bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effects of fluid drilling and seed covering medium on early carrot production under polyethylene mulch
Authors: FINCH‐SAVAGE W. E. 
Published: February 2008

SUMMARYUngerminated seeds, fluid‐drilled germinating seeds and fluid‐drilled uniformly‐germinated seeds were sown in furrows that were either uncovered or covered by soil and left unmulch ed or mulched with polyethylene sheet. The effects of these treatments on the emergence and growth of carrots for early harvest were examined. Leaving seeds uncovered or mulching them with polyethylene advanced seedling emergence and increased the percentage that emerged; leaving seeds uncovered also reduced the spread of emergence times and produced seedlings with larger cotyledons. Uniformly‐germinated seeds emerged before germinating seeds and both emerged before ungerminated seeds. The best combination of treatments (i.e. mulched, uncovered uniformly‐germinated seeds) reduced the mean number of days for emergence from the 52 required by traditionally sown seeds to 29. There was a more variable effect of seed treatments on the spread of emergence times and the percentage emergence. Earlier emergence generally led to roots reaching a marketable size earlier and more uniform emergence led to less variation in root weights at harvest.
A study of the relationship between seedling characters and rate of germination within a seed lot
Authors: FINCH‐SAVAGE W. E. 
Published: February 2008

SUMMARYThe relationship between seedling characters and germination rate within a seed lot was studied in cauliflower, leek and onion seeds. Newly germinated seeds were selected after successive days of imbibition at 20°C and placed on slope tests to assess early seedling growth. In all three species seedling length decreased and the coefficient of variation of those seedling lengths increased with increasing number of days of imbibition required for germination. Slow germinating seeds in all three species produced fewer normal healthy seedlings than faster germinating seeds. The relevance of these results to pre‐germinated seed sowing techniques is discussed.
The effect of previously infested spruce needles on the growth of the green spruce aphid, Elatobium abietinum, and the effect of the aphid on the amino acid balance of the host plant
Authors: FISHER MARTIN 
Published: February 2008

SUMMARYThe effect of chlorosis induced in needles of Sitka and Norway spruce by the green spruce aphid on growth of the aphid is investigated, and the effect of infestation of the aphid on amino acid levels in Sitka spruce foliage is reported.On both Sitka and Norway spruce green spruce aphids were heavier when reared on chlorotic (previously infested) needles than when reared on green (previously uninfested) needles. The effect was more pronounced on Sitka than on Norway spruce. Infestation of the aphid altered the amino acid balance of Sitka spruce foliage but not the concentration of total amino acids. Possible causes of chlorosis, the influence of individual amino acids on aphid growth, the potential effect of chlorosis on outbreaks of the aphid and the differences in susceptibility of Sitka and Norway spruce to damage by the aphid are discussed.
Grasshopper feeding rates, preferences, and growth on safflower
Authors: JOHNSON DANIEL L. , MÜNDEL H.‐HENNING 
Published: February 2008

SUMMARYLaboratory experiments were conducted to measure the feeding rates, preferences, survival rates, maturation times, and weight gain of four common species of grasshoppers (Orthoptera: Acrididae) on four lines of safflower (Carthamus tinctorius). When safflower lines were presented individually, all were readily consumed although consumption differed significantly according to grasshopper species, age and sex, and to safflower line. Consumption was greatest on a safflower line devoid of spines. However, grasshoppers also fed readily on spiny lines, and results of experiments in which all safflower lines were presented together indicated preferences that did not necessarily correspond to the results of the single‐line feeding trials. Camnula pellucida, a graminivorous species, did feed on safflower, but restricted feeding almost exclusively to stem cambium, whereas Melanoplus bivittatus, M. packardii and M. sanguinipes fed mainly on the heads, flowers and leaves.Highly significant differences in grasshopper maturation time and weight gain were apparent among grasshopper species, and among safflower lines. Seedtec‐5, the line which was least digestible, least consumed and least preferred nevertheless yielded rapid development and the greatest body weights of grasshoppers. All species of Melanoplus developed more quickly and gained more weight on safflower than on wheat. One species, M. packardii, was more able to utilise safflower than its congeners, and may gain competitive advantage if safflower becomes widely grown.
Bacterial wilt, a new disease of custard apple: symptoms and etiology
Authors: MAYERS P. E. , HUTTON D. G. 
Published: February 2008

SUMMARY Pseudomonas solanacearum biovar 3 was identified as the causal agent of two disease syndromes in custard apples (Annona spp.), namely sudden death of young trees and the decline of mature trees. Cross inoculation tests using cultures of P. solanacearum from custard apple and tomato on A. squamosa, A. squamosa×A. cherimola hybrids, Capsicum annuum, three cultivars of Lycopersicon esculentum and Solanum tuberosum failed to distinguish differences in virulence among these isolates. Bacterial wilt resistant rootstock clones, particularly of A. cherimola, constitute the most effective control measure available.
Satellite RNA for the control of plant diseases caused by cucumber mosaic virus
Authors: TIEN PO , ZHANG XIUHUA , QIU BINGSHENG , QIN BINGYI , WU GUSUI 
Published: February 2008

SUMMARYTwo virus‐protecting strains, S51 and S52, were obtained for the control of cucumber mosaic virus (CMV) by local lesion selection after adding satellite RNA to the RNA genome of CMV. Both were found to protect pepper plants against a virulent strain of CMV under greenhouse and field conditions. Results from 14 localities in China indicated that the use of protective strains decreased the disease index by 21.6% to 82.8% and increased fruit yields by 10.8% to 55.6%. The host reactions and safety of S51 and S52 were tested, and the effects of the strains on plant growth were also investigated. Possible mechanisms of control of CMV‐caused plant diseases by mild strains are discussed.
Safflower susceptibility and response to feeding by grasshoppers
Authors: MÜNDEL H.‐HENNING , JOHNSON DANIEL L. 
Published: February 2008

SUMMARYFeeding by three grasshopper species, Camnula pellucida, Melanoplus packardii and Melanoplus sanguinipes, on three safflower (Carthamus tinctorius) lines for a 6‐wk period from anthesis was monitored under field conditions. Ratings of feeding damage to different plant parts (leaves, floral parts, capitula, and peduncles) and measurements after termination of feeding (dry weight, seed yield, seed weight, seeds per capitulum, and capitula per row) were compared among grasshopper species and safflower lines.The Melanoplus species fed preferentially on leaves, floral parts, and capitula, while C. pellucida exhibited only peduncle feeding, which resulted in head clipping. Defoliation of 20 to 30% was associated with significant increases in total dry matter, seed yield, and number of capitula. Further defoliation resulted in decreases.The safflower lines differed in response to grasshopper feeding. S‐208 was most susceptible to defoliation by grasshopper feeding, exhibiting decreased dry weight, seed yield, and capitula number. Lesaf 34C‐00 was most tolerant and only M. packardii caused significant dry weight and seed yield reductions. Feeding by C. pellucida on this line resulted in an overall seed yield increase. Feeding by M. sanguinipes on Seedtec‐5 resulted in yield increases of up to 16%. It appears that certain grasshopper species can increase seed yield in some safflower lines by stimulating the production of additional capitula. Therefore, moderate populations of such grasshoppers in fields of appropriate safflower cultivars do not necessarily require control.
A key for stages of development of the pea (Pisum sativum)
Authors: KNOTT C. M. 
Published: February 2008

SUMMARYA key is presented to described stages of development of the pea (Pisum sativum). The aim was to produce a simple system to aid accuracy in communicating instructions for timing of field operations. The coded description is divided into four principal stages: germination and emergence, vegetative, reproductive and senescence. These are sub‐divided into secondary stages. The practical use of the key is discussed with particular reference to the timing of application of agrochemicals.
Effects of sustained immobilisation on aphids
Authors: BERGER P. H. , ZEYEN R. J. 
Published: February 2008

SUMMARYImmobilisation of aphids of three species, Schizaphis graminum, Myzus persicae and Dactynotus ambrosiae, was accomplished using low temperature (6 ± 1°C; or nitrogen (N2), argon (Ar), or carbon dioxide (CO2) gases at 25°C for 1,3,6, or 24 h. Mortality was recorded and also times until treated aphids first walked or probed. Cold immobilisation caused least mortality and allowed rapid recovery of walking and probing abilities. CO2 treatment, even when accompanied by cyclic administration of bottled air, caused excessive mortality when used beyond 6 h, and long recovery times. After 24 h immobilisation with CO2 aphids seldom walked or probed. N2 or Ar gases, when administered with alternating cycles of bottled air, produced a nontoxic, hypoxic immobilisation from which aphids recovered fairly rapidly to walk and probe, apparently normally.
Predation of Rhopalosiphum padi (Homoptera: Aphididae) by polyphagous predatory arthropods during the aphids' pre‐peak period in spring barley
Authors: CHIVERTON PHILIP A. 
Published: February 2008

SUMMARYPolyphagous predators (e.g. Araneae, Carabidae and Staphylinidae), collected from spring barley fields during 1981‐85, were examined by either gut dissection or a R. padi‐specific antiserum in enzyme linked immunosorbent assay (ELISA) in order to detect predation of Rhopalosiphum padi during the aphids' establishment and exponential growth phases.Overall 18% of c. 3000 carabids dissected were shown to feed on R. padi during the aphids' pre‐peak period. No overall relationship was found between percentage carabids with R. padi in the diet and peak R. padi densities. Relatively high proportions of Bembidion spp. (particularly B. lampros) and Pterostichus cupreus fed on R. padi during the aphids' establishment phase, and proportions of those predator taxa containing R. padi increased with increasing R. padi densities in both high and low aphid density years. P. melanarius and Harpalus rufipes mainly fed on R. padi during the aphids' exponential growth phase.Overall 11% of c. 1350 predators examined in ELISA gave positive reactions to the R. padi antiserum. Relatively high proportions of linyphiid and lycosid spiders were positive throughout the aphid pre‐peak period. Several Acari, Opiliones, Trechus spp. (Carabidae), Philonthus spp. (Staphylinidae), Cantharidae and Chilopoda were positive mainly during the aphids' exponential growth phase. Sample sizes were small, however.Very few of the Bembidion spp. tested in ELISA were positive compared with those examined by gut dissection. The maximum period of R. padi protein (antigen) detection in B. lampros was related to temperature, i.e. 8.5 h at 30°C, 20.5 h at 20°C and 34.5 h at 10°C, respectively. It is suggested that the rate of R. padi protein digestion in B. lampros is faster at higher temperatures than the rate of elimination of prey solids from the guts.Several key predators (in this case B. lampros, P. cupreus and linyphiid spiders) which are abundant in spring cereal fields at a time when R. padi emigrants arrive in the crop and which feed on R. padi during the aphids' establishment phase, are identified. The results are compared with those from similar investigations elsewhere with predators of Sitobion avenae and Metopolophium dirhodum.
Flight periodicity and infestation size of Sitona lineatus
Authors: HAMON N. , BARDNER R. , ALLEN‐WILLIAMS L. , LEE J. B. 
Published: February 2008

SUMMARY Sitona lineatus displays two distinct flight periods; a post‐teneral flight in the late summer and a post‐diapausal flight in the spring. The late summer flight begins as soon as adults start to emerge from pupal cells during late July and continues until mid‐October. Maximum aerial density is observed in late August. Less than 10% of newly emerged adults leave the crop by flight, the rest remain in the soil or move to overwintering sites by walking. Spring flight begins in late March if temperatures are above the 12.5°C flight threshold and reaches a peak in mid‐April.Most migratory flight is downwind. Little trivial flight occurs and once individuals have located a crop, redistribution is by walking. Laboratory studies indicate that adults fly most often during the day, particularly at noon.The size of infestations appeared to be independent of the area of legumes grown in a locality with large differences occurring even between neighbouring fields.Examination of the yields of field experiments at Rothamsted demonstrate an unexpected trend for higher yields in later sown spring bean crops. This may be because late sowing avoids infestation by spring migrants.
Stimulation of germination in teliospores of Urocystis agropyri by volatiles from plant tissues
Authors: GOEL R. K. , JHOOTY J. S. 
Published: February 2008

SUMMARYIn tests using pre‐soaked teliospores of Urocystis agropyri, germination was stimulated by tissues from all parts of the host plant (wheat) irrespective of cultivar or resistance to flag smut. Seedling tissues of some non‐hosts (maize, rice, sorghum, cotton, mungbean and groundnut) also stimulated germination. Similar stimulatory effects were achieved by brief exposure to volatiles from wheat seedling tissues, and from the known sources of ethylene, ripening bananas, lemon fruit and ethephon (2‐chloroethyl phosphonic acid) solution. The possibility that ethylene may have a direct triggering effect on teliospore germination is discussed.
Development of appressoria of Erysiphe graminis f.sp. hordei in response to host plant age and water stress
Authors: WOOLACOTT B. , AYRES P. G. 
Published: February 2008

SUMMARYAppressoria were observed to develop in sequence up to three lobes, each of which may establish a penetration of the underlying host cell and, ultimately, give rise to a haustorium and elongating secondary hyphae (ESH). Upon fully susceptible, well‐watered seedling plants increased appressorium development in terms of lobe number led to reduced penetration success, as judged by ESH formation. A concomitant reduction in the initiation of further penetration attempts at lobes newly formed after earlier unsuccessful penetration attempts was also observed. The effects of increased plant age and water stress upon this interaction were examined.
Aphid retention of maize dwarf mosaic virus (potyvirus): epidemiological implications
Authors: BERGER P. H. , ZEYEN R. J. , GROTH J. V. 
Published: February 2008

SUMMARYIn total, 17 589 aphids were assayed for rate of loss of inoculativity and maximum retention times of maize dwarf mosaic (MDMV). The Standard‐treatment, involved acquisition access to MDMV‐infected tissue followed by confinement of active aphids in Petri dishes. In addition various aphid immobilisation treatments were used to prevent probing on solid surfaces after acquisition access to simulate conditions experienced by wind‐borne aphids when aloft. Immobilisation treatments, using nitrogen or argon gases at 25°C, or cold treatments at 6°C after acquisition access greatly increased the efficiency of MDMV transmission by greenbugs, Schizaphis graminum, in an experimental design where insects were individually assayed for transmission over a 7 h period.Further tests in which groups of greenbugs were assayed for MDMV transmission revealed that MDMV strains may be retained for over 21 h, regardless of post‐acquisition access treatment. Experiments with other aphid vectors of MDMV (Dactynotus ambrosiae, Macrosiphum euphorbiae, Rhopalosiphum maidis and Myzus persicae) also demonstrated MDMV retention times exceeding 18 h.These results show that the rate at which aphids lose MDMV inoculativity is lower when solid surface probing behaviour is denied, and that MDMV retention times are longer than those previously published. The findings are discussed in relation to the epidemiology of nonpersistent viruses and their dispersal over great distances.
Effect of cocksfoot mottle virus on resistant and susceptible cocksfoot cultivars grown alone or in combination with healthy or ryegrass mosaic virus‐infected Italian ryegrass
Authors: CATHERALL P. L. , POTTER L. R. 
Published: February 2008

SUMMARYCocksfoot mottle virus (CfMV) was readily transmitted on cutting implements. However, after six harvests, only a quarter as many plants of the resistant cv. Cambria as of the susceptible cv. S.37 became infected. In addition to resistance to becoming infected, cv. Cambria also possessed some resistance once infected, and suffered less mortality than S.37. More CfMV‐infected plants died when competing with healthy plants than when competing with other infected plants.Both CfMV and ryegrass mosaic virus (RMV) caused greater reductions in the yield of their respective hosts in mixed stands of cocksfoot and Italian ryegrass than in single species stands. CfMV reduced the proportion of cocksfoot in the mixture and RMV the proportion of ryegrass. However, CfMV‐infected cv. Cambria competed better than CfMV‐infected cv. S.37 with healthy or with RMV‐infected ryegrass.It is concluded that grass cultivars selected for resistance to virus infection will slow down the rate of disease spread within the sward, and selecting for postinfection resistance will help maintain the aggressiveness and competitive ability of plants once they become infected.
The etiology of hop chlorotic disease
Authors: ADAMS A. N. , BARBARA D. J. , VIES D. L. DA 
Published: February 2008

SUMMARYHop chlorotic disease was first described in England in 1930, but it has since been seldom seen and its etiology has remained unknown. In 1983 a patch of plants with the disease occurred in a large area of hops (Humulus lupulus) cv. Bramling Cross planted at Yalding, Kent in 1967. All plants in a rectangular area enclosing the disease outbreak were infected with hop mosaic, hop latent and prunus necrotic ringspot viruses; the diseased plants were additionally infected with arabis mosaic virus (AMV). The disease was also associated with seed‐transmitted AMV, and was induced in hop seedlings inoculated with partially purified preparations of AMV originating from chlorotic disease‐affected hops prepared from Chenopodium quinoa. The disease appears to be caused by AMV, but AMV isolates from hops with chlorotic disease were serologically indistinguishable from AMV isolates from hops with symptoms of bare‐bine and/or nettlehead and showed similar pathogenicity in diagnostic hosts. The basis of the difference between isolates in their pathogenicity in hop remains unknown.
Physiological and ultrastructural changes in Stellaria media following treatment with fluroxypyr
Authors: SANDERS G. E. , PALLETT K. E. 
Published: February 2008

SUMMARYThe physiological and ultrastructural changes induced by fluroxypyr (4‐amino‐3, 5‐dichloro–6–fluoro–2–pyridyloxyacetic acid) are investigated in a susceptible weed species, Stellaria media. The sequence of symptoms was an initial petiole curvature followed by stem elongation and thickening prior to leaf senescence, stem and petiole necrosis and plant death. Light and electron microscopy revealed leaf tissue containing cells with disrupted and swollen chloroplasts and a disrupted tonoplast. Within the stem tissue there was extensive meristematic differentiation and adventitious root development prior to stem tissue necrosis. Increased levels of reducing sugars and amino acids in treated foliar tissue indicated reserve mobilisation during the initial stages of symptom development.Fluroxypyr induced oat coleoptile elongation with an optimum concentration at 5 × 10‐5 m compared to 10‐4 m for auxin (IAA). A S. media shoot explant system revealed similar elongation which was maximal during the first 24 h of treatment. Uptake and incorporation of 14C‐leucine was stimulated by 96 h after treatment. It is concluded that fluroxypyr activity against S. media is characterised by an initial cell elongation and reserve mobilisation, followed by extensive cell proliferation, increased RNA and protein synthesis, and ultimately plant death.
The complementary effects of plant resistance and the choice of sowing and harvest times in reducing carrot fly (Psila rosae) damage to carrots
Authors: ELLIS P. R. , HARDMAN J. A. , COLE ROSEMARY A. , PHELPS KATHLEEN 
Published: February 2008

SUMMARYThe benefits of combining a partially‐resistant carrot cultivar with different sowing and lifting dates to reduce carrot fly, Psila rosae, damage were investigated at Wellesbourne in 1983 and 1984‐85. The partially‐resistant cv. Sytan was less damaged and supported fewer insects than the susceptible cv. Danvers on all lifting dates. The estimated reduction of carrot fly larvae on Sytan compared with Danvers ranged from 33 to 95%. Nine combinations of sowing and lifting dates provided more than 75% marketable roots of Sytan compared with only three combinations of dates for Danvers. An early June sowing of both cultivars provided roots of a marketable size with the least attack. More than 90% of Sytan roots were still marketable in December and fewer insects were produced by the end of the season on these roots than on those sown earlier. In addition, sowing in June decreased the number of pupae produced on cv. Danvers by 10 times compared with earlier sowings. Combining partial resistance with specific sowing and lifting times enabled satisfactory yields of marketable carrots to be obtained in a field infested by high populations of carrot fly.
Genetic control of resistance to cucumber mosaic virus in Cucurbita pepo
Authors: PINK D. A. C. 
Published: February 2008

SUMMARYSegregation ratios in the F2s of crosses between courgette cultivars and the pumpkin cv. Cinderella indicated that the resistance of the latter to cucumber mosaic virus (CMV), expressed as a failure to develop systemic symptoms, was controlled by two unlinked recessive genes. However, data from the backcross generations were not consistent with this. Biometrical analysis showed significant gene interactions, possibly between the genes for CMV resistance and the background genotype determining plant vigour and a gene dosage effect for resistance.The resistance has been successfully backcrossed into courgette breeding material.