ISSN:0031-613X    

DOI:10.1002/ps.2780410202

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSorption and desorption of ‘Pegosperse’ 100‐O(PEG 100‐O; diethylene glycol monooleate, containing 15% diester) surfactant by unaltered (CM) and dewaxed (DCM) adaxial cuticle membranes isolated from apple (Malus pumilaM.) leaves were studied. The aim of this study was to understand interactions between surfactants and cuticles. Enzymatically isolated cuticles were soaked in buffer or PEG 100‐O solution (pH 7–0). and the weight changes of cuticles were measured to determine the amount of surfactant sorbed or desorbed by the cuticles. For very low surfactant concentrations, sorption was measured by changes in the surface tension of the solutions. PEG 100‐O sorption by both the CMs and the DCMs occurred mainly in the first three hours and was concentration‐dependent. The DCMs always sorbed more surfactant than the CMs. Desorption of PEG 100‐O from both CMs and DCMs was rapid in the first few hours and then decreased to a relatively low rate until the surfactant was totally desorbed from the cuticles after about two months. The sorption and complete desorption of the surfactant by both CMs and DCMs show that PEG 100‐O interacts with both cutins and waxes of the cuticles and the interact

ISSN:0031-613X    

DOI:10.1002/ps.2780410203

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSolid‐phase decomposition of benomyl has been investigated by thermo‐gravimetric analysis; the degradation process (heating rate of 1°C min−1under nitrogen flux) starts atc. 65°C. Semi‐empirical quantum mechanical methods have been used to characterize the benomyl molecule and to obtain information on a possible degradation

ISSN:0031-613X    

DOI:10.1002/ps.2780410204

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe electrophysiological activity of some halogenated analogues of the major component of the sex pheromone of the corn stalk borerSesamia nonagrioidesLef. (1) is presented. The analogues comprise a series of fluoro‐, chloro‐ and bromoacetate analogues4–10as well as trifluoromethyl ketone 11. The fluoro derivatives4–6displayed remarkable electro‐antennogram (EAG) intrinsic activities in comparison with the parent acetate 1, while the remaining analogues elicited significantly lower response. The compounds have also been tested as inhibitors of the sex pheromone perception in EAG and in the field. In the laboratory. fluoro analogues4–6were better inhibitors than chloro derivatives7–9, which in turn behaved similarly to the bromoacetate10. Trifluoromethyl ketone 11, however, was a poor inhibitor of the pheromone action. In the field, baits of mixtures of compounds5–11with the corn stalk borer pheromone in10:1 ratio inhibited the concomitant attraction of the clover cutworm mothScotogramma irifoliiRott., while the difluoro analogue 5, trichloroacetate9and trifluoromethyl ketone11also diminished the number of catches of the armywormMythimna unipunctaHaw. The monofluoroacetate 4. trifluoro analogue6and bromo derivative10significantly disrupted the pheromone action of the corn borer, whereas trifluoromethyl ketone11synergistically increased the number of males attracted to the pheromone trap alone. Addition of11to baits containing the corn borer pheromone caught S.nonagrioidesselectively with regard to the other habitat‐sharing speciesM. unipun

ISSN:0031-613X    

DOI:10.1002/ps.2780410205

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe hydrolysis kinetics of the dicarboximide fungicides procymidone, vinclozolin and chlozolinate in neutral and alkaline solutions of pH 60 to 13·7 at 25°C have been determined conjointly by ultraviolet spectrophotometry and by high performance liquid chromatography. Under alkaline conditions, the fungicides undergo attack by the hydroxide ion on a specific carbonyl group and the rate of hydrolysis increases proportionally to the hydroxide ion concentration. Procymidone gives quantitatively and irreversibly 2‐(3,5‐dichlorophenylcarba‐moyl)‐l,2‐dimethylcyclopropanecarboxylate. The reaction is not subject to general base catalysis and experimental data are in agreement with a rate‐determining attack by the hydroxide ion. After a rapid hydrolytic loss of the ethoxycarbonyl substituent from chlozolinate, the dicarboximide ring cleavage of the two other fungicides leads, by mechanisms which differ with respect to the type of base catalysis and the rate‐determining step, to the corresponding anilides, producing as intermediates the carbamic acids, which undergo loss of carbon dioxide. The hydrolysis of vinclozolin and chlozolinate yields, respectively,N‐(3,5‐dichloro‐phenyt)‐2‐hydroxy‐2‐methylbut‐3‐enanilide andN‐(3,5‐

ISSN:0031-613X    

DOI:10.1002/ps.2780410206

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractSusceptibility to SMY 1500 (4‐amino‐6‐tert‐butyl‐3‐ethylthio‐1.2.4‐triazin‐5(4H)‐one) was studied in durum wheat (Triticum durumDesf.) cultivars in growth‐chamber assays. Weight reduction, photosynthesis inhibition and herbicide levels were determined at various times after a 24‐h herbicide treatment in two cultivars of durum wheat, one cultivar of spring wheat (Triticum aestivumL). and in the weedBromus diandrus(Roth). Measurements of weight reduction distinguished between plants tolerant and plants susceptible to SMY 1500. Tolerant cultivars showed a lower herbicide content and photosynthesis inhibition than susceptible plants after the 24‐h treatment. Thereafter, herbicide levels and photosystem II inhibition decreased faster in tolerant plants. Comparison with previous work showed that plants tolerated doses of SMY 1500 about four times higher than of its analogue, metribuzin. Herbicide content in leaves just after treatment, and rate of detoxification may explain the selectivity of

ISSN:0031-613X    

DOI:10.1002/ps.2780410207

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractIsolates ofPseudocercosporella herpotrichoides(Fron.) Deighton, causal agent of eyespot disease of cereals, with reduced sensitivity to the imidazole fungicide prochloraz were produced by spontaneous selection on fungicide‐amended media or by successive rounds of ultra‐violet (U V) irradiation of conidia. Resistance frequencies were similar to those obtained for other sterol‐biosynthesis‐inhibiting (SBI) compounds. Stability testing indicated that a large proportion of the UV‐induced mutants reverted rapidly to wild‐type sensitivity levels. However, the spontaneously selected strains, and strains produced after the third round of mutation proved more stable. Strains produced by spontaneous selection and from a single round of UV irradiation showed relatively low levels of resistance, in most cases within the range shown by the European field population. Subsequent rounds of UV irradiation raised resistance levels by factors of between 5 and 16 times. Growth rate in culture and sporulation ability were impaired in some, but not all. strains. Spontaneous mutants showed no decrease in pathogenicity to cereal hosts while UV‐induced strains were more variable, with some giving significantly reduced infection scores. The spontaneous mutants, and some of the UV‐induced strains, gave higher infection scores on plants treated with prochloraz than on untreated plants. This may have been due to changes in the stem base microflora resulting in reduced competition. The findings from this study suggest a multi‐factorial basis for resistance, resulting in directional rather than disruptive selection for

ISSN:0031-613X    

DOI:10.1002/ps.2780410208

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractFoliar deposits and persistence of azadirachtin were investigated after spraying ‘Margosan‐O’® formulation at three dosage and volume rates on to balsam fir and oak seedlings in a laboratory chamber. Droplet‐size spectra and deposits were assessed using artificial samplers, and foliar residues were measured by high‐performance liquid chromatography (HPLC) at different intervals of time after treatment. Disappearance of azadirachtin from both types of foliage was rapid, and the DT50(the time required for 50% of the initial concentration to disappear) values ranged from 17 to 22 h. The initial azadirachtin concentrations varied widely from 4 to 96 μg g−1(fresh weight), but the rate constants 0.0311 to 0.0414, were not significantly different. The data thus indicated a poor relationship between initial concentrations and the rate of loss.The influence of spray droplet size and cuticular wax content of foliage on persistence of azadirachtin was investigated using both foliar types, and glass microscope slides without and with the foliar wax coating. Neither the type of surface nor the droplet size influenced the persistence. The rate of azadirachtin loss from the glass slides was faster than from both types of foliage, and was unaffected by the presence of wax coating. The fir foliage had higher cuticular wax content than the oak foliage, but the persistance of azadirachtin was similar in both

ISSN:0031-613X    

DOI:10.1002/ps.2780410209

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractThe larvicidal activity of a number of 1‐(substituted benzoyl)‐2‐benzoyl–1‐ten‐butylhydrazines against the rice stem borer (Chilo suppressalisWalk.) was measured. Variations in the activity were examined quantitatively using physico‐chemical substituent and molecular parameters and regression analysis. The results indicated that the molecular hydrophobicity and the electron‐withdrawing inductive/ field effectof onthosubstituents are favourable to larvicidal activity. The bulkiness of substituents at themetaandparapositions was unfavourable to activity, substitution at theparaposition being more unfavourable than that at themetaposition in terms of van der Waals' volume. The 2,3–, 2,5‐ and 2,6‐disubstitution patterns were also unfavourable to activity. Reductions in larvicidal activity caused by the 2,6‐,‐ 2,3,5‐ and 2,3,4,5‐substitutions were greater than those induced by the 2,3‐ and 2,5‐disubstitutions. When the sum of contributions from favourable effects is greater than that from unfavourable effects, the larvicidal activity is expected to be superior to t

ISSN:0031-613X    

DOI:10.1002/ps.2780410210

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY

摘要:

AbstractAromatic heptaene polyenes (AHPs), the largest group of antifungal polyene antibiotics, were detected in steam‐sterilizedSphagnumpeat after treatment with a new biofungicide containing fermenter‐cultivatedStreptomyces griseoviridisAnderson K61, a bacterium capable of producing AHPsin vitro. Three concentrations (0.05 g litre−1, 0‐2 g litre−1and 2.0 g litre−1) of the biofungicide were used and compared to untreated controls. The substrates were incubated for seven weeks under greenhouse conditions, with and without cucumber seedlings, and samples were analysed for heptaene polyenes by HPLC using a photodiode array detector. Changes in AHP concentrations indicated that the fermenter‐cultivated mycelium was a partial source of extractable heptaenes in peat. The identification of p‐aminoacetophenone (PAAP) by HPLC‐MS in peat hydrolysates verified the

ISSN:0031-613X    

DOI:10.1002/ps.2780410211

出版商:John Wiley&Sons, Ltd    

年代:1994

数据来源: WILEY