bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effect of partial defoliation during the vegetative phase on subsequent growth and grain yield of maize
Authors: ALLISON J. C. S. , WILSON J. H. , WILLIAMS J. H. 
Published: February 2008

SUMMARYMaize was grown in two densities, 2–47 or 4–94 plants m‐2, and the following treatments imposed: untreated, plants partly defoliated 51 days after sowing, and alternate plants in a row partly defoliated 44 days after sowing. Plants flowered about 82 days after sowing. Leaf area was decreased by 60–64% by defoliation on day 51.Defoliation resulted in decreases in grain yield and grain number of 6–17%, though when alternate plants were defoliated in the higher density there was a substantial decrease in yield and number of grains in defoliated plants, which was largely offset by an increase in adjacent intact plants.When plants were defoliated on day 51 subsequent growth in leaf area was similar to, and that in leaf weight nearly as large as that in untreated plants, while increase in stem weight was substantially less than in untreated plants. By the time of flowering untreated and defoliated plots differed by c. 30% in leaf area. Increments of dry matter after flowering differed by c. 15% between untreated and defoliated plots. The fraction of these increments which entered the grain was c. 90% in both untreated and defoliated plots.When alternate plants in the row were partly defoliated on day 44 their subsequent increase in leaf area was probably 5–16% less than that of the adjacent intact plants. Increments of dry matter after flowering of plots with alternate plants defoliated were 93–95 % of those of untreated plots; leaf efficiency after flowering was slightly greater than in untreated plots. The fraction of the dry matter increment after flowering which entered the grain was c. 88 % in both intact and defoliated plants of the small density, but was 94% in intact plants and 86% in defoliated plants of the large density.
Genotypic and environmental variation in some colour characteristics of carrots
Authors: DOWKER B. D. , FENNELL J. F. M. , JACKSON J. C. , ARTHEY V. D. 
Published: February 2008

SUMMARYFive colour characteristics were studied in seventeen carrot trials in which four varieties of the Chantenay type and four of the Autumn King type were grown at two densities at several sites for 3 yr. The Chantenay type had lower percentages of green‐topped and green‐cored roots and a higher score for internal colour; the Autumn King type had a lower percentage of purple‐topped roots. Differences between varieties within types were also detected. Large environmental effects mainly resulted from differences between individual trials. Percentages of discoloured roots were higher at the low density.Genotype × environment (GE) interactions of practical importance were detected for all characters except internal colour. Some of these interactions were adequately described in terms of different linear regression coefficients for the genotypes, when genotypic values were regressed on environmental means. The results indicate that a low density should be chosen when selecting for reduced discolorations. Broad‐sense heritabilities, estimated from variance components for the genotypic, environmental and GE effects, show that the most efficient selection for a colour character, in one season and with four test plots per family, would be achieved when such plots were grown at four separate sites.
Strain changes in populations of tobacco mosaic virus from tomato crops
Authors: FLETCHER J. T. , BUTLER D. 
Published: February 2008

SUMMARYThe incidence of tobacco mosaic virus (TMV) Strain 1 in tomato crops of TMV‐susceptible cultivars increased from 12% in 1971 to 64% in 1974. This change coincided with the introduction of cross protection to reduce the effects of tomato mosaic. Of the isolates collected from nurseries where the technique was used in 1974, 94% were of Strain 1 compared with 39 % from the other nurseries. No new strains were found and all the isolates were tomato forms of TMV.
The effect of benomyl sprays on Sclerotinia trifoliorum and yield of red clover
Authors: JENKYN J. F. 
Published: February 2008

SUMMARYBenomyl sprays, applied monthly from September to January, increased the survival and dry‐matter yield of red clover and decreased the numbers of apothecia of Sclerotinia trifoliorum. Two sprays increased dry‐matter yield in the first harvest year, if applied between October and December, but decreased yield in the second harvest year.
The effect of crowding on alate production and weight of apterous exules of the apple‐grass aphid, Rhopalosiphum insertum
Authors: DEWAR A. M. 
Published: February 2008

SUMMARYOffspring of Rhopalosiphum insertum are most sensitive to crowding immediately before and after birth. Crowding throughout the nymphal and adult life of the mothers irreversibly determines most offspring as alatae whether the offspring are crowded or not. Offspring of mothers having less exposure to crowding require additional stimuli after birth. The possible evolutionary advantages of such a system are discussed. Hormonal control of alary polymorphism is implicated.The weight of apterae declined with increased crowding. This is correlated with an increase in alate production, and may thus serve to limit the population increase to a level tolerable by the plant without killing it.
Effects of temperature on overwintering populations of the green spruce aphid Elatobium abietinum
Authors: POWELL W. , PARRY W. H. 
Published: February 2008

SUMMARYRecorded minimum temperatures of – 7 oC or lower noticeably reduced overwintering populations of the green spruce aphid, Elatobium abietinum, in north‐east Scotland. It is suggested that, at these temperatures, ice formation in the needles of the host Sitka spruce, caused attached aphids to freeze. Aphid mortality also occurred when maximum temperatures did not rise above + 6 oC for prolonged periods, possibly as a result of starvation following an extended chill coma.A diagrammatic representation of the main factors affecting anholocyclic populations of E. abietinum during the winter is presented to emphasize the governing role played by temperature. The balance between mortality and recruitment determines the size of the population at the end of the winter, and this in turn determines the subsequent summer infestation. It should be possible, therefore, to predict aphid outbreaks either from winter temperatures or from the number of aphids present at the end of the winter.Temperature records obtained from integrating thermometers indicated that the inside of the lower crown tended to be the warmest part of the tree during the winter, resulting in greater aphid survival in the lower branches.
Synthesis of mycorrhiza on Pinus oocarpa
Authors: MOMOH Z. O. 
Published: February 2008

SUMMARYMycorrhiza was synthesized using Pinus oocarpa and Rhizopogon luteolus. After one year's successful growth in the laboratory, the seedlings raised were planted out in the field where the inoculated plants continued to grow normally. The uninoculated plants died after planting out. The results are believed to be significant in that a field establishment of mycorrhiza synthesized in controlled conditions is possible. The experiment also demonstrates the absence of suitable mycorrhizal fungi for pine establishment in Nigerian soils.
Variation in Phytophthora infestans on potatoes grown in walk‐in polyethylene tunnels
Authors: SHATTOCK R. C. 
Published: February 2008

SUMMARYSmall areas of potatoes were grown and the foliage successfully infected with Phytophthora infestans over a 10 wk period using walk‐in polyethylene tunnels which had been modified to allow easy transport from one site to another. These protected the infected crops from possible outside sources of blight and contained the disease spatially. The fungus populations spreading from foliage inoculated with P. infestans race (3,4,10, 11) were monitored for racial stability and some variation in race was recorded. In general, novel races were less, rather than more, virulent than the introduced race.
Effect of temperature, light and host on prepenetration development of Puccinia graminis avenae and Puccinia coronata avenae
Authors: KOCHMAN J. K. , BROWN J. F. 
Published: February 2008

SUMMARYThe influence of temperature and light on prepenetration development of single and mixed isolates of Puccinia graminis avenae and Puccinia coronata avenae was studied on 0–2% water agar and on leaves of three oat cultivars and on three non‐cultivated species of Avena. Germination of uredospores of P. graminis avenae and P. coronata avenae occurred best at 10–30oC and at 20oC respectively. The optimum temperature for germ‐tube growth and for appressorial formation was 20oC for both rusts.An inverse relationship was observed between light intensity and prepenetration development with maximal germination of uredospores, germ‐tube growth and appressorial formation occurring in darkness. Under optimum conditions maximum percentage germination and appressorium formation of both rusts was attained within 4 and 12 h after inoculation respectively. The proportion of germinated uredospores of crown rust which gave rise to appressoria was about twice that observed for stem rust.No significant differences were observed in prepenetration development between the single and mixed race inocula of the two rusts. Although germination of uredospores was significantly greater on water agar than on oat leaves, there were no significant differences in prepenetration development of the rusts on the various oat cultivars and species examined. Consequently, the data failed to indicate the presence of resistance mechanisms operating during the prepenetration phase of the infection process on the cultivars and species examined.
Host and environmental effects on the penetration of oats by Puccinia graminis avenae and Puccinia coronata avenae
Authors: KOCHMAN J. K. , BROWN J. F. 
Published: February 2008

SUMMARYThe frequency of penetration from appressoria of Puccinia graminis avenae and P. coronata avenae varied among Avena species and between oat cultivars, although both rusts produced susceptible infection type pustules on the cultivars tested. Penetration on cv. Garry was significantly less than that on the Avena species (A. barbata, A.fatua and A. sterilis) studied and penetration of these Avena species was significantly less than on the cvs Algerian and Fulmark. When the rusts were allowed to develop into pustules on seedlings which had been inoculated with fixed amounts of inoculum, there was a direct relationship between number of pustules produced and penetration frequency.The effects of temperature, light and dew period on penetration from appressoria of ‘single race’ and ‘mixed race’ inocula was also studied on these cultivars and species. Penetration by P. graminis avenae was greatest at 30–35 °C and at light intensities of 5625 lux and above, whereas that by P. coronata avenae was greatest at 20 °C and was unaffected by artificial light intensities up to n 250 lux. Maximal penetration by P. graminis avenae and P. coronata avenae was observed after inoculated plants had been exposed to dew periods of 16 and 12 h respectively. Some penetration was observed after a dew period of 8 h. The time taken for each rust to attain maximum penetration varied from 36 to 52 h after inoculation, depending on the environment, and was usually less for P. coronata avenae than for P. graminis avenae.
Weather and fireblight in England
Authors: BILLING EVE 
Published: February 2008

SUMMARYA method for assessing potential fireblight activity in the field in southeast England is described. It is based on potential doublings (PD), derived from in vitro growth rates of Erwinia amylovora at different temperatures, combined with a rain score (R) derived from daily precipitation values. Where the incubation period (I) was known, the coefficient of correlation between I/R and PD was 085 (P < 0–001). When I was regressed on PD and R, the multiple correlation coefficient was 0–97. The low level of fireblight in England precluded direct testing of the predictive value of the relationship between PD, I and R but its application to growing season weather of 1955‐74 highlighted those years when fireblight activity was high in a particular host. Whilst within the range 65–86 oF (18–30 oC) there is good agreement between accumulated potential doubling values and accumulated degree days, the rain score would probably require modification in other climates.
Some factors affecting the control of Rhizoctonia solani by systemic and non‐systemic fungicides
Authors: KATARIA H. R. , GROVER R. K. 
Published: February 2008

SUMMARYIn laboratory tests, Rhizoctonia solani grew best on agar at 30 oC and pH 5‐5. Mycelial growth was strongly inhibited by benomyl, chloroneb and quintozene, less so by thiophanate‐methyl. The optimum temperature for inhibition was 25 oC for quintozene; the other three fungicides gave greatest inhibition at the lowest temperature tested (20 oC). Benomyl and thiophanate‐methyl were most inhibitory at pH 7–8, chloroneb and quintozene at pH 5–6.In pot trials using mung bean, long melon, egg‐plant, common pea and sugar beet, R. solani caused maximum disease at 20 oC and in wet and alkaline soils. As seed treatments, benomyl and thiophanate‐methyl gave optimum control at 20 oC and pH 7‐6; chloroneb and quintozene were most effective at 30 oC and pH 5‐4. All four fungicides gave maximum control on plants growing in wet sandy loam.Comparisons of host effects showed that, on all the four hosts tested, thiophanate‐methyl wettable powder at 0.25% (0.175% a.i.) gave 90% control, chloroneb w.p. at 0.3% (0.195% a‐i‐) gave 80% control on mung bean and sugar beet, benomyl w.p. at 0.3% (0.15% a.i.) was satisfactory on mung bean, egg‐plant and sugar beet but not on long melon, quintozene w.p. at 0.3 % (0.225 % a‐i‐) gave effective control on sugar beet only.The senior author is grateful to the Council of Scientific and Industrial Research, New Delhi, India, for the award of a Research Fellowship for undertaking these studies. Thanks are due to Dr S. D. Gupta and Mr S. L. Verma for determining the soil characteristics.
The epidemiology of potato blight in the East Midlands 1923–74
Authors: CROXALL H. E. , SMITH L. P. 
Published: February 2008

SUMMARYExamination of the East Midlands records of potato blight epidemics and the meteorological data on critical 90 % relative humidity infection periods for the years 1923–74 indicates the importance of the amount of inoculum carried over from one season to the next in influencing the rapidity of progress of the disease and the date of destruction of the haulm. The success of forecasting outbreaks based on 90% r.h. periods is reviewed. The importance of taking into account both amount of inoculum and weather conditions in devising a disease control programme is discussed. It is concluded that the succession of seasons since 1968 without a major potato blight epidemic was due mainly to a combination of low carry‐over of infection and sub‐optimal weather conditions for the development of the disease and that the current control measures have not yet been subjected to a severe test.
Benomyl tolerance in isolates of Botrytis cinerea from tomato plants
Authors: FLETCHER J. T. , SCHOLEFIELD SUSAN M. 
Published: February 2008

SUMMARYThree hundred and forty‐nine isolates of Botrytis cinerea were collected from tomato crops on forty‐one nurseries and 173 (40/6 %) were found to be tolerant to benomyl. There was no obvious association between disease incidence and the occurrence of tolerance.In a fungicide comparison experiment on tomatoes in 1973, twenty of the sixty‐four (31 %) isolates examined were benomyl tolerant, the majority of these were from benomyl sprayed plants. In 1974 in a similar experiment, 384 of the 394 (97‐5 %) isolates examined were tolerant.Tolerance was monitored in two tomato experiments in relation to a spray programme in which benomyl and dichlofluanid were used in various combinations. There was no marked effect of the spray programmes on the incidence of tolerance on either site.In the experiments B. cinerea was controlled and significant increases in yield were obtained with benomyl in 1973 but not in 1974. This difference is attributed to the change in the pathogen population with a large increase in the incidence of tolerance on the experimental site in 1974.
Systemic fungicides in the control of strawberry wilt (Verticillium dahliae)
Authors: TALBOYS P. W. , FRICK E. L. , DAVIES MOIRA K. 
Published: February 2008

SUMMARYIn a series of experiments between 1970 and 1973 the application of benomyl or thiophanate methyl to field‐grown strawberries, planted on Verticillium‐mtested land, gave control of wilt for up to 5 months, the duration of control being related to the amount of fungicide applied in the spring. Treatment of inoculated plants grown on in chloropicrin‐fumigated soil was effective for at least two seasons.An autumn‐planted multi‐factorial experiment in heavily‐infested soil showed that, to achieve maximum wilt control, it was advantageous to grow cv. Gorella rather than cv. Cambridge Vigour; to drench the runners at planting rather than to dip them in the fungicide suspension; and to use a high concentration (0–075 % a‐i‐) and large volume (600 ml per plant) for a supplementary treatment in May rather than a lower concentration (0.025 %) or smaller volume (400 ml). There were small but significant advantages in applying benomyl rather than thiophanate methyl, and in using 0–2% a.i. suspension at planting rather than 0–05%. No advantage was gained by dividing the spring application into two equal doses applied 2 wk apart. Extrapolation from the logarithmic relation between wilt index and total dose of fungicide applied in the spring suggested that I.I g/plant would have given almost complete control until October; such control had been achieved in an earlier experiment in which 1–2 g/plant was applied. Crop yield in the second year was determined by the treatment applied in the first year, but although these treatments had given significantly better control of wilt in Gorella than in Cambridge Vigour, the greater growth and yield potentials of the latter cultivar had an over‐riding effect on crop production; Cambridge Vigour yielded more than Gorella under all chemical treatments, but in the absence of treatment Gorella gave a larger crop than Cambridge Vigour.A proposed regime, entailing spring and autumn applications, is aimed at minimizing the colonization of the plant throughout the year, thus reducing the production of new inoculum and, by limiting the quantity of the pathogen in contact with the systemic chemicals, minimizing the probability of selecting fungicide‐resistant variants of V. dahliae.
The effect of time to emergence on head weight and variation in head weight at maturity in lettuce (Lactuca sativa)
Authors: GRAY D. 
Published: February 2008

SUMMARYIn lettuce, results of three experiments showed that between 60 and 90 % of the variation in mature head weight and the date of head maturity could be accounted for by variation in the date of seedling emergence. Sowing pre‐germinated seeds using a fluid drill considerably reduced the time spread of both emergence and maturity compared with size‐graded natural seed sown conventionally.
Development of biological methods for the control of Tetranychus urticae on tomatoes using Phytoseiulus persimilis
Authors: FRENCH N. , PARR W. J. , GOULD. H. J. , WILLIAMS J. J. , SIMMONDS S. P. 
Published: February 2008

SUMMARYThe biological control of red spider mite using the predatory mite Phytoseiulus persimilis was investigated in 1971, 1972 and 1974. Experiments in small glasshouse compartments showed that the predator should be introduced when the leaf damage index is < 0–3.Uniform and/or patch introductions of P. persimilis at different rates were made into naturally occurring red spider mite infestations on commercial nurseries. In eleven of the seventeen experiments good control was achieved. Introduction of the predator soon after damage appeared on the crop was essential. Poor control was obtained when the predator failed to establish itself, where very large numbers of diapausing mites emerged and built up rapidly or where the predator, introduced into patches, failed to colonize infested plants elsewhere in the crop.When spider mites and predators were introduced on to one‐fifth or one‐tenth of the plants in a propagating house, a satisfactory interaction was maintained for 4–6 wk after planting out. The predators then died unless red spider mites emerged from diapause or were introduced.Petroleum oil sprays were sometimes used successfully in the presence of the predator to reduce high red spider mite infestations and re‐establish the biological equilibrium.
Laboratory studies on the fungus Verticillium lecanii, a larval pathogen of the large elm bark beetle (Scolytus scolytus)
Authors: BARSON G. 
Published: February 2008

SUMMARYFrom 1972 to 1974, estimates of the natural larval mortality (> second instar) of elm bark beetles caused by pathogenic organisms were always below 7'5 % of the beetle population. The pathogenic fungus Verticillium lecanii was frequently isolated from field‐collected dead larvae, and in the laboratory all larvae were killed in 5 days when exposed to spore concentrations of 4·5 × 106 spores/ml. V. lecanii begins to lose its pathogenicity after prolonged culture on artificial media. The time taken for V. lecanii to kill Scolytus scolytus larvae when exposed to a logarithmic series of spore dilutions from 9·1 × 107/ml to 9·1 × 103/ml increased with decreasing amounts of inoculum. Even at spore concentrations as low as 9·1 × 103/ml the mortality of treated larvae was greater than that of untreated individuals. At 100% r.h. all treated larvae were killed over a temperature range of 5–30 °C; those maintained at 25 °C were killed most rapidly and those kept at 5 °C the slowest.
Glasshouse tests of quinones, polyhydroxybenzenes and related compounds against potato common scab
Authors: Mcintosh A. H. 
Published: February 2008

SUMMARYForty quinones, polyhydroxybenzenes and related compounds were tested for possible control of potato common scab, caused by Streptomyces scabies. They were incorporated, at 50 μg/g or less, into scab‐infected soil in which potato plants were then grown in the glasshouse. Quintozene at 50/μ g/g was used as standard.The chemicals varied very widely in their effects on scab, and in their phytotoxicity, as measured by decrease in yield of tubers.Corresponding 1,4‐benzoquinones and hydroquinones behaved similarly. The unsubstituted and the phenyl‐, chloro‐,2,5‐ and 2,6‐dichloro‐com‐pounds were as effective as quintozene; with the exception of chloro‐hydroquinone, they did not decrease yield. Chloranil and chloroneb (the dimethylether of 2,5‐dichlorohydroquinone) were much less effective, and chloroneb decreased yield as well.4‐terf‐butyl catechol was more effective than any other compound tested, including quintozene, and at suitable rates (25 or 12‐5 μg/g) did not decrease yield.Other hydroxybenzenes and some 1,4‐naphthaquinones (including dichlone) and anthraquinones were almost ineffective.
Control of seed‐borne Fusarium nivale on wheat and barley by organomercury seed treatment
Authors: BATEMAN G. L. 
Published: February 2008

SUMMARYThe effectiveness of organomercury seed treatments in controlling seedling disease caused by seed‐borne Fusarium nivale was studied in pot experiments. Ethyl mercuric chloride was more effective than phenyl mercuric acetate (PMA) on barley. Storing treated seed for 6 wk before sowing improved the performance of both compounds. PMA was less effective in controlling F. nivale than Septoria nodorum on wheat, although F. nivale was only slightly less sensitive to PMA in agar plate tests. Control of JF. nivale was usually more effective on wheat than on barley for the two seed samples used. PMA rates two to four times those applied commercially did not completely eliminate infection. Rates of PMA less than about 0–125μg Hg/seed did not significantly control F. nivale on wheat or barley.