摘要:

Summary:Five herbicides were tested in the dry and in the wet season for their effectiveness in conlrolling perennial nutsedge (Cyperus rotundus L.) in direct‐seeded upland rice in the tropics. K‐223 [N‐(α,α‐dimethylbenzyl)‐N'‐P‐tolyl urea] gave the best results. When broadcast sprayed at 8.0 kg a.i./ha in the dry season and 10 kg a.i./ha in the wet season and immediately mixed into the soit just before drilling, K‐223 gave excellent perennial nutsedge control with no visible crop damage and increased the grain yield. Bentazone at 2.0 kg a.i./ha applied 7 days after crop emergence was highly selective and gave fair control of nutsedge without being toxic to the crop.MBR 8251 [1.1,1‐trifluoro‐4′‐(phenylsulfonyl) methane‐sulfono‐o‐toluidide] at 2.0 kg a.i./ha, mecoprop (MCPP) at 1.5 kg a.c./ha and fenoprop (silvex) at 1.0 kg a.e./ha applied 7, 14 and 7 days, respectively after crop emergence provided a fair degree of nutsedge control. Fenoprop and MBR 8251 caused slight and mecoprop moderate initial toxicity, but the injury sustained did not

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00368.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:The effects of asulam applied in September 1970 at 0.55, 1.12 and 2.24 kg a.i./ha onRumex obtusifolius(L.),Lolium perenne(L.), Other grasses andTrifolium repens(L.) growing in two swards in Wales were investigated. Good short‐term control ofRumexwas achieved by all rates of asulum although regeneration was occurring by the spring following treatment. Dry matter yields of L.perennewere slightly lowered by 2.24 kg a.i./ha 6 weeks after spraying but production in the spring following treatment was substantially greater than on untreated plots.Poa trivialis(L.) andAgrostis stolonifera(L.) were substantially reduced but invasion of the bare spaces by P.trivialisandP. annua(L.) seedlings tended to mask the success of this control. No harmful effects on T. repens were recorde

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00369.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:Photosynthesis in the shoots of winter wheat (Triticum aestivum L.) was inhibited by certain phenylurea herbicides applied via the nutrient solution. Recovery from this inhibition after short treatments was used as a measure of the rate of inactivation of these herbicides in the leaf tissue of a variety tolerant to metoxuron (Caribo) and of a less tolerant variety (Manella). The introduction of chlorine atoms into fenuron greatly reduced the rate of inactivation in both varieties, whereas that of a methyl or butoxy group had little or no effect. Metoxuron was inactivated more readily than chlortoluron and both compounds were inactivated more rapidly in Caribo than in Manella.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00370.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:A range of plant species was treated with three commercial herbicides to which a cuticule‐damaging kaolin was added. The addition of the kaolin resulted in increased phytotoxicity forColeus blumeiBenth.,Phaseolus vulgarisL. and young leaves ofTaraxacum offcinaleWeber in laboratory and field trials, but failed significantly to increase phytotokicity for twelve common weed specie

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00371.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:The hydrolysis of the iso‐propyl, n‐butyl‐and iso‐octyl esters of 2,4,5‐trichlorophenoxyacetic acid (2,4,5‐T), the n‐bytyl ester of 2,4‐dichlorophenoxybutyric acid (2,4‐DB) and the iso‐octyl ester of 2,4‐dichlorophenoxypropionic acid (2,4‐DP) was studied in four prairie soils of differing textures and pH at 25±1°C. The esters were analysed using gas chromatography.After 24 h in soils at wilting point moisture, and above, less than 20% of the applied iso‐propyl and n‐butyl esters could be recovered from one soil type and none from the remaining three. Loss of the iso‐cotyl esters was slower; however, no trace of the 2,4,5‐T and 2,4‐DP esters was observed in any of the moist soils after 48 and 72 h respectively. In all cases loss of all esters from air‐dried soils minimal.The phenoxyalkanoic acid hydrolysis products were recovered from all soil types, treated with the various esters and ident

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00372.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:Methazole [2‐(3,4‐dichlorophenyl)‐4‐methyl‐1,2,4‐oxadiazolidine‐3,5‐dione] was applied post‐emergence at 2‐1 kg/ha to crops of onion (Allium cepa L.) grown on a sandy loam and the activity present in the surface 0–5 cm of soil assessed by bioassay. In spring‐sown crops, activity at harvest varied from 25 to 78% of the initial acitivity in different years; losses were restricted by low temperature and low rainfall. In autumn‐sown crops, little loss occurred during winter and most of the activity remained in the surface 0‐5 cm. The results emphasize the need for caution in choice an

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00373.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:Delays of 40 or 60 days in weeding peanuts (Arachis hypogaea L.) gave lower yields and fewer pods per plant but did not affect seed number per pod. Yield, pod number per plant, seeds per pod and mean weight per seed were all less in unweeded plots.In three herbicide trials crop yields were not closely correlated with crop vigour scores made several weeks before crop maturity, or with weediness scores. Correlations between yields and weed dry weights were better, but certain high‐yielding herbicide treatments gave poor weed control and in some cases had low crop vigour scores. Most yield differences reflected differences in pod number per plant, with additional smaller compensating or additive effects on the other components. Certain herbicides apparently gave high mean seed weights without diminishing seed numbers per pod. Pre‐emergence alachlor was the most promising herbicide, combined with preplant incorporated vernolate if nutgrass was serious. Napropamide and metobromuron merit further test

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00374.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:Persistence of ethofumesate [(±)2‐ethoxy‐2.3‐dihydro‐3,3‐dimethylbenzofuran‐5‐yl‐methansulphonate] in soil was associated with soil temperature. Ethofumesate applied at 4.5 kg/ha in November persisted about twice as long in soil as that applied the following March. In another field study, 88–91% of the herbicide had dissipated after 24 weeks in sandy loam soil, compared to 72–77% in loam soil when it was applied at rates of 2.2, 3.4, 4.5, and 9.0 kg/ha. The rate of degradation was independent of the initial rate of chemical applied. The time required for 50% of the herbicide to dissipate in sandy loam and loam soils was 7.7 and 12.6 weeks, respectively. The movement of ethofumesate in these two soils over a 24‐weeks sampling period was confined mainly to the upper 7.5

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00375.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:The recording of the stage of growth of crops and weeds by directly photocopying the plants is described.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00376.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Summary:In glasshouse experiments 1,8‐naphthalic anhydride (NA) and N,N‐diallyl‐2,2‐dichloroacctamide (R 25788) were investigated in combination with perfluidone for the control of Rottboellia exaltata Linn. F. in maize. Both protectants were used as seed dressings and R 25788 also as a spray mixture with the herbicide.Surface application of the herbicide generally resulted in greater crop damage than incorporation. The protectants caused no damage than used alone. Both compounds greatly reduced crop damage from perfluidone treatments. In most experiments protection with NA was better and more reliable than with R 25788. Even when kept until flowering no adverse effect at later stages of growth were noted.Good control of R. exaltata was achieved in all trials where perfluidone was applied to the soil surface. Incorporation reduced activity. Mixtures of R 25788 with the herbicide did not significantly protect the weed.Field treatments to improve the tolerance of maize to perfluidone while controlling a wide range of weeds arc su

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1976.tb00377.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY