bluuebunny/crossref_metadata_2025 huggingface dataset:
Alate aphid (Homoptera: Aphididae) species and their relative importance as field vectors of soybean mosaic virus
Authors: HALBERT SUSAN E. , IRWIN MICHAEL E. , GOODMAN ROBERT M.
Published: February 2008

A technique was developed and deployed in central Illinois to trap and assay aphid alatae for incidence of soybean mosaic virus (SMV) transmission among naturally occurring transient aphid populations downwind of a field of infected soybean. In a 2‐yr study, 1709 alate aphids were trapped alive and assayed, 4.2% of which transmitted SMV. Five species of aphids accounted for more than 93% of the transmissions: Aphis craccivora Koch, Macrosiphum euphorbiae (Thomas), Myzus persicae (Sulzer), Rhopalosiphum maidis (Fitch), and Rhopalosiphum padi (L.). At least 55 additional species were assayed, five of which transmitted only once. Others did not transmit. Because virus infection during the early growth stages of soybean increases the loss of yield and the percentage of seed‐borne virus, vector species that tend to fly middle to late spring are, from an economic point of view, more important in the spread of SMV. R. maidis flew in mid‐ to late summer and in autumn. R. padi was not abundant at any time of year and its transmission efficiency was low. M. persicae tended to fly in mid summer. Two species (A. craccivora and M. euphorbiae) which had major flights in late spring and early summer and relatively high transmission efficiencies are potentially important in the economic spread of SMV in central Illinois. A third species, Aphis citricola Van der Goot, may also be important because it flies in late spring and laboratory data suggest it is a relatively efficient vector of SMV. A. citricola was not assayed by our technique because we trapped in the morning and this species appears to fly later in the day.
Phenological and geographical relationships between catches of pea moth in sex‐attractant traps
Authors: PERRY J. N. , MACAULAY E. D. M. , EMMETT B. J.
Published: February 2008

Traps containing a sex attractant of the pea moth (Cydia nigricana) were used to monitor numbers of male moths in individual fields in south‐eastern and eastern England from 1976 to 1978 at 16 or more sites/yr. Data concerning catches at different sites on several occasions over the flight season, and dates on which a ‘threshold catch’ was achieved were examined, and were related weakly to site locations within areas. Area spray warnings, based on trap catches at a few sites within a large area, provide a less reliable indication of the need to spray than on‐site monitoring (two traps) in each pea field. On‐site monitoring may be improved by specialist interpretation of trap catches.
Effects of Didymella applanata and Botrytis cinerea on axillary buds, lateral shoots and yield of red raspberry
Authors: WILLIAMSON B. , HARGREAVES A. J.
Published: February 2008

The viability of axillary buds and the growth and potential yield of lateral shoots at nodes of red raspberry (Rubus idaeus) infected naturally by Didymella applanata or Botrytis cinerea were measured on excised nodes, decapitated nursery canes or on canes from fruiting plantations. In comparison with lesion‐free nodes, buds at infected nodes were smaller and fewer of them were capable of growth when excised and ‘forced’, although the difference in growth between infected and uninfected nodes decreased during late winter. After February, those buds at infected nodes which were capable of forced growth did so as early and with a similar growth rate as those at lesion‐free nodes. In April, 70% of buds at infected nodes were capable of growth compared with 94% of those at lesion‐free nodes.

When nursery canes of cv. Mailing Delight were decapitated above infected nodes the emergence of lateral shoots from the terminal infected node did not differ significantly from that at lesion‐free nodes. On a range of farm sites in Scotland the emergence of shoots at infected nodes in the cropping region of canes was significantly poorer than from uninfected nodes but substantially better at infected nodes of cv. Glen Clova than at those of cvs Mailing Jewel and Mailing Orion. It is suggested that cv. Glen Clova is relatively tolerant of spur blight and cane botrytis. The length and potential yield of laterals which developed at infected nodes in the cropping region of canes in these three cultivars did not differ significantly from those at lesion‐free nodes. In all tests there was no significant difference in growth at nodes infected by D. applanata and B. cinerea which may indicate a common mechanism for suppression of buds.
The prevalence of viruses of honey bees in Britain
Authors: BAILEY L. , BALL BRENDA V. , PERRY J. N.
Published: February 2008

Adult individuals of honey bee colonies in Britain are commonly infected with several small RNA viruses. Black queen cell virus and bee virus Y are the commonest and occur most frequently about June, together with Nosema apis with which both viruses are intimately but independently associated. Bee virus X is less common than bee virus Y and showed no pronounced seasonal fluctuations in local surveys, but was detected mostly in winter and early spring. Sacbrood virus occurred in adults of most local colonies in summer, chronic paralysis virus and cloudy wing particle occurred commonly but without seasonal variations and acute paralysis occurred commonly throughout the active season of bees but does not multiply sufficiently to cause overt disease. Slow paralysis virus was rare.
The role of Anthocoris species (Hemiptera: Anthocoridae) in the integrated control of the damson‐hop aphid (Phorodon humuli)
Authors: AVELING C.
Published: February 2008

Field studies in 1974, 1975 and 1976 investigated integrated control of the damson‐hop aphid Phorodon humuli on hops. After the aphicidal effects of an early‐season soil drench of mephosfolan had declined, natural enemies controlled the aphids for the remainder of the season. Anthocorid bugs, particularly Anthocoris nemoralis, were the most abundant predators. In each year a rapid decline in aphid numbers occurred in mid‐ to late‐July, coinciding with the peak numbers of fourth and fifth instar larvae and adults, the most voracious anthocorid stages. Aphids in the cones remained under control for the rest of the season in 1974 and 1975, and increased in 1976 but damaging numbers did not develop. When predators were excluded by caging mephosfolan‐treated bines, high aphid densities developed on the leaves, and the cones were heavily infested. Plants not treated with an insecticide were almost completely defoliated by late‐July. Heavily infested ‘missed bines’, due to uneven uptake of mephosfolan, attracted large numbers of anthocorids, which later dispersed into the surrounding plants.
Action of mephosfolan on anthocorid predators of Phorodon humuli
Authors: AVELING C.
Published: February 2008

In glasshouse and field studies, soil drenches of the systemic insecticide mephosfolan were applied to hop plants to control the aphid Phorodon humuli, and to study the toxicity to anthocorid predators. The mortality of Anthocoris nemorum and A. nemoralis eggs in the leaf tissues increased with the dosage of mephosfolan while A. confusus eggs, which were laid in the petioles and veins, appeared to be unaffected at the dosages used, up to 2 g a.i./plant. Mortality of A. nemorum eggs, which were laid mainly in the leaf margins, was higher than in A. nemoralis eggs, which were laid mainly in the interveinal areas. For both species mortality was highest for the eggs laid in the leaf margins, and susceptibilities appeared similar. It is suggested that mephosfolan becomes unevenly distributed within the leaves, being most concentrated in the leaf margins and least concentrated in the veins and petioles. No species showed any preference when offered mephosfolan‐treated and untreated leaves for oviposition, and the oviposition rates were unaffected by various mephosfolan dosages. Oviposition rates, larval mortality and duration of larval development were unaffected when specimens of each species were reared from eclosion to maturity on a diet of either mephosfolan‐killed or heat‐killed P. humuli.
The effect of sprays of thiophanate–methyl on cane diseases and yield in red raspberry, with particular reference to cane blight (Leptosphaeria coniothyrium)
Authors: WILLIAMSON B. , HARGREAVES A. J.
Published: February 2008

Spur blight (Didymella applanata), cane botrytis (Botrytis cinerea) and cane blight (Leptosphaeria coniothyrium) were studied in two consecutive seasons in unsprayed raspberries and in plots sprayed with thiophanate‐methyl in the first season alone, (a) twice pre‐harvest, (b) twice post‐harvest, or (c) twice pre‐ plus twice post‐harvest. Pre‐harvest, but not post‐harvest sprays, gave moderate control of both spur blight and cane botrytis; both diseases occurred mainly on the lower halves of canes, the latter being the less common.

Cane blight occurred at the base of canes where they were wounded by old cane stubs. In the first year it was severe; 37% of canes died before harvest in the unsprayed plots. The three spray programmes all decreased cane death due to cane blight and they all increased yield by c. 45% even in those plots sprayed post‐harvest where spur blight was severe and not controlled. Clearly this last disease, despite its high incidence, had no effect on potential yield in this experiment. In the second year cane blight was common but less severe and the incidence of its lesions was reduced similarly by all programmes, but only 4% of canes died in control plots.

Analysis of the potential yield and the sizes of lesions caused by L. coniothyrium in canes inoculated at fortnightly intervals in the previous year showed that potential yield loss occurred only when lesions girdled canes. A bimodal distribution in the lesion sizes, measured by length or girdling, indicated some endogenous control of lesion development which might explain the marked differences in the effect of cane blight on potential yield in two seasons.
The effect of pH on host plant ‘preference’ for strains of Rhizobium trifolii using fluorescent ELIS A for strain identification
Authors: JONES D. GARETH , MORLEY SUSAN J.
Published: February 2008

The effect of pH on host plant ‘preference’ for strains of R. trifolii was studied using the fluorescent ELISA technique. Four white clover cultivars were compared growing at pH 5, 6 and 7 inoculated with 1:1 mixtures of two strains of R. trifolii, CP3B and R4. The growth of these two bacterial strains was also studied at the same pH levels in pure culture. At pH 5, in pure culture, CP3B grew very well but R4 failed to reach the log phase. CP3B also produced the majority of nodules at this pH (86%). At pH 7, in pure culture, R4 grew better than CP3B and also produced 66% of the nodules in the nodulation experiment. However, there was good evidence of host cultivar ‘preference’ with cv. Milkanova having no nodules inhabited by CP3B at pH 7 but cv. S100 having 32%.

The results are discussed from the point of view of the establishment of white clover in acid soils and the usefulness of the fluorescent ELISA technique for Rhizobium strain identification is also emphasised.
Purification of carrot red leaf virus and evidence from four serological tests for its relationship to luteoviruses
Authors: WATERHOUSE P. M. , MURANT A. F.
Published: February 2008

Carrot red leaf virus (CRLV) was purified from infected chervil by centrifuging whole plant extracts at low speed and incubating the resuspended pellets with Driselase; the digest was then treated with 1% (v/v) Triton X‐100 and the virus concentrated by centrifugation twice at high speed through a layer of 20% sucrose. The preparations (about 1 μg virus/g tissue) contained isometric particles c. 25 nm in diameter which formed a single u.v.‐absorbing component in sucrose density gradients. Chervil seedlings exposed to aphids (Cavariella aegopodii) that had been injected with or had fed on fractions from the u.v.‐absorbing zone developed typical symptoms of infection with CRLV. CRLV particles had a sedimentation coefficient (s20,w) of 104 S, buoyant density in CsCl of 1.403 g/cm3 and A260/A280 of 1.62. Antiserum with a gel‐diffusion titre of 1/512 was obtained from a rabbit injected intradermally with 100 μg purified virus. CRLV was detected by immunosorbent electron microscopy and enzyme‐linked immunosorbent assay in extracts of the petioles and leaf midribs of infected chervil and in groups of five to 20 viruliferous C. aegopodii.

Analysis of antiserum/virus reactions by density gradient centrifugation showed that CRLV is distantly related to all luteoviruses tested; its relationships were closest to barley yellow dwarf virus (RPV strain), and perhaps also to beet western yellows virus, more distant to tobacco necrotic dwarf, potato leafroll and bean leafroll viruses, and very distant to barley yellow dwarf (MAV strain) and soybean dwarf viruses. Some of these relationships were detected by double diffusion in agarose gels and by electron microscopy of antiserum/virus mixtures. Immunosorbent electron microscopy detected all these relationships but suggested that CRLV was more closely related to tobacco necrotic dwarf and potato leafroll viruses than to barley yellow dwarf virus (RPV strain).

The results show that CRLV should be considered a definitive member of the luteovirus group, and provide confirmation of recent evidence that potato leafroll virus is a luteovirus.
A study of sugar beet growers' pest control decisions
Authors: MUMFORD J. D.
Published: February 2008

The results of a survey of sugar beet growers are reported which provide subjective information on farmer perceptions of the hazard from pests and diseases on sugar beet, the control methods available and used, farmers' estimates of the costs and effect of controls, their objectives for pest control, and their attitudes to advice. In addition, objective information from research and field observations on losses and control methods is provided. The basis of pest control decisions and implications from comparisons of subjective and objective perceptions of the various problems and solutions are discussed.
A solution culture method for observing the development of clubroot symptoms on young brassica plants
Authors: CRUTE I. R. , BUCZACKI S. T. , STEVENSON KAREN
Published: February 2008

A method which allows the sequential observation of gall development on young brassica plants following infection by Plasmodiophora brassicae is described. Plants were grown under controlled conditions in solution culture contained in specimen tubes and their development and subsequent symptom production closely paralleled that in a soil/peat mixture. The method should prove useful for studying the biology of the disease.
Methods for inoculating field crops with mycorrhizal fungi
Authors: HAYMAN D. S. , MORRIS E. J. , PAGE R. J.
Published: February 2008

Four methods were compared for inoculating red clover with selected mycorrhizal fungi when sown in a field containing an indigenous mycorrhizal population. The largest amount of mycorrhizal infection (around 65% of root length infected) was obtained by placing inoculum with the seeds in furrows. The inoculum used was standard soil inoculum from stock plant cultures spread by hand or the same inoculum concentrated to about one seventh by wet‐sieving, and then fluid‐drilled. The effectiveness of multiseeded pellets (seeds stuck onto pellets of soil inoculum) applied broadcast was more variable, infection ranging widely around an average of 30%. Applying both soil inoculum and seeds broadcast produced just under 10% infection, similar to that in the controls given autoclaved inoculum. Seedling establishment, in contrast, was‐better where seeds were applied broadcast than in furrows. It seemed therefore that multiseeded pellets might be the best compromise for achieving reasonable infection in most plants, but fluid drilling had the advantages of greatly reducing the amount of inoculum needed and of readily combining seeds and inoculum in a single carrier.
Growth and nutrition of mycorrhizal guayule plants*
Authors: BLOSS H. E. , PFEIFFER C. M.
Published: February 2008

Synthesis of mycorrhiza in guayule plants was achieved by inoculation of 8‐day‐old seedlings with hyphae and chlamydospores of an undescribed Glomus species. There was a five‐fold increase in total dry weight of 30‐day‐old mycorrhizal‐ compared to nonmycorrhizal‐guayule grown in sterile loamy‐sand without additional fertiliser. Thirty‐day‐old, inoculated‐ and uninoculated‐seedlings were transplanted to sterile or unsterile soil and grown an additional 60 days. The greatest total dry weight of guayule was attained by inoculated transplants grown in sterile soil. Inoculated transplants increased two‐ to three‐fold in total dry weight compared to uninoculated transplants, both grown in unsterile soil. After 90 days, uninoculated plants grown in unsterile soil had formed mycorrhizae with resident vesicular‐arbuscular mycorrhizal fungi to the same extent as inoculated‐plants grown in unsterile soil. Total mineral uptake increased in inoculated guayule, irrespective of soil treatment or the presence of resident VA mycorrhizal fungi.
Multiplication of the agent of X‐disease in a non‐vector leafhopper Macrostelesfascifrons
Authors: PURCELL BY ALEXANDER H. , RICHARDSON JEAN , FINLAY ALLAN
Published: February 2008

The relative titre of the causal agent of X‐disease of stone fruits in the non‐vector leafhopper Macrosteles fascifrons was tested by injecting dilutions of M. fascifrons extracts into non‐infective Colladonus montanus leafhopper vectors. The recipient C. montanus were fed on celery test plants which were then observed for X‐disease symptoms. M. fascifrons were assayed at various intervals for up to 37 days after they were fed on X‐diseased celery or injected with infectious extracts of the X‐agent. Infectivity was detected in M. fascifrons only after 25 or 37 days in separate trials. Whole body extracts but not extracts from detached heads of M. fascifrons that had fed on X‐diseased celery were infectious, whereas extracts prepared from the heads of M. fascifrons previously injected with X‐agent extracts were infectious. This infectivity was retained for up to four serial passages in M. fascifrons.

Electron microscopy of M. fascifrons that had been injected with extracts of the X‐disease agent revealed mycoplasma‐like organisms (MLO) only intercellularly and appressed to various organs in the haemocoele. No MLO were observed in uninjected M. fascifrons or those injected with extracts from non‐infectious C. montanus. These results suggest that, despite multiplication of the X‐agent in vivo. barriers in the gut and salivary glands prevent its transmission to plants by M. fascifrons.
The invasion of root tips of cereals by the cereal cyst nematode Heterodera avenue
Authors: PRICE N. S. , HAGUE N. G. M.
Published: February 2008

Newly germinated seedlings of susceptible cultivars of oats, wheat, barley and rye were inoculated with second‐stage juveniles of Heterodera avenae in pots of sand. Subsequent examination showed oat root tips to be more commonly invaded, and by a greater range of nematode numbers than the other cereals.

A comparison of oats and barley showed that lower nematode numbers in barley were not due to a higher emigration from barley; invasion, establishment and emigration by nematodes all being greater in oats. Second‐stage juveniles were more likely to migrate prior to establishment in barley than in oats.
Effects of water shortage on the yield of winter wheat
Authors: GALES K. , WILSON N. J.
Published: February 2008

The effects of water shortage on the yield of winter wheat (cv. Maris Huntsman) were investigated in covered field plots on silt‐loam soil. Plants were subjected to drought at different stages of growth, but none of the treatments significantly decreased yield. Some treatments decreased the number of ears per unit area, and number of grains per ear, but these effects were offset by increases in individual grain weight.

We estimate that the soil water deficit (151 mm) in the treatment which had the largest effect on yield, albeit non‐significant, would be expected in nature about 15 years in 100 or less.

Drought also had little effect on plant water potential and stomatal conductance. The lack of effect of drought on plant water status and yield may be attributable to the large available water content of the silt loam and the deep rooting of winter wheat.

On this type of soil, therefore, water shortage appears not to be an important cause of variation in the yield of winter wheat.
Inter‐plant variation in temperate crops of maize
Authors: BREEZE V. G. , MILBOURN G. M.
Published: February 2008

Maize grown at northern latitudes suffers from variation in the yield from individual plants, as well as uneven uniformity in the stage of maturity. The contributions of genotype, environment and some seed characteristics to phenotypic variation of weight and stage of development were studied in maize from experiments that included treatments of sowing date, density and planting arrangement, and which used hybrids with differing uniformity of genotype. It was not possible to divide the variation simply into genotypic or environmental components, and the performance of varieties was inconsistent.

Single cross material was only slightly more uniform than a double cross variety Using large sized seed led to 1–2 days earlier silking but to little effect on final yields. The size of plants was not influenced by the size of neighbouring plants along the row and spacing in a square arrangement only had a small effect on improving uniformity of plants. More variation occurred at a high density planting.

Inter‐plant variation appeared to occur either in dry weight or in the stages of development, but also there was an association between the two, e.g. the largest plants tended to be the most advanced. There was a tendency for the first emerged plants to silk first and to produce the highest grain yield (although this was not consistent in the double cross INRA 200). The first plants to silk in a crop were up to 7 days earlier than the average at harvest and yielded double the grain weight.

As reliability of harvest limits the acceptance of grain maize in north‐west Europe, it is suggested that one method that could improve the uniformity in stage of maturing, without seriously reducing final grain yield, is to use a somewhat lower planting density (6 plants/m2 for grain) than has hitherto been recommended.
Grass scorch due to pot ale
Authors: NAYLOR ROBERT E. L. , SHORTREED K.
Published: February 2008

Grass scorch sometimes occurs when pot ale, a waste product of malt whisky distilling, is used as a liquid fertiliser. Experiments performed on grass turves show that a high concentration of solids in the pot ale, and a large amount of foliage on the sward result in higher amounts of scorch, as determined by visual assessment. Sward yield is independent of the amount of leaf scorch but appears to be linked to the proportion of dead tillers or plants in the sward. It is suggested that leaf scorch itself does not limit yield, but if the scorching compound runs off foliage and acts against roots then tiller or plant death may occur, accompanied by a yield loss. This interpretation may help to explain some conflicting evidence on scorch effects in the literature.
Black tea manufacture.
Authors: HARRIS N. , ELLIS R. T.
Published: February 2008

A comparison of the structure of the leaf manufactured by different processing systems has been made by transmission and scanning electron microscopy. A single harvest of clonal leaf was divided into batches and commercially manufactured by Orthodox, Rotorvane only, Rotorvane combined with Cutting, Tearing and Curling and the Lowrie Tea Processor methods. The different manufactures produced leaf with characteristically different damage patterns. The relationship of the different forms of damage to the qualities of made tea is discussed.
Insecticidal phytotoxicity and cereal grain yield
Authors: MCKINLAY R. G.
Published: February 2008

A simple statistical procedure has been derived from field experimental data on insecticidal seed coatings for control of wheat bulb fly larvae to measure the direct effect of the insecticides on the yield of wheat.
Brown spot disease of citrus caused byPhaeoisariopsissp.
Authors: EMECHEBE A. M.
Published: February 2008

Brown spot disease ofCitrusspp. was shown to be caused byPhaeoisariopsissp. It severely affects all varieties of sweet orange, tangerine, grapefruit, lime and rough lemon, smooth lemon being relatively resistant. Fruits and leaves are much more susceptible than stems on which symptoms are rare. On the young fruit circular, slightly sunken, brown necrotic lesions are often associated with a surrounding ring of raised epicarp, giving the fruit a blistered appearance. Lesions on older fruits are usually flat and brown and surrounded by yellow haloes. Premature abscission, especially of young fruits, is common. Leaf symptoms start as greenish yellow patches and a fully formed leaf spot consists of light brown or greyish centre which is surrounded by a dark brown margin bordered by a yellow halo. Generalised foliar chlorosis, caused by coalescence of several lesions, culminates in premature defoliation. During wet weather, centres of both fruit and foliar lesions sporulate and become black. Stem lesions, dark brown and mostly occurring as extensions of petiole lesions, may coalesce causing stem die‐back or resulting in the formation of corky internodal lesions.

In artificial culture, the fungus sporulated only on media containing an extract of citrus leaf or fruit peel. The characteristics of the fungus mostly based on examination of structures formed on naturally infected parts of the plant, are described. This is probably the first report of aPhaeoisariopsissp. on citrus.
Properties of Scottish isolates of cocksfoot mild mosaic virus and their comparison with others
Authors: TORRANCE LESLEY , HARRISON B. D.
Published: February 2008

Two isolates of cocksfoot mild mosaic virus obtained from cocksfoot (Dactylis glomerata) in Scotland differed in symptomatology, and apparently in host range, from isolates obtained in Germany and Wales. They were serologically more closely related to a Dutch isolate from cocksfoot, and to a Scottish isolate from timothy (Phleum pratense), than was the German isolate from cocksfoot. The Scottish isolate from timothy was somewhat more virulent than, but serologically closely related to a Welsh isolate from timothy.

Particles of Scottish isolates from cocksfoot and timothy were best preserved for electron microscopy by fixation with osmium tetroxide. In 1.0 m KCl or 0.01 m ethylene diamine tetraacetate they were stable at pH 5.2–5.3 but unstable above pH 7; they were disrupted by 0.5% sodium dodecyl sulphate. The particles contained major and minor RNA components of mol. wt c. 1.5. 106(RNA‐1) and 0.5. 106(RNA‐2) respectively, together with polydisperse RNA of intermediate mol. wt and protein of mol. wt c. 27 000. In CsCl gradients, major and minor nucleoprotein components of density 1.39 and 1.38 g/ml respectively were distinguished. The less dense particles contained a larger proportion of intermediate‐sized RNA molecules and of RNA‐2, and a smaller proportion of RNA‐1, than did the denser particles. Particles seem to contain either RNA‐1 or various combinations of smaller RNA molecules.

Despite the differences in antigenic constitution, symptomatology and particle stability between virus isolates obtained from cocksfoot and timothy in different countries, these isolates seem sufficiently similar to be considered one virus.
Techniques for distributing non‐fumigant nematicides in soil to control potato cyst‐nematodes, Globodera rostochiensis and G. pallida
Authors: WHITEHEAD A. G. , TITE D. J. , BROMILOW R. H.
Published: February 2008

Potato cyst‐nematodes can be controlled and potato yields increased by applying aldicarb or oxamyl in vertical bands 12.5 or 25 cm apart in the top 15 cm of infested soil and incorporating it by rotary harrowing. This new ‘Vertical Band‐Roterra’ technique spreads the nematicides almost as uniformly in the soil as does spreading them on the soil surface and incorporating them by rotary cultivation, and gives equally effective nematode control. It is also faster, does not mix weathered with unweathered soil and does not smear the soil. The nematicide, or any other substance requiring incorporation in the top 15 cm of the soil, can be applied in either granule or liquid form by the new technique. Merely spreading the nematicide on the soil surface and incorporating it by rotary harrowing leaves most of the substance in the top 5 cm of the soil, lessening nematode control. Spreading the nematicide on the soil surface and in horizontal layers 5 and 10 cm deep, followed by rotary harrowing, controls the nematodes as well as does the rotary cultivation method, but is inconvenient.
Aspects of the laboratory production of mushroom phorid flies (Megaselia halterata) parasitised by the nematode Howardula husseyi
Authors: RICHARDSON P. N. , CHANTER D. O.
Published: February 2008

Economic mass‐production of mushroom phorids parasitised by Howardula husseyi is essential if the release of parasitised Megaselia halterata on farms is to become a practicable alternative to insecticidal control of the pest. The effects on parasite incidence in the succeeding fly generation of two methods of spawning mushroom compost, and of three initial levels of parasitism (numbers of parasitised parental flies), were studied in the laboratory. In emerging flies percentage parasitism, and mean number of adult parasites per fly, were significantly affected by the original number of parasitised females. Estimates showed that for every 10 additional parasitised parental flies there was an increase of 0.166 adult parasites per fly in the next generation. ‘Top spawning’ resulted in a significantly higher percentage parasitism than ‘through spawning’. Emerging female progeny were significantly more highly parasitised than males. Statistical models, used to assess the ability of H. husseyi infectives to parasitise M. halterata larvae in compost, indicated that even at very high host densities > 20% of the potential parasites successfully invaded a phorid larva. The results suggest that unless an in vitro method of rearing H. husseyi can be developed the nematode will not be of practical use in phorid control.
The effect of introducing aphid‐pathogenic Entomophthoraceae into field populations of Aphis fabae
Authors: WILDING BY N.
Published: February 2008

During two warm, dry seasons (1975 and 1976) aphid‐pathogenic species of Entomophthoraceae introduced into Aphis fabae populations on field beans established briefly but failed to spread. In cool moist seasons (1977 and 1978), the fungi, principally Erynia neoaphidis and Neozygites fresenii, spread more rapidly in treated than untreated plots. In 1977, the maximum aphid population in plots treated with fungi reached a mean of 9000/plant on 19 July compared with 16 000/plant 1 wk later in untreated plots. The corresponding yield of beans in treated plots was twice that in untreated plots though only half that in plots kept free of aphids with pirimicarb. In two experiments in 1978, the maximum aphid population in treated areas was 700/plant, half that in untreated areas and 1 to 2 wk earlier. Yields from treated plots, however, were not significantly different from those from untreated plots. In nature, the fungi attack A. fabae populations in England only after they have become damaging, partly because fungal inoculum is sparse when the aphid population is small.
Lindane‐resistant strains of the leather beetle Dermestes maculatus in the United Kingdom
Authors: BINNS T. J. , PEMBERTON G. W.
Published: February 2008

Adult Dermestes maculatus were tested for resistance by exposing them to films of lindane in oil on filter papers. Insects which survived a discriminating dose, designed to knock down 100% of susceptible insects, were classed as resistant. Of 42 strains intercepted on imports or collected from infested poultry houses, 34 were found to be resistant when first tested. The F1 progeny of survivors from 19 of these resistant strains were also exposed to the discriminating dose. Significant increases in survival confirmed the presence of resistance in 18 strains.
Effects of vernalisation and aphid culture history on the relative susceptibilities of wheat cultivars to aphids
Authors: KAY D. J. , WRATTEN S. D. , STOKES SUZANNE
Published: February 2008

The weight and embryo number of adults of the cereal aphid Metopolophium dirhodum were compared on vernalised and unvernalised seedlings of six winter wheat cultivars. Aphids were smaller when reared on vernalised plants and contained fewer embryos than those reared on unvernalised material. Resistance rankings of the cultivars also changed markedly; cultivars at the extremes of the resistance sequence when vernalised were not separable statistically when unvernalised. When Sitobion avenae was tested on five of the six unvernalised cultivars, results agreed with earlier work on this species but the ranking differed from that for M. dirhodum. The plant species on which the test aphid's parent had been reared markedly affected the level of resistance and this and the vernalisation effects are discussed in relation to earlier work on aphid resistance in cereals.
The tolerance of black currant flowers to induced frosts
Authors: DALE A.
Published: February 2008

Flower buds on potted plants of 17 varieties of black currant were frosted to ‐3.3, ‐4.5 and ‐5.2 °C between the grape stage and full flower in 1979 and 1980. In all varieties more flower buds died after the ‐5.2 °C frosts and at full flower, and less after the ‐3.3 °C frosts and at the grape stage. Varieties related to Ben More and Ojebyn tolerated the ‐4.5 °C frosts until after first flower while Baldwin and Magnus became susceptible at the grape stage. Seabrooks Black, Greens Black and Ben Lomond and its relatives were intermediate. In both years flower buds tolerated frosts to similar growth stages but in 1980 the varieties flowered about 2 wk earlier than in 1979 and suffered more frost damage at full flower. The frosted plants had slightly larger fruits than the unfrosted ones in 1979. The immature fruit drop was similar in frosted and unfrosted plants in both years except when it was increased after ‐5.2 °C in 1980. It is pointed out that for reliable cropping, varieties should flower late as well as tolerate spring frosts and that tests of frost tolerance should be done for at least three growth stages.
A new strain of the rust fungus Puccinia chondrillina for biological control of skeleton weed in Australia
Authors: HASAN BY S.
Published: February 2008

A strain of the rust fungus Puccinia chondrillina introduced into Australia in 1971 for the biological control of skeleton weed, Chondrilla juncea, attacked only the narrow‐leaf form of this weed. Studies were, therefore, undertaken in the Mediterranean region to discover strains of the rust which will attack the other two Australian forms of skeleton weed, intermediate‐ and broad‐leaf. Several strains of the rust were found to be highly virulent against the intermediate form. One of these strains from Manisa, western Turkey, was both highly specific to its host and safe for use as a biological control agent. This strain has recently been introduced into Australia for the control of the intermediate form of Chondrilla.
Isolation of corn stunt spiroplasma in Jamaica, and probable dual infection with maize mosaic virus
Authors: EDEN‐GREEN BY S. J. , WATERS HENRY
Published: February 2008

Spiroplasma isolated from naturally diseased corn (Zea mays) plants in Jamaica, produced symptoms typical of the Rio Grande strain of corn stunt spiroplasma (CSS) following experimental transmission to corn by Dalbulus maidis. Isolates were serologically closely related to a reference culture of CSS. Bacilliibrm virus‐like particles associated with a related disease condition were transmitted experimentally to a small proportion of plants by D. maidis. Both virus‐like particles and CSS were detected in one experimentally infected plant, suggesting that this leafhopper could acquire both agents and transmit then simultaneously to corn.
Chemical suppression of virus in cultured plant tissues
Authors: SIMPKINS I. , WALKEY D. G. A. , NEELY HEATHER A.
Published: February 2008

The concentrations of cucumber mosaic (CMV) and alfalfa mosaic viruses, present in various types of cultured plant tissues, were significantly less when ribavirin (syn. Virazole) at 50 or 100 mg/litre was present in the culture medium. CMV concentrations decreased within 24 days in infected cultures treated with ribabirin, but incubation periods of up to 127 days were required before the virus was undetectable. However, virus‐free cultures were obtained from CMV‐infected meristem‐tips irrespective of the presence or absence of ribavirin. Kinetin at concentrations up to 25.6 mg/litre had no persistent antiviral effect.
A Neoaplectanid nematode in the larch sawfly Cephalcia lariciphila (Hymenoptera: Pamphiliidae)
Authors: GEORGIS R. , HAGUE N. G. M.
Published: February 2008

A nematode parasitic on prepupae of larch sawfly (Cephalcia lariciphila) appears to be indistinguishable from Neoaplectana carpocapsae. Of three temperatures tested the optimum for development was 25 °C at which most eggs were produced in both the first and second generations. Infective nematodes entered sawfly prepupae through the anus and mouth, but the preferred mode of entry was through the spiracles; prepupal hosts were extremely attractive to infective nematodes. Nematodes overwintered in prepupal hosts and in the soil. Dauerlarvae penetrated 10 cm of packed moist soil to infect prepupae constrained at the bottom of a vertical tube, sawfly mortality decreasing with depth. Dauerlarvae may also migrate 8 cm horizontally, and 5 cm upwards, to invade the host.

It is suggested that the nematode could be used to supplement biological control of Cephalcia lariciphila.
Control of whitefly, Trialeurodes vaporariorum and cotton aphid, Aphis gossypii in glasshouses by two isolates of the fungus, Verticillium lecanii
Authors: HALL R. A.
Published: February 2008

The abilities of two isoiates of the entomopathogenic fungus, Verticillium lecanii (one isolated from whitefly and one from aphids), to control both aphids and whitefly on glasshouse cucumbers was investigated. Control of homologous hosts was better than that of heterologous hosts. A single spray of a commercial substrate‐containing formulation of the ‘whitefly’ isolate controlled established whitefly populations satisfactorily on sprayed foliage and also when the whitefly moved up to younger untreated foliage. In addition, because the substrate permitted growth and sporulation of the fungus on leaf surfaces, whitefly populations introduced after a V. lecanii application were also controlled. Control of whitefly by the ‘aphid’ isolate alone was unsatisfactory although control could be obtained in conjunction with the hymenopterous parasite Encarsia formosa. Control of Aphis gossypii by the ‘aphid’ isolate was obtained by spraying a commercial formulation containing a substrate but not by spraying pure spore suspensions. The ‘whitefly’ isolate did not control aphids satisfactorily. The difference between the two isolates in pathogenicity for aphids and whitefly was supported by laboratory infectivity experiments.
Viruses detected in Ullucus tuberosus (Basellaceae) from Peru and Bolivia
Authors: BRUNT A. A. , PHILLIPS SUE , JONES R. A. C. , KENTEN R. H.
Published: February 2008

Ullucus tuberosus (Basellaceae) plants from 12 locations in the Andean highlands of Peru and Bolivia contained complexes of either three or four viruses. Specimens from six sites in Peru contained a potexvirus, a tobamovirus, a potyvirus and a comovirus, but those from another location lacked the potexvirus. All samples from five sites in Bolivia lacked the tobamovirus.

The potexvirus (PMV/U) is a strain of papaya mosaic virus differing slightly from the type strain (PMV/T) in inducing milder symptoms in some common hosts and failing to infect a few other species. It symptomlessly infected U. tuberosus, and infected 15 of 29 species from seven of nine other families. PMV/U showed a close serological relationship to PMV/T and to boussingaultia mosaic virus and a distant relationship to commelina virus X, but it is apparently unrelated to any of ten other potexviruses.

The tobamovirus (TMV/U) induced symptomless or inconspicuous infection in U. tuberosus, and infected 21 of 30 species from six of eight other families. It showed a very distant serological relationship to some strains of ribgrass mosaic, tobacco mosaic and tomato mosaic viruses, but failed to react with antisera to cucumber green mottle mosaic, frangipani mosaic, odontoglossum ringspot and sunn‐hemp mosaic viruses.

The potyvirus, tentatively designated ullucus mosaic virus (UMV), alone in U. tuberosus induced leaf symptoms indistinguishable from the chlorotic mottling and distortion found in naturally infected plants. UMV infected 12 of 20 species from four other families, and was transmitted in the non‐persistent manner by Myzus persicae. It showed a distant serological relationship to only two (bidens mottle and alstroemeria mosaic) of 25 members or possible members of the potyvirus group tested.

Some hosts and properties of the comovirus are described in an accompanying paper.

None of the four viruses infected potato (Solanum tuberosum) and, with the possible exception of UMV, they differed from viruses reported previously to infect three other vegetatively propagated Andean crops (Oxalis tuberosa, Arracacia xanthorrhiza and Tropaeolum tuberosum).
The influence of berries infected with Botrytis cinerea on the enzymic breakdown of sulphited strawberries
Authors: HARRIS JANE E. , DENNIS COLIN
Published: February 2008

Endo‐polygalacturonase produced by Botrytis cinerea is rapidly inactivated in infected strawberry tissue both by the naturally occurring fruit phenolics and also by those oxidised compounds formed as a result of polyphenol oxidase activity in the infected tissue. In contrast, the endo‐polygalacturonases of Mucor piriformis, Rhizopus sexualis and R. stolonifer are more resistant to inactivation by the fruit phenolics and no polyphenol oxidase was detected in tissue infected by these fungi. The presence of Botrytis‐infected berries in sulphited fruit containing tissue infected with Mucor or Rhizopus resulted in more rapid inactivation of the endopolygalacturonases from the latter fungi, and hence reduced the amount of softening and breakdown of the fruit. This inactivation is considered to be due largely to the oxidised phenolics present in Botrytis‐infected tissue.
The effect of host quality and crowding on the settling and take‐off of cereal aphids
Authors: WALTERS K. F. A. , DIXON A. F. G.
Published: February 2008

Settling and take‐off behaviour of Sitobion avenae was studied in the laboratory using infested and uninfested wheat at a range of developmental stages.

Of the later developmental stages of wheat alate S. avenae preferred to settle on and gave birth to relatively more offspring on flowering and watery‐ripe plants.

The time to take‐off of alatae which matured on wheat was influenced by both the developmental stage of their host plant and the degree of crowding they experienced. All alatae flew but those isolated on flowering plants stayed longer than those crowded or isolated on any of the other developmental stages tested. Similarly the number of offspring produced before take‐off was inversely related to the degree of crowding and positively to the time spent on a plant before take‐off.
The protection of carrots against carrot fly (Psila rosae) with granular and emulsifiable concentrate formulations of chlorfenvinphos incorporated in gels used for drilling pre germinated seed in a sandy loam
Authors: THOMPSON A. R. , SUETT D. L. , PERCIVALL A. L.
Published: February 2008

Field experiments were done in a sandy loam in 1979 and 1980 to investigate the performance against carrot fly on carrots of e. c. and granular formulations of chlorfenvinphos incorporated in gels used for drilling pre‐germinated seed.

With 9·4–66·7 mg a. i./m row, the two formulations performed similarly in a natural hydrocolloid and a mineral colloid gel. Thus the emergence of carrot seedlings 6–7 wk after drilling was similar on plots with untreated gel and those with insecticide‐treated gel and, about 6 months after drilling when > 90% of carrots grown without insecticide were damaged by carrot fly larvae, an approximately six‐fold increase in dose of both formulations increased the estimated larval mortality from about 70 to 95%. Mean concentrations of residues of total (Z + E) isomers of chlorfenvinphos in harvested carrots treated with 9·4–56·5 mg a. i./m row were<the proposed FAO/WHO tolerance for chlorfenvinphos (0·4 mg/kg). The initial rates of release of available chlorfenvinphos from a granular formulation immersed in the two types of gel differed markedly but, after 48‐h immersion, >50% of the insecticide had been released into both gels.
Fungicidal control of Rhizoctonia solani in soil amended with organic manures
Authors: BANDYOPADHYAY R. , YADAV J. P. S. , KATARIA H. R. , GROVER R. K.
Published: February 2008

Amendments of nutrient‐deficient soil with three organic manures and one non‐edible oil‐cake reduced the disease controlling potential of methoxyethyl mercury chloride (MEMC), quintozene and carbendazim used as seed treatments on cowpea and cotton against seedling rot caused by Rhizoctonia solani.

Biogas sludge (BGS) and farm yard manure (FYM) nullified the activity of MEMC and quintozene and reduced markedly the efficacy of carbendazim. Humic acid extracted from BGS inactivated MEMC and carbendazim but had little effect on quintozene. Green manure (Sesbania aculeata) slightly reduced the efficacy of MEMC only. Soil amendment with mahua (Madhuca indica) cake and soil drench with its aqueous extract greatly reduced the efficacy of the three fungicides.
Identification of Rhizobium strains on antibiotic concentration gradients
Authors: BROMFIELD E. S. P. , STEIN MICHÈLE , WHITE R. P.
Published: February 2008

Antibiotic concentration gradients were used to characterise several cultures of R. phaseoli and Rhizobium spp. (isolated from Cicer arietinum) by differences in intrinsic antibiotic resistance (IAR). Differentiation between cultures was facilitated by use of cluster analyses. The method permitted 15/16 cultures of R. phaseoli to be distinguished on 14 antibiotics. Two cultures which exhibited similar IAR patterns were shown to be the same strain obtained from different collections. The validity of the technique for strain identification was demonstrated by fluorescent antibody tests which gave corresponding identity for 50 nodule isolates from plants inoculated with a mixture of three strains of R. phaseoli. The method was less suitable for characterising cultures of the slow‐growing Rhizobium spp. because several antibiotics produced growth lacking a clearly defined boundary between resistance and susceptibility. Although 15/16 cultures of Rhizobium spp. could be differentiated, several isolates were distinguishable only by a difference on a single antibiotic. Similarity between stock cultures and derivative nodule isolates indicated that IAR on gradient plates was a stable property unaffected by plant passage.