Control Of Broad-leaved Weeds Research Articles

Comparative RFLP mapping of the chlorotoluron resistance gene (Su1) in cultivated wheat (Triticum aestivum) and wild wheat (Triticum dicoccoides).

Chlorotoluron is a selective phenylurea herbicide widely used for broad-leaved and annual grass weed control in cereals. Variation in the response to chlorotoluron (CT) was found in both hexaploid bread wheat (Triticum aestivum L.) and wild tetraploid wheat (Triticum dicoccoides KöRN.). Here, we describe the comparative mapping of the CT resistance gene (Su1) on chromosome 6B in bread and wild wheat using RFLP markers. In bread wheat, mapping was based on 58 F(4) single-seed descent (SSD) plants of the cross between a genotype sensitive to chlorotoluron, 'Chinese Spring' (CS), and a resistant derivative, the single chromosome substitution line, CS ('Cappele-Desprez' 6B) [CS (CAP6B). In T dicoccoides, mapping was based on 37 F(2) plants obtained from the cross between the CT-susceptible accession B-7 and the resistant accession B-35. Nine RFLP probes spanning the centromere were chosen for mapping. In bread wheat Su1 was found to be linked to alpha-Amy-1 (9.84 cM) and Xpsr371 (5.2 cM), both on the long arm of 6B, and Nor2 (2.74 cM) on the short arm. In wild wheat the most probable linkage map was Nor2-Xpsr312-Su1-Pgk2, and the genetic distances between the genes were 24.8cM, 5.3cM, and 6.8cM, respectively. These results along with other published map data indicate that the linear order of the genes is similar to that found in T. aestivum. The results of this study also show that the Su1 gene for differential response to chlorotoluron has evolved prior to the domestication of cultivated wheat and not in response to the development and use of chemicals.

Flupoxam Induces Classic Club Root Morphology but Is Not a Mitotic Disrupter Herbicide

Flupoxam, an herbicide representative of a powerful new class of herbicides intended for control of broad-leaved weeds in cereals, has been identified as a mitotic disrupter herbicide. Flupoxam was evaluated on watercress seedlings for evidence of antimicrotubule effects characteristic of mitotic disrupter herbicides. At 1 μM,flupoxam inhibited root elongation and induced club root morphology. However, examination by light microscopy and tubulin immunofluorescent microscopy revealed that flupoxam is not a mitotic disrupter herbicide.

A Review of Analytical Methods for Sulfonylurea Herbicides in Soil

Abstract The sulfonylurea herbicides are a group of about twenty compounds used for the control of broad-leaved weeds and some grasses in cereal crops. These herbicides are non-volatile, and their water solubilities are pH dependent being greater in alkaline than in acidic solutions. Their soil adsorption is generally low, with leaching potential in alkaline field soils. Sulfonylurea herbicides are degraded in soils by both chemical and biochemical mechanisms. Chemical degradation is particularly important in acidic soils where herbicide degradation is considerably more rapid that in soils of pH > 7. Application rates in the order of 10 g ha−1 necessitate analytical techniques capable of quantifying soil based residues in the sub μ kg−1 levels. Analytical methodologies based on plant bioassays, and chemical extraction followed by gas chromatographic (GC), high performance liquid chromatographic (HPLC), and enzyme immunoassay techniques are described and discussed.

Identification of Microbial and Rat Metabolites of Triflusulfuron Methyl, A New Sugar Beet Herbicide

Triflusulfuron methyl (methyl 2-[[[[[4-(dimethylamino)-6-(2,2,2-trifluoroethoxy)-1,3,5-triazin-2-yl]amino]carbonyl]amino]sulfonyl]-3-methylbenzoate) is a new selective low use rate sulfonylurea herbicide for the control of many broad-leaved weeds and grasses in sugar beets. Our studies show the compound undergoes rapid microbial metabolism using Streptomyces griseolus and that a mixture of similar metabolites is excreted by triflusulfuron methyl-dosed rats. Nine intact sulfonylurea metabolites were tentatively identified in microbial studies, and five of these were later identified in urine or feces of rats dosed with radiolabeled triflusulfuron methyl. Metabolic reactions include alkyl and/or aryl oxidation, N-dealkylation, and ester hydrolysis. All identifications were made using liquid chromatography/mass spectrometry (LC/MS) with fast atom bombardment (FAB) ionization. FAB mass spectra gave strong protonated molecular ions and structurally useful fragment ions of these extremely thermally labile metabolites

Mustard tolerance to clopyralid applied alone or with ethametsulfuron

Mustard is a drought-tolerant crop well adapted to the Brown and Dark Brown soils of the Prairies; however, lack of broad-leaved weed control limits production. Two field studies were conducted at Indian Head, Saskatchewan and Lethbridge, Alberta to determine the response of brown and oriental mustard (Brassica juncea (L.) Coss), and yellow mustard (B. hirta Moench) to clopyralid. Clopyralid was applied at 0.10, 0.15, 0.20, 0.30, 0.60 kg a.i. ha−1 at the 4- or 10-leaf stage in one experiment. The other was a factorial experiment of clopyralid at 0.10, 0.20, and 0.30 kg a.i. ha−1 with ethametsulfuron at 0.01, 0.02, and 0.03 kg a.i. ha−1. Clopyralid applied at 0.15 kg a.i. ha−1, the lowest rate at which it is registered for weed control in canola, resulted in brown mustard yield reductions of 21%, oriental mustard yield reductions of 23% and yellow mustard yield reductions of 9% over 5 site years. This rate of clopyralid applied with ethametsulfuron reduced brown, oriental and yellow mustard yield by 30, 33 and 8%, respectively. Oil content was also reduced by clopyralid. Clopyralid cannot be used for weed control in mustards. Key words: Crop tolerance, growth stage, clopyralid, ethametsulfuron, seed yield, oil content

Performance of reduced herbicide doses in spring cereals

The consequences of dose reduction of three new herbicide formulations were studied for the control of annual broad-leaved weeds in fields of spring barley (Hordeum vulgare L.) and spring wheat (Triticum aestivum L.). The herbicide formulations were MCPA/mecoprop-P, MCPA/dichlorprop-P and MCPA/fluroxypyr. The efficacy of the lowest recommended dose and a 30% lower rate were tested and compared with the reference herbicide tribenuron-methyl. Trials were conducted at seven sites for three years. Considerable annual fluctuations in weed infestation were recorded. Although the dose reduction occasionally caused considerable decline in control (on %-scale), suppression of weed biomass was still satisfactory in most of the trials. On average, a 75% reduction of weed biomass in spring barley and an 83% reduction in spring wheat were achieved with reduced herbicide doses. Use of reduced herbicide doses for three years in the same fields caused neither a significant increase in weed infestation nor changes in the species composition of weed populations compared with treatments at recommended rates of application. There was a significant difference in biomass production between weed species. Consequently, the total biomass production of annual dicotyledonous weeds correlated only weakly (r=0.48) with the total weed density. Even in untreated plots the weed biomass at harvest constituted, on average, only 3.1-3.6% of the total vegetative biomass of crop stands. Thus, the crop yield responses to chemical weed control remained low.

Broadening weed control with imazamethabenz combinations

Broad-spectrum weed control by use of imazamethabenz (AC 222 293) in herbicide combinations was investigated in the greenhouse. Imazamethabenz at rates ranging from 0·1 to 0·4 kg a.i./ha effectively controlled wild oats ( Avena fatua L.). Additional control of redroot pigweed ( Amaranthus retroflexus L.) was achieved when imazamethabenz, plus octoxynol surfactant, was applied in combination with MCPA (amine or ester) or commercial MCPA mixtures (bromoxynil/MCPA and cyanazine/MCPA). Only inclusion of propanil/MCPA in the combination reduced wild-oat control by imazamethabenz at the lower rate (0·1 kg/ha). Control of green foxtail ( Setaria viridis (L.) Beauv.) was also obtained by use of fenoxaprop-ethyl in combination with imazamethabenz (plus octoxynol). Three-way mixtures of imazamethabenz (or plus octoxynol), MCPA alone or mixture, and fenoxaprop-ethyl may provide practical control of grass and broad-leaved weeds in the field.

Yield response to pre-emergence control of broad-leaved weeds in winter cereals with isoxaben in France

A series of 59 trials was designed to assess the yield response to the control of broad-leaved weeds in winter cereals in the 1982/83, 1983/84 and 1984/85 seasons. When apllied pre-emergence to winter cereals, isoxaben provided season-long control of a wide spectrum of broad-leaved weeds including Veronica spp., Viola spp., Stellaria media, Aphanes arvensis, Papaver rhoeas and Matricaria spp. In 22 trials on winter barley and 37 trials on winter wheat treated pre-emergence with isoxaben in the autumn, mean yield increases of 0 · 22 t/ha and 0 · 14 t/ha respectively were recorded over that produced by herbicide combinations applied as post-emergence treatments in the spring. The mean yield increases with isoxaben over untreated controls were 0 · 30 t/ha and 0 · 26 t/ha on winter barley and winter wheat respectively.

CHEMICAL WEED CONTROL IN NEWLY PLANTED RASPBERRIES IN COASTAL BRITISH COLUMBIA

Over a 5-yr period (1980–1984) the efficacy of napropamide, simazine and terbacil applied singly and in mixture was investigated when applied to newly planted raspberries (Rubus idaeus L. ’Willamette’). Napropamide (4.48–8.97 kg/ha) gave less than satisfactory to good broadleaved weed control and excellent annual bluegrass and barnyard grass control. There was little improvement in efficacy with increased rate except when lady’s-thumb and shepherd’s-purse were the major weeds. Simazine (1.12–2.24 kg/ha) gave good to excellent broadleaved weed and grass control. Creeping yellow cress invaded the simazine-treated plots later in the season. Terbacil (0.67–2.24 kg/ha) generally gave good to excellent broadleaved weed and grass control except when common groundsel and pineappleweed were the major weeds. Significant year × herbicide × planting method interactions occurred on yields and plant vigor. Napropamide caused some reduction in the number of primocanes at emergence and some growth retardation. But, by late August, in all plots the primocane height was equal to or better than those in the control plots. First year fruit yields were not affected detrimentally. In 1 yr only (1980) primocane emergence from root cuttings initially was reduced by simazine at 2.24 kg/ha but not from dormant canes. There was no difference in primocane number or height by late August in any year. Yields were not affected. Again, depending on the year and rate, terbacil caused various degrees of injury from chlorosis to necrosis of new primocane growth. This injury was reflected in decreased yields in plants from root cuttings but not from dormant canes. Napropamide (1.1–2.2 kg/ha) in combination with simazine (0.6–1.1 kg/ha) or terbacil (0.34–0.67 kg/ha) showed considerable promise by the elimination of crop injury and the broadening of the weed control spectrum during early establishment of the raspberry plantation. There was no herbicide × planting method interaction for primocane height and number, although year effect was highly significant. Yields were equal to or greater than those from the control plants.Key words: Napropamide, simazine, terbacil, raspberry tolerance, raspberry, Rubus idaeus L.

Weed Competition, Yield and Tuber Size of Potato as Affected by Herbicides Under Sudanese Conditions

SUMMARYThe effects on the potato crop of the herbicides metribuzin, linuron and metobromuron, singly and in combination with each other and with hand weeding, were investigated and compared with cropped and uncropped weedy controls. Weed competition was determined by measuring weed dry weight. When the three herbicides were applied singly metribuzin gave the lowest weed dry weight, while the combination of metribuzin, metobromuron and hand weeding gave the lowest weed dry weight per unit area of all treatments in both seasons. However, the best potato yield was obtained from the combination of metribuzin and hand weeding. Metobromuron consistently reduced yield through reduction of tuber size irrespective of its effect on weed competition. Metribuzin was the best herbicide for the control of broad leaved weeds and many grasses.

An evaluation of pre-emergent herbicides for container-grown ornamental plants

Two applications of 5 herbicides were evaluated during spring and summer for weed control and phytotoxicity on 25 species of trees, shrubs and herbaceous perennials. Weed control was considered to be effective if herbicide-treated pots contained at most 20% of the weeds in untreated pots. Oxyfluorfen applied at 1.25, 2.5 and 5.0 kg ha −1 provided effective control of grass and broad-leaved weeds for 8 weeks after the first application, and the 2 higher rates effectively controlled all weeds for 12 weeks after the second application. Oxadiazon at 2.0, 4.0 and 8.0 kg ha −1 effectively controlled all weeds for 8 weeks after the first application, but only the highest rate was effective 12 weeks after the second application. Napropamide at 5.0, 10.0 and 20.0 kg ha −1 effectively controlled grasses for up to 12 weeks, but only effectively controlled broad-leaved weeds at the 2 higher rates for 8 weeks after the first application and failed to control them after the second application. Alachlor at 4.0, 8.0 and 16.0 kg ha −1 and oryzalin + trifluralin at 0.5, 1.0 and 2.0 kg ha −1 provided effective control of grasses for 8 weeks after the first application. These herbicides at the highest rate also controlled broad-leaved weeds for 8 weeks after the first application. However alachlor and oryzalin + trifluralin failed to provide effective control of any weeds after the second application. Competition from weeds reduced the shoot dry weight (SDW) of unweeded control pots by 20% compared with hand-weeded control pots. None of the herbicides produced visible clamage in any plants. The SDW of 8 species treated with some of the herbicides was significantly lower than the corresponding hand-weeded control plants, and for 6 of these species some herbicide treatments were identified as being possibly phytotoxic. Oxyfluorfen appeared to inhibit the growth of Photinia and Coleonema, and alachlor inhibited the growth of Photinia, Eriostemon, Azalea ‘Splendens’, Lavendula and Coleonema. Oryzalin + trifluralin appeared to inhibit the growth of Bauhinia, and napropamide and oxadiazon inhibited the growth of Coleonema.

CONTROL OF BROADLEAVED WEEDS IN CREEPING RED FESCUE GROWN FOR SEED

Field studies were conducted from 1977 to 1981 on the control of dandelions (Taraxacum officinale L.) and other broadleaved weeds in creeping red fescue (Festuca rubra var. geniuna L.). Creeping red fescue was established either alone or with a companion crop of barley (Hordeum vulgare L.) or rapeseed (Brassica campestris L.). The barley was harvested in early August for fodder or in early September for grain. Several herbicide treatments were applied to each crop situation. Bromoxynil plus MCPA applied at 0.28 + 0.28 kg a.i./ha when the creeping red fescue was in the three-leaf stage (and 1–2 mo old) controlled 75% or more of the annual weeds during the year of seeding. This herbicide combination also provided substantial control of dandelions and other weeds during the year following seeding. A second herbicide treatment of dicamba plus 2,4-D at 0.28 + 0.56 kg a.i./ha in May of the year following seeding provided an improvement in the control of dandelions and other weeds over the single application of bromoxynil plus MCPA in some but not all seedings. The use of rapeseed as a companion crop without any herbicide treatments did not provide consistent weed control. Seed yields during the second production year were increased by 25% or more from the use of herbicide treatments when creeping red fescue was seeded alone or with barley harvested for fodder. First production year seed yields were not increased by any of the herbicide treatments. Similarily, first and second production year seed yields were not increased by any of the herbicide treatments when creeping red fescue was seeded with barley harvested for grain. Harvesting barley as fodder rather than grain produced marginally higher first production year creeping red fescue seed yields but had no effect on second production year seed yields.Key words: Creeping red fescue, dandelion, companion crop, 2,4-D plus dicamba, MCPA plus bromoxynil

Research on the control of wild oats and broad-leaved weeds by herbicide mixtures

The large number of pesticides which are frequently required for crop protection makes it impracticable to apply them individually to crops, and there has been increasing resort to the use of mixtures of chemicals. This presents difficulties, however, in that the overall effect of a mixture is often different from the sum of the effects of its components: this may be apparent as reduced performance or even crop damage. This article describes some of the most severe antagonisms that have been observed, the results of investigations into their causes, and methods of overcoming them.

Effect of ammonium sulphate and related salts on the phytotoxicity of dichlorprop and other herbicides used for broadleaved weed control in cereals

SummaryIn glasshouse experiments, additions of 10–100 g 1−1 ammonium sulphate enhanced the phytotoxicity to broadleaved weeds and cereals of several water‐soluble herbicides applied post‐emergence in 75–300 1 ha−1 with hydraulic nozzles. Studies with dichlorprop potassium salt and chickweed Stellaria media (L.) Vill. examined interactions between ammonium sulphate and environmental, application and formulation factors. Simulated rainfall immediately after spraying greatly reduced dichlorprop activity, whether or not ammonium sulphate was present. However, when there was an interval of 2–24 h between spraying and rainfall, the additive increased phytotoxicity. Surfactants tended to reduce dichlorprop phytotoxicity to Stellaria media, both in the presence and absence of ammonium sulphate. Certain other inorganic salts including sodium sulphate also enhanced phytotoxicity. Applications by rotary atomizer in very low spray volume (15 1 ha−1, 250–280 μm drops) were less effective than conventional 150 1 ha−1 applications. When very low volume application was used, addition of ammonium sulphate or nitrate tended to reduce activity further. In the field, ammonium sulphate significantly increased the effects against weeds of a commercial dichlorprop potassium salt formulation applied conventionally in 200 1 ha−1 spray volume. Neutralized phosphoric acid had a similar effect but a mixture of this additive and ammonium sulphate reduced phytotoxicity. Both additives slightly increased dichlorprop injury to barley.

INFLUENCE OF SEVERAL HERBICIDES FOR BROAD-LEAVED WEED CONTROL AND TWEEN 20 ON THE PHYTOTOXICITY OF PARAQUAT

Paraquat at 0.28 kg/ha provided excellent control of barley (Hordeum vulgare L.), wheat (Triticum aestivum L.) and oats Avena sativa L.) when applied at the four-leaf stage of growth. Applications of paraquat in tank mixtures with ester formulations of 2,4-D, MCPA, bromoxynil or bromoxynil/MCPA did not affect paraquat activity on the grasses. Tank mixtures of paraquat with dimethylamine formulations of 2,4-D and MCPA resulted in a permanent reduction of paraquat activity on the annual grass species. Sequential applications of 2,4-D amine or MCPA amine in relation to paraquat did not reduce paraquat activity on the annual grass species. Control of rapeseed (Brassica campestris L.) with 0.28 kg/ha paraquat was not acceptable and was variable. However, excellent control of rapeseed was obtained when one of several herbicides for broad-leaved weed control were combined with paraquat.

Weed control in peanuts in north Queensland

Experiments conducted over two seasons with Virginia Bunch peanuts on krasnozem soils in north Queensland showed that cultivation controlled weeds sufficiently to prevent significant reduction of crop value. In one of these experiments two cultivations made 2 and 5 weeks after sowing increased the percentage of edible kernel by a mean of 4.8%. A range of herbicides tested in conjunction with cultivation did not significantly increase crop yields or weed control over that obtained by cultivation. Most of the herbicide treatments had no adverse effects on crop yield although some foliar damage occurred on plants treated with vernolate, MCPB, 2,4-DB and dinoseb. Vernolate, incorporated before planting at 4.78 kg active ingredient ha-1 caused a reduction in yield of nut-in-shell and in crop value when compared with the hand weeded, cultivated control. In both experiments, uncontrolled weeds markedly reduced crop yields (by a mean of 69%) and their monetary value (by a mean of 68%). In a third experiment a single application of 2,4-DB plus dinbseb (0.5 kg acid equivalent ha-1 each) made 3 weeks after sowing, with or without multiple applications of 2,4-DB (0.5 kg acid equivalent ha-1) made at 6,9 and 12 weeks, did not significantly reduce crop yields or values, and increased the control of Hyptis suaveolens and other broad-leaved weeds when compared with a standard trifluralin-plus cultivation treatment.

Interaction between glyphosate and various herbicides for broadleaved weed control

Summary:The effects of several herbicides for broadleaved weed control on glyphosate (n‐phosphonomethyl glycine) phytotoxicity to wheat (Triticum aestivum L.), barley (Hordeum vulgare L.) and wild oats (Avena fatua L.) were studied in the greenhouse. In tank mixtures, dicamba (3,6‐dichloro‐o‐anisic acid), 2,4‐D (2,4‐dichlorophenoxy‐acetic acid) and bromoxynil (3,5‐dibromo‐4‐hydroxy benzonitrile) reduced the phytotoxicity of threshold rates of glyphosate on all three species. With increasing rates of the herbicides for broadleaved weed control relative to a fixed rate of glyphosate, there was a general trend towards increased antagonism. Increasing glyphosate rates above the threshold level in mixtures containing a fixed rate of herbicides for broadleaved weed control overcame the antagonism. Both the inert and active ingredients of 2,4‐D amine and ester appeared to be involved in the antagonism. There was no reduction in glyphosate phytotoxicity on the annual grasses when 2,4‐D or bromoxynil were sprayed sequentially at various times in relation to glyphosate. When droplets of bromoxynil and glyphosate were placed side by side on a leaf, glyphosate phytotoxicity was not reduced, whereas when the two herbicides were mixed and applied as one droplet, considerable reduction in glyphosate phytotoxicity occurred. These results suggest that the reduction in glyphosate phytotoxicity caused by tank mixing with herbicides such as 2,4‐D, bromoxynil and dicamba may be due to a physical or chemical incompatability within the tank mixture rather than to a biological interaction in the plant.

Interaction between benzoylprop ethyl, flamprop methyl or flamprop isopropyl and herbicides used for broadleaved weed control

Summary:A marked antagonism of A. fatua control was found when 2,4‐D, dicamba, 2,4‐D‐dicamba‐mecoprop or bromoxynil were added to benzoylprop ethyl, flamprop methyl or flamprop isopropyl. Because of the much poorer control of A. fatua by these mixtures obtaining broad spectrum weed control with them in one spray operation would not be possible. The A. fatua herbicides did not affect the activity of the added herbicides on Fagopyrum lataricum. In eight out of nine mixtures tested there was no significant antagonism in the field conditions when MCPA or bromoxynil‐MCPA was added to the A. fatua herbicides. There were significant antagonistic effects, however, in six out of nine such mixtures in glasshouse experiments. This suggests that under farm use conditions benzoylprop ethyl, flamprop methyl or fiamprop isopropyl can be mixed with MCPA amine or ester or with bromoxynil‐MCPA to obtain broad spectrum weed control from one spray operation, though slightly poorer A. fatua control may be expected with these mixtures.

Interaction between difenzoquat and other herbicides for wild oat and broadleaved weed control in barley

Summary: Résumé: ZusammenfassungThe interaction between barban and difenzoquat was additive upon application at the two‐or four‐leaf stage of wild oat. Wild oat control with a mixture of barban and difenzoquat at 0.14 + 0.42kg/applied at the two‐or four‐leaf stage was as effective as the recommended field rate of barban alone (0.28 kg/ha) at the two‐leaf or difenzoquat alone (0.84 kg/ha) at the four‐leaf stage. Barley yield increases with the mixture were comparable to those obtained with the full rates of the herbicides used alone their correct leaf stages This mixture offers the farmer excellent wild oat control, an extended Leaf‐stage latitude (two‐to four‐leaf), excellent barley yield increases and the possibility of reduced operating costs. The herbicidal activity of difenzoquat or a barban + difenzoquat mixture was reduced on addition of amine formulations but not ester formulations of herbicides for broadleaved weeds. MCPA ester and bromoxynil plus MCPA were the most compatible broadleaf herbicides when mixed with difenzoquat Difenzoquat or difenzoquat + barban significantly stimulated the activity of various herbicides on Tartary buckwheat. A mixture of burban + difenzoquat + bromoxynil‐MCPA or MCPA ester provided effective wild oat and Tartary buckwheat control The latter mixtures enable a farmer to eliminate one spray operation. The interaction between difenzoquat and diclofop methyl [4‐(2,4‐dichlorophenoxy) phenoxy propionic acid methyl ester was additive. Wild oat control with the mixtures was good and barley yield was increased over that obtained with a recommended field rate of diclofop methyl. Interaction entre le difenzoquat et d'autres herbicides pour la lutte contre la folle acoine et les mauvaises herbes dicotylédones dans l'orge L'interaction entre le barbane et le difenzonzoquat a été additive en ce qui concerne l'application aux stades 2‐ et 4‐ feuilles de la folle‐avoine. L'efficacité contre la folle avoine avec un mèlange de barbane et de difenzoquat à difenzoquat à 0.14 + 0.42 kg/ha appliqué aux stades 2 ou 4 feuilles a été aussi bonne que la dose recommandée au champ de barbane seul (0.28 kg/ha) au stade 2 feuilles ou que le difenzoquat seul (0.84 kg ha) au stade 4 feuitles. Les augmentations de rendement de l'orge avec le mélange ont été comparables employès seuls au stade correct de développement foltaire. Ce folle‐avoine. une latitude de stades plus grande (2 á 4 feuilles). de substantielles augmentations de rendement pour l'orge et la possibilité de réduire le prix de revient de l'opération. L'activité herbicide du difenzoquai ou d'un mèlange barbane + difenzoquat a été réduite par l'addition de formulat ions amine mais pas avec les formulations ester des herbicides pour les mauvaises herbes dicotylédones L'ester de MCPA et le bromoxynile plus MCPA ont été les plus compatibles parmi les herbicides anti‐dicotylédones lorsqu'ils ont été mélangés avec le difenzoquat. Le difenzoquat ou le mélange difenzoquat + barbane ont significativement stimulé l'activité de divers herbicides vis‐à‐vis du Fagopyrum tartaricum. Un mèlange de barbane + difenzoquat + bromoxynil‐MCPA ou MCPA ester s'est montré efficace contre la folle‐avoine et F tartaricum Ces derniers mélanges permettent au cultivateur de faire l'èconomie d'un traitement. L'interaction entre le difenzoquat et le diclofop mèthyle (ester méthylique de l'acide 4(2,4 dichtorophénoxy)phénoxy propionique) a été additive. L'efficacite contre la folle‐avorne avec les mèlanges a été bonne et le rendement de l'orge a été meilleur que celui obtenu avec la dose recommandée de diclofop méthyle. Wechselwirkungen zwischen Difenzoquat und anderen Herbiziden zur Bekämpfung von Flughafer und dikotylen Unkräutern in Gerste Wenn Barban und difenzoquat im 2‐oder 4‐Blattstadium des Flughafers appliziert wurden, konnte etne additive Wirkung zwischen den beiden Herbiziden beobachtet werden. Die Flug‐haferbekampfung war mit einer Mischung von Barban und Difenzoquat bei Aufwandmengen von 0.14 + 0.42 kg/ha und Anwendung im 2‐ Oder 4‐Blattstadium genauso gut wie bei alleiniger Anwendung von Barban mit der empfohlenen Aufwandmenge von 0.28 kg/ha im 2‐Blattstadium. oder von Difenzoquat mit O.84 kg/ha im 4‐Blattadium. Die Mehrerträge an Gerste die mit der Mischung erzielt wurden. entsprachen den Mehrerträgen bei alleibuger Anwendung der Herbizide im empfohlenen Entwicklungsstadium Diese Mischung beitet dem Landwirt eine ausgezeichnete Bekämpfung des Flughafers bei erweitertem Anwndungsbereich (2‐ bis 4‐Blattstadium). deutlich Mehrerträge bei Gerste und die Möglichkeit geringerer Anwendungskosten. Die Wirkung von Difenzoquat oder der Barban + Difenzoquat‐Mischung war schlechter. wenn Amin‐formulierungen von Herbiziden zur Bekämpfung dikotlyer Unkräuter zugesetzt wurden, jedoch nicht bei Zusatz von Ester‐formulierungen. MCPA‐Ester und Bromoxynil plus MCPA waren die geeignetsten Mischungspartner für Difenzoquat gegen dikotyle Arten. Difenzoquat oder Difenzoquat + Barban steigerten signifikant die Wirkung verschiedener Herbizide gegenüber Fagoyprum tataricum. Die Mischung von Barban +Difenzoquat + Bromoxynil‐MCPA oder MCPA‐Ester ergab eine gute Bekàmpfung des Flughafers und von F. tataricum. Mit diesen Mischungen kann eine Spritzung emgespart werden Für Difenzoquat und Diclofop‐methyl [2‐[4‐(2′,4′‐Dichlorphenoxy)‐phenoxy]‐propionsäuremethylester wurde eine additive Wirkung festgestellt. Die Flughaferbekämpfung mit diesen Mischungen war gut und der Gersteertrag war höher als bei Anwendung der empfohlenen Aufwandmenge von Diclofop‐methyl.

Weed Control in Wheat and Barley in the Middle East

Abstract Wheat and barley constitute the bulk of agricultural production in the Middle East. Unfortunately, these crops are grown on marginal soils which are infested with annual and perennial weeds. The principal weed species include Avena sterilis L., Convolvulus arvensis L., and Sinapis arvensis L. and it has been estimated that yield losses due to weeds are between 20 and 30%. Control is mostly by hand pulling, hoeing or mechanical tillage, the use of herbicides being limited to about 2–5%, of the cereal area. The chemical used is usually 2,4-D but there are a few applications of barban. With the increase in wages, and unavailability of agricultural labour it is suggested that herbicide application should be widely used in the Middle East. Mixtures with benzonitriles and dicamba should be used in addition to the economical phenoxy herbicides to widen the spectrum of control of broadleaved weeds. Glyphosate may also be used after grain harvest for the control of perennial weeds and tri-allate, chlortol...