bluuebunny/crossref_metadata_2025_split huggingface dataset:
Evaluation of the activity of a number of procaine derivatives and analogous compounds against powdery mildew (Sphaerotheca fuliginea) on cucumber*
Authors: NIEMANN G. J. , DEKKER J. 
Published: February 2008

SUMMARYAbout fifty derivatives and analogues of procaine have been prepared and tested in three different tests for activity against powdery mildew of cucumber. Most of the compounds were active but few equalled procaine.The results obtained seem to afford little evidence for simple structure‐activity relationship based on physico‐chemical or electro‐chemical properties.
Colonization of cellulose membranes by species of Verticillium
Authors: GRIFFITHS D. A. , ISAAC IVOR 
Published: February 2008

SUMMARY Verticillium dahliae Kleb. (from Brussels sprouts), non‐pathogenic to tomato, and V. tricorpus Issac, a virulent pathogen to tomato, differed in their ability to colonize samples of commercial Cellophane, their rate of colonization being dependent upon external sources of carbohydrate. Cellophane and filter paper were both utilized in culture as the sole carbon source and it appears that both fungi have identical cellulase enzyme systems. Prolonged growth of the isolates is liquid medium containing sucrose as the carbon source resulted in lysis of the mycelium, which coincided with the production of polysaccharide material in culture.
The epidemiology of tomato mosaic: Sources of TMV in commercial tomato crops under glass
Authors: BROADBENT L. , FLETCHER J. T. 
Published: February 2008

SUMMARYOf the several possible sources of tomato mosaic virus, seeds and root debris in the soil are considered to be of greatest importance. A survey of 374,000 seedlings on ten commercial holdings found 0.05% of them infected, and although these were removed virus had been spread to other young plants which did not show infection when transplanted into the growing houses, seven of twenty‐two of which contained a few infected plants when sampled shortly after planting. Virus overwintering on clothing, and debris on structures, are thought to be of minor importance, and smoking tobacco is seldom a source of infection for the tomato crop. A further survey of seventy‐eight samples from tomato crops in Britain confirmed the 1960‐61 survey: all were infected with tomato strains of TMV, none with tobacco strains, but one of the 187 infected seedlings referred to above was carrying a tobacco strain. Petunia was not as satisfactory as a special cultivar of White Burley tobacco for distinguishing between the tobacco and tomato TMV isolates.Observations and tests on a commercial holding showed that TMV was readily carried from plants in infected glasshouses into clean ones by workers, and once introduced, spread rapidly within the crop.
Further studies on a British form of pea early‐browning virus
Authors: HARRISON B. D. 
Published: February 2008

SUMMARYAn isolate of pea early‐browning virus from Britain (PEBV (B)) has tubular particles most of which are either about 103 or 212 mμ long with sedimentation coefficients of 210 and 286 S respectively. Both types show cross‐banding at intervals of 2.5 mμ. Virus preparations containing only the shorter particles were not infective.PEBV (B) was transmitted to pea seedlings by both adult and juvenile Trichodorus primitivus (de Man) (Nematoda) and persisted for 32 days in T. primitivus kept without plants. In two experiments T. primitivus failed to transmit a Dutch isolate (PEBV (D)), which is distantly related serologically to PEBV (B). PEBV (B) was transmitted by nematodes to cucumber roots more readily in soil at 20d̀ than at 24d̀ C., and more readily at 24d̀ than at 29d̀ C.When transmitted by inoculation of sap, PEBV (B) and PEBV (D) caused similar symptoms in some pea varieties but differed in virulence towards others. Thirty‐one varieties resistant to natural infection with PEBV in The Netherlands were susceptible to PEBV (B) when manually inoculated with sap or when grown in naturally infested soil from one site; twenty‐six of these varieties did not become infected in soil from a second site, in which several other varieties that are susceptible in The Netherlands were infected. Varieties should therefore be tested for resistance by growing them on many infested fields. All but one of the pea varieties resistant to PEBV in The Netherlands became infected with the English form of tomato black ring virus when grown in soil containing infective Longidorus attenuatus Hooper.
Effects of barley yellow dwarf virus on the growth and yield of single plants and simulated swards of perennial rye‐grass
Authors: CATHERALL P. L. 
Published: February 2008

SUMMARYIrish perennial rye‐grass plants infected with barley yellow dwarf virus (BYDV) showed inconspicuous leaf symptoms but were more stunted and yielded less total herbage, but more early spring herbage, than healthy plants. During a period of 2 years, infection did not decrease plant survival; infected plants produced more tillers and gave a higher ratio of vegetative to fertile tillers than healthy plants. BYDV caused a greater loss of yield in simulated rye‐grass swards cut twice a year than in those cut four times. Swards in which half the plants were infected gave yields intermediate between those of healthy and infected swards. Infected plants tended to dominate healthy ones in swards cut four times, but in those cut twice a year the initial status quo was maintained. In swards containing rye‐grass and white clover, the clover yielded more for most of the year when with BYDV‐infected than with healthy rye‐grass, but this trend was reversed in spring.The different effects of barley yellow dwarf virus on rye‐grass plants and of cocksfoot streak virus on cocksfoot seem reflected by the different effects of the viruses on the competition between infected grass, healthy grass and white clover plants, when these are grown in different combinations.
The activation of diazinon by ganglia of the cockroach Periplaneta americana L. and its action on nerve conduction and cholinesterase activity
Authors: BURT P. E. , GREGORY G. E. , MOLLOY FRANCES M. 
Published: February 2008

SUMMARYWhen sixth abdominal ganglia of the cockroach Periplaneta americana were irrigated continuously with diazinon solution in situ, its effects on nerve conduction and cholinesterase activity closely resembled those of diazoxon; spontaneous activity and after‐discharge increased until conduction was blocked, which happened while some cholinesterase was still uninhibited. The symptoms were only slightly relieved by irrigating ganglia with saline.Though the LD50's of diazinon and diazoxon applied topically to adult male P. americana were similar (2.5 ± 0.33 and 4.5 ± 0.38 μig. per insect), diazoxon was about 300 times more active than diazinon against nerve function and cholinesterase activity in the sixth abdominal ganglion. This is probably because in the nerve preparations contact between the insecticide and the tissues surrounding the nerve cord, which in whole insects convert diazinon, a thionophosphate, into its phosphate analogue diazoxon, a more active anticholinesterase, was minimized. Indeed, taking into account the evidence of workers who previously compared in vitro the anticholinesterase activities of several thionophosphates with those of their phosphate analogues and found the phosphates much more active, the effect of diazinon on cholinesterase activity and nerve function in our experiments was unexpectedly great. By applying diazinon to nerve cords with SKF 525‐A, a compound likely to prevent oxidation of diazinon to diazoxon, an attempt was therefore made to decide whether diazinon directly affected nerve conduction or whether the effect resulted either from its conversion to diazoxon within the nerve tissue or from impurities in the diazinon used. Results were inconclusive, for SKF 525‐A (p‐diethylaminoethyl diphenylpropylacetate hydrochloride) not only failed to prevent the inhibition of cholinesterase, but interfered with the action of both diazinon and diazoxon on nerve conduction, and itself affected nerve conduction when applied alone. The possibility that diazinon is itself a mild anticholinesterase was not excluded.SKF 525‐A applied to sixth abdominal ganglia at 2 × 10‐4M blocked conduction from cereal nerves to giant fibres in 50–97 min. and at 4 × 10‐5M decreased the post‐synaptic response; applied to giant fibres at 2 × 10‐4M it blocked conduction in 90–208 min. The effects of the larger concentration were not completely reversible. Although SKF 525‐A has been widely used to study the metabolism of drugs, its direct effects on conduction in nerve axons seem not to have been noted previously.
Seed‐transmission in the ecology of nematode‐borne viruses
Authors: MURANT A. F. , LISTER R. M. 
Published: February 2008

SUMMARYVirus‐free populations of vector nematodes can acquire tomato black ring (TBRV), raspberry ringspot (RRV) and arabis mosaic (AMV) viruses from weed seedlings grown from virus‐carrying seed. When soils from fields where nematode‐borne viruses occurred naturally were air‐dried to kill vector nematodes and then moistened, TBRV and RRV occurred commonly in the weed seedlings that grew, but AMV occurred only rarely. Similar tests did not detect tobacco ringspot, grapevine fanleaf or tobacco rattle viruses in weed seeds in the single soil studied in each instance, although these three viruses are also seed‐borne in some of their hosts. Many weed species, when infected experimentally, readily transmit TBRV and RRV to their seed, but the viruses were much commoner in naturally occurring seed of some of these species than of others. These discrepancies between the frequency of seed‐transmission of viruses from experimentally infected plants and the extent of natural occurrence of infected seed seem largely to reflect the host preferences of the vectors.Infective Longidorus elongatus kept in fallow soil retained TBRV and RRV only up to 9 weeks. When weed seeds in the soil were then allowed to germinate, the nematodes reacquired virus from the infected seedlings. Some weed species were better than others as sources of virus. Persistence of these viruses in fields through periods of fallow or fasting of the vector therefore depends on a continuing supply of infected seedlings produced by virus‐containing weed seeds. This is probably less true of viruses like AMV and grapevine fanleaf, which persist for 8 months or more in their vectors (Xiphinema spp.). A few seeds containing TBRV and RRV were found in soils free of vector nematodes, suggesting that the viruses are disseminated in weed seed. This probably explains how TBRV and RRV have reached a large proportion of L. elongatus populations in eastern Scotland.
Intra‐specific mechanisms in relation to the natural regulation of numbers of Aphis fabae Scop
Authors: WAY M. J. , BANKS C. J. 
Published: February 2008

SUMMARYParthenogenetic virginoparous apterae of Aphis fabae Scop. on field beans (Vicia faba) reproduced faster initially in populations of eight colonizing apterae than in those with 2–4 or 16–32 per plant. The aphids were at first mutually benefited but were quickly affected by competition as numbers rose above the critical density represented by about eight apterae and their first progeny. This is because the aphids remained densely aggregated and seemingly created a local shortage despite abundant food and space elsewhere on the plant. Such self‐induced competition provides the basis for self‐regulation of numbers of A. fabae in relation to (1) food and space provided by the growing plant and (2) mortality from natural enemies and from other causes including insecticides.As competition increased, the multiplication of A. fabae populations slowed, newly formed adult apterae emigrated and increasing numbers of alatae were formed. The mean weights of apterae decreased from about 1·8 mg. to 0·3 mg. and of alatae from 0·9 to 0·2 mg. Such decrease probably favours production of many adults that might otherwise fail to mature.Experiments in a glasshouse and in field cages indicated the success with which an A. fabae population adapts to and exploits a growing plant. Field bean plants sown in mid‐March and infested as in the field produced an average of 15,000–17,000 A. fabae emigrants per plant of which 78–84% were adults (mostly alatae). This is equivalent to about 1600 million alate emigrants from 1 acre (0·4 hectare) of an infested field bean crop.
Studies on the fungitoxicity of captan
Authors: RICHMOND D. V. , SOMERS E. , MILLINGTON P. F. 
Published: February 2008

SUMMARYThe cytological changes in Neurospora crassa conidia following treatment with captan at the ED 50 fungicidal dose have been examined by electron microscopy. With dormant conidia the only observable effect of captan was to produce a characteristic convoluted form of the nuclear membrane. It is suggested that this effect may be due to the reaction of captan with the sulphydryl groups of the nuclear proteins leading to an inhibition of cell division. The cytoplasmic membrane was unaffected by captan, confirming that this fungicide does not destroy cell permeability barriers.After incubation in Fries medium, captan‐treated spores showed an almost complete loss of internal fine structure. Similar results were obtained with ‘protoplasts’ of N. crassa which showed disorganization of mitochondrial structure after captan treatment.
Glasshouse experiments on apple scab
Authors: MOORE M. H. 
Published: February 2008

SUMMARYExperiments with fungicide mixtures used protectively and curatively against apple scab showed no advantage from adding phenylmercury chloride (PMC) to certain protective fungicides. Sulphur fungicides greatly impaired the curative activity of PMC, especially in mixtures applied 24 hr. after infection, but captan showed little and dodine acetate no such effect. PMC, however, contributed appreciably to the curative effectiveness of mixtures with captan or dodine acetate. Commercially prepared mixtures of dispersible sulphur with phenylmercury dimethyldithiocarbamate and of zineb with mancozeb gave promising results, and an experimental mixture of dodine/glyodin acetates at low rates was effective protectively and especially curatively.Dodine acetate, dichlofluanid, lime‐sulphur, and isobutyl‐o‐coumarate showed little translocated activity against scab when applied after infection, and PMC, which earlier showed strong translocated activity when applied in summer before infection, was much less effective when applied in spring 24 hr. after infection.Uncontrolled powdery mildew early in the scab‐incubation period greatly reduced the establishment of scab infection on the test plants (clonal root‐stocks); methods of mildew control in such experiments are suggested.
Verticillium wilt of the hop: field studies on wilt in a resistant cultivar in relation to nitrogen fertilizer applications
Authors: SEWELL G. W. F. , WILSON J. F. 
Published: February 2008

SUMMARYIn two large‐scale observation trials on commercial farms inorganic nitrogen fertilizer was applied at 70 lb. N/acre (N1), 1401b. N/acre (N2) and at a normal commercial rate of 210 lb. N/acre (N3). Mean wilt incidence was 60 and 25% less with Ni and N2 respectively than with N3 during 5 years at one site and 3 years at the other. During these periods wilt declined progressively and this was tentatively attributed to the reduced intensity of host colonization, and to progressive declines in soil infectivity resulting from effects on the quantity, quality and longevity of annually produced inoculum.Marked annual fluctuations of wilt incidence and yields occurred at one site and these were associated with weather in the spring and early summer: wilt incidence was inversely related to soil temperature, and yield was directly related to rainfall. Yields were not diminished by the low‐N treatments, but clear correlations between yields and wilt incidence were probably obscured by the differential effects of weather conditions at the three levels of N application.The results emphasized the importance of reducing traditionally high N applications and, on farms where fluctuating wilt is severe, of applying the minimum levels of N commensurate with the maintenance of satisfactory yields.
Studies on pollination and fertilization in the field bean (Vicia faba L.)
Authors: HANNA A. S. , LAWES D. A. 
Published: February 2008

SUMMARYThe percentage of cross‐fertilization in the field bean was found to be around 45%, and to be higher on the lower nodes of the plants than on the upper. No differences in the relative pollen tube growth rates of self and foreign pollen were observed.The different lines and genotypes investigated responded differently to open pollination, selfing with manual tripping, and selfing without tripping.Fertilizer application and date of sowing affected the number of flowers produced and the number of seeds set, but did not affect the ratio of seeds to flowers, i.e. the index of self fertility.
Effects of shading on inflorescence size and development in temperate perennial grasses
Authors: RYLE G. J. A. 
Published: February 2008

SUMMARYSingle plants of S24 perennial ryegrass (Lolium perenne L.) and S215 meadow fescue (Festuca pratensis Huds.) were transferred between, or exposed continuously to, contrasting light intensities obtained by decreasing the natural light in a glasshouse with Tygan shades. Inflorescence development in main shoots was studied by dissections of shoot apices, and by counts of branches and florets when ears emerged. Apical growth was slower, and spikelet initiation and inflorescence development were delayed or inhibited, in decreased light intensities. The number of main branches in the ear depended on the rate of apical growth before and after spikelet initiation, and on the time of spikelet initiation. In meadow fescue these processes were influenced by light intensity. Floret numbers per inflorescence branch were generally decreased by decreased light intensity. Most of the effects of light intensity on inflorescence development were smaller in ryegrass than in meadow fescue.
Insecticidal control of cabbage root fly (Erioischia brassicae (Bouché)) in the axillary buds of Brussels sprouts
Authors: COAKER T. H. 
Published: February 2008

SUMMARYThe occurrence of dipterous larvae in the axillary buds (buttons) of Brussels sprouts was investigated at Wellesbourne in 1963–66. The most severe infestations occurred on early crops harvested in August, in which up to 10% of the buttons were damaged by cabbage root fly larvae. Most of the damaged buttons were on the lower part of the stem and were present on only a small proportion of the plants. Laboratory and field tests of insecticides showed that trichlorphon gave up to 88 % control. The principles involved in an insecticidal control method are discussed.
Laboratory and field tests of zineb and other fungicides against downy mildew of lettuce (Bremia lactucae Regel)
Authors: CHANNON A. G. , WEBB M. J. W. 
Published: February 2008

SUMMARYIn laboratory tests on young lettuce plants, the protection provided by sprays of zineb wettable powder against artificial inoculations with Bremia lactucae was less than that obtained with tank‐mix zineb, and with several other dithiocarbamates and related fungicides.Experiments on autumn lettuce in the field also showed that tank‐mix zineb was more effective than the wettable powder. On winter lettuce in frames, however, zineb wettable powder gave control similar to or better than that given by any of the other materials tested.Infection in most of these outdoor experiments was not heavy. None of the fungicides gave very high control or markedly increased the number of hearted or marketable plants.When zineb wettable powder was sprayed on autumn lettuce at the rate of 2 lb./acre it gave similar disease reductions whether applied in low, medium or high volumes of water.
The effect of a post‐harvest heat‐treatment on the storage behaviour of Cox's Orange Pippin apple fruits
Authors: SHARPLES R. O. 
Published: February 2008

SUMMARYSamples from a wide range of commercially grown Cox's Orange Pippin apple fruits were immersed in water at 45° C. for 10 min. to control rotting due to Gloeosporium spp. In two seasons the incidence of rotting following storage for 19 weeks at 3·3° C. (38° F.) was reduced to about 40% of the level in the untreated samples. However, there was a marked increase in the incidence of breakdown and core flush in the treated fruit, particularly when stored in a controlled atmosphere of 5% CO2, 3 % O2. A similar but less severe increase in the incidence of breakdown was also recorded in the second season in treated fruit stored in 2% O2 (with continuous removal of CO2). The treated fruit tended to develop a more yellow ground colour and softened more rapidly during storage in 5% CO2, 3% O2. It is concluded that the treatment advances fruit senescence and that the increased incidence of physiological disorders is likely to limit the use of this method for the control of Gloeosporium rotting in English‐grown Cox apples.
Strains of Prunus necrotic ringspot virus in hop (Humulus lupulus L.)
Authors: BOCK K. R. 
Published: February 2008

SUMMARYPurified preparations of Prunus necrotic ringspot virus (NRSV) from hop plants formed two light‐scattering zones when centrifuged in sucrose density gradients; the upper and lower zones contained particles 25 mμ and 31 mμ in diameter respectively whose sedimentation coefficients were 79 S and 107 S.NSRV isolates from hop were of two distinct serological types: ‘A’ strains, serologically very closely related to NRSV isolates from apple; and ‘C’ strains more nearly related to NRSV from cherry.The variety Fuggle is tolerant to hop mosaic (not related to NRSV) and different selections of apparently healthy female plants usually contained A strains; but C strains were usually isolated from nettlehead‐diseased plants. Either A or C strains occurred in male plants grown with the hop‐mosaic tolerant varieties. In mosaic‐sensitive varieties (Goldings and Bramlings) apparently healthy female plants tested were usually infected with C strains; either A or C types occurred in mosaic‐sensitive male plants. NRSV was not detected in the seventy‐four hop seedlings obtained from virus‐infected plants.Some varieties developed nettlehead when infected with NRSV (A) or (C) + the hop form of arabis mosaic virus, but not with NRSV (A) or (C) alone. Others developed nettlehead when infected with arabis mosaic virus + NRSV (C) but not with arabis mosaic + NRSV (A).A and C strains can multiply together in the same hop plant. There is evidence of partial antagonism, however, and the fluctuating behaviour of the nettlehead syndrome probably reflects changes in the relative concentration of the two serotypes.
Rates of decay in wood measured by carbon dioxide production
Authors: GOOD H. M. , DARRAH JOSEPHINE A. 
Published: February 2008

SUMMARYThe applicability of two methods of respirometry to measurement of the carbon dioxide output of naturally decaying branches and wood of standing trees was studied. The Warburg respirometer was judged unsuitable for general use on decaying wood. A conductivity respirometer was found satisfactory.Carbon dioxide production was essentially unaffected by fragmentation suggesting that the measurements obtained are likely to be a valuable indication of decay in the intact tree or branch. The carbon dioxide production of samples was fairly stable when conditions were kept constant but responded promptly to increased or decreased moisture. Wood from branches infested with Polyporus tulipiferae in which moisture was increased from approximately 20%–50% (fresh weight basis) increased its carbon dioxide output over a 4‐day period by some seven times. Comparable wood in which the moisture content was reduced from 45 to 20 % showed an almost linear reduction in rate over a similar period to about one‐sixth the original rate.Rate of decay in stained and unstained zones of living trees showed no consistent effect of the stain. However, rates of decay in heart‐rot of poplar caused by Fomes igniarius were only one‐third those reported by Verrall (1937) for decay in culture.