ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04776.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYA range of fungicides and herbicides was tested againstGaeumannomyces graminis(causal agent of take‐all) on agar plates, and on wheat seedlings in pots and in liquid culture. Benomyl, the standard in all tests, was consistently most effective: like iprodione, nuarimol and KWG0599, it diminished infection from inoculum placed just below the seeds more effectively when applied as a drench than as a soil‐mix. Benomyl as a soil‐mix was most effective in soils with least organic matter. Some compounds toxic to the pathogen on agar plates and in plants grown in liquid culture were ineffective as soil treatments. The practical limitations of soil treatment with conventional fungicides and application methods are disc

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04777.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYIsolated purified fractions containing haustorial complexes and mesophyll protoplasts were used to investigate the relative affinitiesin vitroof the host‐parasite interface and host for the mildew specific fungicide, ethirimol. Compounds labelled with [14C] were used throughout this study.Isolated haustorial complexes accumulated fungicide against a concentration gradient and, in 15 min, to much higher concentrations than they accumulated glucose, sucrose, uracil, glycine, ethanolamine hydrochloride, inulin carboxylic acid, thiocyanate ions or uridine diphosphate glucose. Accumulation of ethirimol ceased after 30 min when the internal concentration was over twenty times greater than in the ambient medium. Similar quantities were absorbed in 15 min at pH 4.2 and 6–2. The quantities absorbed during 1 h incubation were directly related to the ambient concentration (4–400 μm). Ethirimol introduced into haustorial complexes was easily removed by washing; one third was removed in the first 5 min and only one sixth of the original remained after 3 h. Analysis of the kinetics of ethirimol efflux showed that it was located in two compartments within the complexes; thus it most probably entered the fungal cytoplasam.Ethirimol entered pea mesophyll protoplasts showing biphasic kinetics with considerable uptake in the first 30 min and a more gradual influx during the following 18 h. It was not accumulated against a concentration gradient until 6 h and after 18 h the internal concentration exceeded that of the ambient by only 1.74 fold.Extraction and chromatography showed that only small proportions of the ethirimol were degraded by haustorial complexes and protoplasts during the experimental periods.Thesein vitroexperiments indicate competitive accumulation of ethirimol by the host‐parasite interfac

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04778.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYAmsinckia douglasianawhen infected with beet curly top virus (BCTV) produces more exudate, which is highly infective, than any other known host. Attempts were made to purify BCTV from the phloem exudate of infectedAmsinckia douglasianaby differential centrifugation and sucrose density gradient fractionation. A260/280ratio of virus preparations was 1.58; S values were 74 and 147. Infectivity was distributed among several fractions during density gradient purification. Electron microscopy revealed the presence of pentagonal and hexagonal particles of 14–23 nm, some of which were paired. The virus was insensitive to DNAse, RNAse, and trypsin when these enzymes were tested individually but infectivity was substantially decreased when the virus was subjected to trypsin treatment followed by DNAse, suggesting that DNA is associated with the beet curly top viru

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04779.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYThe transmission of beet curly top virus (BCTV) by leafhoppers,Circulifer tenellus, fed virus through Parafilm® membranes was compared with their transmission when injected with virus from phloem exudates ofAmsinckia douglasiana. Virus uptake from32P‐labelled test solutions and the resulting virus transmission, as measured by an infectivity index, varied widely. By contrast, insects injected with virus transmitted with similar efficiencies. If insects were fasted for 3, 5, or 7 h before a 6 h acquisition access period on test solutions, their32P, and presumably virus uptake, was greater than that of nonfasted insects and their variability in virus transmission decreased. The proportion of insects transmitting curly top virus, after fasting and given a 6 h acquisition access period, was similar to that of insects injected with virus. Maximum liquid uptake by the beet leafhopper occurred with a 12% sucrose soluti

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04780.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYTwo inhibitors of hatching inGlobodera rostochiensis, ruthenium red and lanthanum, have been shown to bind to the eggshell using the techniques of microdensitometry for ruthenium red and X‐ray microanalysis for lanthanum. Neither inhibitor penetrated or adhered to unhatched or hatched viable juveniles. Scatchard analysis for binding of lanthanum and ruthenium red to eggshells gave dissociation constants (K) of KLa32.5 ± 14.0 μM and KRured33.5 ± 5.0μM respectively. Both values are within the 95% fiducial limits of those shown to cause 50% inhibition of hatch in previous work. Pretreatment with sodium hypochlorite separated an outer part of the eggshell from an inner region which exclusively bound ruthenium red. It is the inner lipoprotein layer that is believed to include the membranes controlling the permeability of the tylenchid eggshell. The rate of binding of ruthenium red was similar for intact and isolated eggshells with 50% binding occurring after 6.11 ± 0.91 min and 4.95 ± 2.38 min but the latter gave a significantly higher maximum binding suggesting that rupture of the eggshells made available additional binding sites on their inner surface. The binding of ruthenium red to the eggshells was pH dependant over most of the range pH 2.8–8.5 with 50% binding, given with its standard deviation, occurring at pH 5.75 ± 0.85.Competitive binding of lanthanum influenced the binding of ruthenium red to the eggshells from which Scatchard analysis gave Klaof 176 ± 79 μM. Similarly, calcium influenced the binding but this caused a biphasic plot with high and low affinity binding sites of K“caof 0.423 ± 1.16 μm and K‘caof 1078 ± 462 μM. The existence of a high affinity site for calcium that also binds ruthenium red, suggests that the eggshell membrane includes a calcium binding glycoprotein as found in some other

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04781.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYA screening method is described whereby potato plants are grown in soil in closed plastic containers in the dark, producing root systems upon which potato cyst nematodes can reproduce. Tubers are planted in John Innes No. 2 compost at 30% moisture and inoculated with an egg suspension. The canisters are held at 20°C for 7 wk after which, visible developing females are counted. This method of screening is more rapid, economical and produces data as reproducible as those from conventional pot tests. The value of the test for detecting resistance early in a potato breeding programme is discussed

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04782.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYA single foliar application of oxamyl (12.5 μg) in acetone significantly reduced invasion of cucumber seedlings byMeloidogyne incognitajuveniles for at least 21 days but did not affect the early stages of development of juveniles which had already invaded the roots. In contrast, application of oxamyl to the roots significantly reduced both invasion and development of juveniles. Concurrent studies using radiolabelled oxamyl showed that the amount of toxicant in the roots after 3 days was 13 times greater following root application than after foliar treatment.It is probable that oxamyl concentrates at the sites of nematode attack as an overall concentration of only 3 ng oxamyl g‐1root was sufficient to prevent invasion. Much greater concentrations than this were required to affect the nematodein vitro. Oxamyl appeared to be lost from the roots into the soil principally in the form of its non‐toxic oxime and it is suggested that the site of action following foliar application is at the root surface or outer cortex. Studies on the invasion behaviour ofM. incognitajuveniles on agar showed that the action of oxamyl had a sensory compo

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04783.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

摘要:

SUMMARYStudies on the herbicidal activity of 3,5–dibromo‐4–hydroxybenzonitrile (bromoxynil) and 3,5–dibromo‐4‐hydroxyphenyl methyl sulphone (bromoxysone) have been extended to include 3,5–dibromo‐4‐hydroxyphenyl methyl sulphide (bromoxyside), its esters and other related compounds.Bromoxyside produced chlorotic effects in barley and wild oat seedlings, the herbicidal activity being similar to that of bromoxysone but quite different to that of bromoxynil. A range of aliphatic and aromatic esters of bromoxyside were prepared and examined as herbicides using barley and wild oat seedlings as test plants. The acetate and propionate were the most active against both species. No compound tested was more herbicidal to wild oat than to barley. Introduction of a further bromo or methyl ring‐substituent into bromoxyside removed herbicidal activity.Spraying plants of differing age showed that the herbicidal effect was greater when th

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04784.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1980.tb04785.x

出版商:Blackwell Publishing Ltd    

年代:1980

数据来源: WILEY