bluuebunny/crossref_metadata_2025_split huggingface dataset:
Seasonal changes in incubation time of Erysiphe graminis f.sp. hordei.
Authors: JENKYN J. F. 
Published: February 2008

SUMMARYIncubation time of Erysiphe graminis f.sp. hordei varied seasonally, but between early May and late September it was always between 5 and 8 days. This is approximately the time of year when the 30‐year weekly mean air temperature exceeds 10oC. Amount of infection during summer was decreased by hot, dry weather. In winter, incubation times were more variable and long incubation times were usually associated with few infections. Variation in incubation time during the summer is unlikely to be of practical importance in determining the rate of epidemic development.
The effect of viruses on growth and cropping of pear trees
Authors: CROPLEY R. , POSNETTE A. F. 
Published: February 2008

SUMMARYTwo virus diseases, vein yellows and mosaic, that commonly infect pear trees, reduced the growth and crop of four cultivars (Beurré Hardy, Doyenne du Cornice, Conference and Williams' bon Chrétien) in an experiment continued for 13 years. Reduction in yield was mainly due to the smaller size of infected trees. These produced about 30% less fruit than healthy trees when infected with vein yellows and 40 % less fruit when also infected with mosaic. Fruit size was decreased in only one year. The fertility of Cornice flowers was impaired.The greater vigour of healthy trees did not delay cropping; they produced over 30% more fruit than infected trees in the first three harvests.
Growth and yield of maize at different altitudes in Rhodesia
Authors: WILSON J. H. , CLOWES M. ST. J. , ALLISON J. C. S. 
Published: February 2008

SUMMARYA late (SR 52) and an early (N × K) variety were grown, with irrigation, on well fertilized soil at three sites, Chiredzi (altitude 420 m), Henderson (1260 m) and Grasslands (1620 m). Mean incoming radiation was similar at all sites, while mean temperature decreased as altitude increased.Final total and grain dry weights were greatest at Henderson, and those of SR 52 exceeded those of N × K, although not greatly at Chiredzi. Initially, leaf area index (L) decreased with increase in altitude, but plants flowered later as altitude increased, and L at the time of flowering was greatest at Henderson. L at flowering was greater in SR 52 than in N × K, though only slightly so at Chiredzi. Leaves withered sooner after flowering at Chiredzi and Grasslands than at Henderson, but leaves of the two varieties withered at about the same time after flowering at each site.During most of the vegetative phase the efficiency of the leaves and crop growth rate (C) increased with decrease in altitude, and were greater in N × K than in SR 52. More dry matter was accumulated after flowering at Henderson than at the other sites, and more by SR 52 than by N × K at Henderson and Grasslands, but not at Chiredzi. Leaf area duration (D) after flowering was greater at Henderson than elsewhere, and greater in SR 52 than in N × K, except at Chiredzi. After flowering leaf efficiency (dry weight increase ÷D) was least at Henderson and greatest at Grasslands, but differed little between varieties at each site. The fraction in the grain of the dry matter accumulated after flowering decreased with increase in altitude and was greater in SR 52 than in N × K.
The effect of sowing date and photoperiod on panicle morphology in naked oats (Avena nuda)
Authors: JENKINS G. 
Published: February 2008

SUMMARYVariations in panicle morphology in different environments were investigated for eight cultivars of naked oats (Avena nuda) and two cultivars of husked oats (A. sattva) in two experiments. The first experiment involved successional sowings in the glasshouse at monthly intervals from February to June. In the second experiment, the plants were grown continuously under constant photoperiods of 9, 11, 13 and 15 h. All the cultivars were found to be photoperiod sensitive, with Victory showing the greatest reduction in time to panicle emergence with increasing photoperiod.The proportion of multiflorous spikelets in all the cultivars of A. nuda except Nuprime and Laurel was greatest at constant photoperiods below 15 h. With successional sowings the proportion of multiflorous spikelets increased until mid April and thereafter decreased. The proportion of husked grains in the A. nuda cultivars was not markedly affected by variation of sowing date or photoperiod except for an increase in the variety Balkanischer following early sowing and subjection to a 15 h photoperiod. Under certain photoperiod treatments, some A. nuda varieties had a very low proportion of multiflorous spikelets but produced completely naked grain. The implication of these results in studies of the A. nuda genotype is discussed.
Formation and ultrastructure of microsclerotia of Pyrenochaeta lycopersici
Authors: WHITE J. G. , SCOTT A. C. 
Published: February 2008

SUMMARYThe formation of microsclerotia of Pyrenochaeta lycopersici Schneider & Gerlach was observed in culture, in isolated tomato root segments and in roots of intact tomato plants. In culture microsclerotia formed in the aerial mycelium, and submerged in the agar; in tomato roots they formed in single cells of the outer cortex.The microsclerotium of P. lycopersici is structurally unspecialized and has cell walls of similar thickness throughout. Microsclerotia are thought to have powers of long survival in soil. In isolation the microsclerotia of P. lycopersici maintained viability over 2 years with consistently high germinability. Transverse hyphae were never seen in sections of microsclerotia, suggesting that germ‐tubes arise from the outermost layers of cells.
Comparative transmission of bean leaf roll and pea enation mosaic viruses by aphids
Authors: COCKBAIN A. J. , COSTA C. L. 
Published: February 2008

SUMMARY Acyrthosiphon pisum was a more efficient vector than Myzus persicae of bean leaf roll virus (BLRV), but the two species transmitted pea enation mosaic virus (PEMV) equally well and much more often than Megoura viciae. M. viciae did not transmit BLRV, and Aphis fabae did not transmit BLRV or PEMV.BLRV and PEMV were transmitted more often by nymphs of A. pisum than by adult apterae or alatae that fed on infected plants only as adults, but both viruses were readily transmitted by adults that had developed on infected plants. The shortest time in which nymphs acquired BLRV was 2 h, and 50 % transmitted after an acquisition period of 4 days. Some nymphs acquired PEMV in 30 min and 50% in 8 h. The shortest time for inoculation of BLRV by adults was 15 min, but some transmitted PEMV in probes lasting less than 1 min. The median latent periods of BLRV and PEMV in aphids fed for 12 h on infected plants were, respectively, 105 and 44 h.Clones of A. pisum differed in their ability to transmit BLRV and PEMV, and efficiency in transmitting the two viruses seemed to be unrelated. Some aphids that fed successively on plants infected with each virus transmitted both viruses, and infectivity with one virus did not seem to affect transmission of the other.
Host range and overwintering sources of bean leaf roll and pea enation mosaic viruses in England
Authors: COCKBAIN A. J. , GIBBS A. J. 
Published: February 2008

SUMMARYBean leaf roll virus (BLRV) and pea enation mosaic virus (PEMV) were each transmitted by Acyrthosiphon pisum (Harris) to fifteen of thirty species of legumes in the glasshouse; eleven species were susceptible to both viruses. The only biennial or perennial species infected by BLRV were hop trefoil (Medicago lupulina L.), lucerne (M. sativa L.) and red clover (Trifolium pratense L.), but naturally infected sainfoin (Onobrychis viciifolia Scop.) and white clover (T. repens L.) were found. The only perennial species infected with PEMV in the glasshouse was kidney vetch (Anthyllis vulneraria L.).Eggs of A. pisum, which seems to be the main vector of BLRV and PEMV in England, were found in winter on several species of cultivated perennial legumes, most on lucerne, fewest on white clover. In spring, more viviparae of A. pisum were found on lucerne than on other perennial legumes, and many on lucerne, but few on red or white clover, were infective with BLRV. Lucerne is probably the main overwintering source of BLRV in areas where lucerne is common, but elsewhere red and white clovers are probably as important. No aphid collected from perennial legumes between 1965 and 1968 was infective with PEMV, but this virus can overwinter in common vetch (Vicia sativa L.).Lucerne infected with BLRV was usually symptomless or showed only transient mild yellowing of young leaves. Lucerne plants showing vein‐yellowing, similar to that previously reported as a symptom of BLRV, were possibly infected with an aberrant strain of BLRV but more probably with BLRV and another aphid‐transmitted agent. Inoculations from lucerne with vein‐yellowing symptoms sometimes caused vein‐yellowing, and sometimes typical BLRV‐symptoms, in crimson clover (Trifolium incarnatum L.).
Glasshouse tests of chemicals for control of potato common scab
Authors: MCINTOSH A. H. 
Published: February 2008

SUMMARYQuintozene is the only chemical used successfully in practice to control soil‐borne Streptomyces scabies, the cause of potato common scab. However it may be carcinogenic, and the aim of this work was to find a substitute for it.About 100 chemicals, most of which had known fungitoxic action or were related to such chemicals, were tested in the glasshouse by growing potato plants in soil with which the chemicals had been mixed, usually at 50 ppm. Many of the chemicals failed to decrease the incidence of scab, or decreased the yield of tubers, or both. The most effective chemical was captafol, which was as effective as quintozene and, unlike quintozene, did not decrease yield. Captan and folpet, which are very closely related to captafol, were ineffective.
Control of potato cyst‐nematode, Heterodera rostochiensis, in silt and peat loams by ten pesticides applied to the soil at planting time
Authors: WHITEHEAD A. G. , TITE D. J. , FRASER JANET E. , FRENCH EILEEN M. 
Published: February 2008

SUMMARYIncorporated in silt or peat loam top‐soil in spring before susceptible potatoes were planted, three carbamoyl oximes, aldicarb, Tirpate (2,4‐dimethyl‐2‐formyl 1‐1,3‐dithiolane oxime iV‐methylcarbamate) and Du Pont 1410 (S‐methyl i‐(dimethylcarbamoyl)‐N‐((methylcarbamoyl) oxy) thioformimidate) and one organophosphate, Nemacur (O‐ethyl‐O‐(3‐methyl‐4‐methylthiophenyl)‐isopropylamidophosphate) all at n‐2 kg a.i./ha greatly increased the yield of tubers and effectively controlled potato cyst‐nematode (Heterodera rostochiensis Woll.). At the same dosage thionazin was as effective in the peat loam but was ineffective in the silt loam; phorate and Mocap (O‐ethyl S,S‐dipropyl phosphorodithioate) were less effective and chlorfenvinphos, diazinon and a coarse granule formulation of fensulphothion were ineffective in controlling potato cyst‐nematode.
Treating potato ridges in spring with aldicarb, D‐D or dazomet to control potato cyst‐nematode, Heterodera rostochiensis, in sandy clay and peat loam soils
Authors: WHITEHEAD A. G. , TITE D. J. , FRASER JANET E. , FRENCH EILEEN M. 
Published: February 2008

SUMMARYApplied to potato ridge soil in spring, before potatoes were planted, small amounts of aldicarb (10‐3 kg/ha or less) controlled potato cyst‐nematodes (Heterodera rostochiensis Woll.) better than large amounts of dazomet (110–466 kg/ha) or D‐D (102–439 kg/ha). Applied in spring 1968 and 1969 to heavily infested sandy clay soil 466 kg dazomet/ha allowed Majestic potatoes to grow and yield well in both years without increasing the number of nematodes in the soil after harvest, but in peaty loam dazomet was toxic to potato plants and, when applied in autumn, killed fewer nematodes. D‐D in potato ridges in spring controlled nematodes less well than dazomet or aldicarb, but 896 kg D‐D/ha injected in sandy clay soil in autumn increased potato yield the following year without increasing the number of nematodes after harvest.
Some properties of pelargonium flower‐break virus
Authors: STONE By OLWEN M. , HOLLINGS M. 
Published: February 2008

SUMMARYA virus obtained from pelargonium cvs Irene and Paul Crampel appears to differ from any previously reported; although symptomless in most pelargonium cvs tested, it caused colour break in the flowers of two seedling clones. It seems uncommon in pelargoniums. The virus was readily transmitted by inoculation of sap, but not by Myzus persicae with short feeds, by dodder or through seed. It infected only fifteen of 100 species tested in six of thirty‐five plant families. Pelargoniums were freed from the virus by heat‐treatment.The virus remained infective after 10 min at 85 oC, 3 wk at 20 oC or 27 wk at 2 oC; it was infective at 1/500000 dilution of Nicotiana clevelandii or Chenopodium quinoa sap.Purified preparations were readily made by several methods, and contained isometric particles c. 30 nm diameter. Although a good antigen, the virus was serologically unrelated to any of forty‐two isometric viruses. In immunoelectrophoresis, the virus moved as a single antigenic component towards the cathode. It gave a single, specific zone in density‐gradient centrifugation, and one moving component (s020 w= 125 S) in analytical centrifugation. The virus contained one protein of mol. wt. c. 41000. The present cryptogram of the virus is (R)/*: */*:S/S:S/*, and the name pelargonium flower‐break virus is proposed.
The effects of trifluralin and related dinitroaniline herbicides on clubroot of Brassicae
Authors: BUCZACKI By S. T. 
Published: February 2008

SUMMARYIn glasshouse tests, trifluralin, when mixed with the soil before sowing, lowered the incidence of clubroot on cabbages.An emulsifiable concentrate was more effective than a wettable powder and control was better in soil alone than in a soil/peat mixture. Four other dinitroaniline herbicides were tested; benfluralin and isopropalin lowered clubroot incidence at non‐phytotoxic rates whereas nitralin and dinitramine did not.
The modes of action of two benzimidazoles and thiophanate‐methyl used for the control of Verticillium wilt of strawberry
Authors: JORDAN By V. W. L. 
Published: February 2008

SUMMARYBenomyl, thiabendazole and thiophanate‐methyl were found to be fungistatic against Verticillium dahliae in vitro. All materials suppressed wilt symptoms on artificially inoculated strawberry plants when applied as a root dip, soil drench or a foliar application.Quantitative bioassays of the amount of toxic residues and fungal colonization in tissues of treated plants after root treatment revealed that these materials or their toxic breakdown products were readily translocated to crown and leaves: they suppressed the internal spread of the pathogen throughout the plant. After foliar application there was no marked basipetal movement of material within the plant: fungal colonization was greatly reduced in treated leaves, but the roots and crowns were colonized to a similar extent to those of untreated plants.
Investigations on fungicides: XV. The fungitoxicity and systemic antifungal activity of N‐(2, 2, 2‐trichloro‐1‐methoxyethyl) formamide and related compounds
Authors: CARTER By G. A. , CHAMBERLAIN K. , WAIN R. L. 
Published: February 2008

SUMMARYThe direct and systemic antifungal activity of 100 compounds structurally related to iV‐(2, 2, 2‐trichloro‐i‐methoxyethyl)formamide has been measured. Some of the compounds showed either protectant or systemic activity against powdery mildew fungi. Compounds not possessing a terminal formamido group showed little anti‐mildew activity and for good systemic activity an alkyloxy or alkylamino side‐chain in the molecule appeared to be necessary.
Effect on carrot root yield and size distribution of the growth‐retardants chlormequat chloride and aminozide
Authors: THOMAS By T. H. , CURRAH I. E. , SALTER P. J. 
Published: February 2008

SUMMARYIn two experiments, foliar sprays of either chlormequat chloride or aminozide depressed top growth, increased root yield and enhanced leaf and root colour in six carrot cultivars. In the first experiment, a direct correlation between concentration of the two retardants and root yield was apparent within the range 0–2000 mg/1 a.i. applied as run‐off sprays to two cultivars. In the second experiment, increases in total root and canning‐size yield and root/shoot ratio were obtained with four cultivars, but the magnitude of these effects was dependent on the time at which the retardants were applied and the time of harvest of the crop. The effects of aminozide on root yield were less persistent than those of chlormequat chloride, the yield differences between untreated and aminozide‐treated plots decreasing with time after application.
Some effects of seed source on early growth in Maris Peer potatoes
Authors: GRAY D. 
Published: February 2008

SUMMARYPotato seed tubers cv. Maris Peer obtained from a number of sources in England and Scotland were graded into a range of weights and after storage for approximately 3 or 7 months in 1971 or 3 months in 1972 they were planted to determine the effect of seed source on early foliage growth.In both years there were large differences between seed sources on the effect of seed tuber weight on the dry weight of foliage produced in a glasshouse from seed stored for 3 months. In some instances small seed from one source produced the same weight of foliage as large seed from another source. In 1971 after seed storage for 7 months there was no effect of source on foliage dry weight produced in the field. There was, however, no consistent effect of the site of production of the parent seed, of fertilizer treatments of the seed crop, or of N content of the seed tubers. Seed tuber N content increased, though not proportionally, with an increase in seed weight. It was unaffected by source except for seed tubers from one site m 1972.
Changes in developing pea (Pisum sativum) seeds in relation to their ability to withstand desiccation
Authors: MATTHEWS S. 
Published: February 2008

SUMMARYIn two separate experiments in 1970 and 1971 the germination ability of seeds that had been rapidly desiccated following harvesting from glasshouse‐grown pea plants improved with time after fertilization. In 1970 the germination of seeds directly after harvesting also improved with time. In both years the readiness with which electrolytes were leached from dried seeds decreased with seed age, measured as time after fertilization. The germination ability of desiccated seeds, and of undried seeds in 1970, improved after the cessation of seed moisture increase on the parent plant. This improvement coincided, in 1970, with a fall in the readiness with which electrolytes could be leached from seeds and with a decline in the rate of oxygen uptake of seeds directly after harvest.Vital staining of dried seeds from harvest samples indicated the viability of the samples as determined by germination tests. In both years, when the cotyledons first showed complete staining, the staining was very intense; in 1970 this occurred in a harvest sample with a greater than 50% germination level, but in 1971 it occurred in a sample that showed incomplete staining in the embryo axis and less than 5 % germination.In 1971 the comparative rates of moisture loss from seeds, measured with a sensor element diffusion porometer, were very low at 25 days after fertilization, increased up to a peak at 35 days and fell to a rate at the final harvest (44 days) which was nearly three times faster than the initial rate. Thus, during the period of dehydration, after 37 days, the seeds were able to lose moisture.When seeds were allowed to lose moisture slowly after harvest, before being desiccated rapidly, their eventual condition as measured by leaching improved. Also, the faster the initial water loss preceding rapid desiccation the more readily were the dried seeds leached.It is suggested that seeds can only withstand rapid desiccation after the cessation of moisture increase and after some slow dehydration, which is accompanied by a slowing down in physiological activity.
The ecology and economics of damage to Brassicae by wood‐pigeons Columba palumbus
Authors: MURTON R. K. , JONES BARBARA E. 
Published: February 2008

SUMMARYDamage caused by wood‐pigeons, Columba palumbus, to spring cabbage and Brussels sprouts was measured during three winters in two areas in the Vale of Evesham, Worcestershire. In one area (experimental) special attempts were made to reduce pigeon damage in addition to the normal efforts of the growers. In the other (control) area no such additional measures were taken. There was slightly more damage in 1969‐70, but low market prices made it less important than in 1968‐9 or 1970‐1. There was no significant difference in any season between the damage in the control and experimental areas. No damage was caused to Brussels‐sprout buttons as the birds ate only the tops of the plants; they preferred Brussels sprouts to cabbages and it is likely that the presence of the former helped to reduce the amount of damage to nearby cabbage fields. The amount of damage was not correlated with the amount spent on crop protection; actual damage was not correlated with the grower's estimates in the control area.In the second season a very intensive shooting campaign in the experimental area did not result in less damage, but the movements of local inhabitants and farm workers near a village did afford protection. The significance of the damage in the Vale and elsewhere is assessed in relation to the economics of crop production, the cropping pattern for cabbages and the behaviour and ecology of the wood‐pigeon.
The feeding behaviour of Phytoseiulus persimilis (Acarina: Phytoseiidae), particularly as affected by certain pesticides
Authors: JACKSON G. J. , FORD J. B. 
Published: February 2008

SUMMARYDetailed observations were made of the behaviour of Phytoseiulus persimilis while searching for, identifying and feeding on eggs of Tetranychus urticae. A theory is proposed to explain how P. persimilis may identify prey eggs and distinguish them from non‐prey objects. The existence of a water‐soluble feeding stimulant on prey eggs is postulated.The effect of residues of captan, dinocap and malathion on the feeding behaviour of P. persimilis was investigated. Residues of the fungicide dinocap on the eggs of the prey did not affect acceptance by the predator, but captan had a marked repellent effect. Malathion had an even stronger repellent effect.It is suggested that, by making the prey eggs less acceptable to the predator, the use of certain fungicides could render more difficult the prediction of population interactions on which biological control depends.We wish to thank Dr N. W. Hussey of the Glasshouse Crops Research Institute for helpful comments and for supplying predatory mites. Mr Jackson wishes to thank the Overseas Development Administration for financial support during this work.
Variation in the intensity of diapause in winter eggs of fruit tree red spider mite, Panonychus ultni
Authors: CRANHAM J. E. 
Published: February 2008

SUMMARYWinter eggs of Panonychus ulmi from six orchards in Kent showed a range of 3 weeks in the dates of 50 % hatch at field temperatures. From the effects of the duration and temperature of chilling, and the temperature of incubation, it was concluded that samples varied in their chilling requirement, and not in threshold temperatures for development. Diapause was terminated most effectively by chilling initially at o oC (for late‐hatching strains) or 5 followed by 9 for the last month or two. Heritable variation in diapause intensity is discussed in relation to heat sums and the forecasting of hatch, and to phenology.