-dern auch in den oberirdischen Teilen und kon-nte zur Ausbildung von Knospen ohne Sinks führen. Die Wirkungen des Ethephons auf die herbizide Wirkung des Fluazifop-butyls war unregelmaßig, und die moglichen Grunde dafiir werden diskutiert.  相似文献   

14.
M. ANDREWS 《Weed Research》1990,30(5):331-340
Avena saliva cv. Amuri and A. fatua were sprayed with diclofop methyl (1.0 kg a.i. ha?1) alone and in combination with 2,4-D (1.1 kg a.i. ha?1), bentazone (1.0 kg a.i. ha?1), chlorsulfuron (15 g a.i. ha?1) or dicamba (0.3 kg a.i. ha?1). Effects of the herbicides on leaf extension rate during the first 8 to 10 days after spraying and subsequent growth (dry weight) after 57–75 days were determined by comparison with unsprayed plants. Diclofop-methyl applied alone did not cause a decrease in leaf extension rate of A. saliva or A. fatua until at least 4 days after spraying. All broadleaf weed herbicides in combination with diclofop-methyl caused a decrease in leaf extension rate of both species within 2 days of spraying. Ten days after spraying, leaf extension rates for plants sprayed with a broadleaf weed herbicide plus diclofopmethyl (all combinations) were lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. With the exception of A. fatua sprayed with bentazone, long-term growth of plants sprayed with a broadleaf weed herbicide plus diclofop-methyl (all combinations) was lower than for unsprayed plants but greater than for plants sprayed with diclofop-methyl alone. Bentazone applied with diclofop-methyl caused a substantial decrease in leaf extension rate of A. fatua within 24 h of spraying but at harvest, dry weight of plants from this treatment was similar to or less than that for plants sprayed with diclofop-methyl alone. Application of diclofop-methyl with bentazone at a rate of 0.3 kg a.i. ha?1 also caused a reduction in leaf extension rate of A. fatua within one day of spraying. At this rate of bentazone, dry weight of plants at harvest was intermediate to that of unsprayed plants and those sprayed with diclofop-methyl alone. It is proposed that decreased leaf expansion rate during the first few days afte spraying is the cause of broadleaf weed herbicide antagonism of diclofop-methyl.  相似文献   

15.
Losses of about 40% in cane yields due to natural stands of weeds were found in experiments conducted in sugarcane var. Co 527 in the year of planting at Guneid Sugarcane Research Station, Sudan. Weed competition lowered millable stalks per metre row by 32%, stalk height by 24%, stalk thickness by 15% and number of nodes per stalk by 14%. Tillering was the growth phase most affected by weed competition. Cane yields were increased as number of hand weedings increased, but four weedings were not markedly better than three. The average yield (67·04 t ha?1) obtained from four weedings was not significantly (P= 0·05) better than that of three weedings carried out at 3, 6 and 9 weeks after cane planting. Juice analysis components were also affected by weeds and a 15% reduction in sucrose recovery was recorded. Reductions in the other components were only 4–7%. Atrazine and diuron (3·3 kg ha?1), metribuzin (2·4 kg ha?1) and metribuzin (1·3 kg ha?1) in tank mixture with diuron (1·5 kg ha?1) gave excellent residual weed control of the dominant weed species, Ipomoea cordofana Choisy., Brachiaria eruciformis (Sm.) Griseb., Corchorus fascicularis Lam., Ocimum basilicum L. and Dinebra retroflexa (Vahl) Panz., for most of the first growing season. Excellent control of weeds achieved by the herbicide treatments resulted in comparable yields to frequently-weeded cane. These herbicides were not phytotoxic to sugarcane var. Co 527.  相似文献   

16.
Unrestricted weed growth reduced the yield of transplanted onions (Allium cepa L.) by 26–48%. Hand-weeding once, 42 days after transplanting reduced the yield loss to 15%. Application of oxadiazon (1.1–1.3 kg ai ha?1), pendimethalin (1.2–1.8 kg ai ha?1), oxyfluorfen (0.14–0.43 kg ai ha?1) and chlorthal-dimethyl (8.3–13.1 kg ai ha?1) resulted in yields comparable to the hand-weeded control (82–126%). When sprayed at transplanting these herbicides gave excellent and persistent control of grasses (86–100%). However, they were less effective on broad-leaved weeds (38–94% control). Désherbage chimique de l'oignon repiqué (Allium cepa L.) dans la Gezireh soudanaise La croissance incontrôlée des mauvaises herbes réduit le rendement des oignons repiqués de 26–48%. Un désherbage manuel, 42 jours après le repiquage, ramène la baisse de rendement à 15%. L'application d'oxadiazon (1,1–1,3 kg ma ha?1), de pendiméthalin (1,2–1,8 ka ma ha1), d'oxyfluorfen (0,14–0,43 ka ma ha?1) et de chlortal-diméthyle (8,3–13,1 kg ma ha?1), a permis d'atteindre des rendements comparables aux témoins désherbés manuellement (82–126%). Lorsqu'ils ont été administrés au moment du repiquage, ces herbicides ont permis un contrôle efficace et persistant des monocotylédones (86–100%). Toutefois, ils se sont montrés moins efficaces à l'égard des dicotylédones (38–94% du témoin). Chemische Unkrautbekämpfung in verpflanzten Zwiebeln (Allium cepa L.) in der Region Gezira (Sudan) Ungehinderte Unkrautentwicklung in verpflanzten Zwiebeln (Allium cepa L.) verringerte die Ernte um 26–48%. Eine Handjätung, 42 Tage nach dem Auspflanzen, reduzierte den Ernteverlust auf 15%. Die Applikation von Oxadiazon (1,1–1,3 kg ai ha?1), Pendimethalin (1,2–1,8 kg ai ha?1), Oxyfluorfen (0,14–0,43 kg ai ha?1) und Chlorthal- dimethyl (8,3–13,1 kg ai ha?1) erbrachte Ernten, die mit denjenigen, der von Hand gejäteten Kontrollparzellen vergleichbar waren (82–126%). Diese Herbizide, zur Ausflanzzeit ausgebracht, ergaben eine ausgezeichnete und andauernde Kontrolle von Gräsern (86–100%), während die Wirkung gegen breitblättrige Unkräuter geringer ausfiel (38–94%).  相似文献   

17.

Weeds are a major biotic constraint; compete with crop for the same resources and ultimately reduce productivity. This study evaluated the impact of irrigation intervals and weed management treatments on chlorophyll content and morphological growth of tomato to find an appropriate integrated weed management strategy. Two-year field experiments (2018/2019) were conducted at district Mardan (34°15′38″ N and 72°6′36″ E). Tomato F1 hybrid (Taj?3592) was transplanted during March. The experiments were laid out in a randomized complete-block design in split-plot arrangement with three replications. The main block comprised three irrigation intervals (3, 6, and 9 days) and the sub-block included weed management treatments: transparent polythene, black polythene, weeding except Orobanche, sole weeding of Orobanche, weeding of all weeds, copper oxychloride 1.5?kg a.i ha?1 (single dose), copper oxychloride 1.5?kg a.i ha?1 (split doses), copper oxychloride?+?humic acid 25?kg ha?1 (single dose), copper oxychloride?+?humic acid 25?kg ha?1 (split doses), copper sulphate 2?kg ha?1 (single dose), copper sulphate 2?kg ha?1 (split doses), ammonium sulphate 200?kg ha?1 (single dose), ammonium sulphate 200?kg ha?1 (split doses), pendimethalin 33 EC 1.44?kg a.i ha?1, glyphosate 48 SL 1.5?kg a.i ha?1, and weedy check. Lowest relative weed density (RWD) of O. cernua (2.23%) and highest RWD of O. cernua (38.01%) were recorded in the 3? and 9?day irrigation intervals, respectively. However, 3?day irrigation interval resulted in highest fresh weed biomass (5794?kg ha?1). Moreover, the 6?day irrigation interval significantly increased chlorophyll content by 11 and 5%, leaf area by 23 and 6%, and number of branches plant?1 by 30 and 22% compared to 9? and 3?day irrigation intervals, respectively. Among the weed management treatments, black polythene resulted in the highest weed control efficiency (96%), increasing chlorophyll content by 16%, leaf area by 33%, and number of branches plant?1 by 64% vs. weedy check. Consequently, 6?day irrigation intervals?×?black polythene could be the best weed management strategy, followed by transparent polythene, weeding of all weeds, pendimethalin, glyphosate, and ammonium sulphate.

  相似文献   

18.
Field studies were conducted over a 4-year period to determine whether weed emergence could be increased by incorporating germination stimulants into the soil. Sodium azide (4.5–36 kg azide ha?1), ammonium nitrate (34–67 kg nitrate ha?1), and butylate (0.2–0.4 kg ai ha?1) were used. Sodium azide was the most consistent stimulant of indigenous weed emergence over all experiments and seasons, but there was great variability in its effects and the highest application rate sometimes inhibited emergence. Consistent stimulation of broad-leaf weed emergence occurred following September applications of 4–5 kg azide ha?1 of sodium azide. Sodium azide at 4.5 kg azide ha?1 increased grass plus broad-leaf weed emergence 43% based on summer applications in three growing seasons. No general recommendation for stimulating the emergence of weeds can be made because stimulation was a function of rate of application, season of the year, and post-treatment environment. Influence de traitments chimiques sur la levée des mauvaises herbes Des études portant sur une durée de quatre ans ont été conduites afin de déterminer si l'incorporation dans le sol de stimulants de germination pouvait augmenter la levée des mauvaises herbes. Les produits essayés ont été le nitrure de sodium (4, 5–36 kg de nitrure ha?1), le nitrate d'ammonium (34–67 kg nitrate ha?1), et le butylate (0, 2–0, 4 kg ma ha?1). C'est avec le nitrure de sodium que la stimulation de la levée des graines en place a été observée le plus régulièrement, au cours de plusieurs expériences effectuées en différentes saisons; cependant, une grande variabilité de l'effet de ce produit a été notée, et les doses d'application les plus élevées ont parfois inhibé les levées. Appliqué en septembre à la dose de 4, 5 kg nitrure ha?1, le nitrure de sodium stimule d'une manière régulière la levée des dicotylédones. Des traitements d'été opérés durant trois années ont montré qu'à cette dose, il augmente la levée des mono et des dicotylédones de 43%. Il n'est cependant pas possible de donner des recommandations générales pour la stimulation des levées de mauvaises herbes, car cette stimulation dépend de la dose appliquée, de la saison pendant laquelle elle est opérée, et des conditions qui régnent après le traitement. Chemische Beeinflussung des Auflaufens von Unkräutern In einer über vier Jahre laufenden Feldstudie wurde untersucht, ob durch das Einarbeiten von Keimungsstimulatoren das Auflaufen von Unkräutern beschleunigt werden kann. Zu die-sem Zweck wurden Natriumazid (4, 5–36 kg azid ha?1), Ammoniumnitrat (34–67 kg nitrat ha?1) und Butylat (0, 2–0, 4 kg ai ha?1) verwendet. Natriumazid war in allen Versuchen das am regelmässigsten wirksame Auflaufstimulans für die an den verschiedenen Standorten vorkommenden Unkräuter, wobei die höchsten Applikationsraten hin und wieder das Auflaufen hemmten. Applikationen von 4, 5 kg azid ha?1 Natriumazid im September erhöhten die Auflaufrate regelmässig; sie wurde in drei Vegetations-perioden bei grasartigen und breitblättrigen Unkräutern um 43%, vergleichen mit den Sommerapplikationen, gesteigert. Es kann keine all-gemein gültige Anwendungsempfehlung gegeben werden, da der Stimulationseffekt stark von Dosierung, Jahreszeit und den Umweltsbedingungen nach der Applikation abhängt.  相似文献   

19.
J. E. DALE 《Weed Research》1985,25(3):231-238
Experimental granules were made from moistened calcareous loess (pH 8·5) containing 2% w/w gum xanthan and chloramben sodium salt at w/w concentrations of 0·4–3·6%. Haloxyfopmethyl * * Approved WSSA common name.
(DOWCO-453 ME) {Methyl 2-(4-((3-chloro-5-(trifluoromethyl)-2-pyridinyl)oxy)-phenoxy)propanoate) was dissolved in tung oil at a range of concentrations and poured on the dried chloramben granules with stirring. In the glasshouse, dry granules containing chloramben plus haloxyfop-methyl spread pre-emergence at the rate of 0·8 + 0·4 kg ha?1 reduced the dry weight of maize (Zea mays L.), red rice (Oryza sativa L.), Abutilon theophrasti Medic., and Sesbania exaltata (Raf.) Cory by 89, 100, 94, and 68%, respectively, with no injury to soybeans [Glycine max (L.) Merr.]. Coated granules spread pre-emergence controlled A. theophrasti and volunteer maize grown from seed sown in soil up to 10 cm deep. In a preliminary field test, the experimental granules reduced numbers of weeds in soybeans and improved crop yield. Ten weeks after treatment, chloramben granules coated with haloxyfop-methyl gave 97% control of Sorghum halepense (L.) Pers compared to 80% by uncoated granules. Linuron granules coated with haloxyfop-methyl gave 85% control compared to 12% by uncoated granules. Yields in plots treated with coated and uncoated chloramben were 3280 and 2700 kg ha?1, respectively. In coated and uncoated linuron plots, yields were 2920 and 2340 kg ha?1, respectively. Except for the uncoated linuron plot, all yields were significantly higher than 2050 kg ha?1 obtained in the weedy untreated plot.  相似文献   

20.
Two bioassay procedures, using petri-dishes and pots, based on the root growth of pregerminated maize were used to study the residual phytotoxicity of chlorsulfuron under field conditions. Both bioassay procedures appeared to be equally reproducible and sensitive with residues of chlorsulfuron being detectable from 0·25 to 10·0 ng g-1. The results indicated that persistence, movement and phytotoxicity increased with increasing rate of chlorsulfuron, but persistence of the herbicide was shorter in wet compared to dry field conditions. As little as 1 g a.i. ha-1 of incorporated chlorsulfuron under warm and dry field conditions caused a stunting effect on maize plants (Hybrid F1, Damon) and reduced yield by 53% compared to untreated control plants; while 5·0 and 10·0 g a.i. ha-1 of incorporated chlorsulfuron killed all maize plants. However, under wetter field conditions, incorporated chlorsulfuron at 1·25, 2·5 and 5·0 g a.i. ha-1 caused a stunting effect on maize plants (Hybrid F1, ARIS) and decreased yield by 16, 57 and 92%, respectively, compared to untreated control. Incorporation of 50 kg ha-1 of activated charcoal inactivated completely chlorsulfuron incorporated at 1·25 and 2·5 g a.i. ha-1 and did not affect yield of maize compared to untreated control. Higher rates of activated charcoal such as 100 and 200 kg ha-1 also inactivated chlorsulfuron applied at 1·25–5·0 g a.i. ha-1 and did not affect grain yield of maize. Phytotoxicité et persistance du chlorsulfuron Deux méthodes d'essais biologiques, à savoir en boîte de Petri ou en pot, Basées sur la croissance des racines de maïs prégermé ont été utilisées pour étudier la phytotoxicité résiduelle du chlorsulfuron en conditions de plein champ. Les deux méthodes sont également reproductibles et sensibles à des niveaux de détection pour les résidus de chlorsulfuron de 0,25 à 10 ng g-1. Les résultats montrent que la persistance et la phytotoxicité augmentent avec des doses croissantes de chlorsulfuron, mais la persistance est plus courte dans des conditions de plein champ humides que séches. Une dose aussi faible que 1 g de matiére active ha-1 de chtorsulfuron incorporé en conditions chaudes et séches a causé un effet retard sur les plants de maïs (hybride F1, Damon) et a réduit de 53% le rendement par rapport au témoin non traité; des doses de 5 à 10 g de matiére active ha-1 de chlorsulfuron incorporé ont tué tous les pieds de maïs. Cependant, en conditions plus humides, le chlorsulfuron incorporéà 1,25, 2,5 et 5 g de matiére active ha-1 a causé un effet retard sur le maïs (hybride F1 ARIS) et a réduit le rendement par rapport au témoin non traité respectivement de 16, 57 et 92%. L'incorporation de 50 kg ha-1 de charbon actif a complément inactive le chlorsulfuron incorporéà 1,25 et 2,5 g de matiére active ha-1 et n'a pas eu de répercussion sur le rendement par rapport au témoin non traité. Des doses plus élevées de charbon actif comme 100 et 200 kg ha-1 ont inactivé le chlorsulfuron appliquéà 1,25–5 g matiére active ha-1et n'ont pas affecté le poids en grain du maïs. Ueber die Beeinflussung von Phytotoxizität und Wirkungsdauer von Chlorsulfuron durch Aklivkohle Zum Studium der Residualwirkung von Chlorsulfuron unter Feldbedingungen wurden zwei Bioassaymethoden, eine in Petrischalen, die andere in Töpfen, eingesetzt. Beide Methoden basierten auf dem Wurzelwachstum von vorgekeimtem Mais. Es zeigte sich, dass beide Versuchsverfahren in gleichem Masse reproduzierbar und empfindlich und in der Lage sind Rückstände von 0,25–10,0 ng g-1 nachzuweisen. Mit steigender Chlorsulfurondosis wurde eine zunehmende Phytotoxizität, Persistenz und Mobilität des Herbizids festgestellt. Die Persistenz war unter feuchten Feldbedingungen kürzer als bei Trockenheit. Bis zu einer unteren Grenze von 1,0 g a.i. ha-1 verursachte inkorporiertes Chlorsulfuron, unter trockenen und warmen Feldbedingungen an Mais (Hybride F1, Damon) Wachstumshemmungen und Erntereduktionen von 53%, verglichen mit unbehandelten Kontrollpflanzen. Unter feuchteren Bedingungen, jedoch, hatten 1,25, 2,5 and 5,0 g a.i. ha-1 eingearbeitetes Chlorsulfuron an Mais (Hybride F1 ARIS) Wachstumshemmungen und Ernteverluste von 16, 57 und 92% zur Folge. Die Einarbeitung von 50 kg ha-1 Aktivkohle inaktivierte 1,25 g und 2,5 g ha-1 inkorporierles Chlorsulfuron vollständig und hatte keinerlei negative Auswirkungen auf die Maisernte, im Vergleich zu unbehandelten Kontrollen. Höhere Mengen von Aktivkohle, wie 100 und 200 kg ha-1, inaktivierten auch Chlorsulfuronmengen von 1,25–5 g ha-1 und hatten keinen Einfluss auf den Kömerertrag.  相似文献   

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