bluuebunny/crossref_metadata_2025 huggingface dataset:
Specific immunological response against the granulosis virus of the codling moth (Cydia pomonella) in woodmice (Apodemus sylvaticus): field observations
Authors: BAILEY M. J. , FUJITA FRANCES R. HUNTER
Published: February 2008

Antibodies specific to the granulosis virus (GV) of the codling moth (Cydia pomonella) were detected by indirect ELISA in sera of woodmice (Apodemus sylvaticus) trapped in an apple orchard sprayed by tractor‐drawn mist blower with 2 × 1013 virus granules C. pomonella GV/ha. Such antibodies were absent from sera of mice trapped before virus had been applied. Virus antigens were detected by double antibody sandwich ELISA on the ground in and around the orchard and also in the faeces of woodmice inhabiting the orchard, but did not persist from one year to another. Some, but not all, of the samples containing virus antigens were found to be infective.
The feasibility of producing inbred rather than F1 hybrid cultivars in Brussels sprouts: predictions from early generations
Authors: ROGERS W. J. , KEARSEY M. J. , SMITH B. M.
Published: February 2008

Predicting the performance of recombinant inbred lines derived by single seed descent (SSD) following crosses between inbred lines is most reliable for traits in which epistasis and genotype environment interaction are absent. The analysis of two field trials of Brussels sprouts indicated the presence of such effects in seven quantitative characters. These effects could be minimised by transforming the scale on which each character was measured. Predictions were made of the likely performance of the recombinant inbred lines currently being produced by SSD at the Institute of Horticultural Research, Wellesbourne, compared with that of current F1 hybrid varieties.

The predictions from the first trial of F2 material were encouraging for harvest date, stem length and waste weight, but low for sprout number, quality, marketable yield and total yield. Predictions from F3 material in the second trial were good for sprout number and total yield (in addition to harvest date, stem length and waste weight as before), but still low for marketable yield and quality, with less than 0 01% of lines expected to perform better than the F1. Model fitting to variances suggested the presence of linkage disequilibrium in dispersion for waste weight, but no information could be obtained about linkage disequilibrium for the two most important characters, marketable yield and quality.

The broad heritability of each character except stem length was lower than 0 5 (0 3 or lower for total yield, waste weight and quality), suggesting that advanced generation selection, as used in SSD, might be more successful than selection in the early generations.
Modification and testing of a domestic freezer for use in studies of plant growth and survival at low temperatures
Authors: HAYCOCK R. , AULD M. H. D. , OLLERENSHAW J. H. , STEWART W. S.
Published: February 2008

Modifications of a domestic freezer are described, which convert it to a versatile controlled environment chamber capable of maintaining temperatures between ambient and ‐ 18 °C and therefore useful in investigations both of plant growth at low positive temperatures and of survival of sub‐zero temperatures. The temperature control mechanism can provide a wide range of diurnal temperature regimes and of cooling and warming rates.

Measurements in two such chambers showed air temperatures were always uniform to within ° 1 °C of set temperature except in a 6 cm band round the inside walls, where they were lower by 0°6 °C, at most; CO2 concentration was always close to 300 v.p.m.; relative humidity was usually in the range 80–90% and photon flux densities during the light period were 180 ° 10 μmol m‐2 s‐1.

The uniformity of environmental conditions within each chamber was confirmed by measurements of leaf growth and plant survival of tillers of a single genotype of perennial ryegrass growing in pots of compost. These tests also confirmed the lower temperature of the 6 cm band adjacent to the chamber walls.

Although temperature settings were identical, air and compost temperatures were 0°3 °C higher in one of the two chambers tested. Although this difference did not result in significant differences in plant survival, significant differences in leaf lamina extension were found between cabinets.

Problems encountered in the design and testing of the chambers are discussed.
Factors affecting the production of caffeoylquinic acid levels in germinating carrot seedlings and its estimation by u.v. epifluorescence microscopy
Authors: COLE ROSEMARY A.
Published: February 2008

Conditions for obtaining reproducible estimates of caffeoylquinic acids in carrot seedlings, by fluorescence intensity determined using epifluorescent microscopy were investigated. The optimum germination conditions for the test were established as 9–10 days at 20 °C. Factors such as the presence of microflora on seed material and the environment of the seed during production were found to influence the mean radicle fluorescence.
Seasonal changes in the free amino acids of oat and barley phloem sap in relation to plant growth stage and growth of Rhopalosiphum padi
Authors: WEIBULL J.
Published: February 2008

The concentrations and composition of free amino acids in phloem sap from two cultivars of oats and barley, both susceptible to the aphid Rhopalosiphum padi, were determined by means of high performance liquid chromatography. Sap was collected from excised aphid stylets at three developmental stages (seedlings, tillering plants and plants undergoing stem elongation) from plants given or not given fertiliser and grown outdoors. In connection, the growth of individual R. padi nymphs was estimated at the same phenological stages on plants grown in the greenhouse.

The content of free amino acids was consistently higher in seedlings than in plants at the early tillering stage. Only in seedlings did the addition of fertiliser increase amino acid levels. Barley phloem sap contained more free amino acids than that of oats when fertiliser was added and at later developmental stages.

Phloem sap of oats and barley showed similar patterns in their composition of free amino acids at the seedling stage, but as the plants grew older the patterns became increasingly different. Plants given fertiliser had higher amounts of dicarboxylic amino acids (glutamic and aspartic acid) than unfertilised plants. The concentrations of γ‐amino butyric acid, glycine, histidine, and methionine were very low in all treatments.

The relative growth rates of R. padi nymphs were low when amino acid content was low and vice versa. The results are discussed in relation to host plant suitability and plant resistance mechanisms.
Effect of spacing in cow pea (Vigna unguiculata) on damage by the black cowpea moth, Cydia ptychora (Lepidoptera: Tortricidae)
Authors: OFUYA T. I.
Published: February 2008

Three indeterminate cowpea cultivars with different growth habits were each planted at four inter‐row spacings in two different seasons at Ile‐Ife, Nigeria, and at harvest assessed for Cydia ptychora damage. Damage by the moth increased with decreasing inter‐row spacing much more in the erect and semi‐erect cultivars, than in the semi‐prostrate cultivar.
Populations of Rhizoctonia solani in soil under crops in rotation with sugar beet
Authors: HERR LEONARD J.
Published: February 2008

Using a soil debris isolation method, populations of Rhizoctonia solani were monitored over a 4 ‐yr period in four fields which were initially cropped to sugar beet and in which four areas of Rhizoctonia crown rot diseased beets (DA) and four areas of apparently healthy beets (AH) had been selected and precisely located. Soil from these areas was assayed during the subsequent crops, which included sugar beet, tomato, cucumber, maize and soybean. No significant differences in colony counts were found between the soils in DA and AH on any of 30 sampling dates. R. solani population counts were, in general, quite low, except under sugar beet and following tomato harvest. Areas of diseased beet and high R. solani soil populations that developed in subsequent sugar beet crops did not necessarily coincide with the previously selected diseased areas. High R. solani populations developed from parasitic activity on sugar beet or saprophytically on tomato crop residues. Of the other crops, both maize and soybean may have slightly increased the low R. solani residual populations in soil. The monitoring of R. solani populations in the season prior to, and during the early season of sugar beet cropping did not provide a basis for forecasting disease in fields or sites within fields. The initiation of disease patches in these sugar beet fields was therefore governed by factors other than inoculum density.
Effect of Globodera rostochiensis on the growth of reciprocal grafts between two potato cultivars of different tolerance in a field trial
Authors: TRUDGILL D. L.
Published: February 2008

The tolerance of plants produced from reciprocal grafts between cv. Cara and cv. Pentland Dell were compared in field plots containing different initial population densities of Globodera rostochiensis. Both stock and scion contributed to the greater tolerance of cv. Cara as compared with cv. Pentland Dell. Ground cover measurements, made by a novel photographic method, showed that a heavy infestation of G. rostochiensis decreased the top growth of all plants: more for those with scions of Pentland Dell than those with scions of Cara. The stock did not initially affect the extent to which top growth was reduced in the heavily infested plots but later measurements showed a progressively increased effect on top growth for plants with stocks of Pentland Dell and a decreased effect for those with Cara. In a destructive harvest 13 wk after planting the relatively small effect of G. rostochiensis on the top growth of plants with Cara scions was not reflected in the tuber yields which were markedly decreased. However, plants with Cara stocks were considerably more tolerant (i.e. tuber yields were affected less) than those with stocks of Pentland Dell. Overall, plants of Pentland Dell scions on Cara root stocks were most tolerant at this stage. Between 13 and 16 wk, when a second destructive harvest was made, plants with Pentland Dell scions were senescent and their yield increased little. In contrast, plants with Cara scions were still growing and their yield increased markedly so that by 16 wk the most tolerant combination was Cara on Cara.
Changes in the second stage juveniles of Globodeva rostochiensis prior to hatching in response to potato root diffusate
Authors: ATKINSON H. J. , TAYLOR JILL D. , FOWLER M.
Published: February 2008

cAMP levels in eggs of G. rostochiensis and the diameter of the nucleolus of the nucleus within the dorsal pharyngeal gland cell of the second stage juvenile have been measured as indicators of the response of the nematode to the hatching stimulus in potato root diffusate. The nucleolus increased from 2.72 ± 0.103 μm for unhatched individuals to 3.28 ± 0.14 μm and 3.88 ± 0.15 μm after soaking eggs in potato root diffusate for 3 and 4 days respectively. Juveniles expressed from unstimulated eggs in water to potato root diffusate for 4–5 days showed a similar increase in size of the nucleolus to 3.94 ±0.15 μm but those released into water for this time had smaller nucleoli of 3.20 ± 0.98 μm. The change in diameter of the nucleolus is probably related to the accumulation of secretions in this gland cell before hatching.

Preliminary results with dibutyryl analogues of CAMP and cGMP showed some inhibition of hatch in 10% potato root diffusate. Theophylline had a similar effect but NaF was dissimilar in that the effect of this inhibitor was not reversible. A standard radioimmunoassay showed that significant changes in cAMP levels occurred in the unhatched juveniles within cysts after treatment with potato root diffusate for 2.5 or 8 h compared with values for cysts kept in water. This change occurs before other known responses of the juveniles to potato root diffusate and it defines the period of interest for future work on the initial action of hatching factor.
Control of beet cyst‐nematode, Heterodera schachtii, by aldicarb applied to the soil by a vertical band‐reciprocating harrow technique or by rotary cultivation
Authors: WHITEHEAD A. G. , TITE D. J. , FRASER JANET E. , NICHOLS A. J. F.
Published: February 2008

As little as 0.8 kg aldicarb ha‐1 applied to bands of soil 15 cm wide × 15 cm deep, in which sugar beet seeds were sown, increased beet yields as much as did 2.6 or 5.0 kg ha‐1 rotary cultivated into the top 15 cm of soil lightly or moderately infested with beet cyst‐nematode, Heterodera schachtii. In a very heavily infested soil, 1.7 kg ha‐1 applied to the bands of soil increased beet yields as much as 2.6 kg ha‐1 rotavated into the top 15 cm of the soil; yields were further increased by 5.0 and 9.9 kg ha‐1 rotavated in but not by 3.5 kg ha‐1 in the bands of soil. Soil populations of the nematode increased little or not at all whether the soil was treated with aldicarb or not. The band treatment was achieved by a vertical band‐ reciprocating harrow technique, which is described. The advantages of this new technique for the control of beet cyst‐nematode and other soil pests of widely spaced row crops are safer application of less pesticide, thereby minimising cost of treatment and any risk to the environment, faster seedbed preparation and adequate control of pest population increase on the susceptible crop, especially if coupled with biological control.
Post‐harvest age‐induced seed dormancy ofAcer ginnalaand its alleviation by growth regulator and low temperature treatments
Authors: NORTON COLIN R.
Published: February 2008

One‐month‐old fruits ofAcer ginnalawith winged pericarp attached gave 44% germination and this was not increased by cold treatment at 4°C for 0, 10, 20, or 30 days, gibberellic acid treatment at 0, 1, 10, 100 or 1000 mg litre‐1, or ethephon treatment at 0, 2, 20, 200 or 2000 mg litre‐1.

After 6 months of storage at 20–25 °C, germination of untreated fruits fell to 5% but could be restored to that of 1‐month‐old fruits by incubation at 4 °C for 30 days.

After 9 months storage, no germination occurred in untreated fruits. Cold treatment (30 days at 4 °C partially restored germination (26%). Treatment with either gibberellic acid (1000 mg litre‐1) and 30 days at 4 °C (40%) or ethephon (100 mg litre‐]and 30 days at 4 °C improved germination (69%). The combination of all three treatments, i.e. 100 mg litre‐1gibberellic acid, 100 mg litre‐1ethephon and 30 days at 4 °C, optimised germination (86%).

Thus, dormancy ofA. ginnaladeveloped during storage but could be reversed by a combination of treatment with low temperature and growth regulators. The highest germination (86%) was achieved after low temperature and growth regulator treatment of stored fruit.
Effects of growth retardants on bulbil production by Narcissus twin‐scales
Authors: HANKS GORDON R.
Published: February 2008

Narcissus twin‐scale propagules, cut from various positions in the parent bulb, were incubated with gibberellic acid (GA3) or growth retardants. Bulbil production was inhibited in all cases by GA3 at 10–100 mg/litre. Chlormequat chloride, chlorphonium chloride and paclobutrazol also inhibited bulbil production; in the case of paclobutrazol, outer twin‐scales were more sensitive to lower concentrations of the retardant than inner ones. Ancymidol enhanced bulbil production (in numbers by up to 15%) in the outermost twin‐scales, and had no stimulatory effect on the inner twin‐scales. Treatments affected bulbil numbers and bulbil lengths about equally.
The effect of cane management techniques on raspberry yellow rust (Phragmidium rubi‐idaei)
Authors: ANTHONY VIVIENNE M. , WILLIAMSON B. , SHATTOCK R. C.
Published: February 2008

The effects of various cane removal treatments on the epidemiology of Phragmidium rubi‐idaei were studied in four experiments in infected raspberry plantations in Wales and Scotland. In 1981, removal of 15 cm high young canes either by cutting or by spraying dinoseb‐in‐oil reduced infection of a second flush of canes (replacement canes) compared to that of the first flush of canes on untreated plots of cv. Mailing Delight in Wales and of cv. Glen Clova in Scotland. In 1982, removal of 20 cm high young canes reduced infection of cv. Mailing Delight in Wales but in Scotland only removal of 60 cm high canes by cutting reduced infection of replacement canes. Removal of all fruiting canes and old cane stubs reduced rust infection of young canes, but removal of successive flushes of replacement canes did not reduce infection of lateral shoots on the fruiting canes.

Dinoseb‐in‐oil applied to the bases of fruiting canes before emergence of young canes had no effect on infection of young canes in Wales or Scotland. The production of basidiospores was inhibited in vitro by dinoseb‐in‐oil at concentrations over 1.0 μg a.i./ml.
The effect of irrigation on powdery scab and other tuber diseases of potatoes
Authors: ADAMS M. J. , READ P. J. , LAPWOOD D. H. , CAYLEY G. R. , HIDE G. A.
Published: February 2008

In field experiments seed tubers affected with powdery scab cankers were planted and the effect on disease incidence of timing of irrigation and some seed‐tuber fungicides was investigated over 3 yr. For 2 yr, irrigation to maintain soil wetter than—20 centibars (—20 kPa) during the first half of the growing season increased disease compared to unirrigated plots. Disease incidence was not affected by irrigation at 2 wk intervals or when applied during the second half of the season. Little disease developed in 1983 even in irrigated plots, probably because of high soil temperatures. None of the fungicides tested gave consistent disease control.

Common scab and silver scurf were both decreased by irrigation but in two years, black dot was increased. The relative importance of black dot could increase in irrigated crops where fungicides are used to control silver scurf.
Possible explanations of synergism in fungicide mixtures against Phytophthom infestans
Authors: SAMOUCHA Y. , GISI U.
Published: February 2008

Single foliar sprays of oxadixyl, mancozeb or cymoxanil alone or the mixtures oxadixyl/mancozeb and oxadixyl/cymoxanil were applied to tomato plants (cv. Baby) one day before inoculating with a sensitive or a phenylamide‐resistant strain of Phytophthora infestans. Fungicide mixtures were far more effective in controlling both sensitive and resistant strains compared to the individual components alone, representing significant levels of synergistic interactions. When analysed by the Abbott method, synergy ratios continuously decreased with increasing amounts of fungicides in the mixture. All fungicide mixtures showed higher synergy ratios against resistant strains when using the Abbott method, whereas only mixtures containing cymoxanil showed this phenomenon when using the Wadley method for interpretation of interactions. Synergism significantly decreased when the components were used as foliar split applications with intervals of 48 and 72 h. A combination of a drench application of oxadixyl and a single spray application of mancozeb or cymoxanil resulted in a high level of synergism. The explanation of synergism may be that the exposure of sporangia to sublethal concentrations of one fungicide affects them to an extent that sublethal doses of the other fungicide becomes detrimental.
Chemical control of stem nematode, Ditylenchus dipsaci, in field beans (Vicia faba)
Authors: WHITEHEAD A. G. , TITE D. J.
Published: February 2008

‘Giant race’ stem nematode (Ditylenchus dipsaci) was well controlled in spring beans (Vicia faba) by up to 5 kg aldicarb or carbofuran ha‐1 applied to the seed furrows at sowing. Carbofuran was rather more effective in the clay loam soil used than was aldicarb. The best treatments almost eliminated injury to the stems and nematode infestation in the harvested seed. Similarly applied, oxamyl and fenamiphos were less effective and phorate, dimethoate and disulfoton were ineffective. Applying part of the dosage of an effective nematicide to the seed furrows and part along the plant rows mid‐season was no more effective and was sometimes less effective than applying the whole dose to the seed furrows. Treating the plant rows mid‐season with aldicarb or phoxim sometimes enhanced control but thiabendazole applied thus did not. Seed furrow applications of aldicarb or carbofuran were much less effective in controlling the nematodes in winter beans and seed dressings were less effective than seed furrow treatments. In one experiment, in plots in which aldicarb or oxamyl had been applied to the seed furrows, phoxim or thiabendazole applied over the rows of plants, enhanced nematode control. In two other experiments, thiabendazole was ineffective when applied in this way or when applied as a combined soil and plant treatment.
Effects of host stage on the development of the facultative autoparasitoid Encarsia tricolor (Hymenoptera: Aphelinidae)
Authors: AVILLA J. , COPLAND M. J. W.
Published: February 2008

Encarsia tricolor is a facultative autoparasitoid of the glasshouse whitefly, Trialeurodes vaporariorum, with a potential in biological control. The rate of development, number of mature oocytes at emergence, number of ovarioles and size of the emerged adults were studied. Five nymphal instars (N1, N2, N3, N4, and pharate adult) of T. vaporariorum were used as hosts for the females. Female larvae and pupae of E. tricolor and Encarsia formosa were used as hosts for the males. Females developed faster when the egg was laid on N3 (18.0 days from egg to adult) and slower on N1 (22.3 days). Females were bigger when developing from N1 and N3 than from N4 and pharate adult. On emergence the mean number of mature oocytes was always small (0.8–2.6). Males developed faster and were smaller than females, and developed faster and were larger on larvae of E. formosa.
Effect of waterlogging yam vines on vegetative growth and tuber yield
Authors: IGWILO NDUBISI , UDEH ARTHUR C. D.
Published: February 2008

The effect of waterlogging the vines of two yam varieties for 24, 48 and 72 hours at two stages of growth, with or without fertiliser application, was studied in the field.

Waterlogging caused a progressive degeneration of the leaf starting with the development of fresh lesions on the lower leaf surface, through necrotic spots or portions, to complete leaf necrosis. The degree of leaf damage was greater with Um 680 (Dioscorea alata) than with Obiaoturugo (D. rotundata). Waterlogging also caused the breakdown of the apical buds of the vines. The degree of damage increased with the duration of waterlogging. Younger plants suffered more damage than older plants, and plants treated with fertiliser suffered more than plants without fertiliser. Waterlogging ultimately hastened the final senescence of the yam vine.

Waterlogging vines for 24 h had no effect on tuber yield, while waterlogging for 48 and 72 h reduced tuber yield by 32.4% and 43.2% respectively (P< 0.01). Waterlogging vines at the early growth stage produced 47.6% (P <0.01) less yield than waterlogging at a later stage.

It is suggested that short‐term or long‐term waterlogging of the yam vine, or parts thereof, is the main cause of reduced leaf area and low yield in unstaked compared with staked yarn crops. Waterlogging may also be a predisposing factor to disease infection of yam vines by soil‐borne micro‐organisms.
The inhibition of potato sprout growth by light.
Authors: McGEE E. , BOOTH R. H. , JARVIS M. C. , DUNCAN H. J.
Published: February 2008

When potato seed tubers (Solanum tuberosum cv. Pentland Javelin) were stored in darkness or diffuse daylight at 9°C and transferred at intervals to conditions suitable for sprouting, their capacity for sprout growth was unaffected by the presence or absence of light during previous storage. When similar tubers were stored at 10°C, 18°C or 25°C, sprout growth commenced earliest at 25°C, but the date was unaffected by fluorescent light. It was concluded that light did not affect the length of the dormant period, but only the rate of sprout elongation after that period had ceased.

When tubers with growing sprouts at 10°C or 18°C were transferred from darkness into fluorescent light, sprout growth virtually ceased. Transfer from light into darkness resulted in immediate sprout growth, at a rate comparable with tubers stored continuously in the dark.

Tubers of three Peruvian cultivars, stored in farm‐scale diffuse‐daylight stores, grew progressively shorter sprouts with increasing daily exposure to light from 30 min to 12 h. Storage of cv. Wilja under 21 Wm‐2 (total) of white fluorescent light for 10 h per day maintained the sprouts at the same length as ten times this light intensity for 1 h per day. In a subsequent experiment with cv. Bintje the 10 h, low‐intensity light regime gave slightly shorter sprouts. It appeared that the total light energy falling on the tubers was the dominant factor controlling sprout growth.
Seasonal radiation interception, dry matter production and yield determination for a semi‐leafless pea (Pisum sativum) breeding selection under contrasting field conditions
Authors: HEATH M. C. , HEBBLETHWAITE P. D.
Published: February 2008

Radiation interception, dry matter accumulation, flower and pod production and yield were measured for a semi‐leafless pea (Pisum sativum) breeding selection (BS3) on three contrasting sites. Differences in soil moisture availability were largely responsible for a three‐fold difference in yield between sites.

Radiation interception was related to dry matter production by calculating photosynthetic efficiencies. In the absence of lodging, crop canopies converted intercepted radiation into dry matter with constant efficiency (ɛ) throughout the season; under conditions of moisture stress ɛ was reduced. Serious lodging during the post‐flowering period on one site resulted in a mean seasonal photosynthetic efficiency (ɛ) 17% lower than ɛ.

The ability of the pea crop canopy to intercept radiation was related also to yield components.
Effects of cypermethrin and deltamethrin on the feeding behaviour of Aphis craccivora and transmission of cowpea aphid‐borne mosaic virus
Authors: ATIRI G. I. , THOTTAPPILLY G. , LIGAN D.
Published: February 2008

The effects of two synthetic pyrethroids, cypermethrin and deltamethrin, on the feeding behaviour of Aphis craccivora and its transmission of the nonpersistent cowpea aphid‐borne mosaic virus (CAMV) were compared to those of an organophosphate (dimethoate) and carbamate (pirimicarb) in greenhouse and laboratory tests. Cypermethrin at 100, 150 and 200 mg a.i. litre‐1 and deltamethrin at 75, 100 and 150 mg a.i. litre‐1 restricted the acquisition and inoculation of CAMV, whereas dimethoate and pirimicarb had no significant effect. Cypermethrin protected against transmission of CAMV longer after application than deltamethrin and there was a strong interaction between

The duration of the first probe was shorter on pyrethroid‐treated plants than on dimethoate‐or pirimicarb‐treated plants, and on pyrethroid‐treated plants aphids probably did not probe long enough to acquire or inoculate CAMV.

It is concluded that the use of synthetic pyrethroids is potentially valuable in controlling CAMV in the field until resistance against the virus has been bred into cultivars.
Thickening and browning of cortical cell walls in seminal roots of wheat seedlings infected with Gaeumannomyces graminis var. tritici
Authors: PENROSE L.
Published: February 2008

This paper examines a little studied reaction of wheat roots to invasion by Gaeumannomyces graminis var. tritici, namely the thickening and browning of cortical cell walls. Examination was confined to distal segments of young seminal roots grown in sand. Browning and thickening of walls of cells were associated with the lignification of tissue and appeared to be a response of living or recently live cells to invasion by weakly virulent isolates. Wheat genotypes differed in their ability to thicken and lignify cell walls, and the difference between two wheat cultivars appeared to be under simple genetic control. There was some evidence that cortical browning temporarily retarded radial invasion by hyphae of G. graminis into young seminal roots of wheats.
Comparison of paint and gel formulations for the treatment of Nectria cankers on apple trees
Authors: CLIFFORD D. R. , GENDLE P. , HOLGATE M. E. , HUNTER T.
Published: February 2008

A gel formulation containing carbendazim and triadimefon completely eradicated infection from scraped or unscraped cankers and none became re‐infected. Paint formulations containing mercuric oxide or octhilinone completely eradicated infection from scraped cankers but 30–50% of unscraped cankers receiving these treatments became re‐infected. Scraping alone encouraged callus tissue formation but did not greatly reduce infection.

Fungicide moved from gels into the wood beneath cankers and persisted there for up to 6 months; movement of fungicide from mercuric oxide or octhilinone paints was minimal.

Carbendazim was more effective than thiophanate‐methyl and xanthan gum than sodium alginate or alginate ester as fungicide and gel component respectively. Rainfall shortly after treatment probably aided movement of fungicide from gels into the wood but salt formation, by incorporation of acid, did little to improve fungicide performance.

Unequivocal assessment of efficacy of canker treatment requires data on canker area changes, movement and persistence of active ingredient in the wood and extent of re‐infection after 12 months.
Effects of fungicide spray regimes on incidence of dicarboximide resistance in grey mould (Botrytis cinerea) on strawberry plants
Authors: HUNTER T. , BRENT K. J. , CARTER G. A. , HUTCHEON J. A.
Published: February 2008

In tunnel experiments, the efficacy of dicarboximide sprays in controlling grey mould of strawberries was greatly decreased by the presence of dicarboximide‐resistant forms of Botrytis cinerea. The use of dichlofluanid, as a tank‐mix or in an alternating programme, with a dicarboximide fungicide, procymidone, helped to maintain the efficacy of disease control but failed to prevent an increase in the proportion of dicarboximide‐resistant forms of the pathogen.

Alternative ‘partner’ fungicides (thiram, chlorothalonil) delayed build‐up of resistance to dicarboximides. Build‐up of resistance was absent or relatively small in unsprayed plots. Application of dichlofluanid alone was always associated with a substantial increase in dicarboximide resistance, although less than in procymidone‐treated plots. Monitoring dicarboximide resistance in the tunnels during the winter, when no further sprays were applied, revealed a gradual decline in the proportion of dicarboximide‐resistant forms in all previously treated plots.

In laboratory studies on inoculated leaf debris, dichlofluanid treatment induced the build‐up of dicarboximide‐resistant forms of B. cinerea. Leaf‐disc tests revealed cross‐resistance of dicarboximide‐resistant isolates towards dichlofluanid but not towards thiram or chlorothalonil. Dichlofluanid is widely used for control of B. cinerea and the implications of these results for the practical management of dicarboximide resistance in this pathogen are discussed.
Purification and properties of cassava green mottle, a previously undescribed virus from the Solomon Islands
Authors: LENNON ANGELA M. , AITON MAUD M. , HARRISON B. D.
Published: February 2008

A sap‐transmissible virus obtained from cassava with a green mottle disease occurring at Choiseul, Solomon Islands, was transmitted to 30 species in 12 plant families and was readily seed‐borne in Nicotiana clevelandii. In cassava plants infected by inoculation with sap, the first leaves to be infected systemically developed a mottle with some necrosis whereas leaves produced subsequently were symptomless but contained the virus. Most other species developed chlorotic or necrotic local lesions and systemic mottle or necrosis. This was followed, in several species, by production of small symptomless virus‐containing leaves. The virus was cultured in N. clevelandii; Chenopodium quinoa was used for local‐lesion assays. Leaf extracts from infected N. clevelandii were infective after dilution to 10–5 but usually not at 10–6, after heating for 10 min at 60°C but not at 65°C, and after storage at 20°C for at least 12 days. The virus has isometric particles of 26 nm diameter which sediment as three components, all containing a protein of mol. wt c. 53000. The two fastest sedimenting components respectively contain single‐stranded RNA of mol. wt, estimated after glyoxylation, c. 2.9 × 106 and 2.3 × 106. Both RNA species are needed for infection of plants. In tests with antiserum prepared to purified virus particles, the virus was detected in cassava and N. clevelandii by gel‐diffusion precipitin tests, by immunosorbent electron microscopy and by ELISA. Despite its similarity to nepoviruses, the virus did not react with antisera to 18 members of the group. It was named cassava green mottle virus and is considered to be a previously undescribed nepovirus.
Components of partial resistance as criteria for identifying resistance
Authors: GRIFFITHS HELEN M. , JONES D. GARETH
Published: February 2008

The components of partial resistance, incubation period, lesion area, latent period and sporulation were recorded on plants of six winter and two spring wheat cultivars which had been artificially inoculated with Septoria nodorum spores. Incubation period gave a guide as to how the cultivars would respond in the field to Septoria nodorum but statistical analysis showed that it could not be used alone to predict accurately the resistance of each cultivar to the pathogen. Average sporulation, however, could be used with more confidence for predicting the field resistance of the cultivars. From a regression analysis of NIAB rating versus incubation period, lesion area, latent period and sporulation, an equation was devised to obtain resistance indices for each cultivar. These resistance indices clearly reflected the NIAB ratings for the cultivars. It would therefore appear that resistance indices could be used as a pre‐field evaluation method for identifying resistance to Septoria nodorum and thus be a valuable technique in breeding programmes.
Propagation of lettuce (Lactuca sativa) breeding material by tissue culture
Authors: PINK D. A. C. , CARTER PHILIPPA J.
Published: February 2008

A tissue culture method using Murashige and Skoog's (MS) medium was devised to propagate healthy plants from field grown lettuce plants selected for seed production. Explants (2–3 mm long) from axillary buds were successfully grown on MS + 1.0 or 2.0 mg litre‐1 kinetin and 6.4 mg litre‐1 IAA to promote shoot growth. Concentrations of 0.5 and 4.0 mg litre‐1 kinetin gave poor shoot growth. The cultures were successfully rooted after 3–4 wk on MS + 6.4 mg litres‐1 IAA after transfer from MS + 1.0 mg litre‐1 kinetin and on MS + 4.8 mg litre‐1 IAA after transfer from MS + 2.0 mg litre‐1 kinetin. Concentrations of 3.2 and 8.0 mg litre‐1 IAA gave poor root initiation. Root initiation was more successful when cultures were grown at 40 Wm‐2 than in cultures grown at 5 Wm‐2. Rooted cultures were established in compost with a 90–95% success rate and the regenerated plants flowered c. 18 wk after the cultures were initiated.
Tiller development and flowering in swards of Bmchiaria decumbens
Authors: STUR W. W. , HUMPHREYS L. R.
Published: February 2008

Swards of Brachiaria decumbens were burnt and the development of tillers emerging 5 (T5) or 10 (T10) days later was studied. The stages of raceme initiation, spikelet initiation, spikelet differentiation and inflorescence exsertion occurred in 50% of tillers c. 14.5, 21, 26.5 and 59 days after tiller emergence respectively. Growth of T5 tillers was faster than that of T10 tillers, and raceme initiation occurred when T5 tillers were slightly longer and heavier than T10 tillers, making the external identification of early development events unreliable. Attention is directed to the large variability in the development of tillers emerging on the same day and to the need for better synchrony of raceme initiation as a basis for increased uniformity of inflorescence exsertion.
An inhibitor in faba bean sap suppressing infection of Chenopodium quinoa by bean yellow mosaic virus
Authors: GOVIER D. A. , WHITE JACQUELINE
Published: February 2008

An inhibitor in faba bean sap decreased the infectivity of bean yellow mosaic virus in undiluted sap to 0.2% of its potential infectivity calculated from diluted preparations.
Migration of alate morphs of the bird cherry aphid (Rhopalosiphum padi) and implications for the epidemiology of barley yellow dwarf virus
Authors: TATCHELL G. M. , PLUMB R. T. , CARTER N.
Published: February 2008

Suction trapping data indicate three periods of migration of Rhopalosiphum padi in spring, summer and autumn. Four alate morphs are present at different times during the year. A comparison of data from suction traps operating at 12·2 and 1·5 m suggests a different behaviour of females in autumn with more being recorded at 12·2 than 1·5 m. Males, which are only present in autumn, were also more numerous at 12·2 m. During tests to measure barley yellow dwarf virus (BYDV) infectivity, only 9% of female R. padi reproduced on oat seedlings in autumn compared with 74% in summer. Tests on alate female R. padi trapped alive showed that in summer all were exules, but during the first half of September these were largely replaced by gynoparae so that in autumn only 5% of all R. padi trapped at 12·2 m were alate exules. The aerial densities of gynoparae and males were 10 times greater at 12·2 than 1·5 m while densities of alate exules were similar at both heights. It is suggested that gynoparae and males fly higher to increase the chance of finding a taller dispersed host plant.

The implications for BYDV epidemiology of the behaviour and presence of the various R. padi alate morphs indicate that autumn‐sown cereals emerging before mid‐September are particularly at risk from colonisation by alate exules before the transition to a mainly sexual migrant population is complete. Alate exules introduce BYDV from comparatively local sources. The ratio of total R. padi to Sitobion avenae in suction trap samples in autumn usually exceeds 100: 1, but on crops it was only 10: 1. The ratio of alate exule R. padi to S. avenae in suction traps in autumn was only 12: 1, similar to that observed on crops.
Factors affecting the efficacy of methyl bromide fumigation to control Liriomyza trifolii in imported chrysanthemum cuttings
Authors: MORTIMER E. A. , POWELL D. F.
Published: February 2008

Laboratory investigations were made into the effect of cultivar type, prior cold storage, fumigation temperature and methyl bromide concentration, on the efficacy of a fumigation treatment to control Liriomyza trifolii in chrysanthemum cuttings. The tests related to the standard quarantine treatment used in the UK to control Spodoptera littoralis on imported chrysanthemum cuttings: cold storage for 2 days at 1 – 2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m3. L. trifolii larvae, within detached leaves, and 1 – 2 and 2 – 3 day old pupae, were treated. Methyl bromide concentrations of 6·75 or 13·5 g/m3 were used to achieve a range of CTPs and thus obtain accurate dose‐response lines and estimates of the LD99 and LD99·9 for each insect stage. Fumigation temperatures were 8, 11 or 15°C.

Efficacy of the standard treatments differed between the three cultivars tested, but the LD99 for larvae remained below 54 g h/m3. Decreasing fumigation temperature to 11°C or less increased LD99 values for larvae and pupae and substantially increased variability. There is therefore little scope for using fumigation temperatures of less than 15°C for quarantine purposes. Omitting the cold storage treatment prior to fumigation did not significantly affect efficacy of fumigation. Reducing the methyl bromide concentration from 13·5 to 6·75 g/m3 did not significantly affect the LD99 for larvae but significantly reduced LD99s for pupae.
The short‐term effects on birds and mammals of the use of chlorpyrifos to control leatherjackets in grassland
Authors: CLEMENTS R. O. , BALE J. S.
Published: February 2008

The impact on birds and mammals of treating two grass fields in Devon and Yorkshire with chlorpyrifos (Dursban 4*) to control leatherjackets was assessed. Both fields had leatherjacket populations in excess of 3 million/ha.

Samples of leatherjackets and earthworms were collected for chlorpyrifos residue analysis at intervals before and after spraying. Samples of leatherjackets and earthworms, were also obtained for residue analysis from a nearby unsprayed field, 7 and 10 days after the day on which the treated field was sprayed.

Observations of birds and mammals were made for 2 h at dawn and dusk, on two days before spraying and on six occasions afterwards. Several species of birds, many of which appeared to feed on leatherjackets brought to the surface by chlorpyrifos treatment, and three species of mammals were observed in the treated fields. Some of the bird species, e.g. magpie and carrion crow, together with hares were present frequently and it is probable that the fields were part of their feeding territories and that the same individuals were returning to feed at frequent intervals. At least some of the birds, e.g. starlings and carrion crows appeared to feed on leatherjackets. None showed any immediate sign of abnormal behaviour and the consistent reappearance of the territorial species during the study period suggests there were no longer‐term effects.

Thorough searches were made of the field, its hedgerows and ditches for dead birds and animals on seven occasions. None was found.
Dispersal of Rhynchosporium secalis conidia from infected barley leaves or straw by simulated rain
Authors: FITT B. D. L. , McCARTNEY H. A. , CREIGHTON N. F. , WALKLATE M. E. LACEYP. J.
Published: February 2008

Simulated rain (mean drop diameter c. 1 or 3 mm) was allowed to fall for 10 – 15 min on to barley leaves or straw infected by Rhynchosporium secalis (leaf blotch). The leaves were supported on a mesh through which run‐off water drained and the straw was supported on a rigid surface on which run‐off water collected. The numbers of R. secalis conidia and spore‐carrying splash droplets collected by horizontal samplers (microscope slides and pieces of photographic film) decreased rapidly with increasing distance from and increasing height above the sources, with half‐distances of 2 – 10 cm. Less than 10% of the spores or droplets reached heights of more than 30 cm. Incident drops 3 mm in diameter produced more spore‐carrying droplets and dispersed more conidia than did 1 mm drops. The size category of splash droplets with the greatest proportion of the spore‐carrying droplets dispersed by 3 mm drops was 200 – 400 μm, whether the source was infected barley leaves or barley straw. For leaves or straw the greatest proportions of spores were carried in droplets > 1000 μm in diameter. The mean diameter of spore‐carrying droplets (478 μm) dispersed from free‐draining leaves was less than that of droplets from straw plus run‐off water (563 μm). However, the leaf source had more spores cm‐2 and the mean number of spores per droplet was greater (113 as opposed to 6·8) than for the straw source.
Confirmation of the transmission of barley yellow mosaic virus (BaYMV) by the fungus Polymyxa graminis
Authors: ADAMS M. J. , SWABY A. G. , JONES P.
Published: February 2008

Resting spores (cystosori) of Polymyxa graminis, selected from roots of barley plants infected with barley yellow mosaic virus (BaYMV), were used to start mono‐fungal sand cultures. Out of 20 attempts using over 800 cystosori, P. graminis became established in 12, and in two of these BaYMV symptoms also occurred.

BaYMV was detected by ELISA in extracts of dried roots heavily infected with cystosori and in zoospores of P. graminis. Calculations suggested that, on average, each zoospore carried less than 100 virus particles.

In two virus acquisition experiments, non‐viruliferous isolates of P. graminis failed to acquire BaYMV from roots of mechanically‐inoculated plants. In two further experiments, non‐viruliferous isolates were grown on rooted tillers produced from healthy plants and those infected with BaYMV by either vector or mechanical inoculation. Zoospores and cystosori of P. graminis subsequently transmitted the virus, but only from plants where it had been introduced by the vector. Repeated mechanical transmission appeared to have selected a strain of virus that could not be acquired and/or transmitted by the vector.

The results provide convincing evidence that P. graminis is a vector of BaYMV but suggest that, in natural populations, only a small proportion of spores may be viruliferous.
Quantitative methods for detecting invertebrate predation occurring in the field
Authors: SUNDERLAND K. D.
Published: February 2008

Brief descriptions are given of methods that can be used either to determine the mortality caused by a complex of predators to a single target prey species or to quantify the diet of a single target predator species.

The following methods can be used quantitatively; direct observation, field caging, recovery of labelled prey, electrophoresis, single radial immunodiffusion, rocket immunoelectrophoresis, enzyme‐linked immunosorbent assay.

The following methods have potential for quantitative use; faecal analysis, gut dissection, tube precipitin test, ring test, Oakley‐Fulthorpe test, crossed immunoelectrophoresis, crossover immunoelectrophoresis, fluorescence immunoassays.

The following tests are likely to remain qualitative; chromatography, double‐diffusion, immunofixation, standard immunoelectrophoresis, latex agglutination, passive haemagglutination inhibition assay, complement fixation test.

Examples are given of the use of these tests in predation studies.

Precautions associated with the use of these methods are described.

Various equations are reviewed for estimating predation rates using data on predator density, proportion positive and detection period in post‐mortem tests.

There are limitations to the use of all current methods. Direct observation and field caging are of restricted application and often involve disturbance to the system being studied. Faecal analysis and post‐mortem methods can confuse scavenging and secondary consumption with predation and they measure biomass ingested rather than number of prey killed or injured. Recovery of labelled prey has the faults of all these methods.

Potential new techniques are described for determining, from an examination of its gut contents, what a predator has eaten, when it ate it and in what quantity.
The relationship between the Andean strain of potato virus S and pepino latent virus
Authors: DOLBY CHRISTINE A. , JONES R. A. C.
Published: February 2008

The titres obtained in microprecipitin tests with purified preparations of pepino latent virus (PepLV) and the Andean strain of potato virus S (PVSA) using PepLV antiserum and two antisera to the ordinary strain of PVS (PVS°) indicated a close serological relationship between PepLV and PVSA. Using antiserum to PVS°, both viruses were detected by ELISA when infective Chenopodium quinoa sap was diluted to 10‐5but not to 10‐6. Particles of both viruses were decorated equally well by antibodies to PVSo, PVSAand PepLV in all virus‐antiserum combinations. When PepLV was inoculated to C. quinoa, C. amaranticolor and potato plants, the symptoms induced closely resembled those of PVSAin these hosts. It is concluded that PepLV is an isolate of PVSAfrom pepino.