bluuebunny/crossref_metadata_2025_split huggingface dataset:
STUDIES IN PLANT NUTRITION
Authors: STREET H. E. 
Published: February 2008

The addition of an aqueous extract of leaf mould to lettuce and radish plants, grown in sand with inorganic culture solutions, caused significant increases in fresh and dry weights. An aqueous solution of a yeast extract caused significant, though smaller, increases in fresh and dry weights of radish plants. An aqueous extract of ‘bacterized’ peat had no significant effect on the growth of radish and was toxic to lettuce. The organic supplements had no significant effect on oats grown under similar conditions.Neither the beneficial nor the toxic effects of the organic supplements can be satisfactorily explained on their content of auxins active in the Avena test.
STUDIES ON THE PHYSIOLOGIC SPECIALIZATION OF YELLOW RUST (PUCCINIA GLUMARUM (SCHM.) ERIKSS. & HENN.) IN GREAT BRITAIN
Authors: MANNERS J. G. 
Published: February 2008

During 1945‐8, 223 British collections of yellow rust were determined on Gassner & Straib's differential hosts, with the addition of the wheat variety Wilma. Physiologic races 2, 3, 5, 6, 7, 8 and 17 were obtained from wheat, race 46 from barley, race 33 from Hordeum murinum and race 28 from Agropyron repens. Three new races, 6x from wheat, M from H. marinum and G from Dactylis glomerata were also isolated. High temperatures increase the susceptibility of some differential hosts to certain wheat races, but decrease that of others. Biotypes of races 2, 6 and 8, differing from the ‘type’ cultures of those races, were isolated.Of the commoner wheat races, nos. 6 and 8, occurring on many wheats, were widespread, but races 5 and 7, on fewer varieties, were confined to the north of Britain, and races 2 and 3, on very few varieties, to the south. Certain grasses are partially susceptible to some of the cereal races. The uredospores of race 2 germinate less well than those of races 5 or 8, other wheat races being intermediate. The optimum temperature for spore germination of race G is 22‐5 C, that of all other races 10–13oC.Twelve wheat varieties were inoculated in the field with each of the eight wheat races, and some varieties developed field resistance to certain races. The races attacking a variety the most severely in the field inoculations were usually the races isolated from that variety in collections received.
SOME EFFECTS OF HOST‐PLANT NUTRITION ON THE MULTIPLICATION OF VIRUSES
Authors: BAWDEN F. C. , KASSANIS B. 
Published: February 2008

The amounts of tobacco mosaic virus present in systemically infected tobacco plants varied greatly with the mineral nutrition of the plants and were related to the effects on plant growth. With plants in soil, supplements of phosphorus produced the greatest increases in plant size, in virus concentration of expressed sap, and in total virus per plant; nitrogen increased plant size only when phosphorus was also added, and only then increased virus concentration and total virus per plant. Combined supplements of phosphorus and nitrogen doubled the virus concentration of sap and increased the total virus per plant by factors up to forty. Potassium slightly reduced the virus concentration of sap, though it usually increased plant size and total virus per plant. From all plants, only about one‐third of the virus contained in leaves was present in sap. Virus production seemed to occur at the expense of normal plant proteins, and the ratio of virus to other nitrogenous materials was highest in plants receiving a supplement of phosphorus but not of nitrogen.The effects of host nutrition on the production of virus in inoculated leaves resembled those in systemically infected leaves, but were more variable.No evidence was obtained, with plants grown in soil or sand, that host nutrition had any consistent effect on the intrinsic infectivity of tobacco mosaic virus.The concentration of virus in sap from potato plants systemically infected with two strains of potato virus X was not consistently affected by fertilizers; the chief effect of host nutrition on virus production was indirect by altering plant size.
VIRUS DISEASES OF CACAO IN WEST AFRICA
Authors: POSNETTE A. F. , ROBERTSON N. F. , TODD J. McA. 
Published: February 2008

Of the tested plants which are indigenous to West Africa, three species in the Bombacaceae and four in the Steruliaceae are susceptible to one or more of four viruses from cacao, three occurring in the Gold Coast and one in Nigeria. These species are less affected than cacao by the viruses; some show transient leaf symptoms and others are symptomless carriers. The development of spines on the stems of Ceiba pentandra seedlings is suppressed by infection with virus 1 A.In general, the indigenous species are more difficult to infect than cacao, and mealybugs do not become infective as readily when feeding on them as when feeding on infected cacao. The availability of the viruses to vectors seems to be correlated with severity of symptoms, and transmission from infected plants to cacao becomes less frequent with increasing duration of infection. Ceiba pentandra trees were found naturally infected in the Gold Coast and Nigeria. In the Western Province of the Gold Coast, Cola chlamydantha trees in cacao farms and forests were naturally infected with viruses apparently identical with those causing swollen shoot of cacao there.There is little doubt that C. chlamydantha trees are an important source of virus for cacao trees. Whenever possible these and other alternative hosts growing near to cacao should be destroyed.
OBSERVATIONS ON THE BIOLOGY and CONTROL OF CABBAGE ROOT FLY, ERIOISCHIA BRASSICAE (BCHE)
Authors: MILES MARY 
Published: February 2008

In the south‐east of England egg‐laying by Erioischia brassicae Bche began in the third week of April and was at its maximum in the fourth week of April and the first week of May. From then on to early October small numbers of eggs were continually present about brassica crops. Egg counts on cauliflowers at the end of April showed up to 141 eggs/plant and on spring cabbage on 6 May up to 117 eggs; the flies showed no preference for newly set plants. Eggs on the soil were almost exclusively those of Erioischia brassicae; eggs on the plants were mainly those of Pegohylemyia fugax Meig., with small numbers of Erioischia brassicae and Delia cilicrura Rond.Larvae were found continuously from the fourth week of April to mid‐January, those found in December and January were from the previous autumn. Larvae, up to eighty‐one per plant, at the roots of brassica crops were almost exclusively Erioischia brassicae. A few Pegohylemyia fugax and Delia cilicrura occurred, but no Erioischia floralis Fall, were found. A technique for separating larvae from the soil and plant roots is described.Great variation in the size of puparia was noted. Small puparia (4‐4‐5 mm. long) were heavily parasitized by cynipid wasps.In trials on cauliflowers and brussels sprouts the efficiency of calomel dust (4 %) and benzene hexachloride (flea beetle and wireworm dusts) was compared. An application of B.H.C. wireworm dust at 40 lb./acre (approximately 11,000 plants) appeared to have the same efficiency as an application of calomel dust at the rate of 80 lb./acre. The concentration of benzene hexachloride in flea beetle dust applied at rates up to 40 lb./acre (11,000 plants) was insufficient to secure the measure of control given by calomel dust at 80 lb./acre. In 1949 calomel dust remained effective from 2 July, when it was applied, until 30 August when observations ceased.Good growing conditions masked injury and were very important in preventing loss from injury by cabbage root fly.
THE COMPARISON OF SUCTION TRAP, STICKY TRAP and TOW‐NET FOR THE QUANTITATIVE SAMPLING OF SMALL AIRBORNE INSECTS
Authors: JOHNSON C. G. 
Published: February 2008

The sticky trap and stationary aerial ‘tow‐net’ catch insects which alight or fly on to them or are blown against them by the wind. It would be expected that such traps would be inefficient in light winds or in calm weather; and even though their efficiency should increase with stronger winds, errors of unknown magnitude may occur not only in estimations of density and of proportions of species in the air, but also with comparisons of actual catches. These errors are due to unknown degrees of weighting as the traps sample by means of a variable wind from a changing population density. The suction trap, on the other hand, samples a constant quantity of air in all relevant wind‐speeds and does not appear to suffer so seriously from these disadvantages. It also works efficiently in perfectly calm weather when maximum densities of insects are often in the air.The performances of the three traps in the field operating over a range of wind‐speeds are described. Particular attention has been paid to aphids, for which the sticky trap and tow‐net are generally used and for which the suction trap was primarily designed. Density estimates of these insects in winds below about 3 m.p.h. are much larger when calculated from suction trap catches as compared with estimates from sticky trap and tow‐net catches. There is reason for the belief that the suction trap is neither attractive nor repellent to aphids to a significant extent, and that it catches these insects at random by virtue of its air stream alone; weighting of catches due to variable quantities of air being sampled does not occur. It is considered, therefore, that the suction‐trap values of density are likely to be the more accurate ones. Sampling of other small insects is also discussed.
NOTES ON THE FEEDING HABITS OF HOUSE‐RATS IN RANGOON, BURMA
Authors: HARRISON J. L. , WOODVILLE H. C. 
Published: February 2008

During a poison campaign against house‐rats, particularly of the species Bandicota bengalensis, Rattus rattus nr. khyensis and R. exulans concolor, a number of incomplete experiments were carried out on feeding habits and the take of poison.The rats showed a reaction to new objects similar to that of R. norvegicus in England.A marked preference was shown for boiled rice over any other available foodstuff. The amount eaten was roughly proportional to the surface area of the rat. Barium carbonate in boiled rice was an acceptable poison bait, and the optimum concentration of poison was in the range 10–20%.
HOST ALTERNATION IN APHIS FABAE SCOP. I. FEEDING PREFERENCES AND FECUNDITY IN RELATION TO THE AGE AND KIND OF LEAVES
Authors: KENNEDY J. S. , BOOTH C. O. 
Published: February 2008

The feeding preferences and comparative fecundity of laboratory‐bred, alienicolae alatae of Aphis fabae were investigated in small leaf cages on spindle and sugar beet leaves, representing a winter and a summer host respectively, both in pots in the greenhouse and while growing naturally outdoors.The aphids' readiness to stay and feed, and their average reproduction rate, both varied between leaves of different ages and kinds, and there was evidence of true fecundity differences among aphids feeding on different leaves. As a general rule, readiness to settle and reproduction rate varied together in the same sense, but they did so significantly less often in comparisons between leaves of different kinds, spindle and beet, than in comparisons between leaves of one kind only. Among the leaves on the same kind of plant, the aphids preferred to feed and reproduced faster, on the whole, on young and early senescent leaves than on mature ones. To a limited extent, this rule seemed to govern also the aphids' comparative readiness to settle and reproduce, as between leaves of the two different kinds of plant. Allowing for age‐differences among the leaves, the aphids settled and reproduced better on spindle than on beet leaves. Since the aphids used were alienicolae, this tends to confirm the usual designation of the winter host as primary and the summer hosts as secondary, for a given aphid species.These findings form the basis of a dual discrimination theory of host selection, which assumes that aphids respond behaviourally to at least two main classes of leaf property: one associated with the age of the leaf and the other with the kind of plant. It is suggested that in nature these two sensory requirements of the aphids may be essentially contradictory, and that the shifting patterns of aphid distribution among leaves and plants may depend on the shifting distribution of leaves offering a satisfactory compromise between them. The phenomenon of host alternation is considered in the light of the dual discrimination theory, as a particular instance of a shifting distribution‐pattern probably connected with the alternation of the seasons of active growth and senescence in the winter and summer host plants.
AGGREGATION IN APHIS FABAE SCOP. I. AGGREGATION ON PLANTS
Authors: IBBOTSON ALAN , KENNEDY J. S. 
Published: February 2008

A study of free infestations of Aphis fabae Scop. on the leaves of its host plants, spindle and sugar beet, showed that the clustered distribution of the aphids within the boundaries of each leaf was not a matter of chance but involved active aggregation. Experiments in small leaf cages showed that aggregation could take place independently of any differences between portions of a leaf, being brought about by truly gregarious reactions between the aphids. Experiments in which walking aphids were made to encounter other live or dummy aphids fixed to leaves, showed that the gregarious reactions were of at least two kinds. The aphids both probed more often, and remained inserted for longer, near other aphids than apart from them.It appears that the unequal distribution of aphids among the leaves of a plant is due primarily to intrinsic differences between leaves, but is aided by gregariousness, while the aggregations observed on leaves are due primarily to gregariousness, and only secondarily to differences between portions of a leaf. It is suggested that the primary function of gregariousness is to concentrate the aphids on to the best feeding sites, both among the parts of a plant, and among whole plants; that is, it acts as an aid in host selection, even with aphids which do not aggregate so compactly as A. fabae. The functions of compact aggregation and other specialized forms of gregarious behaviour remain to be discovered.
THE POTATO TUBER NEMATODE, DITYLENCHUS DESTRUCTOR THORNE, 1945; THE CAUSE OF EELWORM DISEASE IN BULBOUS IRIS
Authors: GOODEY J. BASIL 
Published: February 2008

For about twenty‐five years a fairly widespread disease of bulbous iris has been known, the cause of which has always been attributed to a biologic race of the stem eelworm Ditylenchus dipsaci (Kühn, 1857), Filipjev, 1936.Thorne (1945) showed that the nematode causing rot in potato tubers is different from D. dipsaci and named it D. destructor. This nematode has since been reported from Mentha arvensis L. by Hurst (1948) and from Sonchus arvensis L. by Goodey & Goodey (1949).Examination of nematodes from diseased iris bulbs showed them to possess rounded tail tips and six incisures on each lateral field; characters by which Ditylenchus destructor is distinguished from D. dipsaci.Cross‐inoculation experiments showed that the eelworm causing disease in potato tubers would invade and set up characteristic symptoms in iris bulbs and, in the opposite direction, the eelworm responsible for disease in iris bulbs would give rise to characteristic symptoms in potato tubers. Transfer was also effected from potato and iris to Mentha arvensis and from iris to Sonchus arvensis.The history of the disease in bulbous iris is briefly reviewed and the biology of Ditylenchus destructor discussed and compared with that of D. dipsaci.The conclusion that D. destructor is the nematode causing eelworm disease of bulbous iris has been reported earlier (Goodey, J. B. 1950).
THE INSECTICIDAL ACTIVITY OF PARATHION, ITS ISOMERS AND SOME RELATED COMPOUNDS
Authors: WOODCOCK D. , STRINGER A. 
Published: February 2008

Heat treatment of parathion at 140° C. and above resulted in isomerization and then thermal decomposition; the loss of toxicity to Calandra granaria being correlated with a reduction of the thiono‐sulphur content. Similar results were obtained with O:O‐dimethyl‐(4‐nitrophenyl)‐thiophosphate. Paraoxon, O:S‐diethyl‐(4‐nitrophenyl)‐thiophosphate, and O:O‐diethyl‐S‐(4‐nitrophenyl)‐thiophosphate, although all possessing considerable contact activity, were less insecticidal than parathion; O:O‐dimethyl‐(4‐nitrophenyl)‐thiophosphate, on the other hand, was considerably more effective than parathion. O:O‐bis(2‐chloroethyl)‐O‐(4‐nitrophenyl)‐thiophosphate was considerably less toxic than parathion and appeared to have a different mode of action. Compounds, S‐ethyl‐bis‐(4‐nitrophenyl)‐thiophosphate, O‐ethyl‐bis‐(4‐nitrophenyl)‐thiophosphate, and triethyl thiophosphate were ineffective as contact insecticides.In the series of compounds examined, replacement of the group P = S by P = O or alteration in size of the groups attached to the central phosphorus atom caused a reduction of insecticidal activity.
THE CONTROL OF WIREWORM BY GAMMA BENZENE HEXACHLORIDE: THE DEVELOPMENT OF A SEED DRESSING FOR CEREALS
Authors: JAMESON H. R. , THOMAS F. J. D. , TANNER C. C. 
Published: February 2008

Gamma benzene hexachloride has been used successfully as a seed dressing in field trials for wireworm control. For application to cereals at 2 oz./bushel, the optimum concentration of γ‐isomer was 20–30 % in a dressing which advantageously included an organomercurial seed disinfectant.Risks to germination and plant growth were thoroughly explored in the field. The 20 and 30 % dressings were safe; over‐strength dressings containing 50 or 70 %γ‐B.H.C. did not reduce grain yields significantly.Seed dressed with 20 or 30 %γ‐B.H.C. germinated normally after storage for 12 months. When seed was dressed at 4 oz./bushel with 35 %γ‐B.H.C. and 1 % mercury as organomercurial, germination was delayed but total emergence was not affected.
THE EFFICIENCY OF CHEMICAL TREATMENTS OF VEGETABLE SEEDS AGAINST SEED‐BORNE AND SOIL‐BORNE ORGANISMS
Authors: JACKS HARRY 
Published: February 2008

Out of thirty‐four newer fungicides tested in greenhouse and field trials, red cuprous oxide (Cuprocide), tetrachloroparabenzoquinone (Spergon), methyl mercury dicyandiamide (Panogen), tetramethylthiuram disulphide (T.M.T.D.), ferric dimethyldithiocarbamate (F.D.D.), zinc trichlorophenate (Dow 7B) and 1‐p‐sulphamylphenyl‐3:5‐dimethyl‐4‐nitrosopyrazole (36L) were selected for detailed investigation on lettuce, pea, French bean, turnip, red beet, tomato and celery. Derivatives of dithiocarbamic acid, and 36L and Spergon among non‐metallic compounds compared favourably with cuprous oxide and organomercurial compounds. Addition of hormones, insecticides or nemacides did not improve emergence. Soil tests were more satisfactory than laboratory selection. Rates of application recommended by manufacturers often injured small seeds, and the optimum dosages were determined by extensive tests.Results obtained depended on conditions of test. Under glass, emergence was lower at 5–12° C. than at 16–20° C. Emergence was optimum at 45 % water‐holding capacity, and additional tests are required at higher and lower moisture to assess phytocidal and protectant action.In field trials seed treatments were generally most beneficial in cool and moist soil, and improved emergence in all but driest soil. T.M.T.D., Spergon and 36L were the most effective seed protectants. Mixing of these materials did not improve emergence. Emergence in relatively dry soil (25 %w.h.c.) was improved by watering after sowing, but emergence was decreased in moist soil by watering within 2 days of sowing.A seed‐borne form of Rhizoctonia solani was isolated from most seeds. Pythium, Rhizoctonia and Fusarium were commonly isolated from seedlings. Pythium was commoner at low and Fusarium at higher temperatures. Surface disinfection of seed by Spergon and Panogen compared favourably with acidulated mercuric chloride. Ascochyta on pea seed was not controlled, but all treatments except Cuprocide improved emergence of spotted pea seed. T.M.T.D., 36L and Spergon were the most efficient in controlling pre‐emergence damping off. Seed treatment was more beneficial for pea than other vegetables, but emergence was usually improved by protectants except for turnip and celery seed.Treated seed stored dry for 10 months gave better emergence than untreated seed, and showed no evidence of diminished germination.
BACTERIAL WET ROT OF POTATO TUBERS FOLLOWING PHYTOPHTHORA INFESTANS
Authors: DOWSON W. J. , JONES D. RUDD 
Published: February 2008

Potato tubers infected with Phytophthora infestans in the field produce abnormal amounts of liquid which often appear on the surface of tubers kept in a saturated atmosphere. Under these conditions a soft rot, associated with bacteria, develops.Healthy tubers artificially infected with pure cultures of P. infestans produce a similar liquid and, if further inoculated with pure cultures of certain bacteria, develop a wet rot which spreads if the bacteria are pathogenic or is confined to the zone of fungal invasion if the bacteria are saprophytes.Sap extracted from Phytophthora‐infected tissue contains more sugar and has a greater osmotic pressure than sap extracted from healthy tissue. Thus, water may be withdrawn from healthy tissue which would result in the infected tissue containing more liquid than does the healthy tissue.
THE EFFECT OF INFECTION WITH BEET YELLOWS AND BEET MOSAIC VIRUSES ON THE CARBOHYDRATE CONTENT OF SUGAR‐BEET LEAVES, AND ON TRANSLOCATION
Authors: WATSON M. A. , WATSON D. J. 
Published: February 2008

The loss of total carbohydrate (sugars and starch) per cent of residual dry matter (dry matter less total carbohydrate) during a period of darkness from leaves of sugar‐beet plants infected with yellows virus was as great as that from the leaves of healthy plants. The conclusion of previous workers, based on the results of the Sachs iodine test for starch and the occurrence of ‘phloem gummosis’ in infected plants, that starch accumulates in infected leaves because translocation is prevented by blockage of the sieve‐tubes, is therefore incorrect.Older leaves of infected plants had a higher content of reducing sugars and sucrose, and usually but not invariably of starch, both at the beginning and end of the dark period, than comparable leaves of healthy plants. By far the greater part of the increase was in reducing sugars. In leaves taken in late September from infected plants growing in the field, 20 % or more of the total dry matter was present as reducing sugars. The reducing sugars in both healthy and yellows‐infected leaves were shown by paper chromatography to be glucose and fructose in approximately equal amounts.Accumulation of carbohydrate in infected leaves is probably not a passive consequence of differences in carbohydrate production, distribution and utilization, but is attributable to changes in the physiology of the cells of the leaf.The carbohydrate content of sugar‐beet leaves was little affected by infection with beet mosaic virus.Yellows‐infected leaves had a lower water content per cent of fresh weight than healthy leaves. This was accounted for by the higher carbohydrate content of infected leaves, for the ratio of water: residual dry matter was not affected by infection or was slightly reduced. This implies that hydration was independent of carbohydrate content.