bluuebunny/crossref_metadata_2025_split huggingface dataset:
Application of enzyme‐linked immunosorbent assay to the detection of potato leafroll virus in potato tubers
Authors: TAMADA T. , HARRISON B. D. 
Published: February 2008

SUMMARYFactors affecting the detection of potato leafroll virus (PLRV) by enzyme‐linked immunosorbent assay (ELISA) in tubers of field‐grown potato plants with primary or secondary infection were studied. The reactions of extracts of virus‐free potato tubers were minimised by pre‐incubating the extracts at room temperature and by careful choice of the dilution of enzyme‐conjugated globulin. PLRV was reliably detected in tubers produced by secondarily infected plants of all six cultivars tested. PLRV concentration was greater in heel‐end than in rose‐end vascular tissue of recently harvested tubers but increased in rose‐end tissue when tubers stored at 4°C for at least 5 months were placed at 15–24°C for 2 wk.PLRV occurred at greater concentration in tubers from plants of cv. Maris Piper with natural or experimentally induced primary infection than in tubers from secondarily infected plants; again PLRV concentration was greater in heel‐end than in rose‐end vascular tissue. Plants whose shoots were infected earliest in the growing season were invaded systemically and produced the greatest proportion of infected tubers; plants infected late in the season also produced infected tubers but PLRV was not detected in their shoot tops. PLRV concentration in tubers from the earliest‐infected plants was less than in tubers from later‐infected plants. PLRV was detected reliably by ELISA in tubers from progenies that were totally infected but was not detected in all infected tubers from partially infected progenies.ELISA is suitable as a routine method of indexing tubers for PLRV, although the virus will not be detected in all infected tubers produced by plants to which it is transmitted late in the growing season.
Water stress in field‐grown perennial ryegrass.
Authors: JONES M. B. , LEAFE E. L. , STILES W. 
Published: February 2008

SUMMARYTwo sets of irrigated and water‐stressed swards of perennial ryegrass (Lolium perenne) growing in the field were compared. One set of swards was grown normally (field swards) and the other was established in boxes of low water‐holding capacity (simulated swards). Rain covers were used to exclude rain from half of both sets of swards: the others were kept within 20 mm of field capacity.Daily minimum values of leaf water potential fell to —12 bars (—1.2 MPa) in the irrigated swards, —16 bars in the stressed field swards and —20 bars in the stressed simulated swards. Dry‐matter production was reduced in the stressed field swards and leaf extension declined markedly in both the field and simulated swards.Canopy photosynthesis at saturating light intensity was reduced by about half in the stressed field swards and by more than 80% in the stressed simulated swards. In the former case a proportion of this reduction was due to the lower leaf area but the mean rate of leaf photosynthesis at saturating light intensity (Pmax/LAI) was reduced by about 40% and this was attributable to increased stomatal resistance calculated from canopy transpiration rates or measured with a porometer. The more marked decline in photosynthesis in the stressed simulated swards was not only the consequence of more complete stomatal closure but also a decrease in the quantum efficiency of photosynthesis.When water stress occurs naturally in the field it appears that changes in the leaves take place as stress is developing and these changes result in a less severe effect of water stress on leaf photosynthesis. When stress is imposed with unnatural rapidity, as in the simulated swards, there is no opportunity for these changes in the leaf to occur and stress leads to a rapid and severe decline in leaf photosynthesis.The importance of these findings for the grass sward under water stress is discussed.
Prospects for fungicidal control of take‐all of wheat
Authors: BATEMAN G. L. 
Published: February 2008

SUMMARYA range of fungicides and herbicides was tested against Gaeumannomyces graminis (causal agent of take‐all) on agar plates, and on wheat seedlings in pots and in liquid culture. Benomyl, the standard in all tests, was consistently most effective: like iprodione, nuarimol and KWG 0599, it diminished infection from inoculum placed just below the seeds more effectively when applied as a drench than as a soil‐mix. Benomyl as a soil‐mix was most effective in soils with least organic matter. Some compounds toxic to the pathogen on agar plates and in plants grown in liquid culture were ineffective as soil treatments. The practical limitations of soil treatment with conventional fungicides and application methods are discussed.
Fluxes and accumulation of ethirimol in haustoria of Erysiphe pisi and protoplasts of Pisum sativum
Authors: MANNERS J. M. , GAY J. L. 
Published: February 2008

SUMMARYIsolated purified fractions containing haustorial complexes and mesophyll protoplasts were used to investigate the relative affinities in vitro of the host‐parasite interface and host for the mildew specific fungicide, ethirimol. Compounds labelled with [14C] were used throughout this study.Isolated haustorial complexes accumulated fungicide against a concentration gradient and, in 15 min, to much higher concentrations than they accumulated glucose, sucrose, uracil, glycine, ethanolamine hydrochloride, inulin carboxylic acid, thiocyanate ions or uridine diphosphate glucose. Accumulation of ethirimol ceased after 30 min when the internal concentration was over twenty times greater than in the ambient medium. Similar quantities were absorbed in 15 min at pH 4.2 and 6–2. The quantities absorbed during 1 h incubation were directly related to the ambient concentration (4–400 μm). Ethirimol introduced into haustorial complexes was easily removed by washing; one third was removed in the first 5 min and only one sixth of the original remained after 3 h. Analysis of the kinetics of ethirimol efflux showed that it was located in two compartments within the complexes; thus it most probably entered the fungal cytoplasam.Ethirimol entered pea mesophyll protoplasts showing biphasic kinetics with considerable uptake in the first 30 min and a more gradual influx during the following 18 h. It was not accumulated against a concentration gradient until 6 h and after 18 h the internal concentration exceeded that of the ambient by only 1.74 fold.Extraction and chromatography showed that only small proportions of the ethirimol were degraded by haustorial complexes and protoplasts during the experimental periods.These in vitro experiments indicate competitive accumulation of ethirimol by the host‐parasite interface in vivo.
Behaviour of the systemic nematicide oxamyl in plants in relation to control of invasion and development of Meloidogyne incognita
Authors: WRIGHT D. J. , BLYTH A. R. K. , PEARSON P. E. 
Published: February 2008

SUMMARYA single foliar application of oxamyl (12.5 μg) in acetone significantly reduced invasion of cucumber seedlings by Meloidogyne incognita juveniles for at least 21 days but did not affect the early stages of development of juveniles which had already invaded the roots. In contrast, application of oxamyl to the roots significantly reduced both invasion and development of juveniles. Concurrent studies using radiolabelled oxamyl showed that the amount of toxicant in the roots after 3 days was 13 times greater following root application than after foliar treatment.It is probable that oxamyl concentrates at the sites of nematode attack as an overall concentration of only 3 ng oxamyl g‐1 root was sufficient to prevent invasion. Much greater concentrations than this were required to affect the nematode in vitro. Oxamyl appeared to be lost from the roots into the soil principally in the form of its non‐toxic oxime and it is suggested that the site of action following foliar application is at the root surface or outer cortex. Studies on the invasion behaviour of M. incognita juveniles on agar showed that the action of oxamyl had a sensory component.
A method for pre‐harvest assessment of latent infections in fruits
Authors: PRUSKY D. , FUCHS Y. , ZAUBERMAN G. 
Published: February 2008

SUMMARYA method was developed for the assessment of latent infections of Alternaria alternata in mango fruits. Fruit discs were sampled and assayed for fungal contamination under suitable growth conditions. By this method it was possible to evaluate the percentage of infections and the relative surface infected by Alternaria in mango fruits before harvest. The percentage of infections increased during the growing season but fungicide treatments prevented this increase. A significant positive correlation was found between the relative surface infected by latent Alternaria at harvest time and the incidence of black spots that developed on the fruit during storage.
Duration of cereal aphid populations and the effects on wheat yield and breadmaking quality
Authors: LEE G. , STEVENS D. J. , STOKES SUZANNE , WRATTEN S. D. 
Published: February 2008

SUMMARYField‐caged and open‐plot populations of the aphid Sitobion avenae on winter wheat (cv. Maris Widgeon) were sampled approximately twice‐weekly in the summer of 1978. Cage populations began at growth stage 10.2 (Feekes scale) (Zadoks, G. S. 52); they were removed by spraying with pirimicarb at growth stages 10.54 (71), 11.1–11.2 (77) and 11.2–11.3 (85) respectively. All cage populations reduced mean weight per grain but the effect per aphid unit was lowest in the population of longest duration. Although the aphid index in the open plots was higher than that in the early cage treatment, yield was unaffected. Cage infestations affected the breadmaking quality of the grain: percentage flour extraction was reduced and there was an increase in colour, nicotinic acid content and thiamine (vitamin B1) content of the flour; percentage nitrogen in the flour was unaffected but there was a reduction in baking value and in the high molecular weight glutenin content; infestation also reduced α‐amylase activity. Different aspects of grain quality did not change in parallel with one another or with yield changes and thus damage thresholds will vary according to the yield/quality measure under consideration.
Effects of common scab (Streptomyces scabies) on potatoes
Authors: ADAMS M. J. , HIDE G. A. 
Published: February 2008

SUMMARYSeed tubers with severe (71% cover) or slight (12% cover) common scab selected from a badly infected crop of cv. Maris Piper were boxed for sprouting in November and February and planted in field experiments at Woburn and Rothamsted in 1980.The severely scabbed seed lost more moisture than the slightly scabbed seed during sprouting and sprouted from a larger number of eyes but total stem numbers were greater on plants from the slightly scabbed seed. Plant growth during the first 6–9 wk after planting was less from the severely scabbed than from the slightly scabbed seed. This was shown by records of ground cover, leaf area index, fresh weights of stems and leaves, total tuber yield (18% lower at 9 wk) and tuber number. Subsequently these differences became non‐significant. Seed with slight scab boxed in November produced smaller numbers of progeny tubers than that boxed in February but there were no other consistent effects of boxing date on growth and yield. Scab incidence on progeny tubers was very slight and unrelated to the severity of disease on the seed tubers.It seems unlikely that severe scab infection of seed tubers would significantly decrease tuber yields except perhaps in early potato production.
Peanut green mosaic virus — a member of the potato virus Y group infecting groundnut (Arachis hypogaea) in India
Authors: SREENIVASULU P. , IIZUKA N. , RAJESHWARI R. , REDDY D. V. R. , NAYUDU M. V. 
Published: February 2008

SUMMARYA virus, now named peanut green mosaic virus (PGMV), was isolated from groundnut (Arachis hypogaea) in India and identified as a member of the potato virus Y group by electron microscopy, aphid transmission, and its chemical properties. It was sap transmissible to 16 species of the Leguminosae, Solanaceae, Chenopodiaceae, Aizoaceae and Pedaliaceae; Phaseolus vulgaris was a good local lesion host. PGMV remained infective in buffered groundnut leaf sap at dilutions of 10‐3 after 3 to 4 days at 25 °C, or heating for 10 min to 55 °C but not 60 °C. PGMV was transmitted in the non‐persistent manner by Aphis gossypii and Myzus persicae but was not seed‐borne.Purified virus preparations contained flexuous filamentous particles c. 750 nm long which sedimented as a single component with a sedimentation coefficient (S°20w) of 171S, and contained a single polypeptide (mol. wt 34 500 daltons) and one nucleic acid species (mol. wt 3.25 × 106 daltons). PGMV is serologically unrelated to peanut mottle virus (PMV) and other viruses infecting leguminous crops. Infected leaves contained cylindrical, cytoplasmic inclusions.
Garlic yellow streak virus, a potyvirus infecting garlic in New Zealand
Authors: MOHAMED N. A. , YOUNG B. R. 
Published: February 2008

SUMMARYIn New Zealand, all garlic (Allium sativum) plants tested were infected by a virus with flexuous filamentous particles 700–800 nm long. This virus, called garlic yellow streak virus (GYSV), infected only two of 12 species tested and was transmitted to garlic by the aphid Myzus persicae in a non‐persistent manner. In garlic sap, GYSV was infective at a dilution of 10‐4 but not 10‐3, after heating for 10 min at 60°C but not 65°C, and after 2 days but not 3 days at 25°C.The yield of virus, purified from naturally infected garlic, was 3–4 mg/kg fresh leaf. Preparations had A260/A280= 1.28 and Aman/Amin= 1.08. The virus particles had a sedimentation coefficient of 149S and a buoyant density in CsCl of 1.334 g/cm3. Mol. wt estimates for the virus nucleic acid were 2.95 × 106 by electrophoresis in polyacrylamide gels and 3.46 × 106 from the sedimentation coefficient (41.4S) in linear‐log sucrose density gradients. Two polypeptides were detected in virus preparations; one (mol. wt 30 500) was possibly a breakdown product of the other (mol. wt 33 000). GYSV was serologically distantly related to onion yellow dwarf and leek yellow stripe viruses but was considered to be a separate virus because it differed from them in host range.
Further properties of peanut clump virus and studies on its natural transmission
Authors: THOUVENEL J. C. , FAUQUET C. 
Published: February 2008

SUMMARYPurified preparations of particles of peanut clump virus (PCV) had A260/A280 values (corrected for light scattering) of 1.00. They contained rod‐shaped particles with sedimentation coefficients of 183 S and 224 S, and a density in CsCl of 1.32 g/ml. PCV infected 36 species in 8 plant families. No serological relationship was detected between PCV and barley stripe mosaic, beet necrotic yellow vein, Nicotiana velutina mosaic and tobacco mosaic viruses.PCV was seed‐borne for two generations in groundnut (Arachis hypogaea) but was not seed‐borne in great millet (Sorghum arundinaceum), Phaseolus mungo or Nicotiana benthamiana.Seedlings of groundnut, great millet and wheat (Triticum aestivum) became infected when grown in soil from groundnut fields with outbreaks of clump disease, and the infectivity of soil survived air‐drying at 25°C for 3 months. Groundnut seedlings became infected when grown in sterilised soil contaminated with washed roots of naturally‐infected S. arundinaceum but not in soil to which roots of naturally infected groundnut or shoots of infected groundnut were added, or in which mechanically inoculated groundnut seedlings were grown at the same time. The patchy distribution of PCV in a crop was related to the infectivity of the soil for groundnut and to the presence of Polymyxa graminis resting spores which could be detected in the roots of S. arundinaceum bait seedlings, but not in those of groundnut.The results indicate that PCV is transmitted by a vector that is resistant to air‐drying and closely associated with S. arundinaceum roots. For these reasons P. graminis is thought to be the vector of PCV.
A dispenser for the rapid delivery of standard inocula of the cyst nematode Globodera rostochiensis
Authors: MARKS R. J. , McKENNA L. A. 
Published: February 2008

SUMMARYA simple machined dispenser is described, capable of providing rapid repetitive delivery of standard volumes of potato cyst nematode cysts. Standard volumes of cysts of mixed sizes, drawn from unsieved populations of G. rostochiensis, contain titres of infective eggs and larvae which are largely independent of cyst numbers; the method reduces inoculum variability compared with other cyst inoculation techniques. Standard volumes of cysts of mixed sizes may be used directly as the inoculum for plant resistance testing programmes without the operator error associated with hand‐held scoops or the need for the subjective and time consuming selection of groups of individual cysts.
Observations on the trapping of the whitefly Bemisia tabaci by glandular hairs on tomato leaves
Authors: KISHA JENNIFER S. A. 
Published: February 2008

SUMMARYObservations were made on the role of glandular leaf hairs of four tomato cultivars in trapping cotton whitefly, Bemisia tabaci, adults. Dead, trapped whitefly occurred in similar numbers on both the upper and lower surfaces of leaves even though glandular hairs were denser on the former. Females constituted 58% of untrapped but 86% of trapped adults, many becoming trapped during oviposition which occurred mainly on the lower surfaces. Of the four cultivars studied, Strain B trapped more whitefly than Ace, Marglobe or Moneymaker.
Aspects of the biology of the black cowpea moth, Cydiaptychora (Lepidoptera: Tortricidae) related to host plant phenology
Authors: OLAIFA J. I. , AKINGBOHUNGBE A. E. 
Published: February 2008

SUMMARYFemales of Cydia ptychora oviposited on cowpea, Vigna unguiculata ssp. unguiculata in the field between 18.00 and 19.00 h commencing about 30 days after planting with a few eggs laid on the leafbuds and the undersides of leaves. Oviposition increased as the host plant developed the preferred sites, floral sepals and their remains on pods, and peaked at about 58 days after planting regardless of planting date. First instar larvae were found wandering on the plant between 06.45 and 11.15 h but other larval instars were rarely encountered outside the pod except when changing pods or leaving pods to pupate in the soil. Contrary to previously reported observations, larval development occurred in leafbuds and inside flowers both in the field and in laboratory rearing. Development was optimal on pods, and mortality was high in leafbuds.
The effect of chlormequat chloride formulated with choline chloride on the height and yield of winter wheat
Authors: MATHEWS P. R. , CALDICOTT J. J. B. 
Published: February 2008

SUMMARYTwenty‐one field trials were conducted on commercial crops of winter wheat from 1976 through to 1978, with a mixture of 460 g chlormequat chloride and 320 g choline/litre at rates ranging from 0.67 kg to 2.07 kg of chlormequat chloride/hectare.The mean increase in grain yield in the absence of lodging following treatment with chlormequat chloride was 0.31 t/ha, with a greater yield increase where lodging occurred on untreated controls. Chlormequat chloride when applied in mixture with carbendazim fungicide usually resulted in yield increases which were less than the sum of the increases from the two products applied separately. Yield increases following the use of chlormequat chloride were usually greater when used in a traditional system of wheat growing than when used in the Laloux system.Effects of chlormequat chloride on crop height were poorly determined in the dry season of 1976 but there were consistent reductions up to 1.15 kg a.i./ha in 1977. Crop height was reduced by 1.61 kg of chlormequat chloride/ha in 1978.
Use of a nematode, Heterorhabditis heliothidis, to control black vine weevil, Otiorhynchus sulcatus, in potted plants
Authors: BEDDING R. A. , MILLER L. A. 
Published: February 2008

SUMMARYApplication of aqueous suspensions of infective juvenile Heterorhabditis heliothidis, isolate T327, to the soil resulted in up to 100% parasitisation of larvae of the black vine weevil, Otiorhynchus sulcatus, in potted yew, raspberries and grapes in nurseries, and over 87% parasitisation on potted cyclamens and strawberries. Pupae and newly emerged adults on grapevines were also parasitised. Another isolate, T310, produced 92.5 to 98.5% parasitism of O. sulcatus larvae on potted cyclamens in glasshouse, but was less effective on strawberries. Neoaplectana bibionis was found to be less effective than H. heliothidis T327 strain.The use of these nematodes provides an economical and effective method for controlling O. sulcatus on potted plants in glasshouses and nurseries.
A method for mass rearing the aphid predatorAnthocoris nemorum
Authors: PARKER N. J. B. 
Published: February 2008

SUMMARYAnthocoris nemorumis currently under investigation as a potential agent for the control of damson‐hop aphidPhorodon humulion hops. Detailed here is a method of rearingA. nemorumto provide a large number of insects with a predetermined age structure for mass release in the field. It is designed to minimise culture maintenance, with components and materials which are readily obtained as, or can be modified from, stock items. Initial cultures are collected from the field, as adults, in early autumn and artificially overwintered. These are recovered in early spring, with females being placed in oviposition chambers, and the harvesting of ova regulated to provide synchronisation of eclosion within batches. Larvae are reared until they reach the desired instar for mass release and then held in controlled cold storage until required.
Fertility of the polyembryonic parasite Copidosoma koehleri, effect of humidities on life length and relative abundance as compared with that of Apanteles subandinus in potato tuber moth
Authors: KFIR KAMI 
Published: February 2008

SUMMARYMales and females of Copidosoma koehleri were kept separately in desiccators producing relative humidities of 20, 40 and 70% at 24 and 28°C and found to be very susceptible to low relative humidity. They lived less than 1 day at 20%, about 2 and 4 days at 40% and about six times longer than these respectively at 70% r.h. When kept at 26°C and 70% r.h. females of C. koehleri parasitised 98.8 hosts. The number of parasites that emerged from a male brood was 21.2 and from a female brood 33.2. Mated females produced 3026 progeny and unmated 2289. The sex ratio of broods produced by mated females was 1:1 and the female percentage among progeny was 59. It is known that C. koehleri is rare at the beginning of the potato‐growing season and becomes the predominant parasite later on. It is known also that in potato crops when the plants are small at the beginning of the season the air within the crop is less humid but as the canopy of foliage develops, relative humidity rises and becomes higher than at 1.2 m above ground. It is suggested that relative humidity in the potato crop is the major factor affecting the relative abundance of C. koehleri and Apanteles subandinus in South Africa.
The effect of insecticides on Bemisia tabaci, tomato leaf curl virus disease incidence and yield of tomatoes in the Sudan
Authors: KISHA JENNIFER S. A. 
Published: February 2008

SUMMARYThe whitefly Bemisia tabaci infested winter‐sown tomatoes immediately after germination. Soil‐applied granular insecticides and foliar sprays of a synthetic pyrethroid reduced the number of nymphs and adults, but insecticides failed to reduce the incidence of tomato leaf curl virus disease which is transmitted by this insect. Results from pot experiments using aldicarb granules to tomato and to cotton plants indicated that the time and rate of application influence whitefly mortality and reproduction.