摘要:

SummaryThe non‐ionic surfactants, Tween 20 (polyoxy‐ethylene 20 sorbitan monolaurate) and Renex 36 (polyoxyethylene 6‐tridecyl ether) enhanced the retention of a glyphosate‐dye spray solution by barley (Hordeum vulgareL.) leaves. Tween 20 also enhanced absorption of14C‐glyphosate applied as droplets to barley leaves whereas Renex 36 similarly applied, reduced both absorption and movement of14C‐glyphosate. Renex 36 alone or mixed with glyphosate increased leakage of electrolytes from barley leaf segments whereas neither Tween 20 nor glyphosate, alone or mixed together, had any effect. No14C‐glyphosate complexes were detected in mixtures with either surfactant and neither surfactant affected the pH of the glyphosate solution. The results indicate that the reported enhancement of glyphosate phytotoxicity by Tween 20 is due to increased retention and absorption of the herbicide while the reported antagonism caused by Renex 36 is due to reduced glyphosate absorption and movement possibly as a result of alteration of membr

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00621.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryYarrow (Achillea millefoliumL.) has arisen as a problem weed in arable land in New Zealand. A spring‐sown yarrow population of 58 plants m−2produced approximately 243000 seeds. These were capable of immediate germination in the autumn, but virtually no germination occurred in the winter and up to 80–100% at other times of the year. Seeds are positively photoblastic, but a considerable percentage of seed (>30%) may germinate in the dark after chilling, coat pricking, exposure to high nitrate concentrations or to alternating temperatures. Seed buried at 32 cm in undisturbed soil lost viability slowly over 4 years while seed in the top 8 cm lost viability almost completely within 2

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00622.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryVarious methods were tested to control the annual grassRottboellia exaltataL.f. in maize (Zea maysL.) under small‐farm conditions in Bukidnon Province, Mindanao, Philippines during 1977 and 1978.No single method was satisfactory. Despite adequate early season control, late‐germinatingRottboelliatillered profusely. By harvest, plots had heavy infestations and were carpeted with seed. At harvest, untreated controls averaged 8·6 tRottboelliadry matter ha−1and only half the maize yield of handweeded plots.The ‘karase’ spike‐tooth harrow, or 0·2 kg paraquat ha−1, effectively removedRottboelliaflushes before maize emergence, but these techniques delayed planting, which can intensify downy mildew disease (Sclerosporasp.). Even though handweeding increased maize yields and decreasedRottboelliadry weights, it is impractical on typical 3‐ to 5‐ha maize farms. Mungbean (Vigna radiata(L.) Wilczek var.aureus), intercropped with maize, suppressedRottboelliainitially. Openings caused by mungbean harvest, however, allowed explosive late‐season weed growth in maize.Three herbicide treatments were as effective as handweeding: pendimethalin plus atrazine, either banded over the maize row (followed by cultivation), or broadcast; and pendimethalin followed by 2, 4‐D, both broadcast.In one experiment, low‐cost practices, including weed flush removal, cultivation, or handweeding, provided high net returns, whereas expensive herbicide treatments produced low net returns.Fertilizer, applied without weed control, increased maize yield 62%. Without fertilizer, weed control increased yield 107%. Combining

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00623.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe dynamics ofSorghum helpense(L.) Pers. rhizome sprout emergence was followed in three different crop systems. A simple exponential model relating the number of rhizome sprouts m−2to accumulated thermal units, calculated as the sum of the daily mean air temperatures above 15°C, provided a good estimate of cumulative shoot emergence populations (r2= 0·93) over all sampling dates between June and January. A good description of the dynamics of shoot emergence in an independent experiment was obtained from the model.The possible influence of the crop structure and soil water supply in relation to the model fitness is discus

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00624.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

RásumáLa dégradation chimique en phase sèche du barbane a étéétudiée après dèpôt à température ambiante sur diverses bentonites homoioniques (Cu2+; Ag+). La bentonite Ag+présente une réactivité particulièrement intéressante. Le schéma général de cette dé

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00625.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

RásumáLa dégradation chimique en phase sèche du chlorbufame a étéétudiée après dépôt à température ambiante sur diverses bentonites homoioniques (Cu2+; Ag+). Un schéma général de dégrada

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00626.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryThe broomrape (Orobanche crenataForsk) susceptibility to glyphosate applied on faba‐bean (Vicia fabaL.) as affected by the parasite growth stages at the time of application was studied under field conditions. Glyphosate treatments delayedO. crenataemergence. Single glyphosate application to faba‐bean infected withO. crenatapredominantly at the stage (a) (small nodule) and (b) (nodules with initial vestigial roots) resulted in a moderate to low control. When the stages (c) (shoot bud already visible) or (d) (shoot and vestigial roots well developed) were the predominant stages, an excellent control was achieved with a single glyphosate application at 60 g ha−1. Increased development stages, with the shoot emerged from the shoot bud, decreased its susceptibility to glyphosate.La lutte contreOrobanche crenataen culture de férerole avec le glyphosate; influence des doses d'herbicide et du stade de développement du

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00627.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryAqueous extracts of fifteenEuphorbiaspecies induced germination ofStriga hermonthica(Del.) Benth. seeds to varying extents. Extracts fromE. supinaRaf.,E. piluliferaJacq.,E. acalyphoidesHochst. ex. Boiss,E. prunifolia(Jacq.) Hort. Schoent.,E. hirtaL.,E. aegyptiacaBoiss,E. splendensBoj., andE. granulataForsk, were the most active. Extracts fromE. acalyphoidesandE. piluliferawere inhibitory at high concentrations. Undiluted extracts fromE. pilulifera, E. aegyptiacaandE. hirtainduced haustorial initiation. The stimulatory substance(s) were widely distributed in plants ofE. aegyptiaca.Extracts fromE. aegyptiacaalso stimulated seed germination and haustorial initiation in a range ofStrigaspecies and strains.

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00628.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryAlopecurus myosuroidesHuds. (blackgrass) in sandy loam soil in pots was treated at the three‐leaf stage with formulated isoproturon. Damage to plants resulted mainly from herbicide entry via the soil. When the soil moisture levels were maintained close to 50, 100 and 150% of field capacity (FC) throughout the experiment damage increased with the amount of water in the soil. After spraying plants raised at field capacity, change to 150 or 50% FC resulted in more and less damage respectively. Water applied to the soil surface compared with sub‐irrigation caused more damage. A delay of up to 21 days between spraying plants in soil at field capacity and surface watering did not reduce damage provided the time interval between the onset of surface watering and assessment remained constant. A delay of 7 days between spraying isoproturon onto plants in dry soil (50% FC) and increasing the moisture to field capacity by surface watering decreased the damage toA. myosuroides.These results are discussed with reference to the soil moisture distribution in soil columns and rainfall patterns under field conditi

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00629.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY

摘要:

SummaryExperiments were done to observe the pattern of early root development of radish (Raphanus raphatnistrumL.) and perennial ryegrass (Lolium perenneL.), the mobility of chlortoluron following application to the soil surface, the effect of protecting the subterranean shoots of four plant species on their response to chlortoluron and terbutryne and the relative quantities of14C‐labelled chlortoluron taken up by radish andAvenu fatuafrom root and shoot zone exposure. Both chlortoluron and terbutryne appear to be able to enter the plants examined,Alopecurus myosuroides, Stellaria media, perennial ryegrass and radish, through roots and shoots. It is suggested that shoot uptake is relatively more important for plants like perennial ryegrass than for those whose roots develop more quickly and invade the soil above the seed, such as radish. The quantities of radioactive chlortoluron taken up from soil containing 400 ng g−1showed that less than 3 ng per plant could reduceA. fatuafresh weight by 17–40% while over 30 ng per plans had little effect on radish. By comparison 2 kg ha−1chlortoluron applied to the soil surface of pots which were sub‐irrigated for 3 weeks gave a concentration of 170 ng g−1in the layer of soil 10–12 mm from the surface. It is suggested that for shallow germinating species with herbicides of physical and phytotoxic properties similar to chlortoluron, the solvent action of rainfall, together with diffusion, is enough to allow the transport of toxic quantities to the target plant although any leaching action is likely to incr

ISSN:0043-1737    

DOI:10.1111/j.1365-3180.1985.tb00630.x

出版商:Blackwell Publishing Ltd    

年代:1985

数据来源: WILEY