bluuebunny/crossref_metadata_2025 huggingface dataset:
Ethylene pollution in the atmosphere
Authors: George E. F. , Clark J. Gordon
Published: February 2008

Plants demonstrate various responses when subjected to relatively low concentrations of ethylene gas in the ambient air. The duration of exposure required depends on concentration and varies in different plants and according to stage and manner of growth. Several external factors may also influence the response of intact plants.

Besides emissions from industrial installations, ethylene is produced externally from many natural sources and in consequence of human activities. The bulk of evidence suggests that ethylene is not at present a serious pollutant but we suggest that further and more precise research is required.
Ripening of tomato fruits at reduced atmospheric and partial oxygen pressures
Authors: Stenvers N.
Published: February 2008

A reduced partial oxygen pressure retards the onset and the rate of ripening of tomato fruits, irrespective of the total atmospheric pressure and the absorption of endogenously evolved ethylene. The reduction of the partial oxygen supply is therefore a main factor in retarding senescence at low pressure storage.
Commercial uses of ethephon in crop production
Authors: Sterry J. R.
Published: February 2008

Since its discovery in 1966, 2‐chloroethylphosphonic acid, with a proposed common chemical name of ethephon (EthrelE) has been increasingly utilized in a number of important crops, including latex stimulation of rubber (Hevea brasiliensis), acceleration of maturity and/or abscission of many fruits and nuts and modification of growth characteristics of various food and fibre crops. It can be an important aid to programmed production, mechanical harvesting and enhancement of quality. Continuing experimentation is still finding new potential uses.
The involvement of ethylene in vascular wilt diseases
Authors: Pegg G. F.
Published: February 2008

Plants exhibiting a wilt syndrome induced by the vascular pathogens Verticillium albo‐atrum or Pseudomonas solanacearum produce increased amounts of ethylene which may or may not include a contribution from the pathogen.

Resistant, infected tomato plants do not produce more ethylene in the absence of visible symptoms. Ethylene is produced rapidly in affected susceptible plants as symptoms appear suggesting a tissue wound response. No correlation could be demonstrated between ethylene evolution and loss of leaf turgor or stomatal density. Many of the symptoms of vascular wilt infection may be reproduced by ethylene. This suggests that ethylene functions as a phyto‐toxin. Gassing inoculated plants with ethylene may, however, protect against symptom development. A multiple role for ethylene involvement in pathogenesis is discussed in relation to host hydrolase activity.
Simulation of the hop Verticillium wilt syndrome by applications of ethrel
Authors: Talboys P. W.
Published: February 2008

Some of the diverse range of leaf symptoms of hop wilt can be induced simply by introducing solutions of ethephon at pH 6‐4 into the vascular system; others require the additional presence of a larger molecule, which can be ‘modelled’ by a polyethylene glycol. Treatments which include ethephon cause enlargement of cells associated with the vascular elements, resulting in tylosis and other anatomical changes similar to those found in Verticillium‐infected plants.
Epidemiology of damping‐off disease (Pythium irregulare) in relation to density of Lepidium sativum seedlings
Authors: BURDON J. J. , CHILVERS G. A.
Published: February 2008

Controlled experiments on post‐emergence damping‐off, using small populations of garden cress seedlings (Lepidium sativum) inoculated with Pythium irregulare, demonstrate that planting density of the host population plays an important role in determining the rate of multiplication and the rate of advance of the disease. At high seedling densities the disease is transmitted readily between host plants, but at lower densities the greater distance between adjacent plants reduces the probability of successful transmissions, and this is reflected in the parameters of multiplication and advance. A simple negative relationship was found between the mean distance separating adjacent plants and both rate of advance of disease front and rate of multiplication of disease in a randomly inoculated seedling stand.
Decrease of take‐all by a transmissible factor in take‐all decline soils
Authors: POPE A. M. S. , HORNBY D.
Published: February 2008

Irrespective of type and cropping history, soils with take‐all decline (D soils) contained a take‐all‐decreasing factor that could be transmitted to cereal soils in which take‐all had not declined (U soils). As little as 0.001 % by weight of D soil decreased take‐all by 50 % in some seedling assays, but in a longer, outdoor test the decrease proved to be temporary and within 10 wk disease increased to equal that in unamended U soil. In two tests in which D soil was amended with U soil there was an unexpected increase in disease in seedling assays. Particulate fractions (0.2‐2.0 μm) from leachates of D soils, but not the coarse fractions (> 1 mm, dry sieved; > 150μm, wet sieved) of these soils, decreased disease in assays. Although moved downwards by water, the transmissible factor in D soil did not spread laterally into adjacent unamended U soil and D soil amendments of U soil were most effective as top dressings and least effective when initially placed below assay seedlings. D soil was slightly less effective when added 14 days after planting wheat in U soil, but incubating soil mixtures for up to 4 wk before planting gave variable results, although there was always some decrease in take‐all. The transmissible factor could be eliminated by heating moist soil for 30 min at 70 oC (but not 60 oC). The evidence suggests that the factor is biological, but is insufficient to suggest that it is the cause of take‐all decline.
The use of weather data and counts of aphids in the field to predict the incidence of yellowing viruses of sugar‐beet crops in England in relation to the use of insecticides
Authors: WATSON MARION A. , HEATHCOTE G. D. , LAUCKNER F. B. , SOWRAY P. ANNE
Published: February 2008

Partial regression equations were calculated that relate the mean percentage of plants infected with yellowing viruses (beet yellows and beet mild yellowing viruses) in sugar‐beet crops at the end of August to the number of days during January, February and March when temperatures fell below – 0.3 °C (31‐5 °F) and the mean temperatures in April, for the 21 yr, 1951–71, using weather records from Rothamsted Experimental Station. Regression analyses were also made to find the effect of other factors including mean and minimum temperatures for the same months, and also mean counts of ‘green aphids’, mainly of the vector Myzus persicae, on sugar‐beet plants during May and June. Significant relationships were established with all factors, but ‘frost‐days’ and April mean temperatures accounted for the greatest percentage of the variance in yellows incidence.

The calculations were made separately for the years from 1951 to 1958, when no routine advice was given to farmers about aphid control, and 1959–71 when a ‘spray‐warning scheme’ was in operation, and many crops were sprayed at critical times to prevent aphid‐ and virus‐spread. Weather factors had the same effects in both periods, but for any particular weather less virus was spread in the second period than in the first, although there were sufficient aphids, i.e. the numbers expected from the prevailing weather conditions. There was no evidence that insecticide treatment used in any one year affected aphid‐incidence in subsequent years.

Regression analyses on weather variables were also calculated separately for each of seventeen beet‐sugar factory collection‐areas, using weather records from local weather stations, and also the Rothamsted weather records. Unexpectedly, the fit of the regressions was always better with Rothamsted weather data than with local weather records. Mean yellows‐incidence for the different factory areas declined from south to north, and there was a linear relationship with the square root of the latitude above 50 °C. At the same time the correlation coefficients relating yellows‐incidence to ‘frost‐days’ became smaller and less significant, and those showing dependence
Some effects of oxamyl on the virus‐vector nematodes Longidorus elongatus and Xiphinema diversicaudatutn
Authors: FORER L. B. , TRUDGILL D. L. , ALPHEY T. J. W.
Published: February 2008

Oxamyl applied to field soil prevented Longidorus elongatus from acquiring and transmitting tomato black ring virus for at least 6 wk, although numbers of nematodes were not greatly decreased compared with the untreated control. Glasshouse and laboratory tests examined the effects of oxamyl on viruliferous L. elongatus and Xiphinema diversicaudatum. In these tests oxamyl (1.0 ppm) in the soil water largely prevented L. elongatus transmitting virus to bait plants over a period of 1 month. X. diversicaudatum was equally affected by smaller concentrations, 0.1 ppm being sufficient to inhibit virus transmission in one test. Inhibition of virus transmission was associated with a decrease in the number of root tip galls produced by nematode feeding, especially that of X. diversicaudatum. Few nematodes were seriously affected by oxamyl, except at the greatest concentration tested (100 ppm), when numbers of L. elongatus, but not of X. diversicaudatum, were decreased. In vitro‐treated viruliferous nematodes protracted their stylets, but their subsequent ability to transmit virus was unimpaired.
Common and newly‐recorded forage crop diseases in Ireland
Authors: O'ROURKE C. J.
Published: February 2008

Surveys of forage crop diseases in the Republic of Ireland have been conducted annually since 1965. Over fifty fungal diseases have been noted, about half of which are of likely economic importance. Disease control investigations were carried out on the more prevalent diseases, such as crown rust and Ophiobolus patch of ryegrass, leaf fleck of cocksfoot and powdery mildew of tall fescue. Some pathogens previously unrecorded in the British Isles were found. These included Spermospora lolii and Lolium mottle virus on ryegrass, and Mastigosporium kitzebergense on timothy.
Surveys of pest incidence on oil‐seed rape in south central England
Authors: GOULD H. J.
Published: February 2008

Surveys of pest incidence on oil‐seed rape in the south of England in 6 yr have shown that Meligethes aeneus can cause a considerable loss of pods on some fields. There is some evidence that control measures are often applied too late to obtain the best results; preliminary observations on the probable effect on yield are also presented.

Ceuthorhynchus assimilis was recorded on the majority of fields with an average of 19% pods infested on spring‐sown rape. Very heavy pod infestations were found on farms where rape had been grown regularly for some years.

Dasyneura brassicae is at present not an important pest with an average of less than 1% pods infested. However, in each year infestations of up to 11% pod attack were recorded on a few fields.
The nature of the effects of the aphids Sitobion avenae and Metopolophium dirhodum on the growth of wheat
Authors: WRATTEN S. D.
Published: February 2008

Field‐caged, post‐anthesis populations of the aphids Sitobion avenae and Metopolophium dirhodum reduced grain weight of wheat by 14 and 7% respectively and induced changes in the senescence of the flag leaf. Spikelet number and grain number were unaffected as they are normally determined by pre‐anthesis factors. Percentage grain protein was significantly reduced by both aphid species.

The pattern of grain weight reduction within the ear was consistent with known limitations on the distribution of flag leaf assimilates among the grains. The relative effects of the two aphid species apparently resulted from the degree of nutrient drain imposed at particular feeding sites and the reduction in the leaf area duration of the flag leaf.
The control of wet bubble disease of mushrooms caused by Mycogone perniciosa
Authors: FLETCHER J. T. , DRAKES G. D. , TALENT C. J. W.
Published: February 2008

In experiments on the control of Mycogone perniciosa there was a good relationship between yield, disease incidence and the rate of benomyl applied to the casing. Casing treatment controlled the disease irrespective of time of inoculation. Benomyl controlled the disease in all experiments and good results were also achieved with thiophanate methyl and to a lesser extent with thiabendazole. Bioassay of sporophores showed the presence of an inhibitory substance from benomyl and thiophanate methyl treatments even after 6 wk of cropping.
Soil‐borne viruses occurring in nursery soils and infecting some ornamental species of Rosaceae
Authors: SWEET J. B.
Published: February 2008

Soil from twelve of twenty‐six sites on ten nurseries growing ornamental trees and shrubs contained viruliferous nematodes, transmitting arabis mosaic virus (AMV) at eight sites, tomato black ring virus at three and tobacco rattle virus at one site. Tobacco necrosis virus was detected at two sites. Xiphinema spp. were found at nine sites, Longidorus spp. at sixteen and Trichodorus spp. at thirteen sites. Thirty‐one ornamental species of Rosaceae were tested for virus infections and AMV was found in Spiraea bumalda, Spiraea japonica alba and Kerria japonica.
Effects of defoliation on growth and yield in groundnut (Arachis hypogea), cowpeas (Vigna unguiculata), soyabean (Glycine max) and green gram (Vigna aurens)
Authors: ENYI B. A. C.
Published: February 2008

Defoliation reduced the dry weight of stems, pods, grains and size of individual grains in all four of the legume crops studied and the dry weight of flowering inflorescence stalk in the case of cowpeas and green gram only. The adverse effect of defoliation was more pronounced when defoliation was complete than when half of the number of leaves were removed. The greatest reduction in grain yield occurred when the plants were defoliated during the early podding stage, the percentage reduction being 59.7, 79.0, 86.4 and 95.3 in groundnut, cowpeas, soyabeans and green gram respectively when completely defoliated at this stage and 43.3, 14.0, 42.4 and 46.1 respectively when only half defoliated. The results show that assimilates produced by the leaves during the early stages of growth are used in the growth of stems and leaves, but the assimilates produced during the reproductive stage are used mainly for the growth of the pods. In groundnut, pod number and grain weight were positively correlated with stem weight. It appears that defoliation reduced pod number by depressing the growth of stems and this in turn reduced the number of flowering nodes.

The reasons for the differences between the crops in their response to the defoliation treatments and the practical implications of the findings in relation to pest and disease control and plucking of leaves for human consumption are discussed.
Stomatal diffusion resistances and leaf growth during droughting of Lolium perenne plants selected for contrasting epidermal ridging
Authors: WILSON D.
Published: February 2008

Groups of Lolium perenne plants selected for either deep or shallow adaxial epidermal ridging were grown in a 16 h day of 70 W m‐2 at 25°C, and either watered daily to 33% or allowed to dry to and then watered daily to 21% or to 16% soil moisture. During a 9 day experimental period, adaxial leaf resistances (r1) were measured with a diffusion porometer four times daily, transpiration was estimated gravimetrically, and daily rates of leaf extension were recorded.

Measurements were also made of minimum abaxial resistances, stomatal frequencies and lengths, and relative leaf water content (RLWC). At 33%, 21% or 16% soil moisture, leaf extension rates of deep ridged leaves were, respectively, slower, the same, and more rapid than those with shallow ridges. At 21% or 16% soil moisture, the adaxial rl of deep‐ridged was much lower than that of shallow‐ridged leaves at all four sampling times. This difference was most marked on leaves below the youngest fully expanded, and was observed among older leaves even when plants were well watered. At low RLWC (< 85%), leaf resistance was greatest in leaves with shallow ridges. There was no significant difference between the leaf types in the calculated contributions of stomatal frequency or of morphology at any one pore opening, to rl but deep‐ridged leaves had more stomataonthe abaxial surface. Daily rate of plant water loss was directly correlated (r=+ 0.86, P < 0.01) with mean daily maximum stomatal conductance (1/rl), and rate of leaf extension negatively with maximum rl. It is suggested that stomata operating in the concavity formed by deep ridges open wider and are less responsive to internal changes in, for example, leaf water status, than those on shallow‐ridged leaves because of a more humid microenvironment at the epidermal surface. The results are discussed in relation to the concept of ‘water‐savers’ and ‘water‐spenders’ and its application to breeding for dry conditions.
Effect of European wheat striate mosaic, acquired transovarially, on the biology of its planthopper vector Javesella pellucida
Authors: AMMAR E.‐D.
Published: February 2008

The proportion of infective nymphs of Javesella pellucida in the progenies of female vectors of European wheat striate mosaic (EWSM) disease ranged from 85 to 96%; 71% of these nymphs infected plants within one week of hatching. Inbreeding for one or two generations significantly decreased the viability of J. pellucida eggs, but EWSM had no effect on the viability of eggs laid by inbred or outbred vector lines. However, EWSM acquired transovarially usually increased the mortality of J. pellucida nymphs by 13 to 17%, although mortality was as high as 30% in some vector lines. EWSM, acquired transovarially for two generations, decreased the longevity of adult males and females of J. pellucida by 14%. Inbreeding for two generations resulted in 40% increase in the mortality of nymphs and more than 50% reduction in the longevity of adults.
Polyacrylic acid‐induced resistance to tobacco mosaic virus in tobacco cv. Xanthi
Authors: KASSANIS B. , WHITE R. F.
Published: February 2008

Polyacrylic acid (PA) of molecular weight 1700A, 1700B and 3500 caused resistance to infection with tobacco mosaic virus in tobacco cv. Xanthi‐nc, when sprayed on the leaves or watered into the soil. The numbers of lesions produced in the treated plants were between 27 and 97% fewer than in the untreated plants depending on the concentration of PA, its molecular weight and the method of application. Some resistance was caused against potato virus X and potato virus Y but only at concentrations that were harmful to the plants. It appears that PA activates a mechanism responsible for localizing viruses in hypersensitive plants.
Observations on the toxic effects of organo‐mercury treatments on sugar‐beet seed
Authors: BYFORD W. J.
Published: February 2008

The toxicity of organo‐mercury fungicides to sugar‐beet seed increased with the amount added and with the moisture content of the seed. Methyl mercury dicyandiamide was more phytotoxic than the less volatile ethyl and phenyl mercury compounds tested. In a bioassay for organo‐mercury fungicides on seeds, the area of inhibition decreased when moist treated seed was stored in airtight containers.
Numbers of mononchid nematodes in soils sown to cereals and grasses
Authors: NELMES A. J. , McCULLOCH JANET S.
Published: February 2008

The distribution of mononchid nematodes Mylonchulus sigmaturus, Mylonchulus brachyuris, Clarkus papillatus, Prionchulus punctatus and Anatonchus tridentatus found in grassland and arable soils in England were studied.

Mononchid nematode populations in excess of 5% of the total soil nematode population and in biomass more than 2% of the total soil nematode population were rare. No relationship was found between numbers of mononchids and those of other soil nematodes.

In soils sown to spring barley there was no difference in the total numbers of female M. sigmaturus, C. papillatus or A. tridentatus found throughout the year. Juveniles of C. papillatus were most common while those of M. sigmaturus were least common. In grass leys and arable soil P. punctatus numbers were extremely low.

Neither phorate nor oxamyl applied at 1.12 kg a.i./ha in March affected mononchid numbers. Although oxamyl at 11.2 kg a.i./ha did not affect the adult female numbers, the numbers of juvenile mononchids were reduced by 38% and 50% in June and November respectively.
Potato tuber lenticels: susceptibility to infection by Erwinia carotovora var. atroseptica and Phytophthora infestans
Authors: ADAMS M. J.
Published: February 2008

In laboratory tests, proliferation increased the susceptibility of lenticels on mature tubers to infection by Erwinia carotovora var. atroseptica. No differences in susceptibility to E. c. atroseptica and Phytophthora infestans were detected on tubers lifted at different stages of growth from soil kept wet or dry for 3 wk prior to each sampling. As tubers aged, fewer lenticels became infected by either pathogen or were penetrated by fluorescein dye, presumably because cells had been suberized and cork barriers formed.
Investigations on fungicides
Authors: CARTER G. A. , CHAMBERLAIN K. , WAIN R. L.
Published: February 2008

The systemic anti‐mildew activity shown by homologous series of alkoxy‐, alkylamino‐ and alkylthio‐trichloroethyl formamides when applied to the roots of wheat or cucumber seedlings has been measured. In general the thio compounds were much less active than their oxy and amino analogues. The alkyl grouping giving most activity varied from one series to another and with test method. In cucumber plants the most prolonged protection against mildew was given by the sec‐butoxy and sec‐butylamino compounds. When inoculated disks of cucumber leaf tissue were floated upon solutions of the compounds, smaller differences in anti‐mildew activity were found than when application was made through the roots.
Field investigations on the control of club root of cabbage in SriLanka
Authors: WIMALAJEEWA D. L. S.
Published: February 2008

Five fungicides and two fumigants were tested in five trials against the club root disease of cabbage. Methyl bromide provided the best control of the disease. Quintozene also gave satisfactory results, and its phytotoxic effects could be avoided or minimized by applying it at least 5–6 wk before seeding or transplanting.

The use of hydrated lime gave relatively poor control of club root, but, either alone or in combination with fungicides, it improved the growth and establishment of seedlings and transplants. It was concluded that quintozene used in combination with hydrated lime provided an effective and practical means of controlling the disease.
Effects of oximecarbamate, organophosphate and benzimidazole nematicides on life cycle stages of root‐knot nematodes, Meloidogyne spp.
Authors: McLEOD R. W. , KHAIR G. T.
Published: February 2008

A study was made of the effects of concentrations of 2 to 32 ppm of oximecarbamate, organophosphate and benzimidazole nematicides on the hatch, larval viability and migration of Meloidogyne javanica, M. incognita and M. hapla and on development of M. javanica in roots. Aldicarb at less than 8 ppm had little effect on hatch and methomyl markedly affected only the hatch of M. hapla. As little as 2 ppm of fenamiphos or thionazin markedly reduced hatch of all three species but less than 8 ppm ethoprophos significantly reduced only the hatch of M. incognita and phorate had little effect on hatch. Benomyl and thiabendazole had no significant effects on hatch. When egg masses of M. incognita were transferred from nematicides which suppressed hatch to water, hatching occurred, but aldicarb, fenamiphos, ethoprophos and thionazin significantly reduced total hatch.

None of the nematicides killed larvae of the three species immersed in 16 and 32 ppm solutions of them for 3 days. Aldicarb at 2 ppm reduced migrations of all three species; the effects of methomyl, fenamiphos or thionazin on migration varied according to species, while phorate, ethoprophos, benomyl or thiabendazole had little or no effect on migration. Aldicarb or thionazin at 2 ppm stopped development of M. javanica in roots of tomato seedlings while methomyl, ethoprophos or fenamiphos at 4 ppm reduced development by 60% and at 8 ppm of ethoprophos or fenamiphos or 16 ppm of methomyl, development was stopped. Phorate had little effect on development and benomyl or thiabendazole had no effect. Nematicide concentrations which reduced development prevented the normal orientation of larvae in the roots and reduced or prevented giant cell formation.
A dust‐free ‘pooter’
Authors: BRETT G. A.
Published: February 2008

A mouth suction sampler, commonly and more conveniently and expressively known as a ‘pooter’, is an extremely efficient instrument for collecting small insects quickly and without damage. However, in dusty situations it is difficult to pick up the insects without also getting a mouthful of dust if the usual gauze or muslin is used as the filter.
Electron microscopy of the particles of cereal tillering disease virus and oat sterile dwarf virus
Authors: MILNE R. G. , LINDSTEN K. , CONTI M.
Published: February 2008

Extracts of maize and oat plants from Sweden, infected respectively with cereal tillering disease virus and oat sterile dwarf virus, were examined in the electron microscope after staining with uranyl acetate or potassium phosphotungstate. Such extracts contained whole virus particles, two kinds of subviral particles and virus‐containing tubular structures. The results indicate that the two viruses are morphologically indistinguishable from each other and from maize rough dwarf virus.
Mushroom mycelium and compost substrates in relation to the survival of the larva of the sciarid Lycoriella auripila
Authors: BINNS E. S.
Published: February 2008

The development of sciarids was reduced in old casing and in casing to which a commercial composting additive was added in large amounts. In laboratory tests, adding water, soya bean, cotton seed or oatmeal to finished mushroom composts reduced the mean development time of the larvae of Lycoriella auripila. Soya bean meal significantly increased the number of adult sciarids which matured. While the presence of mushroom mycelium in large quantities inhibited the development of sciarids, smaller amounts increased either the number of larvae maturing or their rate of development in different tests. Larvae were seen to feed on mycelium. The addition of sucrose solution either reduced or prolonged development time in different tests. Nitrogenous additives encouraged the growth of ‘weed moulds’. Both these and the number of sciarids which developed were reduced by adding a solution of calcium nitrate. The results suggested that more selective composts, favouring rapid mycelial colonization, would provide ‘cultural’ control of mushroom sciarids.
Control of tomato grey mould on unheated crops using non‐ systemic fungicide sprays
Authors: SMITH PAULINE M. , KEMPTON R. J. , LAST F. T. , CASE M. W.
Published: February 2008

High volume sprays of dichlofluanid (0.1 % a.i.) reduced total fruit numbers but gave better control of Botrytis cinerea infections of tomato stems, leaves and fruit than sprays at 0.05 or 0.025% a.i. Surface residues from the sprays at 0–1, 0.05 or 0.025% a.i. were respectively 5.4, 1.6, 0.7 μg/g fresh weight of ripe fruit at harvest. Tank‐mixed zineb (0.12% a.i.) and captan (0.2% a.i.) were less effective and increasing the spray intervals from 1 wk to 2 and 3 wk reduced the fungitoxicity of captan and zineb more than that of dichlofluanid. Harvest residues on ripe fruit were 7.1, 2.8 or 2.4 μg/g when dichlofluanid (0.1 % a.i.) sprays were applied at 1, 2 and 3 wk intervals respectively. Good control of B. cinerea was achieved if the whole plant was sprayed initially with dichlofluanid as soon as the second truss was flowering and subsequent sprays were restricted to the upper section of stem including the four or five youngest trusses of buds, flowers and fruit.

When used as a post‐infection spray there was a period of c. 8 wk before dichlofluanid markedly reduced the incidence of grey mould. Tank‐mixed zineb (0.12% a.i.) controlled Botrytis fruit spotting but not leaf and stem infections. Botrytis stem lesions extended more rapidly on zineb‐sprayed plants than on unsprayed plants or on plants treated with captan or dichlofluanid.
Chemical control of potato cyst‐nematode, Heterodera pallida, on tomatoes grown under glass
Authors: WHITEHEAD A. G. , FRASER JANET E. , FRENCH EILEEN M. , WRIGHT S. M.
Published: February 2008

In sandy clay loam under glass 11.2 kg a.i. Du Pont 1410 alone or with 448 kg Di‐Trapex CP/ha, 441 kg dazomet with 448 kg Telone or 448 kg Di‐Trapex CP/ha, prevented potato cyst‐nematodes, Heterodera pallida, increasing on KNVF tomato rootstocks. In the heated glasshouse where the soil was treated with 441 kg dazomet/ha alone, the nematodes increased in the top 10 cm of soil, whether the soil was sealed with Polythene sheeting or water and whether dazomet was applied as dust or prill (small granules). Methyl bromide at 1276 kg/ha did not control the nematodes in soil 20–30 cm deep in one of the treated plots. Tomatoes grew well after all treatments except Du Pont 1410 which had little, if any, effect on grey sterile fungus (Pyrenochaeta lycopersici). Dazomet with Telone or dazomet with Di‐Trapex CP inhibited root damage by the fungus.
Efficiency of potassium permanganate in differentiating between live and dead nematodes
Authors: JATALA P.
Published: February 2008

An aqueous solution of potassium permanganate provided a simple and reliable means for differentiating live from dead nematodes. The cuticle and body content of dead nematodes were stained light amber to deep brown, whereas live nematodes were not affected. Taxonomic features of lightly or moderately stained specimens were not obscured.
The predators of wheat‐bulb fly
Authors: Jones Margaret G.
Published: February 2008

Wheat bulb fly, a pest of winter weat, has one generation a year and all stages exist for at least a month. The feeding larva inside the shoot is protected, except when moving to a new shoot, but all the other stages are exposed to attack by non‐specific predators, either by soil‐living beetles feeding on eggs and puparia in the soil, or predatory flies and birds feeding on the adults.
Effect of organic soil amendments on damping‐off of lettuce caused by Corticium praticola
Authors: OKPALA E. U.
Published: February 2008

Ten organic amendments were added to unsterile soil which was contaminated 14 days later with Corticium praticola and sown with lettuce seeds. Substantial increases in final stands of seedlings were obtained with grass meal, bran and wood cellulose. Corn and barley meal, linseed cake and fish meal decreased final stands; molassine meal, potato starch and peptone had relatively little effect. Seedlings grown with wood cellulose were very chlorotic and stunted.

Up to 30% of lettuce seeds sown in soil which, 180 days earlier, had been amended with corn meal and contaminated with C. praticola became colonized by the fungus. None was colonized in unamended soil or in soil amended with grass meal. Ninety days after amendment and contamination fewer seeds were colonized in soil amended with grass meal than in unamended soil. The amendment of soil with grass meal was as effective as thiram seed treatment in protecting lettuce seedlings against C. praticola and grass meal was particularly effective in reducing both the numbers of seedlings attacked and the survival of the fungus in the soil.
Investigations on fungicides
Authors: CARTER G. A. , CHAMBERLAIN K. , WAIN R. L.
Published: February 2008

A number of bis‐[(i‐formamido‐2,2,2‐trichloro)ethylamino]‐alkanes and their dioxy and dithio analogues were examined for direct and systemic antifungal activity. All compounds showed very low in vitro fungitoxicity and only slight protectant anti‐mildew activity when applied as a foliar spray. Certain diamino and dioxy derivatives were, however, systemically active against powdery mildew fungi when applied as a root drench to seedlings of wheat or cucumber; the dithio analogues were inactive. The level of systemic activity shown by these compounds was markedly influenced by the nature of the hydrocarbon ‘bridging’ group.
A probable rhabdovirus infection of lemon‐scented thyme
Authors: SCHULTZ M. G. , HARRAP K. A. , LAND J. B.
Published: February 2008

Bacilliform particles were found in the perinuclear space of phloem parenchyma cells of Thymus xcitriodorus (lemon‐scented thyme) showing a marked leaf chlorosis. They were of typical rhabdovirus morphology, of mean dimensions 219 X72nm and composed of a bullet‐shaped internal component surrounded by an envelope. A few unenveloped internal components were seen in the nucleus and the perinuclear space. The bacilliform particles were concentrated and partially purified from leaf material but were not easily detected by negative staining of leaf squashes. They were not transmitted by inoculation of infected sap and the evidence indicates that they were not the causal agent of the leaf chlorosis.
Carotenoid pigments of Dioscorea cayenensis
Authors: MARTIN F. W. , RUBERTÉ RUTH
Published: February 2008

The yellow flesh of Dioscorea cayenensis, a principal yam of Africa, was found to contain xanthophyll esters as the principal pigments. These included neoxanthin, violaxanthin and auroxanthin. In addition β‐carotene, or pro‐vitamin A was found in small quantities. Measurements show that D. cayenensis is a fair source of this nutrient.
A method for inoculating wheat with Cercosporella herpotrichoides
Authors: EVANS M. E. , RAWLINSON C. J.
Published: February 2008

A method for preparing inoculum of Cercosporella herpotrichoides on chemically defined substrates is described. The method is reproducible, needs less time, is less variable than using colonized cylinders of straw and allows infection by mycelium and spores above soil level.
Effects of powdery mildew at different growth stages on grain yield of barley
Authors: GRIFFITHS ELLIS , JONES D. GARETH , VALENTINE M.
Published: February 2008

Pot‐grown barley plants (cv. Proctor) were exposed to infection by powdery mildew during four stages of development, G.S. 2–6, G.S. 7–9, G.S. 10‐10‐5 and G.S. 11 (Feekes scale, Large, 1954). All combinations were examined (i.e. 24 factorial). The numbers of fertile tillers at harvest were significantly reduced by mildew during periods G.S. 2–6 and G.S. 7–9. Numbers of grains per head and grain size (1000 grain weight) were significantly reduced by mildew only during G.S. 2–6. Effects, on components of yield, of the four mildew treatments were found to be almost entirely additive. The only significant interactions found were for grain size: in this instance there was some interaction between treatments at G.S. 2–6 and G.S. 10‐10‐5 and between treatments at G.S. 2–6, G.S. 7–9 and G.S. 10‐10‐5.
Transmission of broad bean stain virus and Echtes Ackerbohnenmosaik‐Virus to field beans (Viciajaba) by weevils
Authors: COCKBAIN A. J. , COOK SARA M. , BOWEN ROBERTA
Published: February 2008

Sitona lineatus and Apion vorax were the two most common species of weevil on field beans (Vicia faba minor) at Rothamsted between 1970 and 1974. In glasshouse tests, A. vorax was a much more efficient vector than 5. lineatus of broad bean stain virus (BBSV) and Echtes Ackerbohnenmosaik‐Virus (EAMV), and both species transmitted EAMV more often than BBSV. Five other species of Apion transmitted the viruses infrequently or not at all. S. lineatus adults transmitted no more often after 8–16 days on infected plants than after 1–2 days. Some A. vorax adults transmitted EAMV, but not BBSV, after feeding on infected leaves for a few minutes. After 4 days on infected plants, A. vorax sometimes remained infective for the following 8 days. No A. vorax collected from woodland plants in spring was infective with BBSV or EAMV, but 4% from bean crops containing seed‐borne infection carried BBSV and 17% carried EAMV. BBSV and EAMV were recovered from triturated weevils, but not from weevil haemolymph. Possibly the viruses are transmitted as contaminants of the mouthparts or by regurgitation during feeding, but A. vorax was observed to regurgitate only when anaesthetized.

BBSV and EAMV were not transmitted by aphids (Aphis fabae and Acyrthosiphon pisum), nor by pollen beetles {Meligethes spp.).

Field observations suggest that infected seed is the main source of BBSV and EAMV in spring‐sown crops, and that crops grown from virus‐free seed, and isolated from infected crops by 250–500 m, remain free of infection for most of the season.
Invasion and development of the cereal cyst‐nematode Heterodera avenae in roots of barley infected by the take‐all fungus Gaeumannomyces graminis
Authors: COOK R.
Published: February 2008

Observations on the invasion and development of Heterodera avenae in relation to take‐all infection of barley roots were made in three pot experiments. Post‐cropping H. avenae populations were lower on fungus‐infected plants, as a result of the production of fewer, smaller and less fecund cysts. The reduction in cyst numbers was associated with reduced larval invasion of take‐all infected roots and with the effects of the unfavourable environment of these roots on female development, possibly through its effects on sex determination and survival of the larvae.
Control of potato cyst‐nematodes, Heterodera rostochiensis and H. pallida, in sandy, peaty and silt loam soils by oximecarbamate and organophosphate nematicides
Authors: MOSS S. R. , CRUMP D. , WHITEHEAD A. G.
Published: February 2008

Small amounts (5.6 or n‐2 kg a.i./ha) of aldicarb or oxamyl, incorporated in the soil before potatoes were planted in spring, controlled potato cyst‐nematodes (Heterodera rostochiensis and H. pallida) on susceptible cultivars equally well in sandy, peaty and silt loam soils. In soils treated with either nematicide, nematode numbers increased little or decreased; in untreated soils nematode numbers increased greatly. In contrast organophosphate nematicides, similarly applied, fenamiphos (proposed BSI common name for O‐ethyl‐O‐(3‐methyl‐4‐methylthiophenyI)‐isopropylamido‐phosphate), ethoprophos (proposed BSI common name for (O‐ethyl S, 5‐dipropyl phos‐phorodithioate), CGA 12223 (O, O‐diethyl O‐[i‐isopropyl‐5‐chloro‐i,2,4‐triazoIyl‐(3)] phosphorothioate) and Dowco 275 (O, O‐diethyl O‐(6‐fluoro‐2 pyridyl) phosphorothioate), were ineffective at one or more of the experimental sites. Potato yields were greatly increased by oximecarbamate or organophosphate nematicides only in soils heavily infested with the nematodes.
Genetic control of durable resistance to yellow rust (Puccinia striiformis) in the wheat cultivar Hybride de Bersée
Authors: JOHNSON R. , LAW C. N.
Published: February 2008

The wheat cultivar Hybride de Bersee is described as possessing durable resistance to yellow rust. Some races of Puccinia striiformis can infect it at the seedling stage but not severely in the field. Using euploid and aneuploid stocks of Bersee it was shown that a large part of this resistance was controlled by chromosome 5BS‐7BS, the effect being detectable in seedlings and at later growth stages. Measurements of spore production from infected seedlings showed that the line ditelosomic for the 5BS arm of the chromosome was more resistant than the line ditelosomic for the 7BS arm under environments favouring high spore production, but more susceptible under environments favouring low spore production. Thus both arms of the chromosome could contribute to resistance in appropriate environments. Chromosome 5BS‐7BS did not carry the factors controlling the race‐specific resistance to race 37 E132 of P. striiformis. The possibility of exploiting the resistance carried by chromosome 5BS‐7BS in wheat breeding programmes is discussed.
Partial purification and serological relationship of three strains of bean yellow mosaic virus
Authors: GRANETT A. L. , PROWIDENTI R.
Published: February 2008

Three biologically distinct strains of bean yellow mosaic virus (BYMVS, BYMV1 PV‐2) were partially purified by centrifugation at relatively low g forces. Serologically these strains appeared to be distinct from each other but were related.
A comparison of the effectiveness of insecticides against glasshouse whitefly (Trialeurodes vaporariorum)
Authors: WARDLOW L. R. , LUDLAM F. A. B. , HAMMON R. P.
Published: February 2008

Tests were made with a glasshouse whitefly population resistant to both DDT and parathion to measure resistance to two organochlorine, eight organophosphate and six carbamate compounds; resmethrin and pyrethrum were also included in the tests. The whiteflies showed marked resistance to endosulfan, thionazin, malathion and resmethrin and low resistance to all other compounds.
Epidemiology of PytMum‐induced damping‐off in mixed species seedling stands
Authors: BURDON J. J. , CHILVERS G. A.
Published: February 2008

Controlled experiments on post‐emergence damping‐off, using mixtures of susceptible (Lepidium sativum) and resistant (Lolium rigidum) seedlings inoculated with Pythium irregulare, demonstrated that rates of multiplication and advance of the disease were determined mainly by the net density of susceptible seedlings and were little affected by the resistant plants present.
Some effects of time, temperature of treatment and fumigant concentration on the fungicidal properties of methyl bromide
Authors: GANDY DOREEN G. , CHANTER D. O.
Published: February 2008

Survival of fungi after fumigation with methyl bromide was affected by fumigant concentration, duration of exposure and treatment temperature. The concentration x time (ct) products required to kill slow growing species were lower than those required for fast growing fungi; in addition, for some species the ct products required also increased with increasing treatment times. In all fungi studied, ct products required decreased with increasing treatment temperature.
Experiments with fungicide sprays to control Ramularia beticola in sugar‐beet seed crops
Authors: FORD W. J.
Published: February 2008

A single fentinhydroxide spray at the end of May controlled Ramularia leaf spot in in‐situ sugar‐beet seed crops and increased seed yield on average by 4%. Sprays controlled leaf spots most effectively in the Cotswolds, but yield increases were larger in Lincolnshire. Benomyl controlled leaf spot as well as did fentinhydroxide; thiabendazole was less effective, and maneb and cuprous oxide gave poor control.
The promotion of ear emergence by gibberellic acid in Ethrel‐induced male sterile wheat
Authors: HUGHES W. G. , BODDEN J. J. , GALANOPOULOU STELLA
Published: February 2008

Ethrel at a concentration of 2000 ppm active ingredient (a.L), applied to the spring wheat cv. Sirius before meiosis was initiated in the oldest florets of the ears, induced almost complete male sterility but prevented full ear emergence. Concentrations of 100, 200 and 300 ppm a.i. GA3, applied 2 or 5 days after the Ethrel, were equally effective in promoting full emergence of sterilized ears, without affecting female fertility or markedly affecting flowering time.
Effect of variation in ear temperature on gibberellin content of wheat ears
Authors: RADLEY MARGARET
Published: February 2008

When the ears of wheat were grown after anthesis at temperatures different from the rest of the plant the gibberellin content of the ears increased more rapidly at higher ear temperatures, whilst the plant temperature had little effect. This greater rate of gibberellin accumulation was associated with a greater rate of ear dry weight increase. Wheat ears detached from the plant increased their gibberellin content over 4 days when provided with sucrose and ewfkaurene.
Genotypic and environmental correlations between leaf growth and bulb size in onions
Authors: DOWKER B. D. , HARDWICK R. C. , FENNELL J. F. M. , ANDREWS D. J.
Published: February 2008

Populations of onion breeding lines were grown in five field trials over 2 years. Measurements were made of leaf length, number of leaves produced during July and August, date of foliage collapse, plant density and bulb yield. Correlations and partial correlations between these attributes, separated where possible into genetic and environmental components, gave similar results from all trials. The genetic and environmental components of leaf length and earliness of foliage collapse were positively associated with yield. Partial correlations showed that short‐leaved plants were lower yielding and later maturing than long‐leaved selections, but that the effects were not attributable to correlations with plant density.
An investigation of persistent infection of stored apples by Gloeosporium spp.
Authors: EDNEY K. L.
Published: February 2008

Orchards of Cox's Orange Pippin apples with a history of persistent Gloeosporium infection were examined for wood infections and fruit susceptibility. The amount of wood infection on the trees was not excessively high and the conidia from wood and fruit infections were not resistant to captan. Extensive rotting developed following the application of conidia of G. perennans to the surface of the fruit after harvest. Mineral analysis indicated low calcium and high nitrogen content and it is suggested that fruit susceptibility associated with mineral imbalance is responsible for much of the rotting encountered in the past.
The insect transmission of an isolate of okra mosaic virus occurring in Nigeria
Authors: LANA A. O. , TAYLOR T. AJIBOLA
Published: February 2008

Three species of chrysomelid beetles (Podagrica sjostedti, P. uniforma and Syagrus calcaratus) transmitted a Nigerian isolate of okra mosaic virus (OMV) to okra (Abelmoschus esculentus) and green gram (Vigna aureus), two (P. uniforma and S. calcaratus) also to cotton (Gossypium hirsutum) and one (P. uniforma) also to cowpea. Using one viruliferous beetle per test plant, P. sjostedti, P. uniforma and S. calcaratus infected 63, 68 and 34% of test plants respectively. Virus was retained by these vectors for up to 6 days. Whiteflies (Bemisia tabaci) also transmitted OMV, although much less efficiently than the beetle vectors.
A comparison of the use of Bacillus subtilis with conventional fungicides for the control of apple canker (Nectria galligend)
Authors: SWINBURNE T. R. , BROWN AVERIL E.
Published: February 2008

In a factorialized field trial cells of Bacillus subtilis or phenylmercuric nitrate (PMN) were applied as sprays in autumn to manually defoliated apple trees, cv. Bramley's Seedling, artificially infected with Nectria galligena. Trees were additionally sprayed with dithianon at intervals in May and June or left unsprayed at this time. B. subtilis in conjunction with dithianon, and PMN with dithianon were equally effective in the control of canker over a 2‐yr period. Dithianon alone gave some control, as did PMN but B. subtilis was not effective without additional applications of dithianon.
Phenotype‐phenotype analysis: field application of the gene‐for‐gene hypothesis in host‐pathogen relations
Authors: WOLFE M. S. , BARRETT J. A. , SHATTOCK R. C. , SHAW D. S. , WHITBREAD R.
Published: February 2008

The frequency of occurrence of a virulence phenotype in a pathogen population is equivalent to its probability of occurrence in that population. From the compound probability law it can thus be shown that the expected frequency of occurrence of phenotypes with combined virulences is a product of the observed frequencies of the individual virulences. In many host‐pathogen interactions, observed and expected frequencies of combined virulences are closely similar. Deviations from expectation, in both directions, do occur however, and these may be of crucial importance in disease control.