bluuebunny/crossref_metadata_2025_split huggingface dataset:
Factors in testing fungicides against powdery mildews. I. A slide spore‐germination method of evaluating protectant fungicides
Authors: ZARACOVITIS C. 
Published: February 2008

SUMMARYThe germination of conidia of Erysiphe betae, E. graminis, E. horridula, E. martii, Oidium begoniae, an Oidium sp. from Crepis taraxacifolia and Uncinula necator was studied on dry uncoated glass slides and on dry slides with the following coatings: cellulose acetate (C.A.); the polyvinyl acetate derivative Gelva 7; nitrocellulose (collodion); and ethyl cellulose. Slides dusted with conidia were incubated at 21±1° C. in a saturated atmosphere in the dark. Germination over 85% and as high as 96±4% was obtained on slides coated with C.A. or Gelva 7. The germination on slides coated with collodion was lower and abnormal, the germ‐tubes growing away from the substrate.The possibility of studying the toxicity of chemicals towards conidia of powdery mildew fungi by incorporating them into a C.A. layer used as a coating for glass slides was examined. ‘Dinocap’, a captan analogue and members of a homologous series of n‐alkyl fatty acids were used, with conidia of E. betae, E. horridula, E. martii and O. begoniae as test organisms. The results obtained demonstrated the potentialities of the method.
Ecological characteristics of nematode‐trapping Hyphomycetes
Authors: COOKE RODERIC C. 
Published: February 2008

SUMMARYConidial germination in sixteen nematode‐trapping Hyphomycete species in amended and unamended soil was studied. On the basis of the pattern of germination the fungi could be divided into two ecological groups: a sensitive group where conidia or germlings quickly gave rise to trapping organs and an insensitive group in which little trap formation occurred. The significance of this in relation to biological control of plant‐parasitic nematodes is discussed.
Observations on the effects of chlorine on the larvae of oysters (Ostrea edulis(L.)) and barnacles (Elminius modestus(Darwin))
Authors: WAUGH G. DUNCAN 
Published: February 2008

SUMMARYThe possibility that chlorine, which is used to prevent fouling of cooling‐water circuits in industrial plants, could be harmful to oyster larvae is considered. Oyster larvae have been exposed for varying periods to chlorine concentrations as high as 200 p.p.m.; in addition they have been subjected to a temperature shock of the order of a 10° C. rise above ambient. At chlorine concentrations normally encountered in industry (up to 10 p.p.m.) the larvae are unharmed and are capable of growing to the pre‐settlement stage. At concentrations of 20 p.p.m. a substantial proportion is still capable of survival and growth, but at concentrations of between 50 and 200 p.p.m. survival and growth is poor.The nauplii ofElminius modestusare far more sensitive to chlorine and the majority are killed by concentrations as low as 2·0 p.p.m.The implications of this work are discussed and the need for confirmatory field trials is emphasized, as is the possible side effect of chlorination and heating in reducing or destroying the food supply of the larvae.
The uncoupling of oxidative phosphorylation in pea shoot mitochondria by 3,5‐diiodo‐4‐hydroxybenzonitrile (ioxynil) and related compounds
Authors: KERR M. W. , WAIN R. L. 
Published: February 2008

SUMMARYThe effect of the new herbicide, ioxynil, and several related compounds, on the oxidative phosphorylation of respiring, isolated pea shoot particles has been studied. Ioxynil and its analogues were found to depress the uptake of inorganic phosphate and, to a lesser extent, of oxygen by the particles; the calculated P/O ratio was eventually reduced to zero. The effect of ioxynil was far greater than that of the well‐known uncoupling agent 2,4‐dinitrophenol and was similar in magnitude to that of the contact herbicide dinitro‐ortho‐cresol.
Inhibition of the ferricyanide‐Hill reaction of isolated bean leaf chloroplasts by 3,5‐diiodo‐4‐hydroxybenzonitrile (ioxynil) and related compounds
Authors: KERR M. W. , WAIN R. L. 
Published: February 2008

SUMMARYThe effect of ioxynil and several related compounds on the photoreduction of ferri‐cyanide by isolated bean leaf chloroplasts has been studied.In general, a close correlation was found between the herbicidal activity of these compounds and their capacity to inhibit the photoreduction; ioxynil was highly active. The established weedkiller dinitro‐ortho‐cresol (DNC) which is a less potent contact herbicide than ioxynil, was also much less effective as an inhibitor for this reaction.
Aqueous formulations of pyrethrum for controlling phytophagous Arthropoda—an evaluation using bioassay techniques
Authors: YULE W. N. 
Published: February 2008

SUMMARYBioassay techniques were used to compare the toxicities of formulations of pyrethrum containing different amounts of surface‐active agents (mainly non‐ionic condensates of ethylene oxide) and synergists (Bucarpolate, piperonyl butoxide, S 421 and Sulfoxide). Phytophagous species of Arthropoda used in the tests were: Acyrtho‐siphon pisum Harris (Aphididae); Phaedon cochleariae F. (Chrysomelidae); Pieris brassicae L. (Pieridae); and Tetranychus telarius L. (Acarina, Tetranychidae).The insects were dosed by spray tower, and the mite by dipping infested leaves. The LC50 pyrethrins with unsynergized formulations were: aphid (adult), 150 p.p.m.; beetle (adult), 50,910 p.p.m.; caterpillar (third instar), 325 p.p.m.; mite (adult) 1168 p.p.m. Formulations whose wetting powers were increased by adding surface‐active agents were more toxic to the aphid and caterpillar (LC50 of 20 and 50 p.p.m., respectively). Addition of piperonyl butoxide or Sulfoxide to formulations, at up to 8 times the concentration of pyrethrins, increased their potencies for the aphid, beetle and mite by factors of 7–10 times, but were ineffective with the caterpillar. Bucarpolate and S 421 were poor synergists.A detailed study was made, using Acyrthosiphon pisum, of the synergizing effect of surface‐active agents on formulations of pyrethrum. Hypotheses for their modes of action suggest that toxicity is influenced by the fineness of dispersion of pyrethrum emulsions, and by the improved coverage and penetration of spray on insects, which results from increased wetting power.The results of bioassay studies are interpreted to indicate that a formulation of pyrethrum synergized with both surface‐active agent and piperonyl butoxide would be a very effective aphicide, with some ovicidal and larvicidal properties, when applied to infested plants as a high‐volume spray.
Studies on plant cuticle
Authors: FERNANDES A. M. SILVA , BAKER E. A. , MARTIN J. T. 
Published: February 2008

SUMMARYThe isolation from plant tissues of cuticular waxes uncontaminated by cellular extractives is described. Surface waxes are removed by washing leaves and fruits with chloroform at room temperature; other solvents give lower yields of waxes, apparently because of selective solvent action.A method is described for the quantitative fractionation of apple fruit and leaf waxes, and the levels and distribution of the wax components in the fruit and leaf cuticles are reported. Ursolic acid predominates in the apple fruitlet wax; esters and ursolic acid are the chief components of the wax of apple fruits in store. Ursolic acid also occurs in apple leaf wax; paraffins and esters are important constituents of blackcurrant and rose leaf waxes. The esters of apple, blackcurrant and rose leaf waxes contain long‐chain fatty and hydroxy‐fatty acids of the kind known to occur in apple fruit wax esters.Recent literature on plant waxes is reviewed.
The effect of kinetin on infection of petunia and tomato leaves with tomato spotted‐wilt virus
Authors: SELMAN I. W. 
Published: February 2008

SUMMARYKinetin supplied to the lower surfaces of petunia leaf strips reduced the number and size of local lesions following mechanical inoculation of the upper surfaces with tomato spotted‐wilt virus' (TSWV). Glucose increased lesion production, but glucose with kinetin reduced it. Kinetin mixed with infective sap did not affect lesion production.Lesions were increased with increasing water content of leaf strip and the regression equation for the relationship is given. Treatment with kinetin after inoculation reduced lesion production over a wide range of water contents, but was most effective at high values.Kinetin inhibited virus multiplication in excised tomato leaflets only when supplied at the site of infection and caused some necrosis of veins and midribs. Treated leaflets took up more water than controls and uptake continued for 4 days.Water uptake by kinetin‐treated petunia leaf strips was less than by controls but continued for 6 days with only slight discoloration of the veins.It is suggested that the inhibitory effect of kinetin may be associated with a capacity to cause increased activity of ribonuclease in the tissues.
The effect of motley dwarf virus on yield of carrots and its transmission in the field by Cavariella aegopodiae Scop
Authors: WATSON MARION , SERJEANT E. P. 
Published: February 2008

SUMMARYIn 1959 and 1961, when the willow‐carrot aphid, Cavariella aegopodiae, infested carrots at Rothamsted and Woburn early and severely, crops were infected with motley dwarf virus in late May or early June and yielded about 6 tons of roots per acre. In 1962, when invasion was late and sparse, the crops remained almost uninfected and yielded 24–25 tons/acre. In 1960, when aphids invaded early but multiplied slowly, about 85% of carrots on unsprayed plots became infected in July and August, and the yield was 9.2 tons/acre. Spraying three times with Metasystox starting at an early stage of growth affected yield little in 1961, or in 1962, but increased yield by about 3 tonslacre in 1960.Field‐plots experimentally infected in 1962 by aphids fed on infected plants in the glasshouse, lost II tons/acre from infection in early June, 8 tons/acre from infection in late June and 6 tons/acre from infection in July. Plots cultured with virus‐free aphids in early June yielded as much as control plots. Experimental infection did not affect yield in 1959 and 1961, when the crop became naturally infected before treatment.The yields in different years were linearly related to the log. mean weekly numbers of C. aegopodiae caught on sticky traps near the sites, and the regression accounted for much of the variance in yield. The residuals of the log. mean weekly trap‐counts were negatively related to residual weekly rainfall in inches; I in. of rain above average approximately halved the increase in aphids. This may explain the failure of early invading aphids to become numerous at Woburn in 1960, when an inch of rain fell in three consecutive weeks in June.Treating seed or seedlings with systemic insecticide did not prevent young plants from becoming infected when infective aphids were cultured on them 10–14 days after treatment.Aphids taken from willow in the spring did not transmit motley dwarf to healthy carrots, but did so after they had fed on infected carrots. Aphids from wild umbellifers often transmitted motley dwarf to healthy carrots.
Persistence and identification of downy mildew Pseudoperonospora humuli (Miy. and Tak.) Wilson in hop rootstocks
Authors: COLEY‐SMITH J. R. 
Published: February 2008

SUMMARYEvidence is presented which suggests that Pseudoperonospora humuli persists, in a high proportion of infected hop rootstocks, for at least 4 years in this country, and the grubbing of these rootstocks is recommended. Methods are described for diagnosis of downy mildew during the dormant season in the field and in the laboratory.
The feeding, growth and reproduction of Aphis fabae Scop. on Viciu fuba under experimental conditions
Authors: BANKS C. J. , MACAULAY E. D. M. 
Published: February 2008

SUMMARYThe total amount of sap ingested by individual larvae and adult (apterous virgino‐parae) of Aphis fabae on field beans was estimated by adding the weights of honeydew excreted and of water lost by evaporation to increases in body weight during growth and to the weight of larvae born throughout the lives of the adult insects. The quantity of respiratory gases was ignored. Temperature and lighting were kept constant; air humidity was kept high to lessen evaporation, and air movements were eliminated. A machine was made to collect simultaneously the excreta of ten individual aphids to record their total daily excreta continuously from birth to death. Honeydew was also collected daily in mineral oil from other aphids of the same age on similar plants, to estimate the size of the droplets. The mean excretion rate was estimated from the product of the mean frequency of excretion and the mean size of the droplets. The reproductive rate, fecundity and length of reproductive and post‐reproductive life of the adult aphids were also recorded. The larva ingested about 3–5‐45 mg. of sap in a life of 7 days and the adult about 30 mg. during a reproductive life of 21 days; only about 10% was used for growth and reproduction.The excretion of the adult rose to a maximum of 30–40 drops per day on the third day of adult life and then declined, apparently because of changes within the aphid itself, for when the insects were transferred to fresh plants the excretion continued to decrease. The rate of feeding, which is about equal to the rate of excretion, therefore also decreased as the insect aged but its rate of reproduction remained fairly steady for about 16 days. The swelling of the abdomen and the slight increase in weight during the post‐reproductive life of about 2 weeks suggested that, although excretion had stopped, small amounts of sap continued to be ingested. The aphids ingested about the same amount of sap on two varieties of field bean but were significantly more fecund on one than on the other, a difference probably attributable to differences in the quality of the sap of the two varieties.
‘Lyamungu dieback’ of arabica coffee in Tanganyika
Authors: BURDEKIN D. A. 
Published: February 2008

SUMMARYThe symptoms of Lyamungu dieback on foliage, branches and roots are described and compared with those of other diebacks of coffee; retention of the dead leaves is a distinguishing symptom. The severity of the disorder is related to the stage of maturity and size of the crop.The degree of brown flecking of the xylem of the roots reflects the severity of the attack but is not determined by infection by Fusarium oxysporurn. The number and weight of secondary roots is reduced in the first year that the coffee is affected and further reduced if the trees survive into the succeeding year.Lyamungu dieback has caused serious losses at the Coffee Research Station, Lyamungu, since 1956, and is randomly distributed on estates in northern Tanganyika.The disorder is associated with heavy cropping and influenced by environment and cultural management. In experimental plots its effects were diminished by artificial shading (which reduced the crop) and by heavy nitrogenous manuring.
The influence of date of origin of the shoot and level of nitrogen on ear size in three perennial grasses
Authors: RYLE G. J. A. 
Published: February 2008

SUMMARYIn plants of S.24 ryegrass, S.215 meadow fescue and S.37 cocksfoot grown in the field, or with controlled nutrition in the glasshouse, ear size decreased the later the date of origin of the shoot between October and March, before flowering in late spring. The smaller ear size in shoots arising at successively later dates resulted from decreased numbers of primary branches in the ear, and also from the development of fewer florets on each branch. The decrease in number of primary branches was correlated with a decrease in number of unexpanded leaf primordia accumulated at the shoot apex before reproduction.No effect of nitrogen on ear size was detected when nitrogen was added as ‘Nitro‐chalk’ to plants growing one yard apart in the field. In contrast, plants receiving the smaller rates of nitrogen in the glasshouse generally developed ears with fewer florets on each lateral branch. Lack of nitrogen also decreased the number of primary branches in ears of ryegrass and prevented many shoots of all three varieties from flowering.
Breeding for tolerance to beet yellows virus and beet mild yellowing virus in sugar beet: II. The response of breeding material to infection with different virus strains
Authors: RUSSELL G. E. 
Published: February 2008

SUMMARYIsolates of beet yellows virus (BYV) and beet mild yellowing virus (BMYV) were collected from different parts of eastern England. Individual strains of BYV were isolated, from field plants infected with mixtures of strains, using a single lesion technique; all the strains thus isolated appeared to be closely related and there was complete cross‐protection between them. Individual strains of BYV produced symptoms of differing severity on sugar beet and other test plants, and caused different losses of sugar yield in sugar beet in the glasshouse and in the field.Considerable differences in sodium contents of the roots, and in serological titres of leaf sap, were observed between plants infected with different BW strains. Simultaneous inoculation of two BYV strains, using Myzus persicae Sulz., usually resulted in a disease which was intermediate in severity between the diseases caused by the strains separately. However, in some experiments, simultaneous inoculation of BYV strains caused a more severe disease than was expected and in others a milder disease.Differences between BMYV isolates were apparently very small in the field and under glass. Field experiments showed that inbred lines and experimental varieties, derived from plants selected for tolerance to BYV and BMYV, were more tolerant than the control varieties when subjected to many different infection treatments. Infection with BYV and BMYV reduced sugar yields and sugar contents and increased sodium and potassium contents of the root. Isolates of BMYV reduced the sugar contents, and increased the sodium contents, more than any strain of BYV. Simultaneous inoculation of BYV and BMYV produced more severe effects on sugar beet than either virus alone. The virus‐tolerant breeding material usually showed smaller reductions in root weight, sugar content and sugar yield than the control varieties, and smaller increases in sodium and potassium contents of the root. The results of experiments indicated that tolerance to one strain of BYV was associated with tolerance to a wide range of BYV strains. Much less is known about BMYV strains but the breeding material yielded well after infection with all the BMYV isolates against which they were tested. It seems unlikely that a rapid breakdown of tolerance would occur if virus‐tolerant sugar beet were widely grown in the field.
The association of split‐leaf blotch virus with nettlehead disease of hops
Authors: LEGG J. T. , ORMEROD P. J. 
Published: February 2008

SUMMARYThe distribution of two virus diseases, split‐leaf blotch and nettlehead, in hop plantations suggested that infection with split‐leaf blotch virus (SLBV) predisposed plants to nettlehead. Also in three field trials, the incidence of nettlehead disease was higher in plants (var. Fuggle) infected with SLBV than in healthy plants.The symptoms shown by Fuggle plants infected with SLBV were unaffected by additional infection with hop line‐pattern virus (HLPV), but plants of the varieties College Cluster and Keyworth's Midseason infected with both viruses developed symptoms resembling nettlehead disease in some respects. Such affected plants did not, however, induce nettlehead in plants of the indicator variety Early Prolific to which they were grafted, and therefore nettlehead disease is not the result of dual infection with SLBV and HLPV.Despite the field association of split‐leaf blotch and nettlehead symptoms, experimental data indicate that SLBV is not a component of the virus complex causing nettlehead disease.
Slug activity in relation to weather
Authors: WEBLEY D. 
Published: February 2008

SUMMARYMultiple regression analysis was carried out on the effect of certain meteorological factors on the numbers of slugs attracted by metaldehyde and bran biscuits at Cardiff in the autumn months. By far the greatest reduction in the variance in numbers of slugs attracted each morning was achieved by taking out the effects of two factors: (1) the length of time the biscuits had been exposed, and (2) the average night air temperature. The percentage relative humidity considered alone had little effect on the variance. Regression coefficients, at each site, for factors (I) and (2) on slug numbers appeared to be in close agreement and it is suggested that these figures would serve as a measure of slug activity. Arion hortensis behaved differently from the other species studied, its day‐to‐day variation in numbers not being tied so closely to the meteorological factors examined.Methods of assessing slug numbers in the field usually rely on the animals' activity. Barnes & Weil (1944) made direct counts on the slugs observable in half‐hourly periods, and Thomas (1944) based estimates of the number attracted to metaldehyde and bran biscuits overnight; Duthoit (1961) used baits of wheat seed in making weekly estimates. Measures of activity, however, may be less directly related to the actual population present than to day‐to‐day climatological variations. The aim of the work described below was to find if it was possible to arrive at more reproducible population estimates by using standard slug biscuits, and allowing for the effect of some of the meteorological variables.
Investigations on fungicides: X. The antifungal activity of 2‐deoxy‐D‐glucose
Authors: ATKIN R. K. , SPENCER D. M. , WAIN R. L. 
Published: February 2008

SUMMARYThe fungitoxicity of 2‐deoxy‐D‐glucose was examined in spore germination tests using Botrytis cinerea, B. fabae, Alternaria brassicicola, Aspergillus niger, Cladosporium cucumerinum, C. fulvum, Sclerotinia fructigena, Verticillium albo‐atrum and Glomerella cingulata. It proved to be toxic, at concentrations below 10 μg./ml., to all of these fungi except G. cingulata which was resistant to concentrations up to 2000 μg./ml. The effect of a‐deoxy‐D‐glucose on the mycelial growth of these fungi was assessed and again G. cingulata proved to be resistant to high concentrations of the compound, as also did A. niger.The results are discussed in relation to the known inhibitory nature of 2‐deoxy‐D‐glucose in other systems.