bluuebunny/crossref_metadata_2025_split huggingface dataset:
PHYSIOLOGICAL STUDIES ON THE VERTICILLIUM WILT DISEASE OF TOMATO
Authors: THRELFALL R. J. 
Published: February 2008

The water loss per unit leaf area of tomato plants was decreased after inoculation with Verticillium albo‐atrum. When diseased plants began to wilt water loss temporarily increased, but then rapidly decreased to become less than that of healthy plants grown under conditions of adequate or restricted water supply.The transpiration of excised leaves from plants grown with a restricted water supply was reduced, but not so severely as that of comparable leaves from infected plants. Water loss from leaves on infected plants was reduced irrespective of any blocking of the petiolar xylem.The rate of water loss from turgid leaf disks on mannitol solutions, and the rate of water uptake of leaf disks on water was similar for disks cut from wilting or turgid leaves of diseased plants or healthy plants grown with an adequate or restricted water supply.Disease or poor water supply reduced leaf growth but had no effect on the rate of leaf initiation. Although the density of stomata was higher on leaves of diseased plants the stomatal area was less than on healthy plants.The resistance to water flow in diseased stems was high and was correlated with vessel blockage. About half the blocked vessels contained hyphae. The severity and localization of symptoms in inoculated plants growing on susceptible or resistant rootstocks was directly related to the extent of invasion by the pathogen and to vessel blockage.Experiments on the wilting activity of cell‐free filtrates from cultures of the pathogen in vitro indicated that it produced a stable substance, not an enzyme, that caused wilting in cut shoots by blocking the end of the stem. It is suggested that an increasing internal water shortage causes major symptoms of disease.
HOST RANGE STUDIES WITH FIFTY‐TWO PLANT VIRUSES
Authors: HOLLINGS M. 
Published: February 2008

The reactions of fifteen plant species in families related to the Caryophyllaceae (Hutchinson's classification) when mechanically inoculated with sixty‐eight isolates of fifty‐two plant viruses are described. No general relationship could be detected between susceptibility to particular viruses and taxonomic relationships of the host plants. Some of the species were susceptible to many more viruses than were others. Chenopodium amaranticolor, Gomphrena globosa and Tetragonia expansa were hosts for many viruses and their reactions make them suitable as standard test plants. Amaranthus caudatus, Celosia argentea, Beta vulgaris and Spinacia oleracea had limited use in diagnostic or quantitative work. Dianthus barbatus and Primula malacoides were convenient plants for maintaining stock cultures of some viruses. Phytolacca americana, Stellaria media, Fagopyrum esculentum and Plantago lanceolata had little use, and Portulaca oleracea and Lythrum salicaria were useless as test plants.All fifteen species contained inhibitors of infection; these did not prevent infection on the fifteen species, but many did so in Solanaceous and Leguminous plants.Systemic invasion in some hosts depended on such factors as temperature, virus concentration in the inoculum, virus strain and type of local lesion.Strains of one virus often had different host ranges or caused different kinds of symptoms, while similar symptoms were sometimes caused by different viruses. But some viruses that caused similar symptoms on several of the test plants also shared other properties. Host‐range studies can be used to separate similar viruses or virus strains, and can suggest similarities between viruses for further study. But host‐range studies are unlikely to provide a useful basis for a natural classification of viruses.
THE FRIT FLY AND ALLIED STEM‐BORING DIPTERA IN WINTER WHEAT AND HOST GRASSES
Authors: JEPSON W. F. , HEARD A. J. 
Published: February 2008

Sampling for stem‐boring larvae was undertaken in 1954‐56 on ley plots of Lolium perenne, Dactylis glomerata, Festuca arundinacea, F. rubra, Agrostis tenuis and Poa pratensis in randomized experiments at Hurley, Berks. The samples showed infestations by dipterous larvae, mainly species of Oscinella, Meromyza and Opomyza. The larvae showed preferences for specific grass hosts. More larvae were found where plots had been grazed throughout the season than where an early hay cut had preceded grazing. The total numbers of larvae varied between o and 688 per sq.yd. in November.The larval populations of the leys were reflected in the populations in winter wheat which followed the plough‐up of the leys. Populations of up to sixty‐five larvae per sq.yd., mostly species of Oscinella, were found in the wheat in March. In 1956 a heavy larval infestation was associated with the death of considerable numbers of wheat plants.
SOME PROPERTIES OF BARLEY STRIPE MOSAIC VIRUS*
Authors: KASSANIS B. , SLYKHUIS J. T. 
Published: February 2008

Barley varieties differed greatly in their reactions to infection with barley stripe mosaic virus (BSMV) obtained from the variety Gloire du Velay growing in Cambridgeshire from seed imported from France. Lolium multiflorum Lam., previously considered immune, proved susceptible, as did Beta vulgaris L. and Chenopodium amaranticolor Coste & Reyn., which gave only local lesions, and Spinacea oleracea L. which became systemically infected.Heating at 65° C. for 10 min. destroyed the infectivity and serological activity of BSMV. Sap was still infective after 32 days at 20° C., but lost its infectivity and half of its serological activity in 3 days at ‐ 20° C.; adding sugar to the sap prevented inactivation by freezing. The virus content of inoculated barley leaves increased most rapidly in plants kept at 24–28° C. At 24° C. increase was most rapid during the first 5 days, and the maximum virus concentration was reached about 10 days after inoculation. The highest infection end‐point of sap was 1/2048, when the precipitation end‐point with virus antisera was 1/256, and sap contained 1013 virus particles per ml.: the ratio of infectivity to serological activity and to number of virus particles is much smaller than with tobacco mosaic virus.The rod‐shaped particles are about 20 mμ wide and, in fresh sap, most are between 135 and 175 mμ long. Various treatments, especially heating to 50° C, cause the particles to aggregate linearly. Preparations partially purified by alternate cycles of low‐ and high‐speed centrifugation and by precipitation with ammonium sulphate contain from 0.35 to 0.53% P, 12.3 to 13.2% N and 6.2 to 10.2% carbohydrate. Such preparations are insoluble in water but dissolve in borate buffer at pH 7.5: they inactivate below pH 4.5.
A COMPARATIVE STUDY OF THE GROWTH OF WILD OATS (AVENA FATUA L. AND A. LUDOVICIANA DUR.) AND OF CULTIVATED CEREALS WITH VARIED NITROGEN SUPPLY
Authors: THURSTON JOAN M. 
Published: February 2008

Growth analysis of wild oats (Avena fatua and A. ludoviciana) grown in pots with different levels of nitrogen supply showed many similarities to spring barley, winter oats and winter wheat.Small differences that could affect competition between wild oats and cereals occurred mainly in the seedlings. Wild oat seedlings were smaller than the corresponding cultivated cereals in total dry weight, total nitrogen content, leaf area and number of shoots. However, very young wild oat plants had higher net assimilation rates than the cultivated cereals and soon caught up and passed them. The difference in net assimilation rate did not persist, and in the later stages of growth differences in dry‐matter production depended mainly on differences in leaf area. Another important difference between wild oats and cultivated cereals was that 98–100% of the wild oat seeds and none of the crop seeds were dormant 2 months after harvest.Ear emergence in wild oats spread over a longer period, the range of ear heights was greater and the tallest ears were taller than in the corresponding cultivated cereals. Assimilation in the ear appeared to account for less of the total dry matter of the plants of wild and cultivated oats than of wheat. The wild oats produced more seeds per plant than the cultivated cereals, but the 1000‐grain weight, and hence the total dry weight of seeds, was lower in the weeds than in the crop.Addition of nitrogen to the soil affected the growth of the wild oats in the same ways as the cultivated cereals; they took up the same amount of nitrogen per plant as winter oats and winter wheat but more than spring barley.It is concluded that wild oats are most susceptible in the seedling stage to competition from the crop and that nitrogenous fertilizer applied to an infested field is unlikely to alter the balance between the yields of crop and of wild oats.
STUDIES ON PLANT GROWTH‐REGULATING SUBSTANCES
Authors: VITOU HELEN , WAIN R. L. 
Published: February 2008

The cress‐root test and the maize‐root segment tests, both of which depend on the measurement of root‐growth inhibition, have been used to assess the growth‐regulating activity of a wide range of phenoxyalkanecarboxylic acids. The results are presented and compared with those obtained with the same compounds in other tests in which shoot tissues were employed. The results are also discussed in relation to current theories on mode of action and structure/activity relationship. These studies included the ‘α‐hydrogen’ effect, the activity of stereoisomers and activity of homologues of seventeen series of ω‐phenoxyalkanecarboxylic acids, considered in relation to their degradation within the tissues by β‐oxidation. Earlier findings were largely confirmed. Compounds which had previously been shown to be active in shoot tests such as the wheat‐cylinder, the pea‐curvature and the pea‐segment tests, were found to be active in the root‐growth inhibition tests and, furthermore, the degree of activity was usually similar.It is concluded that the two root tests investigated are of real value in assessing the activity of phenoxy acids in studies on the relationships between chemical structure and plant growth‐regulating activity.
EXPERIMENTS ON THE MODE OF ACTION OF DIELDRIN SEED‐DRESSINGS AGAINST SEEDLING ATTACK BY THE LARVAL FRIT FLY, OSCINELLA FRIT L
Authors: WAY M. J. 
Published: February 2008

Experiments with dieldrin seed‐dressings were done to see whether the conditions favouring their action against wheat bulb fly larvae apply also to frit fly.Experiments with oats and wheat in boxes and a small field trial with oats showed that fewer newly hatched larvae were killed when dieldrin‐treated seed was sown deeply than when sown 1/4 ‐ 1/2 in. deep; shallow sowing probably puts the insecticide where the larvae are likely to meet it before they attack the plant. Kill was never complete even with dieldrin applied at almost forty times more than the highest rate normally used. This is partly because some larvae hatch from eggs on the plant and these, unlike those from soil eggs, can enter the shoot without touching the seed dressing.Even in the most favourable circumstances (large doses of dieldrin applied to the shallow‐sown seed and the plant at the one‐leaf stage at the time of attack) there was little evidence that frit fly larvae are killed inside the shoot by systemic action of dieldrin translocated from the seed. This is not because the pales which normally surround the oat seed impair the uptake of insecticide, or because of any other factor specific to oats. Frit fly larvae also survived in wheat from seed dressed with doses of dieldrin that can kill almost all wheat bulb fly larvae by systemic action. Possible reasons for this difference are discussed.
SOME OBSERVATIONS ON THE CEREAL‐ROOT EELWORM POPULATION OF FIELD PLOTS OF CEREALS WITH DIFFERENT SOWING TIMES AND FERTILIZER TREATMENTS
Authors: HESLING J. J. 
Published: February 2008

In the autumn of 1953 an experiment was begun to follow changes in the cereal‐root eelworm population of small plots on a field in Shropshire. The plots were cropped with either oats, wheat, barley or rye, sown in the autumn and spring, and some plots had fertilizer. Each plot received the same treatment for 3 years; in the fourth year an indicator crop of spring oats was grown on all the plots.Under rye and autumn‐sown wheat the eelworm population fell to a level which permitted a good oat crop in 1957. Autumn‐sown wheat, barley and rye generally produced lower eelworm populations than their spring‐sown counterparts, but autumn‐sown oats proved to be the most efficient host. The order of host efficiency was oats (best), barley, wheat, rye. The eelworm populations were generally higher on plots receiving fertilizer treatment. In this experiment all oat plots, and spring‐sown barley plus fertilizer, produced populations which severely damaged the 1957 oat crop.
STUDIES ON THE DERMESTID BEETLE TROGODERMA GRANARIUM EVERTS: ECOLOGY IN MALT STORES
Authors: BURGES H. D. 
Published: February 2008

Detailed studies on the environment in malt stores and its effect on the Khapra beetle are described. The observations are correlated with the conclusions from parallel laboratory work.Bulks of malt are stored at 26–69° C. and cooling near their centres is slow. After loading, the distribution of heat is controlled mainly by the position of the kiln, the size of the store and the development of Khapra infestations. Three zones of temperature may be recognized, too hot for Khapra (above 40° C.), favourable (30–40° C.) and too cool for rapid breeding (below 30° C.). Population growth may be progressively retarded by cooling, or heat from the kiln and insect‐heating may allow continuous breeding, although part of the malt may be heated above 40° C., causing migration of the larvae. Some migrants stop in a new favourable zone and others continue into the cool zone, often for a long way.The larva is the most prominent stage in most populations. Throughout population growth, low temperature and the accumulation of faecal pellets cause some larvae to enter diapause and hide either in crevices or on the walls just below the malt surface. After the malt is unloaded, huge numbers of larvae may be hidden and some may survive for more than 4 years. Reloading with new, hot malt stimulates some of the cryptic larvae to emerge, pupate and breed. More larvae emerge from the hottest positions than from elsewhere. The very sharp gradient of humidity in stores does not appear to influence larval behaviour. In contrast to unmalted cereals, malt is too dry to allow a significant upward translocation of moisture above a hot region.Control is very difficult. Current methods involve persistent attack on larvae in empty stores with methyl bromide and contact insecticides, combined with structural improvements. Control by cooling the malt before storage is promising.
THE EFFECTS OF SPRAY TREATMENTS ON INFESTATION OF THE OAT CROP BY THE FRIT FLY (OSCINELLA FRIT L.)
Authors: JEPSON W. P. 
Published: February 2008

Criteria are given for the timing and assessment of the effect of sprays on experimental plots, based on biological observations at Silwood Park from 1950 to 1955 and on previous work.A preliminary experiment on small plots in 1952 indicated that ‘blanket spraying’ with DDT and parathion throughout the life of the crop gave protection against both tiller and grain attack. A more detailed replicated plot trial in 1953 showed that for oats planted on 22 April two carefully timed tiller sprays with parathion reduced tiller infestation from 31 to 3%. Six panicle sprays at weekly intervals reduced a heavy grain attack of 60% to 13%. Dieldrin was also effective but significantly less so than parathion. Much of the damage to the crop was caused by weed growth following initial loss of the primary oat shoots.In 1954 and 1955 two and three parathion sprays were applied to 2‐acre fields in order to study recolonization. Despite almost complete control of the tiller generation, a normal evenly distributed infestation of the panicles was found.It is concluded that good control of the tiller generation may best be achieved by a spray programme based on knowledge of the phenology of the fly combined with that of the crop. The first general emergence in early May is likely to be critical.Reinvasion of a sprayed crop may take place within 4–5 days and panicle infestation may not be causally related to tiller infestation in the same field.
STUDIES OF THE BIOLOGY OF SCLEROTIUM CEPIVORUM BERK: HOST RANGE; PERSISTENCE AND VIABILITY OF SCLEROTIA
Authors: COLEY‐SMITH J. R. 
Published: February 2008

In a number of host range tests infection by Sclerotium cepivorum occurred only on Allium spp.Sclerotia of S. cepivorum were almost unaffected by 2 years' dry storage in the laboratory. A high proportion survived for 4 years under undisturbed conditions in the field. There was no effect of soil pH, soil nutrient status, or inorganic supplementation on sclerotial persistence. Organic soil supplements gave variable results, sometimes reducing sclerotial numbers and on other occasions having no effect.Weekly rubbing of nylon bags containing soil and sclerotia caused the latter to disintegrate, but trowelling of soil containing sclerotia had no effect.It is concluded that S. cepivorum sclerotia persist in soil for many years, in the absence of the host plant, and that outbreaks of white rot on rested land could be due to such survival.
STUMP PROTECTION AGAINST FOMES ANNOSUS: TREATMENT WITH SUBSTANCES OTHER THAN CREOSOTE
Authors: RISHBETH J. 
Published: February 2008

Various substances when added to the stump surface in concentrated solution directly after felling markedly affect the course of fungal colonization. The extent to which applications kill stump tissues probably affects the rate at which saprophytes develop.Nitrogenous applications favour growth of Trichoderma viride and Penicillium spp., which tend to suppress surface colonization by Fomes annosus; ammonium sulphamate is especially effective in this respect.Some other applications are initially toxic to stump fungi but rapid leaching from the stump surface soon permits growth of various moulds, which again tend to suppress F. annosus and to a large extent other primary basidiomycete colonizers. Substances of this type include urea, which encourages growth of Ophionectria cylindrospora, and disodium octaborate, which favours Botrytis cinerea. The probable mode of action of these substances is discussed.Stumps usually die more rapidly after such treatments than after creosoting, and often as fast as untreated ones. The rapid colonization of treated stumps by saprophytes is of advantage where application is incomplete or the stump is subsequently damaged. The effectiveness of treatments in preventing a major spread of Fomes annosus from roots already containing the parasite is variable and apparently depends to some extent on the particular species becoming dominant.Preliminary screening may be performed in the laboratory with sections of pine stem inoculated with stump fungi; potential protectants are then tested in the forest.
VIRUSES OF COWPEA, VIGNA UNGUICULATA L. (WALP.), IN NIGERIA
Authors: CHANT S. R. 
Published: February 2008

The cowpea strain of tobacco mosaic virus was isolated from a range of leguminous hosts at Ibadan, but was rare in cultivated crops. Systemic symptoms in species infected experimentally are described.A new virus of cowpea was also found in Nigeria. The physical properties (thermal inactivation point 56° C., dilution end‐point 1/50,000 and longevity in vitro 4 days at 25° C.) differ from those for cowpea viruses reported elsewhere and the name cowpea yellow mosaic virus is proposed. This virus produces local lesions in French bean (Phaseolus vulgaris L.) and local and systemic lesions in Bengal bean (Mucuna aterrima Holland), but does not infect other leguminous hosts. The virus was purified and an antiserum prepared against it.Both viruses are transmitted by a beetle (Ootheca mutabilis Sahlb.) which loses infectivity within 48 hr. of leaving plants infected with either or both viruses.
FIELD TRIALS OF THE EFFECT OF ALDRIN ON CLUBROOT OF SUMMER CABBAGE
Authors: CHANNON A. G. , KEYWORTH W. G. 
Published: February 2008

Field experiments were carried out from 1956 to 1958 on the effect of soil applications of aldrin on clubroot disease of summer cabbage. In the first two seasons the compound was applied either as a dust, broadcast and worked into the soil, or as an emulsion watered round the plants. Results in 1956 were inconclusive and the same plots were used again in 1957, the same quantities of aldrin being re‐applied. In this season increasing doses of the compound gave increasing control of the disease. The treatment of individual plants with emulsion was more successful than the application of dusts.In 1957 half of each plot received a heavy dressing of ground limestone. Lime alone gave a control equal to that given by the highest aldrin treatment. Lime and aldrin together gave a further reduction in clubbing.In 1958 increasing doses of emulsion were tested. These gave increasing control of disease but the higher doses caused some phytotoxicity which was reflected in a delay in maturation of the crop.A reduction of clubbing from ‘severe’ to ‘moderate’ caused a marked increase in crop, but further reductions in clubbing did not result in any corresponding increase in crop weight.
THE INCIDENCE OF CERTAIN SEED‐BORNE DISEASES IN COMMERCIAL SEED SAMPLES
Authors: MARSHALL GILLIAN M. 
Published: February 2008

The incidence of ergot, Claviceps purpurea (Fr.) Tul., in commercial cereal seed samples submitted to the Official Seed Testing Station from 1918 to 1957 has been examined.Rye samples were more frequently contaminated than wheat or barley and no cereal ergots were recorded in oats.A relatively high proportion of ergot‐contaminated rye samples occurred every 8–10 years. This appeared to be associated with high relative humidity and low maximum temperature during June. Similar trends were found for wheat and barley.No varietal differences in susceptibility to ergot contamination were found for rye or barley, but there was some evidence that spring wheat varieties were more frequently contaminated than winter ones.
THE COLIFORM BACTERIA ASSOCIATED WITH POTATO BLACK‐LEG AND OTHER SOFT ROTS
Authors: GRAHAM D. C. , DOWSON W. J. 
Published: February 2008

The biochemical characteristics of twenty‐five isolates of soft‐rot coliform bacteria from different countries are recorded. Because of the variability of the reactions, strains capable of producing potato black‐leg at both low and high temperatures, or at higher temperatures only, cannot be distinguished from one another with certainty by biochemical tests alone. They do, however, give an indication of potential pathogenic reactions. Thus the low‐temperature strains correspond with Pecto‐bacterium carotovorum var. atrosepticum and are distinguished from the high‐temperature isolates by their gas production, rapid fermentation of lactose and maltose, methyl red and Voges‐Proskauer reactions and failure to give a positive indole test.Because of their delayed lactose fermentation the chrysanthemum blight pathogen, the carnation slow wilt organism, the guayule bacterium and the organism causing leaf rot of Philodendron are classified as a new variety of P. carotovorum (Jones) Waldee.The diagnosis of the coliform soft‐rot bacteria should be based on qualitative and quantitative biochemical reactions rather than on host range.