bluuebunny/crossref_metadata_2025 huggingface dataset:
Factors affecting the resistance of cold‐stored carrots to Botrytis cinerea
Authors: GOODLIFFE J. P. , HEALE J. B.
Published: February 2008

The secondary phloem parenchyma of cold‐stored turgid roots of carrot (Daucus carota) is capable of localizing mycelial infection by Botrytis cinerea, producing a dark resistant lesion. The percentage of roots exhibiting this reaction declined with increasing time in cold‐store: when freshly harvested and wound‐inoculated in October 1974, 99%of roots resisted invasion, whereas only 5% of those stored until March 1975 did so. The surface dimensions of resistant lesions did not increase between 33 and 55 days after inoculation. However, the surface dimensions and mean weights of lesions (arising from inoculations performed at different times over the course of the storage season) were both larger with increasing time in storage of roots prior to inoculation. The ability of the root tissue to localize infection was reduced if the roots lost 5–10% or more of their fresh weight before inoculation, resulting progressively in susceptibility. Compared with roots wound‐inoculated using mycelial disks, there was an overall reduction in infection when carrots were wound‐inoculated using conidia or when conidia or mycelial disks were inoculated onto the apparently undamaged surface of roots.
Aspects of the biological activity of surfactants that are potential eradicants of apple mildew
Authors: HISLOP E. C. , BARNABY VIVIEN M. , BURCHILL R. T.
Published: February 2008

Among several surface active agents tested, both anionic and cationic materials usually caused greater changes in the microflora of treated soil than non‐ionic materials, although the effects of a non‐ionic formulated mixture of aliphatic alcohols (Off‐Shoot T) were considerable. In vitro tests with micro‐organisms and earthworms indicated similar differences in response to types of compound. There was a positive correlation between hydrophobicity and biological activity of a series of alkyl phenol ethoxylates in some tests. Although many surfactants caused gross phytotoxicity to cress (Lepidium) seedlings in the laboratory, the growth of barley and pea seedlings in treated soil was significantly decreased only by one cationic material.
The detection of three viruses of hop (Humulus lupulus) by enzyme‐linked immunosorbent assay (ELISA)
Authors: THRESH J. M. , ADAMS A. N. , BARBARA D. J. , CLARK M. F.
Published: February 2008

The recently described technique of enzyme‐linked immunosorbent assay (ELISA) was used throughout the 1976 growing season to detect hop mosaic, arabis mosaic and prunus necrotic ringspot viruses in hop plants. On each occasion virus was detected quickly, conveniently and with great sensitivity. The technique was particularly suitable for processing numerous samples collected from the field.

Serious difficulties and limitations were encountered in testing comparable material by established techniques. The serology test for the hop strain of arabis mosaic virus by double diffusion in agar gels was very insensitive and only worked satisfactorily early in the growing season. Grafting sensitive Golding hop varieties to detect hop mosaic virus was inconvenient and time‐consuming and symptom expression was so slow and erratic that glasshouse space was utilized for long periods. It became impossible to detect prunus necrotic ringspot virus by sap inoculations to cucumber during an exceptionally hot period in mid‐summer.

The possibilities are discussed of exploiting the ELISA technique for use in large scale surveys and epidemiological studies on viruses of hop and other crops. Changes in the current methods of handling and extracting leaves are considered for increasing the throughput of samples.
Antifungal compounds in winter wheat resistant and susceptible to Septoria nodorum
Authors: BAKER ELIZABETH A. , SMITH I. M.
Published: February 2008

The content of benzoxazinone compounds in Septoria nodorum resistant and susceptible wheat cultivars fell with time, reaching an undetectable level 3–4 wk after germination. The compounds were absent from field‐grown plants extracted at growth stages 2–3, 6–7, 10, 10.5 and 11. Additional antifungal compounds were detected in healthy and diseased field‐grown plants of both cultivars at all growth stages, although qualitative and quantitative differences in inhibitory activity were small and their role in resistance remains open to discussion.
The flow of water into fruit trees. I. Resistances to water flow through roots and stems
Authors: BAXTER P. , WEST D.
Published: February 2008

Relative conductivity (K) to water in healthy apple trees ranged from maximum values of 18.2 cm3.100 s‐1.cm length.0.001 Pas.kPa‐1.cm‐2 xylem area, for major suberized roots to values of 1.6 for 1‐yr‐old twigs. The values for equivalent parts of healthy cherry trees were 26.3 and 3.3. Trees with roots affected by the larvae of the fruit tree root weevil (Leptopius squalidus) which causes either chronic growth decline or sudden wilting and death, had values as low as 1% of healthy trees, in those parts of the tree showing wilting and lack of growth.

Water flow under pressure into the root systems of healthy apple trees increased linearly with increases in pressure from 200 to 800 kPa. Flows into dormant and active root systems respectively were 0.6 and 1.7 cm3.100 s‐1. 100 cm2 root surface area. 100 kPa‐1.
The involvement of fungi in the breakdown of sulphited strawberries
Authors: Dennis C.
Published: February 2008

Between 8000 and 9000 tons of strawberries are used annually for jam manufacture in the UK, c. 65 % of which are stored in sulphite liquor (6 % SO2+lime, c. pH 3.0). Sporadic cases of disintegration of sulphited strawberries have been observed increasingly in recent years.

In laboratory experiments breakdown of whole berries in sulphite liquor was achieved by including berries partly rotted with Mucor mucedo, Rhizopus sexualis or R. stolonifer, 1.5‐2.5 % infected material causing complete breakdown of all of the berries. The inclusion of up to 25 % berries infected with Botrytis cinerea caused no softening of the berries. The addition of culture filtrates to whole fruit in sulphite liquor confirmed observations with the above fungi but also showed that pectolytic enzymes from Aureobasidium pullulans and Trichosporon pullulans could cause breakdown.

The incidence of spoilage fungi on commercially harvested fruit indicated that M. mucedo and R. sexualis were the main cause of breakdown, but that A. pullulans increased tenfold on fruit stored at 15 °C overnight before sulphiting. Results from commercially harvested fruit (cv. Cambridge Favourite) in 1975 and 1976 showed that: (I) fruit should be sulphited as soon as possible after harvest, since the storage of harvested fruit prior to sulphiting may give a poorer quality product; (2) there is little difference in breakdown of fruit from plants treated with the pre‐harvest fungicides, Elvaron, Mildothane, or Daconil, and (3) fruit grown in different areas of the UK shows varying amounts of breakdown. This may be due to differences in the infection level of Phycomycetes and contamination by other pectolytic fungi or inherent differences in the susceptibility of the fruit to enzyme attack.
Effects of cultural practices, Verticillium nubilum and locality on coiled sprout and yield of early potatoes
Authors: LAPWOOD D. H. , HIDE G. A. , LENNARD J. H.
Published: February 2008

Treatments reported to affect the incidence of ‘coiled sprout’ were studied in 1968 with the cultivar Arran Pilot in experiments near Falmouth, Cornwall (F), Rothamsted (R) and near Edinburgh (E).

Most coiled stems occurred at E (37%) with similar proportions at R (19%) and F (16%). Seed tubers with the longest sprouts at planting produced most coils at all sites, those with shorter sprouts less and unsprouted seed least. When coiling was assessed on the number of plants, long‐ and short‐sprouted seed tubers were about equally affected at R and E.

Sprouts emerged within 45 days at E and 30 days at R. Longer sprouts did not emerge more quickly, but emergence was more than 1 wk later from unsprouted seed at R and only a few days later at E. Harrowing ridges after planting to decrease the depth of soil covering seed tubers hastened emergence by about 1 wk at R and decreased the incidence of coiling; it had little effect at E but tended to increase coiling at F.

Seed tubers inoculated with Verticillium nubilum produced more coiled sprouts but this increase was not significant.

The highest final yields were achieved at R (43‐2 t/ha) where short‐sprouted seed outyielded long‐sprouted and unsprouted seed, but cultivation treatments and fungus inoculation had no effect. At E (21‐2 t/ha) only herbicide treated plots gave a significant effect, outyielding harrowed plots by 8 t/ha. At F (18‐2 t/ha) short‐sprouted seed outyielded long‐sprouted and unsprouted seed, and herbicide treated plots outyielded harrowed plots.

When ware yields from individual plants with and without coils from long‐sprouted seed were compared at R on 18 June, coiled plants gave about 30% and on 2 July 60% of the yield of non‐coiled, but by 16 July 120% yield (20% more); similar trends were shown by short‐ and by long‐sprouted seed at E.
Effectiveness of late copper and streptomycin sprays for the control of halo‐blight of beans (Pseudomonas phaseolicola)
Authors: TAYLOR J. D. , DUDLEY C. L.
Published: February 2008

Two sprays of copper oxychloride or streptomycin sulphate (0–1 % a.i., 675 1/ha) applied to dwarf beans at first flowering and at pod set reduced pod infection by c. 70%. When applied as single sprays at pod set, copper was more effective than streptomycin and reduced pod infection by 50%. Although a copper spray at pod set increased the proportion of pods suitable for processing, more effective control was obtained with a regular spray programme, commencing at the seedling stage.
Pathology, soil transmission and characterization of cymbidium ringspot, a virus from cymbidium orchids and white clover (Trifolium repens)
Authors: HOLLINGS M. , STONE OLWEN M. , BARTON R. J.
Published: February 2008

Two strains of a virus, designated cymbidium ringspot virus (CyRSV), were isolated from cymbidium orchids and from Trifolium repens respectively in Britain. Experimentally infected cymbidiums developed slight chlorotic ring‐mottle; T. repens developed flecks and mottling in the leaves, and slight stunting. Of 101 plant species tested, the cymbidium strain infected sixty‐one (thirteen systemically) in twenty‐three of thirty‐five families; the clover strain infected sixty‐four species (eighteen systemically) in twenty‐two families. Both strains were propagated in Nicotiana clevelandii and assayed in Chenopodium quinoa.

CyRSV was readily transmitted by inoculation of sap, and by foliage contact between plants, but not by the aphids Myzus persicae or Acyrtho‐siphon pisum, nor through seed of T. incarnatum, Phaseolus vulgaris or N. clevelandii. Highly infective virus was released into soil from roots of infected N. clevelandii, and acquired by bait seedlings planted in such soil. Similar transmission occurred when purified virus was applied to the surface of sterilized soil containing bait plants; there was no evidence for any living soil vector.

The virus was eliminated from 96 % of small cuttings taken from infected N. clevelandii plants grown at 35–37 °C for 9 wk.

CyRSV was still infective in sap of N. clevelandii after dilution to 10˜5‐io–6 (only 2 × 10_1 in cymbidium sap), or after 10min at 85–90 °C. It survived at least 10 months at c. 20 °C and more than 12 yr at 2 °C. Lyophilized sap was highly infective after over 13 yr at laboratory temperatures under high vacuum.

Purified preparations made by clarification with n‐butanol, followed by differential centrifugation and exclusion chromatography on controlled‐pore glass beads, contained isometric particles c. 30 nm diam., with s°20W= 137 S, and had a buoyant density in caesium chloride of 1–36 g/ml. The A 260/A 280 ratio was 1–55, and A max(26o)/A min(242) was 1–17. The virus contained c. 15 % of single‐stranded RNA of mol. wt 1–7 × 106; the nucleotide base ratios were: G27'8; A24/9; C2I‐3; U26‐I. There was one capsid polypeptide of mol. wt 43600.

The virus was a good immunogen and a strongly reacting antigen in vitro; in Immunoelectrophoresis, each strain migrated as a single antigenic component towards the cathode. The cymbidium and clover strains were serologically closely related, although spurs were produced in immunodiffusion. No serological relationship was found to forty‐three other isometric viruses, including eighteen tombusvirus isolates; CyRSV nevertheless shares many properties with tombusviruses, and we assign it provisionally to this group. The cryptogram is: R/r:1:7/15:S/S:S/O.
Studies on plant growth‐regulating substances
Authors: FARRAHI‐ASCHTIANI S. , TAYLOR H. F. , WAIN R. L.
Published: February 2008

The dwarfing of seedlings of Phaseolus vulgaris cv. Masterpiece by treatment with solutions of 4‐chlorobenzyltributylammonium bromide (B4) as a foliar spray or by application to the roots has been demonstrated. Dwarfing resulted from a reduction of internodal and petiolar lengths but there was no evidence of delayed leaf or flower development. A reduction in transpiration rate was accompanied by some protection against wilting and an increased ability to recover from this condition. No changes in transpiration coefficient were observed.

The primary leaves of treated seedlings retained chlorophyll longer than those of control seedlings, but in other leaves, chlorophyll and carotenoid pigment levels tended to fall following treatment with B4. Evidence was obtained that B4 treatment delayed root nodule formation, an effect which could be associated with the antibacterial properties of quaternary ammonium salts.
A technique for the location of planthopper feeding probes using labial imprints
Authors: WATERS HENRY
Published: February 2008

Labial imprints mark precisely a planthopper's feeding probe. By staining a leaf surface with 1 % aniline blue in lactophenol, the labial imprints may be detected. This technique provides a simple method for the location of stylet tracks without having to kill feeding insects in situ. Using the leaf surface staining technique, the labial imprints of Haplaxius crudus van Duzee (Homoptera; Cixiidae), a possible vector of lethal yellowing of coconuts, were shown to be 70–80μm in diameter with a raised central crown. Such imprints are the mirror image of the distal labial surface.
Autoanalysis of 14C‐labelled amino acids: a simple flow cell technique
Authors: SYLVESTER‐BRADLEY R.
Published: February 2008

A description is given of a simple flow cell and modifications to an amino acid autoanalyser. These allow continuous monitoring of the 14C in effluent from chromatographic columns using a standard liquid scintillation counter.
A disposable Petri dish modified for plant growth
Authors: GORDON D. C. , MACDONALD I. R.
Published: February 2008

A modification to a disposable plastic Petri dish is described making it a simple and convenient growth chamber for cereal seedlings.
The identification of mild and severe strains of tobacco mosaic virus in doubly inoculated tomato plants
Authors: CASSELLS A. C. , HERRICK C. C.
Published: February 2008

Using specific antisera, it was possible to identify mild (MII‐16) and the 0 and 1 strains of tobacco mosaic virus (TMV) in tomato plants infected with the mild strain following challenge inoculation with the wild strains.

In addition, with single lesion isolates of the MII‐16 and o strains it has been shown that both strains can be assayed simultaneously in mixed isolates on Nicotiana glutinosa based on differences in local lesion size. The accuracy of this differential local lesion assay was c. 90% as determined by back inoculation of single lesion isolates into susceptible tomato cultivars.
Experiments with fungicide sprays in late summer and early autumn on sugar‐beet root crops
Authors: BYFORD W. J.
Published: February 2008

Fentinhydroxide and benomyl sprayed on to sugar‐beet root crops in July, August and September frequently increased yield of tops. Sugar yield was increased only if either powdery mildew or virus yellows was prevalent, when on average a single fentinhydroxide spray at 0·7 kg a.i./ha increased sugar yield by 8% and yield of tops by 13%. The mildew specific fungicide fluotrimazole also increased yield, but it could not be determined whether this was due to controlling powdery mildew or secondary parasitic fungi attacking yellows‐infected plants. Repeated sprays of both fentinhydroxide and fluotrimazole, but not benomyl, appeared to be phytotoxic when applied in hot dry weather.
Susceptibility of apples to infection by Gloeosporium album
Authors: EDNEY K. L. , TAN A. M. , BURCHILL R. T.
Published: February 2008

A rain simulator was used to show that the susceptibility of apples to infection by conidia of Gloeosporium album was markedly influenced by the amount of water falling on the fruit prior to inoculation. The rate of infection by G. perennans was also increased by this treatment.
Neck rot (Botrytis allii) of bulb onions
Authors: MAUDE R. B. , PRESLY A. H.
Published: February 2008

Experiments on neck rot of onions, caused byBotrytis alliishowed that, although the disease only became evident in store, a major source of the pathogen was samples of infected seeds. In 1972 and 1973, 39·5 and 71·4% respectively of commercial onion seed samples tested at Wellesbourne were infected. The pathogen was internal in seed and persisted for 3 ½ yr in infected seeds kept in a seed store at 10°C and 50% r.h.

Seedlings raised from diseased seeds became infected by mycelial invasion of the cotyledon leaf tips from seed‐coats many of which remained attached to the cotyledons when seedlings emerged from the soil. The fungus attacked the living tissues of these leaves symptomlessly, producing conidiophores only after the leaf tissue senesced and became necrotic. Because the fungus was symptomless, the rate of spread of the pathogen in onion crops was assessed by incubating successive samples of plants from the field in humid conditions when infected tissues developed conidiophores of the fungus. This method showed that the disease was progressive in onion crops spreading more rapidly in wet humid conditions (e.g. 1972) than in dry ones (e.g. 1973). The principal means of spread were probably fungal spores; conidiophores bearing spores being produced abundantly on plants in the field under high humidity. The fungus invaded the leaves of plants successively, first infecting each leaf at the tip and then growing downwards in the tissues and eventually invading the neck of the onion bulb via the leaves which emerged directly from the top of the neck. By harvest, the fungus was situated deep within the neck tissues of infected maturing onion bulbs.
Neck rot (Botrytis allii) of bulb onions
Authors: MAUDE R. B. , PRESLY A. H.
Published: February 2008

The percentage of bulbs with neck rot in store was determined by the number of onion plants with Botrytis allii infected neck tissues in the field. Since infected plants were obtained mainly by sowing infected seeds, it was established that the seeds were main source of neck rot in stored bulbs.

The disease failed to spread from infected bulbs to healthy bulbs in store but affected bulbs became progressively more rotten during storage.

In 1972, dusting seeds with 1 g benomyl/kg reduced neck rot in the stored bulbs from 50 to 8%. However, there was some cross infection from the control plots to the plots raised from benomyl dusted seeds 1·5 m distant. In 1973 and 1974, all plots were placed 165 m or more from one another to reduce spread of the disease. Benomyl applied to seed samples containing 1, 10 and 20% infection reduced the average neck rot percentage in stored bulbs from 10·1 to 0·4% in 1973 and from 26·2 to 3·8 % in 1974. The amount of neck rot in store was directly related to the percentage infection of the onion seeds. However, the number of infected bulbs in store was proportionally greater in 1974 when weather conditions were more conducive to spread of the disease in the field.
A method for comparing pesticide usage patterns between farmers
Authors: TAIT E. J.
Published: February 2008

A method is described for standardizing data from surveys of insecticide and fungicide usage, to enable comparisons to be made between farmers. Pesticide usage by the fruit and vegetable farmers surveyed was initially coded in units, and then standardized by taking each farmer's deviation from a regional average for the crop, expressed as standard measure. The vegetable farmers studied were less variable in their usage of pesticides for the control of aphid, caterpillar and blight on crops harvested late in the season rather than early (cabbage, lettuce, potatoes and sprouts). There was evidence that farmers did not heed the Beaumont period warnings issued by the Agricultural Development and Advisory Service (ADAS) for blight attack on potatoes. Also on potato crops, insecticide use against aphids was influenced by the level of fungicide usage for blight control. Standardized insecticide and fungicide usage values for individual farmers were very uniform. A two‐way analysis of variance showed that most of the variation in the model was accounted for by variation between farmers rather than by variation between crops on the same farm. By expressing pesticide usage data in this standardized form, one can measure the element in pesticide usage which is not related to pest incidence. This can then be used to study the influence of other factors on pesticide usage.
Evaluation and use of a screening method to aid selection of cocoa (Theobroma cacao) with field resistance to cocoa swollen‐shoot virus in Ghana
Authors: LEGG J. T. , LOCKWOOD G.
Published: February 2008

Seeds of cocoa progenies were inoculated with cocoa swollen‐shoot virus manually or by vector transfer techniques to assess the relative resistance of the progenies to infection. Assessment of progeny included in both inoculation tests and in field trials were positively correlated, indicating that the inoculation technique is suitable for the selection of progenies for testing in the field.

Pure Upper Amazon progenies were more resistant than selfed Amelonado, with hybrids between Amelonado and Upper Amazons usually intermediate. Among the main Upper Amazon populations, Iquitos and Nanay clones were better sources of resistance than Parinari and Scavina clones. A survey of these populations indicated that, within populations, resistance levels do not vary greatly.

A range of progenies based on the Upper Amazon female parents in existing seed gardens was screened for resistance and some were consistently more resistant than the equivalent Amazon x Amelonado hybrid now being distributed to farmers.
An interpretation of the frequencies of host specific phenotypes of Phytophthora infestans in North Wales
Authors: SHATTOCK R. C. , JANSSEN B. D. , WHITBREAD R. , SHAW D. S.
Published: February 2008

Race surveys of Phytophthora infestans over 4 years in North Wales have shown that races unselected by host resistance are frequent. In most cases frequencies of complex races are those expected from the frequencies of simple race characters if these assort at random. These results suggest that recombination between races may be unrestricted. The significance of unexpected deviations from the predicted frequencies are discussed.
Effects of seed deterioration and seed‐bed environment on emergence and yield of spring‐sown barley
Authors: PERRY D. A. , HARRISON J. G.
Published: February 2008

Seedling emergence from barley seeds, deteriorated by storage at supra‐optimal moisture contents and temperatures, was adversely affected by sowing early in spring when soil temperatures were low, and by sowing into wet seed beds. There were significant interactions between seed lots of varying levels of deterioration and seed bed condition, because the more severely deteriorated lots emerged proportionately less well than the control, non‐deteriorated lots.

The yield results also showed significant interactions between seed lots and seed‐bed condition because plants from deteriorated seeds in low populations resulting from partial emergence failure were unable to compensate and produce plot yields similar to those of higher populations.
Studies on an overwintering population of the mushroom phorid Megaselia halterata (Diptera: Phoridae) parasitized by Howardula husseyi (Nematoda: Allantonematidae)
Authors: RICHARDSON P. N. , HESLING J. J.
Published: February 2008

An overwintering population of the mushroom phorid fly Megaselia halterata parasitized by Howardula husseyi was studied in an attempt to explain the winter decline in incidence of parasitism that has been observed in flies from mushroom farms. Fly larvae from eggs hatching in November developed into pupae in December and flies emerged in May. No selective mortality of parasitized specimens of larvae, pupae, or flies was observed. Dead parasites were found in only 10% of parasitized flies. The incidence of parasitism in the emerging flies (50%) was five times that of their parental generation and although parasitism significantly delayed fly emergence the delay was only 2–3 days. There was no evidence of winter decline in parasitism; instead there was strong evidence that parasitism enhanced phorid survival through the winter.
The activity and distribution of wheat bulb fly (Delia coarctata) (Diptera:Anthomyiidae) in cereal crops and over fallow land
Authors: BARDNER R. , FLETCHER K. E. , JONES MARGARET G.
Published: February 2008

The flight activity and local distribution of adult D. coarctata were studied on Rothamsted Farm during 1970‐5 using several trapping methods. Changes in the activity and distribution of the flies were followed as the population aged, and in females these changes were associated with maturation of their eggs. Most females appeared to stay at their emergence sites in winter wheat until egg‐laying started about 1 month later. They then dispersed and both sexes were found in previously uninfested cereals and grass as well as on fallow land where the eggs are laid. Flight occurred chiefly in the late afternoon and evening. The concentration of flies at their emergence sites for several weeks before egg laying could facilitate chemical control, provided the practical difficulties of application can be overcome.
Predisposition of Aster to Phialophora wilt
Authors: BURGE M. N. , ISAAC I.
Published: February 2008

The susceptibility of Aster novi‐belgii to infection by the vascular wilt pathogen Phialophora asteris varied according to the growing conditions to which the host was subjected before inoculation. Relatively low air temperature, high soil moisture, and soil nutrients rich in potassium or phosphorus were pre‐inoculation conditions in which Aster became relatively susceptible. Increased resistance was favoured by growing plants at relatively high air temperatures, low soil moisture, and soil nutrients rich in nitrogen or calcium but low in potassium or phosphorus prior to inoculation.
Effect of thermal shock treatments on symptom expression in test plants inoculated with potato aucuba mosaic virus
Authors: HENDERSON HELEN M. , COOPER J. I.
Published: February 2008

Potato aucuba mosaic virus (PAMV) has few reliable local lesion assay hosts. However, lesions formed when PAMV‐inoculated leaves were exposed to thermal shock (dipping for 40 s in water at 50 or 2 °C). Leaves of Nicotiana tabacum (cv. Xanthi‐nc, Samsun or Samsun NN), Hyoscyamus niger and Datura metel consistently developed necrotic lesions, leaves of Chenopodium amaranticolor developed whitish rings, and leaves of N. glutinosa developed diffuse cream‐coloured rings and spots. In PAMV‐inoculated leaves of Xanthi‐nc tobacco, C. amaranticolor and D. metel, lesions formed only in areas exposed to light. Thermal shocks applied to systemically infected leaves of Xanthi‐nc tobacco induced necrotic vein banding patterns.

In inoculated Xanthi‐nc tobacco leaves, PAMV seemed confined to local lesions. The rate of lesion enlargement was therefore a measure of rate of virus spread. Lesion size increased as the interval between inoculation and shock treatment increased. The mean rates of increase in lesion radius were 17 and 27 Cμm/h at 15 and 25°C respectively. ‘Target’ lesions, composed of concentric necrotic rings, formed when inoculated Xanthi‐nc tobacco leaves were given two or more 50°C shocks. The first of two 50°C treatments decreased subsequent rates of lesion enlargement.
Growth and yield of high‐density cauliflower crops treated with pesticides to control weeds and cabbage root fly (Delia brassicae)
Authors: THOMPSON A. R. , PRICE JEAN L. , ROBERTS H. A.
Published: February 2008

Effects of combinations of insecticides and herbicides on the growth and yield of cauliflower plants (cvs No. 110, Garant and Strong) were determined in two field experiments with seed drilled to give a stand of c. 300000 plants/ha. Granular formulations of chlorfenvinphos or fonofos were applied by the bow‐wave method at 2 kg a.i./ha to control cabbage root fly (Delia brassicae). Weeds were successfully controlled with combinations of trifluralin, incorporated into the soil at 0·6 or 1·2 kg a.i./ha before drilling, and propachlor, applied pre‐emergence at 2·2 or 4·4 kg a.i./ha. Fonofos, with and without herbicides, significantly lessened (P < 0·01) numbers of seedlings that would survive to harvest. Herbicides and chlorfenvinphos generally did not significantly affect the emergence of healthy seedlings of any cultivar. Combinations of herbicides and chlorfenvinphos were compatible for control of target species. Chlorfenvinphos reduced root damage by at least 50% but did not significantly increase (P > 0·05) the total or marketable weight of curds. Numbers of curds were not usually affected and consistent effects of treatments on maturation periods of the three cultivars were not detected.
Matching inbred lines of Brussels sprouts for flowering characteristics, as an aid to improving F1 hybrid seed production
Authors: FAULKNER G. J. , SMITH B. M. , DRAYCOTT A.
Published: February 2008

Previous work at the National Vegetable Research Station indicated that cross‐pollination of Brussels sprouts by honeybees could be improved when parent lines with similar flowering characteristics were used. During 1973‐5 inbred lines were tested at three sites for matching ability based on flowering times, plant height and flower colour. One pair of inbreds satisfied all criteria at all sites, and a further twelve gave satisfactory results.

Two pairs visually matched in 1973 were grown in larger plots in 1973‐4 to assess the effect of matching on honeybee behaviour. Results showed that matching improved cross‐pollination by honeybees between the parent lines.
Effects of temperature and inoculum concentration on infection of narcissus bulbs by Fusarium oxysporum f.sp. narcissi
Authors: PRICE D.
Published: February 2008

Chlamydospores of Fusarium oxysporum germinated, and mycelium grew on agar, at 10 but not 8°C. Numbers of chlamydospores needed to initiate disease suggest that the principal sources of infection are within the stock of bulbs and not the soil.
The environment and the nematode
Authors: Jones F. G. W.
Published: February 2008

It is customary to list the factors affecting animal population as edaphic, climatic and biotic. To these I would add a fourth, intrinsic.
Microplot studies with Xiphinema diversicaudatum under annual and perennial cropping regimes
Authors: Cotten J.
Published: February 2008

Annual and perennial crops were grown in monoculture over three‐ or four‐year experiments. Strawberry, raspberry and ryegrass maintained high population densities of Xiphinema diversicaudatum. Hop maintained relatively low population densities as did all annual crops tested, including winter wheat, winter beans, spring barley, potatoes, sugar beet and cabbage. Differences in nematode population density were not due to differences in soil porosity.
The host plant and the nematodes
Authors: Green C. D.
Published: February 2008

Parasite selection by the host would be expected and is frequently found amongst the specialized plant parasitic nematodes and on perennial plants. Hijink & Oostenbrink (1968) showed that annual cropping could establish distinct nematode communities and such communities can become quickly established (Green, 1975). In carrot crops Aphelenchoides and Rotylenchus species became a larger proportion of the community very early in the growth of the crop (Green, 1976). Stabilization of communities in this way indicates a very close relationship between the nematodes and the host plants even when specialized feeding is not apparent. Cropping alters the plant community so that even these nematodes with a wide host range become dependant on the one host, provided weed control is efficient. Spacing of the crop further restricts the nematodes so they become more dependant on individual plants. Nematode attacks on crops are notable for two features. The hosts appear under‐exploited, that is there are few individual hosts with many parasites but many with few and, the hosts are rarely killed.
Distribution of damson‐hop aphid (Phorodon humuli) migrants on hops in relation to hop variety and wind shelter
Authors: CAMPBELL C. A. M.
Published: February 2008

The distribution of migrant Phorodon humuli was studied in two hopgardens during June 1972. Migrants accumulating upon the young tissues near the bines' apices were counted. Plant size affected distribution, 100 % more migrants were found on 2‐bine than on single bine strings and there was a positive linear relation between bine height and log10 aphid numbers. Plants surrounding wire‐trellis support poles were more heavily infested than plants not at poles, and migrants were more abundant on leeward orientated than windward strings. It is argued that the distribution of alatae reflected local patterns of wind shelter. Differences between plants declined in successive weeks.

The influence of hop variety on migrant settling was studied in one of the hop‐gardens. Fewer migrants settled on the variety Tolhurst than on Northern Brewer, and Fuggle was intermediate. Part, but not all, of the difference between varieties was explained by the larger average size of Northern Brewer plants.

The observed aphid deposition rates in the two hop gardens were compared with hypothetical deposition rates calculated from numbers of P. humuli caught in a nearby 12‐2 m Rothamsted Insect Survey suction‐trap, and used to estimate flight durations. The estimates indicated that most infestation probably resulted from aphids within 1 h flying time of their primary host source.
Ethirimol‐sensitivity in populations of Erysiphe graminis from plots of spring barley
Authors: SMITH JANET E. , PAYNE R. W. , BAINBRIDGE A.
Published: February 2008

Barley plots, cv. Proctor were sown with either ethirimol‐treated or untreated seed. At seedling emergence, plots were inoculated with isolates of Erysiphe graminis either sensitive or insensitive to ethirimol, or left uninoculated.

Mildew samples taken from the coleoptile leaves of seedlings, and later from leaf 6 (next but one to the flag leaf) were compared for ethirimol sensitivity using probit analysis. Probit lines were derived using ‘Wadley's analysis’. This analysis uses the number of survivors to estimate the total number of individuals originally present. In the test for ethirimol sensitivity a count of colonies on inoculated test leaves was taken to represent survivors. Microscopic counting of the original inoculum was thus avoided.

The analyses snowed that the initial leaf inoculation treatments established mildew populations in the plots, which differed considerably in ethirimol sensitivity. Some 6 wk after inoculation the levels of sensitivity in these populations remained unchanged even though inoculum coming into the experiment from external sources was often much more insensitive than the mildew in some plots.

Probit lines of response to ethirimol had shallow slopes, showing that large variability exists in the pathogen for this character.
Further studies on seed transmission of broad bean stain virus and Echtes Ackerbohnenmosaik ‐Virus in field beans (Vicia faba)
Authors: VORRA‐URAI S. , COCKBAIN A. J.
Published: February 2008

Broad bean stain virus (BBSV) and Echtes Ackerbohnenmosaik‐Virus (EAMV) were detected in the seed coat and embryo sac fluid of immature seeds from infected field beans (Viciafaba minor) by inoculation to Phaseolus vulgaris; BBSV was also detected in immature embryos. The proportion of seeds infected with either virus decreased during maturation. The viruses were transmitted to seedlings as often through fully ripened seeds from which the seed coats had been removed as through intact seeds. Both viruses were detected in pollen from infected plants, but in glasshouse tests only BBSV was transmitted through pollen to seeds. Delaying fertilization in plants infected with BBSV or EAMV seemed not to affect seed transmission of either virus.

In glasshouse tests BBSV was transmitted more often through seeds from plants that were inoculated before flowering than during flowering, and was not transmitted through seeds from plants inoculated after flowering; EAMV was transmitted only through seeds from plants inoculated before flowering. In tests on seed from naturally infected plants BBSV was transmitted more often through seeds from plants that developed symptoms before flowering than during flowering. Both viruses were seed‐borne in all cultivars tested and there was no marked difference in the frequency of transmission of either virus among the spring‐sown cultivars most common in Britain. Both viruses persisted in seed for more than 4 yr.
The adenosine triphosphate content of cysts of Globodera pallida and G. rostochiensis as a possible quantitative estimate of field populations
Authors: ATKINSON H. J. , BALLANTYNE A. J.
Published: February 2008

A rapid method is described for estimating the number of juveniles of Globodera pallida and G. rostochiensis in cysts collected from field soils. The technique uses a photometer to measure the adenosine triphosphate (ATP) content of the cysts by bioluminescence. Results for ten to twelve soil samples of 100 g taken from each of four fields showed that the number of juveniles that emerged when the samples were placed in potato root diffusate was significantly related to ATP content of a second series of cyst samples from these fields. Cysts from one field gave a higher ATP content per hatched juvenile than was recorded for the remaining three fields. There are several, untested, explanations of this discrepancy, but some evidence suggests that the hatching test and not the ATP method may have given an unreliable estimate of the viable egg content of cysts from this field. Further work may result in an enhanced precision and increased rapidity in estimating field populations of cyst nematodes by this technique.
The effect of seed deterioration on the growth of barley
Authors: HARRISON J. G.
Published: February 2008

Deterioration of barley seeds, caused by storing them at high moisture contents, was associated with slower germination and seedling emergence, reduced root and shoot growth and a smaller first true leaf compared with non‐deteriorated controls. Growth differences were related to meristematic activity. Plants from deteriorated seeds started to tiller later than controls, but tillering rates were similar. In the field in 1974 more tillers died after ear appearance on plants from deteriorated seeds than those on controls, but the following year similar numbers died. Grain yields from plants from deteriorated and control seeds were similar in both seasons. These results are discussed in relation to season and soil conditions.
Reproductive strategy of winged and wingless morphs of the aphids Sitobion avenae and Metopolophium dirhodum
Authors: WRATTEN S. D.
Published: February 2008

The reproduction of apterous and alate morphs of the aphidsSitobion avenaeandMetopolophium dirhodumis compared on the basis of fecundity in 5‐ and 10‐day periods of adult life. Apterae of both species are consistently more fecund than alatae of comparable weight, producing about three more nymphs on average in any 5‐day period. The reproductive differences are related to the number and quality of embryos at eclosion and to ovulation rates, both of which in turn appear to be linked to wing‐muscle maintenance. These relationships between weight, embryos and reproduction may be used to predict a newly moulted adult aphid's fecundity, a method which may facilitate the assessment of resistance to aphids in new cereal varieties, by obviating lengthy recording of reproduction. The strategies by which alatae of these and other aphid species minimize the difference between their fecundity and that of apterae are discussed.
Field techniques for assessing the reaction of winter wheat cultivars to Septoria nodorum
Authors: SCOTT P. R. , BENEDIKZ P. W.
Published: February 2008

Methods of assessing the reaction of winter wheat cultivars to Septoria nodorum were compared in nine field trials. Plots were inoculated either by scattering naturally infected wheat debris or by spraying with a suspension of conidia at different growth stages, and were subsequently kept damp by several methods. Disease development was monitored by assessing the percentage cover of different organs by lesions, or by measuring the maximum height of lesions above ground. Major differences between cultivars were evident with all methods of inoculation and assessment, but time of assessment was critical for best differentiation. Inoculation with conidia soon after ear emergence, followed by assessment of lesions on flag leaves and ears, was a simple and effective method.

Yield loss due to disease was measured by making comparisons either between inoculated and uninoculated plots, with various degrees of separation, or between inoculated plots with and without fungicidal treatment: the first of these methods was more effective in maintaining a disease differential. Yield loss was positively correlated with severity of disease and there was little evidence that cultivars differed in tolerance of disease. Disease was measured more easily and with less error than yield loss.
Studies on the fungicidal control of stem lesions caused by Botrytis cinerea on glasshouse tomatoes
Authors: CHANNON A. G. , THOMSON MOIRA C.
Published: February 2008

In glasshouse pot experiments, uptake of benomyl, thiophanate‐methyl and carbendazim from equivalent soil applications (in the range 0–003– 0–035 %a‐i‐ atarateof 2&4 ml/plant) gave equal levels of control of Botrytis lesions developing from inoculations of freshly exposed leaf scars on tomato stems. Spray applications of benomyl to exposed leaf scars controlled infection at concentrations down to 0025 % a.i. The effect of lower concentrations of the stem spray could be markedly enhanced either by the addition of a mineral oil (2 % Actipron) or by a prior soil application of benomyl at a low rate which on its own had little effect on lesion development. Protectant spray applications of glycophene and vinclozolin gave levels of control quite comparable to that of benomyl at equivalent concentrations.

Evidence was obtained that the lesions formed at the artificially‐inoculated leaf scars at the top of the stems of young pot‐grown tomato plants were larger than those lower down. In spite of this, the level of disease control with soil applications of fungicides containing or generating carbendazim (MBC) was greater at the top than at the bottom, probably because of the normal migration of the fungicides and their accumulation at the extremities of the plant.

In an observation trial in a commercial crop of tomatoes, benomyl applied either as five soil drenches at approximately monthly intervals, or as two drenches followed by five sprays at three‐weekly intervals, or as five sprays alone gave marked reductions in plant loss and number of Botrytis stem lesions in both cvs Eurocross BB and Cudlow Cross. Those stem lesions which did develop, however, were generally as large as those on untreated control plants. Five sprays of dichlofiuanid gave similar levels of disease control. All the treatments gave apparently higher yields (statistically untested) in Eurocross BB, but less consistent responses were recorded in Cudlow Cross.
Principles of insecticide action on mushroom cropping: incorporation into compost
Authors: WYATT I. J.
Published: February 2008

A series of cropping experiments has demonstrated that mushroom yields show an approximate logistic response to a range of insecticide concentrations incorporated in the compost. This principle applies only to the cumulative yield at any flush, and the response of an individual flush is, therefore, related to the difference between two logistic curves. Increases in crop can thus occur in later flushes, partially compensating for earlier losses. With diazinon treatments, but not thionazin, some of this compensation was due to increases in the size of mushrooms.

It is concluded that commercial applications of 50 ppm diazinon could cause up to 2–5 % reduction in crop and that 10 ppm thionazin may cause a 6% loss which must be weighed against the advantages of treatment. Suggestions are made for the design and interpretation of future trials.
Electrophoretic studies on populations of Myzjus persicae in Scotland from March to July, 1976
Authors: BAKER J. P.
Published: February 2008

Specimens of Myzus persicae have been collected from field populations in Scotland and scored electrophoretically for their phenotypes at three polymorphic loci. These phenotypes were almost invariably present in individuals in one of a small number of favoured combinations, suggesting that these populations may be oligogeneous, that is, composed of large numbers of copies of a few favoured combinations of alleles.

Temporal and spatial sampling at sites in East and West Scotland in 1976 has shown that different allele combination types were present in the two areas. Populations in E. Scotland contained very few specimens belonging to the organophosphorus (OP) resistant clone types (using esterase activity to infer resistance); instead there were large numbers of an OP susceptible type which has not been detected in England, but which came to predominate on cabbage and potato host plants at every site sampled during the period of rapid population increase. In contrast, populations in W. Scotland were characterised by substantial numbers of specimens belonging to OP resistant clone types and by an almost complete absence of this susceptible type. Two other distinguishable OP susceptible types were found to be common to both areas. The W. Scotland populations closely resemble N. England populations while those in E. Scotland appear to be unique to that area. Specimens of OP resistant types were only detected in E. Scotland after the beginning of June and in such relative proportions as to strongly suggest that they were migrants from W. Scotland or N. England.
The life‐history and bionomics of Epitrimerus piri (Acarina: Eriophyidae) on pear
Authors: EASTERBROOK M. A.
Published: February 2008

The majority of Epitrimerus piri on pear, cv. Williams' Bon Chretien, moved from their hibernation sites in small permanently dormant buds on spurs and under loose bark to fruit buds between the stages of green cluster and petal fall. Peak numbers of mites occurred in mid‐June on fruit and early August on leaves with the return to hibernation beginning in July. Development time from egg hatch to adult was 17–1, 6–9 and 4–8 days at 10, 16 and 22 °C, respectively. Mites were dispersed by wind. They were found only on species in the genera Pyrus, Cydonia and Pyronia.

Mite feeding caused browning on the ventral, sides of leaves and russet on fruit which was confined to the calyx end on Williams'. Populations of over 2000 mites/leaf reduced the length and dry weight of new shoots on potted pears by 8 and 14% respectively.