bluuebunny/crossref_metadata_2025 huggingface dataset:
The Influence Of Antiseptics On The Bacterial And Protozoan Population Of Greenhouse Soils: Part I. Naphthalene.
Authors: Jacobs Stanley Edward
Published: February 2008

Summary.

1. The effects of treating cucumber soil, previously air‐dried, with naphthalene, are as follows: (a) The number of bacteria immediately increases rapidly, but very soon decreases again, rapidly at hst, and then more slowly. (b) The development of protozoa is suppressed until most of the naphthalene has disappeared, after which rapid multiplication begins. (c) Ammonia (in an abnormally rich soil) first decreases in amount, and then accumulates to a considerably greater extent.

2. The increased bacterial population is composed partly of organisms which are using the naphthalene as a source of food, and partly of organisms which do not decompose naphthalene.

3. The history of the protozoa in the soil after the disappearance of the naphthalene is one of bursts of activity at irregular intervals. Each period of activity of the amoebae results in a decrease in the numbers of bacteria. The periods of activity of the flagellates are not closely related to fluctuations in the bacterial numbers.

4. The naphthalene‐decomposing bacteria utilise the supply of available nitrogen in the soil; as soon as the supply of naphthalene becomes exhausted, these bacteria attack the organic matter of the soil, resulting in an increase in the amount of ammonia in the particular soil under investigation.

5. The presence or absence of an initial lag in the naphthalene decomposition depends upon the temperature of incubation of the treated soil.

6. Strains of bacteria capable of using naphthalene as their sole source of carbon have been isolated. One of these strains has been shown to produce phthalic acid as an intermediate product in the decomposition of the naphthalene.

7. The reaction of the soil tends to become more alkaline after the disappearance of a quantity of naphthalene. Treatment with a second dose results in a temporary production of acid, which is probably carbonic acid.
Studies on Potato Virus Diseases: IX. Some Further Experiments ON THE Insect Transmission OF Potato Leaf‐Roll
Authors: Smith Kenneth M.
Published: February 2008

Summary.

Experiments bearing on a possible relationship between the leaf‐roll virus and the aphis vector, M. persicae Sulz., are described. The following facts are elucidated by the experiments:

The non‐infective aphis can pick up the virus of leaf‐roll from an infected potato plant after 6 hours' feeding.

The infective aphis is capable of transmitting the leaf‐roll virus to a healthy potato plant after 2 hours' feeding.

The whole process whereby a non‐infective aphis picks up the leaf‐roll virus and infects a healthy plant cannot be performed in 8 hours; a minimum period of approximately 54 hours appears to be necessary.

The incubation period of the leaf‐roll vim in the potato plant, i.e. from the time of infection to the time of the appearance of first symptoms, averages 14 days under the Writer's conditions.

It has not been found possible to infect healthy potato plants with leaf‐roll by needle inoculation with the body juices of infective aphides.

Infection of progressive series of healthy potato plants with virus‐bearing M. persicae showed that the aphides were capable of infecting respectively 6, 7 and 10 healthy potato plants without again having access to a source of leaf‐roll infection. It is noteworthy that occasionally plants in the progressive series of infections failed to develop leaf‐roll, although plants before and after in the series became infected.

The leaf‐roll virus occurring in American potato varieties as exemplified by “Green Mountain,” is as easily disseminated by the aphis M. persicae as the leaf‐roll virus occurring in the British Isles.

Further inoculation tests with five additional species of aphides are described; of these five aphides, two were proved to be capable of transmitting the virus of potato leaf‐roll. These are the potato aphis, M. pseudosolani Theob. and the greenhouse aphis, M. circumfixus Buckt. Negative results were obtained with two other potato aphides, i.e. Macrosiphum gei Koch and A. rhamni Boyer, and one greenhouse apliis A. gossypi Glover.

Illustrations are given of the four chief potato‐feeding aphides in England, together with the greenhouse aphis Myzus circumflexus, which has been proved capable of transmitting leaf‐roll. The chief diagnostic characters of these five aphides are indicated.
Yield Studies in Oats: IV The Influence of Climatic Factors Upon the Growth of A Spring Sown Variety “Record”
Authors: Tincker M. A. H. , Jones Martin G.
Published: February 2008

Summary.

Previously reported studies with oats have been continued. The present paper deals with the rate of growth of the plants in the field in relation to the meteorological conditions experienced in mid Wales. The method employed was to lift plants at weekly intervals and to measure the leaf area and obtain the dry weight of the top growth.

1. It has been shown that the Unit Leaf Rate (measured on the “tops” of the plants only) is correlated with the previous rainfall and also with the temperature, during that period of growth in which the plants are forming new leaves and increasing their leaf area.

2. The relative rate at which the leaf are& increased is correlated also with the previous rainfall; high rainfall ensures leaf development. The rate at which the area increases was negatively correlated with temperature under the field conditions. That is to say that the plant is a cool‐loving cereal.

3. When the relative rate at which the dry weight of the tops increased was employed as the index of growth it was not possible to trace out significant relationships with the meteorological data.

4. A comparison with the correlation studies of other workers is also made. Some of the limitations of the method are pointed out, and brief reference to previous criticisms of similar methods employed by other investigators is made. The method has been shown to provide data of a reliable kind, in the case of field grown plants. Previously no such field studies with our common crops had been made.
ON the Transmission of Potato Leaf‐Roll by Aphides
Authors: Whitehead T.
Published: February 2008

Summary.

1. Evidence is submitted to show that Myzus circumflexus (Buckton) is as efficient a vector of potato leaf‐roll as is Myzus persicae (Sulz). The implications, both practical and academic, of this fact are discussed, particularly in view of the retardation in the development of symptoms shown by plants infested with Myzus circumflexus carrying the leaf‐roll virus.

2. Macrosiphum gei (Koch) only transmitted the disease once and its importance as a field vector is still an open question.

The writer is glad to acknowledge the help given by the laboratory assistant, Mr G. L. Turner, in the above work.
Experiments on the Control of Tomato Leaf Mould (Cladosporium Fulvum) By Fungicides and Fumigants
Authors: Small T.
Published: February 2008

Summary.

1. Experiments have been made on the control of tomato leaf mould (Cladosporium fulvum) by fungicides and fumigants. The results showed that most fungicides gave better control of the disease when Agral I was added as a spreader instead of saponin. Effective control was obtained on pot plants sprayed with ammonium copper carbonate, colloidal sulphur A, and salicylanilide. Preliminary trials on commercial nurseries showed that ammonium copper carbonate and colloidal sulphur A were suitable fungicides for use on glasshouse tomato crops. Further work showed that ammonium copper carbonate was useful for spraying diseased tomato crops.

2. The disease was controlled by the fumigants ethylene dibromide, quinone, and thymol, in laboratory experiments, and by quinone in trials made in a small glasshouse. Further work is necessary to ascertain if quinone fumigation is practicable for the control of tomato leaf mould in large glasshouses.

3. Fumigation with Campbell's sulphur vaporiser protected only the upper side of the leaves from the disease and also failed to kill the spores on the under side of diseased leaves. Experiments made to determine on which leaf surface infection occurs under natural conditions were not successful, but inoculation tests showed that infection may occur on either side of the leaf.

4. It has been shown that large empty glasshouses may be practically freed from infection by fumigation with formaldehyde or sulphur dioxide.
ON the Structure of the Immature Stages of the Frit Fly (Oscinella Frit Linn.)
Authors: Steel A.
Published: February 2008

Summary.

1. The morphology of the immature stages of Oscinella frit are described and figured and certain observations of a biological nature are recorded.

2. The egg is described together with the method of eclosion of the first instar larva.

3. The structure of the larva in its three instars is described in detail with particular reference to the cephalo‐pharyngeal skeleton and the spiracles.

4. The first instar larva differs markedly in structure from that in the two instars which follow. Larvae in the second and third instars are distinguishable, apart from size, only in small structural details.

5. The puparium is described, with particular reference to the spiracles, together with its method of dehiscence during the exit of the imago.
Leaf‐Spot Of Oats, Helminthosporium Avenae (Bri. And Cav.) Eid.
Authors: TURNER D. M. , MILLARD W. A.
Published: February 2008

Summary.

1. The symptoms of the disease are defined. There are two well‐marked phases as described by Ravn (1) on the seedling, (2) on the mature piant. The fist of these is responsible for considerable loss in seedling oats. The second brings about the infection of the grain. Both spot and “stripe” lesions are produced.

2. The disease is especially dependent upon climatic factors. Under adverse conditions the extent and degree of infection is greatly increased, whilst with favourable conditions even plants from infected seed may escape the disease. It is for this reason that the disease assumes serious proportions in northern districts, where an inclement spring is the rule rather than the exception.

3. The causative organism of the disease has been isolated and its pathogenicity verified. It is not pathogenic to wheat or barley.

4. The disease is seed borne by adherent spores and resting mycelium within the pericarp. The percentage infection by spores on a number of commercial samples of Scottish grown oats ranged from 6 to 62 per cent.; the resting mycelium, however, is the more common and the more dangerous type of infection.

5. The infection of the seedling by the fungus has been investigated. The mycelium within the pericarp penetrates the scutellum and the epiblast during the early stages of germination, and this is followed by the invasion of the first, second and third leaves. If the growing point is reached the seedling is killed. Spores are produced abundantly on the dead leaves and initiate the secondary stage on the fifth and subsequent leaves.

No parallel has been found between the mode of infection described and that stated to occur in the smuts. The production of a “stripe” is due to the coalescence of individual spots, and there is, therefore, no analogy between the formation of such lesions and those of stripe on barley as described by Smith.

6. The morphological and cultural characters of the causative fungus have been described and compared with those of other workers. The conclusion is drawn that it is identical with the H. avenae (Bri. and Cav.) Eid., and that whilst its close relationship to H. teres is admitted there are certain morphological and considerable cultural differences between the two species.

7. Control measures for the disease are discussed.
A DISEASE OF THE ARUM LILY CAUSED BY PHYLLOSTICTA RICHARDIAE, N.SP.
Authors: BROOKS F. T.
Published: February 2008

A serious disease of the Arum Lily (Richardia africana) is described, which causes the formation of large brown blotches on all parts of the aerial shoot system.

The cause of the disease is Phyllosticta Richardiae n.sp., a diagnosis of which is given.

Suggestions are made for the control of this disease both under glass and in the open.
STUDIES ON BACTERIA ASSOCIATED WITH THE CHOCOLATE‐SPOT DISEASE OF BROAD BEANS1
Authors: RIKER A. J. , RIKER REGINA S.
Published: February 2008

A bacterium which resembles Ps. seminum Cayley has been isolated from broad beans showing symptoms of chocolate spot in the field. The broad‐bean organism was found to be vigorously pathogenic to broad beans and to garden peas grown in the greenhouse. Two strains have both been passed five successive times through the cycle of isolation, inoculation into broad‐bean plants, the production of disease, and re‐isolation. Further study is necessary before a causal connection between this organism and the disease can be regarded as established.

Temperatures between 20 and 30o C. and high humidity favour infection.

Histological studies of stems which became diseased following puncture inoculations showed the presence of the broad‐bean organism within the vessels, in the intercellular spaces, and inside the cells of the invaded tissue. The tissues about the vessels and immediately under the epidermis seem to be invaded earlier than other tissues.

Bacteriological characters of the broad‐bean organism are described.

A non‐pathogenic strain was found which corresponded in bacteriological characters with the pathogenic strains.
THE GROWTH AND RESPIRATION OF BACTERIA IN SAND CULTURES IN THE PRESENCE AND ABSENCE OF PROTOZOA1
Authors: TELEGDY‐KOVATS L. DE
Published: February 2008

Experiments have been carried out on carbon dioxide production from sand cultures with peptone and glucose solution inoculated with various types of bacteria and protozoa, and with glucose and ammonium sulphate solutions of varying concentrations and C/N ratio. The following results were obtained:

The presence of protozoa increases the carbon dioxide production especially in mixed bacterial cultsres

The increase of carbon dioxide production is greater in glucose solution than in peptone.

A further increase in the number of protozoa has an unfavourable effect on the carbon dioxide production.

The number of bacteria is smaller in the presence of protozoa than in their absence, but the bacterial efficiency is greater and more uniform.

The bacterial numbers and carbon dioxide production are definitely correlated in peptone, but in glucose to a less degree especially in the presence of protozoa.

The reduction of concentrations of glucose from 0–6 to 0–2 per cent. resulted in a greater percentage production of carbon dioxide.

With a lower concentration (0–2 per cent.) of glucose the presence of protozoa causes a greater increase in carbon dioxide production than in higher concentrations (0–6 per cent.).

In the absence of protozoa increasing the C/N ratio had no or only a slight depressing effect on carbon dioxide production.

In the presence of protozoa increasing the C/N ratio is followed by a marked increase in carbon dioxide production.

In bacterial cultures a lessening of the C/N ratio below 10/1 results in a fluctuation of bacterial numbers.

I am indebted to Sir John Russell for his kindness in giving me facilities to carry out the work in this Institution. The work was done in Mr D. Ward Cutler's department, and I take this opportunity of expressing my gratitude for his ever ready help and unfailing kindness. For the culture of Colpidium I am greatly indebted to Miss Jane Meiklejohn of the same department.
A BARK DISEASE OF COFFEE IN EAST AFRICA
Authors: STOREY H. H.
Published: February 2008

A disease of the bark of young leader shoots of arabica coffee occurs in the Usambara Mountains of Tanganyika Territory. The disease may be important when “stumping” is practised in the regeneration of old plantations. A brown sunken lesion, formed of dead extra‐cambial tissues, usually gradually extends and rings the shoots; after a period varying from a few days to several months after complete ringing the foliage above wilts and dies. A leaf spot is also due to the same cause.

The fungus, Fusarium lateritium Nees var. longum Wr., among several isolated from lesions, has been shown to be capable of reproducing the disease by pure culture inoculation. A proportion of the experimental inoculations resulted in the ringing and death of the shoots; many of the lesions, however, after a time ceased to advance and became callused at the margin. Similar recoveries from the disease were observed in the field.

Field observations and experiments demonstrated that a common mode of entry of the fungus into the stem tissues was through freshly exposed leaf scars, and occasionally from a leaf‐spot down the petiole of a leaf. Many shoots also in the field became diseased as the result of the fungus passing to them through the tissues of a stump from the base of a dead shoot.

Coffea arabica alone, of a number of coffee species tested, was susceptible to any extent to this disease.

Excision of the affected bark of a stump was effective in checking the spread of the fungus through the stump. The operation, however, is not considered to offer a practicable means of control in the plantation.
AN ECOLOGICAL STUDY OF CLOSELY CUT TURF TREATED WITH AMMONIUM AND FERROUS SULPHATES
Authors: BLACKMAJST G. E.
Published: February 2008

The changes in botanical composition of closely cut turf (such as that of lawns) which result from the periodic applications of heavy dressings of ammonium sulphate have been followed at five centres during a period of 3 years. These dressings were applied at the rate of 3 lb./1000 sq. ft. (1–2 cwt. per acre) every 2 weeks during the spring and summer months. The applications were “watered in” to avoid injury from a solution of high concentration.

A method of botanical analysis by means of randomly selected quadrats was employed. The changes in botanical composition are expressed as changes in the area covered by each individual species. The data have been treated statistically where possible.

As a result of the treatment the areas covered by the weeds (i.e. all species other than the Gramineae) were greatly diminished. Some species such as Trifolium repens and Achillea Millefolium were more susceptible than others. As an illustration of the order of magnitude of this effect it was found at one centre that there was a decrease in “total weeds” (i.e. the sum of the areas covered by individual species) from 17‐0 to 3–7 per cent., between April and September, of the total area examined. On the control plots the changes were slight.

A reduction in the “total weeds” was associated with an increase in the area covered by the grasses, the dominant species in each case showing the greatest expansion.

In addition to trials with ammonium sulphate, two experiments were carried out, one with ferrous ammonium sulphate and the other with an equivalent mixture of ferrous and ammonium sulphates. It was found that both these treatments produced greater reductions than ammonium sulphate alone. In one case ferrous ammonium sulphate at 10 lb./1000 ft.2 reduced the “weed area” from 12‐5 to 0–3 per cent., while ammonium sulphate applied at an equivalent nitrogen rate, reduced the area from 10‐6 to 5‐0 per cent, during the same period.

The changes of soil reaction show that the view that soil acidity is a pre‐requisite for weed diminution by ammonium sulphate is untenable.

It is suggested that the effect of the ammonium sulphate is due to a differential action of the ammonium ions, which are toxic to the majority of the weeds while increasing the growth of the grasses.

The writer wishes to thank the Secretaries of the Bishop's Stortford, Royal Worlington, Gog and Magog and Stoke Poges Golf Clubs for their help, and also to express his gratitude to Sir Frederick Keeble and Mr Page for their suggestions. Finally, he is indebted to Mr Marmoy of Jealott's Hill for the bulk of the pH determinations.
ON THE GALL MIDGES INJURIOUS TO THE CULTIVATION OF WILLOWS
Authors: BARNES H. F.
Published: February 2008

The bionomics of the bat willow gall midge (Rhabdophaga terminalis H.Lw.), which does serious damage to certain willows grown for basket making and the cricket bat willow grown for sets, have been studied.

The midge exhibits a distinct host‐plant preference, choosing the bat willow (S. coerulea) when possible. But it also breeds readily on a golden willow, S. alba var. vitellina. It will not attack Black Maul (S triandra), Long Skin (S. viminalis) and Dicky Meadow (S. purpurea).

It is shown to be a species which sometimes occurs in epidemic numbers. Intensive cultivation is suggested as a control.
EXPERIMENTS IN ENGLAND, WALES AND AUSTRALIA ON THE EFFECT OF LENGTH OF DAY ON VARIOUS CULTIVATED VARIETIES OF WHEAT
Authors: FOESTEE H. C. , TINCKEE M. A. H. , VASEY A. J. , WADHAM S. M.
Published: February 2008

This paper reports the results of experiments carried out in Surrey and Cardiganshire (lat. 51o 19′ N. and 52o 25′ N.) and a t Werribee in Victoria (lat. 37o 54′ S.) designed to test some Australian and British wheats grown under various periods of illumination. Light of weak intensity (4–5 c.P.) was employed to prolong the daily period.

2. Generally the Australian varieties were “earlier” at all centers under all periods of light than the British.

A sharp distinction between the reaction of spring and winter varieties was observed under short periods of light.

Retardation or omission of floral development was always accompanied by prolonged vegetative vigour. The influence of such treatments upon the longevity of the plants was observed.

Observations are made upon the relationship of the photoperiodic response to the geographic source of varieties.

The results are very briefly considered from the standpoint of the C/N hypothesis and the utilisation of the products of photosynthesis.

Certain economic aspects of the work are indicated.
ON THE BIOLOGY OF THE APPLE SAWFLY, HOPLOGAMPA TESTUDINEA KLUG.
Authors: MILES HERBERT W.
Published: February 2008

The biology of the apple sawfly, Hoplocumpa testudinea Klug., has been under observation for several years in the north‐west of England. Mating and oviposition are described and an account is given of the position of the eggs on the host plant. Usually the eggs are found under the epidermis of the upper surface of the receptacle within the calyx ring, and often within the bases of the stamens.

The incubation period normally varied from 8 to 15 days. During this period the eggs increased slightly in size, and the majority ruptured the epidermis of the receptacle and so became partly exposed within the calyx ring.

The larvae emerge from the eggs on the outside of the fruitlet and proceed to penetrate it either from within The calyx ring, or by passing over the calyx on to the side of the receptacle and tunnelling in from that position. It appears that the larvae seek the ovary but numbers never reach it, and at this stage there may be some mortality among the larvae.

Larvae which reach the ovary feed for a short time on the developing seeds and at about the third instar migrate to older fruits. Circular or ribbon scars appear to be caused by the wanderings of first instar larvae in their first penetration of the fruit.

The larvae are described. They have five instars and a growth ratio of about 1.4. They measure 9–11 mm. when mature.

The larvae over‐winter in cocoons, the majority of those under observation were constructed a t a depth of 3–9 in. in the soil. The pupal period lasts 3–4 weeks.

Notes are given on infestation by apple sawfly in relation to variety and date of blossoming of a number of apple varieties, and the significance of details of the biology of the species on control measures is discussed.
ON THREE NEW VIRUS DISEASES OP HYOSCYAMUS NIGER
Authors: HAMILTON MARION A.
Published: February 2008

The source and general character of three new virus diseases occurring in Hyoscyanzus are described under the names of Hyoscyamus virus (Hy.) 11, 111 and IV. They have a host range of various solanaceous plants not including any variety of potato.

Hy. I1 and 111 are non‐flterable (through L 3) and are transmitted to and from all their hosts except tomato by tEe aphid Myzus persicae. Hy. I11 survives for a relatively short period as clarified juice. Hy. II and Hy. III have many characters in common and are probably closely related.

Hy. IV is a different type of Virus, flterable through an L 3 candle and no insect vector has yet been found for it.

Problems arising from consideration of the data so far accumulated are submitted and discussed.
LIGHTNING STORMS AND THEIR SIGNIFICANCE IN RELATION TO DISEASES OF (1) COCOS NUCIFERA AND (2) HEVEA BRASILIENSIS
Authors: SHARPLES A.
Published: February 2008

This investigation proves that lightning is a factor of the first importance in the causation of disease on coconut palm plantations in Malaya.

The “bud‐rot” symptoms occurring in Malayan coconut palm plantations are produced entirely by lightning or the after‐effects thereof. No evidence of the presence of a Phytophthora has been obtained.

Lightning has been proved to be of some importance in the causation of disease on rubber plantations.

The typical effects on rubber plantations are described, and attention is specially directed to the association of claret‐coloured bark canker at the collar of trees slightly affected by lightning.

The writer wishes to acknowledge the considerable help rendered by his colleague, Mr H. Gunnery, in the preparation of photographs and recording of field work. Thanks are also tendered to Mr H. T. A. Biddle‐combe for great assistance in the coconut investigations and to Mr G. Shelton‐Agar for similar assistance in connection with the work on rubber plantations.
ON THE USE OF THE PRIMARY LESIONS IN QUANTITATIVE WORK WITH TWO PLANT VIRUSES
Authors: SAMUEL GEOFFREY , BALD J. G.
Published: February 2008

The precautions which, should be observed in practical application of Holmes's local lesion method in quantitative work with tobacco mosaic have been examined. The aim has been to obtain results with the greatest statistical significance consistent with the use of reasonably small numbers of plants. The adoption of a standard method of inoculation, and the comparison of viruses on opposite halves of the same leaves, were found to be the most important points to observe, and a method of work has been outlined.

Tomato spotted wilt forms necrotic primary lesions on the leaves of tobacco of a character suitable for quantitative work, and a number of the results obtained with tobacco mosaic have been checked with this virus.

Applications of the method are discussed. It is shown that rapid comparison of virus concentrations from different sources should be possible after further work has been done on dilution curves. An illustration is also given of the application of the method in plotting the curve of “ageing,” or change in virulence with time, of the expressed virus of tomato spotted wilt. This curve was found to be of the logarithmic type.
THE INFLUENCE OF ENVIRONMENTAL CONDITIONS ON THE DEVELOPMENT OF THE ANGULAR LEAF‐SPOT DISEASE OF COTTON
Authors: STOUGHTON R. H.
Published: February 2008

1. Experiments on the influence of variations in the environmental conditions on the bacterial disease of cotton plants caused by Bacterium malvacearum are described.

2. A regular diurnal variation in soil temperature is shown to have the same effect on primary infection of seedlings as a constant temperature near the mean of the fluctuations.

3. The mean soil temperature at the time of sowing and for the first few days of germination is the chief controlling factor in primary infection, other factors being equal. Subsequent variations in the soil temperature have little effect on the incidence of the disease.

4. The amount of disease resulting from infection of the seed, i.e. primary infection, is higher at soil moisture contents approaching saturation than at normal moisture contents in a given type of soil.

5. The amount of primary infection at a given soil temperature and moisture content varies with the type of soil.

6. A regular diurnal variation of air temperature has the same effect on secondary infection resulting from spray‐inoculation of young plants as a constant temperature near to, or slightly above, the mean of the variations.

7. Other things being equal, the amount of infection resulting from spray‐inoculation depends upon the mean temperature prevailing during the incubation period of the disease, the actual temperature at the time of inoculation being unimportant.

8. Atmospheric humidity is a conditioning factor in secondary infection only during a short period (less than 48 hours) following inoculation. Its importance lies in its control of the time during which the infection droplets persist. Once penetration of the tissues has been effected variations in the external humidity have little direct effect.

9. Plants kept in total darkness are relatively resistant to infection.

10. Plants grown in continuous light are no more susceptible than those grown under a daily period of 17 hours' illumination of approximately 1200 foot‐candles.

11. The time of inoculation in relation to the period of illumination does not appear to have any marked effect on the amount of infection.

12. The relations of the whole series of experiments on the influence of environmental conditions are discussed.
STUDIES ON PENICILLIUM CHBYSOOENUM THOM, IN RELATION TO TEMPERATURE AND RELATIVE HUMIDITY OF THE AIR
Authors: GROOM PERCY , PANISSET THERESE
Published: February 2008

(i) Germination and viability of conidia of P. chrysogenum.

1. Conidia were found to germinate in moist air on glass in atmospheres ranging in relative humidity from 100 to 81 per cent, and in temperature from 1 to above 35 but below 40° C, with the optimum temperature lying near 25° C.

2. At constant temperature the latent period of germination generally shortened as the relative humidity of the air rose, and when liquid or gaseous water was replaced by 2 per cent, malt agar.

3. The latent period of germination in water of conidia from old cultures (120 or 210 days old) tended to be longer than that of conidia from young cultures (3 days old). Variations in the intrinsic characters of the conidia caused irregularity in the results which was not shown when the conidia were germinated on 2 per cent, malt agar.

4. Conidia were exposed for periods up to 136 days to atmospheres of temperatures 20 and 30° C. and of relative humidities 72–6, 26 and 0 per cent, (approx.). The percentage germinations in water and on agar within 24 hours, and in water, after submersion for periods up to 216 hours, were determined. No correlation was found between the length of exposure of conidia to various atmospheres and the ultimate germination in water, though during the first 24 hours of germination on agar and in water increased length of exposure generally resulted in decline in percentage germination.

5. Exposure of conidia to atmospheres of 0–100 per cent. R.H. and 1–100° C. showed that conidia possess considerable powers of resistance to heat for temperatures up to 30° C. in atmospheres of relative humidity 0 and 26 per cent, and can live in the latter for more than 129 days; at temperatures above 40° C. the time required to kill the conidia at the same temperature falls with rise in relative humidity, and at the same relative humidity falls with rise in temperature.
THE ECOTYPE CONCEPT IN RELATION TO THE REGISTRATION OF CROP PLANTS
Authors: GREGOR J. W.
Published: February 2008

The ecotype concept as formulated by Tuxesson (1922) postulates the existence, in the wild, of sub‐specific units–ecotypes–which result from the environmental fractionation of a larger population. Details are given of the occurrence of these units in nature.

While the wild ecotypes are not strictly comparable with the agricultural crop units yet the general principles underlying this concept have a definite agricultural application. Suggestions are made for a standard system of crop classification which embodies data relating to the environmental preferences of its units. Two units of agricultural significance are discussed: (1) the agrotype, or ultimate crop unit, and (2) the agro‐ecotype, or groupof agrotypes possessing similar environmental preferences. The measures necessary for the administration of the scheme are briefly outlined.
THE MOVEMENT OF TOBACCO MOSAIC VIRUS IN ITS HOST
Authors: GRAINGER J.
Published: February 2008

1. Experiments on the rate of spread of the virus of tobacco mosaic in the leaves and stems of Nicotiana tabacum L. show that it moves at a logarithmic rate, beginning slowly and later accelerating. The spread seems to be independent of mechanical carriage by the transpiration or translocation streams, and can certainly take place in parenchyma.

2. The virus multiplies in tissue near to the point of inoculation at a logarithmic rate portrayed by an S curve which is also typical of the growth of living organisms and of the rate of accumulation of the catalyst in an autocatalytic reaction.

3. Naturally produced water of guttation from diseased tomato plants does not carry virus infection, but the application of high pressures ruptures the cells of the leaf and gives an infectious liquid.

The author desires to express his sincere thanks to Prof. J. H. Priestley, of Leeds University, for many helpful suggestions and advice, and to Prof. J. Johnson, of the University of Wisconsin, for help in the initial stages of the work. The work has been financed entirely by grants from the Yorkshire Cancer Research Fund.
THE BIOLOGY OF OAT SMUTS
Authors: SAMPSON KATHLEEN
Published: February 2008

The paper deals with microscopic observations on the invasion of a selection of A. strigosa orcadensis by two biological species of U. Kolleri, which differ by nearly 100 per cent, in their capacity for producing smutted panicles on this host. Under certain prescribed experimental conditions both strains enter the oat plant with equal facility, but one is retarded in development and fails to reach the growing apex before the tissues of the primary node become lignined, with the result that the panicles produced are not infected.

The results are discussed in relation to the problem of the inheritance of resistance to smut in oats.
FUSARIUM SPECIES ON BRITISH CEREALS: FUSABIUM NIVALE (FR.) CES. (=?CALONECTBIA GRAMINICOLA (BERK. & BR.) WR.)
Authors: BENNETT F. T.
Published: February 2008

1. F. nivale (?Calonectria graminicola) was commonly present along with one or more other species of Fusarium on the basal parts of oats and perennial rye‐grass that had failed in a field. The pathogenicity of the other species of Fusarium being known from previous investigations, that of F. nivale remained to be ascertained.

2. In wheat, barley, oats and rye, this fungus causes some loss of plants before or after brairding, and it acts as a continuous check on the growth of established plants sown and grown under adverse conditions, whether infection arises from contaminated soil or seed; good growing conditions largely counteract the effects of contamination.

3. F. nivale also attacks ears and grain, preventing grain formation or causing discoloration of formed grains; whilst possible thus to reduce the yield and market value, such attacks are rare in the field.

4. The chief result arising from contaminated soil or seed in practice is a general reduction in vigour, a condition more likely to be attributed to causes other than the true one.

5. Perennial and Italian rye‐grasses on contaminated soils are reduced first in growth; subsequently, the former is largely killed off by the end of the season, but in the field this stage would be reached in the second season.

6. F. nivale grows vigorously within the range of normal summer shade temperature, its optimum being 20–21° C.; it grows slowly at 0–1° C, and in its vegetative state withstands winter conditions, as well as exposure to temperatures as low as – 20° C.; it ceases growth, and loses vitality within a few days, at 32–33° C.

7. In culture the fungus grows on media of hydrogen‐ion concentration from 2–5 to 13, the optimum being 6–5 to 6–9; its conidia do not germinate in media more acid than pH 5–0 to 5–2. Neither the existence nor the pathogenicity of the fungus is appreciably affected by the acid or alkaline condition of soils within ordinary field ranges.

8. Comparative cultural studies of the British and Continental strains of F. nivale show that they differ consistently and significantly in size of conidia, and in form and rate of growth on certain selective media. These morphological and physiological differences are accompanied by difference in pathogenicity, the Continental strain, so far as has been tested, being more virulent toward cereals and less virulent toward grasses than the British strain.

The writer tenders thanks to Dr G‐. H. Pethybridge for helpful criticism of this paper.
OBSERVATIONS ON GROWTH IN LARVAE OF PLODIA INTERPUNCTELLA HUBN.
Authors: MILES MARY
Published: February 2008

Studies on larval growth in four series of P. interfunctella of different provenience, maintained at 21° C. and fed on walnuts, have shown that:

Six larval stadia was usual but development might be accelerated so that larval life was completed in five stadia or retarded so that seven stadia were required.

Number of larval stadia was associated with rate of growth at ecdysis, larvae growing rapidly at each ecdysis having fewer stadia than those growing more slowly.

Duration of larval life was associated with number of stadia and rate of growth at ecdysis, five‐stadia larvae tending to complete larval development in less time than six‐stadia and seven‐stadia larvae.

Duration of the final larval stadium has considerable influence on duration of larval life, and the tendency for the final larval stadium to be prolonged was most pronounced in larvae having seven stadia.

Prolongation of the final larval stadium was frequently followed by failure to attain imaginal development.

Rapid growth and reduction in number and duration of larval stadia are associated with the vigour necessary to pass successfully the several phases of metamorphosis.

Variation in number of larval stadia, rate of larval growth and duration of larval life are the result of acceleration or retardation of physiological processes.

Full details of number and duration of larval stadia, measurements of the width of the head capsule in successive instars and the growth ratios for 74 larvae have been filed at the Department of Economic Entomology, British Museum.
SOME CECIDOMYIDAE ATTACKING THE SEED OF DACTYLIS QLOMERATA L. AND LOLIUM PERENNE L.
Authors: METCALFE MAKGOT E.
Published: February 2008

1. Three species of Cecidomyidae have been observed destroying grass seed on the Park Grass Plots at Harpenden: two species attacking Dactylis glomerata, and the third L. perenne. Of the two species on D. glomerata one has been identified as Gontarinia dactylidis (H. Lw.), the other is described for the first time as Dasyneura dactylidis sp.n. The species present on L. perenne is also a new species and is described as G. lolii sp.n.

2. All three species of midges are single brooded at Harpenden, the larvae overwintering in the soil. D. dactylidis emerges between May 21st and June 6th, C. dactylidis between June 3rd and 24th and C. lolii between May 31st and June 26th. The damage is done by the larvae which feed on the ovary, singly in the case of D. dactylidis, collectively in the other two cases. Parasitism by certain Hymenoptera in 1932 was respectively 42–3, 11–6 and 0–75 per cent.

3. It has not been found possible to cause attack by C. dactylidis on F. rubra or L. perenne. Similarly no infestation by C. lolii was produced on F. rubra, Dactylis glomerata or Alopecurus pratensis. It appears probable that these gall midges are specific in their attack.

4. In a brief discussion of control methods it is suggested that delaying the flowering of the grasses either by grazing sheep or by clipping, or by very early cutting to prevent the development of young larvae, might prove effective.
STUDIES UPON THE COPPER FUNGICIDES
Authors: MARTIN. HUBERT
Published: February 2008

1. To overcome difficulties encountered in the application of Bordeaux mixture as a fine mist‐like spray, two modifications are proposed which may be applied in larger quantities after the manner of an insecticidal wash. By this means the application of the protective fungicide is made easier and more rapid, the wear on the spray pumps may be reduced and difficulties due to the lack of carrying power of the spray are removed. Further, the incorporation of a contact insecticide with the protective fungicide becomes possible, with resultant saving of labour and of time in the routine spraying of fruit and hops.

2. The modifications of Bordeaux mixture proposed are (1) the incorporation of concentrated sulphite lye in the Bordeaux mixture, (2) the glyceride oil emulsion produced by the use of Bordeaux mixture as emulsifier. As examination of the amounts of copper retained on foliage after spraying showed that the presence of oil improves the retention of spray deposit, the content of copper sulphate and lime of the oil‐Bordeaux emulsion was reduced to half that of the Bordeaux mixture used in comparisons of fungicidal efficiency by field trials.

3. The results of field trials show that, under the conditions prevailing in 1931 and 1932, (i) the modified Bordeaux mixtures, applied in heavy amounts, proved as effective as lighter applications of Bordeaux mixture for the control of potato blight, apple and pear scab. In one trial, in which vegetable oil of high free‐fatty acid content was used, the fungicidal efficiency of the oil‐Bordeaux emulsion was below that of Bordeaux mixture containing double the amount of copper sulphate and lime; (ii) the application of large quantities of the modified Bordeaux mixtures did not cause greater leaf injury or fruit russeting than Bordeaux mixture used in smaller amounts; (iii) combinations of nicotine with the modified Bordeaux mixtures gave washes of insecticidal efficiency equal to that of nicotine‐soap wash; (iv) as a result of the use of a spray of larger volume, the application of the modified Bordeaux mixtures was easier and more rapid than that of Bordeaux mixture.

4. A method is described for the estimation of copper retained on sprayed foliage.
THE EFFECT OF RUBIDIUM SULPHATE AND PALLADIUM CHLORIDE ON THE GROWTH OF PLANTS
Authors: BRENCHLEY WINFRED E.
Published: February 2008

1. Comparisons have been made between the action of rubidium sulphate and palladium chloride on the growth of barley, wheat, oats peas and beans in complete nutrient solutions.

2. Over a wide range of concentrations rubidium sulphate was not found to exercise either a beneficial or a harmful action on the growth of any of the species tested. The germination of the seeds was likewise not affected.

3. No benefit was derived from palladium chloride, but at a comparatively low concentration a harmful action occurred which became more intense with increasing concentration. Stunting of the main root and laterals was a characteristic feature of this toxicity. With the lower concentrations the check was temporary, and the roots eventually made normal growth, as good as that in the control plants. With increasing amounts of pallahum chloride the poisoning effect became more persistent, until a concentration was reached which did not allow of any root or shoot recovery.

4. The tolerance of palladium varies with the species, as was indicated b. the measure of recovery. Barley appeared to be the least, and oats the most sensitive of the three cereals tested. Peas responded at much the same concentrations as barley, but broad beans made so complete a recovery from the initial checking that the dry weights were ultimately not reduced even by the strongest concentration tested, the plants being indistinguishable from the controls.

5. The effect of palladium poisoning was similar whether the seeds were germinated in the presence of palladium or whether the seedlings were not introduced to it until they were about a week old.
THE BIOLOGICAL DECOMPOSITION OF PLANT NATERIALS: PART IX. THE AEROBIC DECOMPOSITION OF HEMICELLULOSES
Authors: NORMAN A. GEOFFREY
Published: February 2008

1. The decomposition of the hemicelluloses of plant materials occurs rapidly under normal aerobic conditions. Since a number of fungi have been shown by analyses of pure culture rots to be active in fermenting this group, as well as cellulose, some seventy common fungi, mostly Aspergilli and Penicillia, were tested as to their ability to utilise on agar plates the crude hemicellulose from oat straw.

2. All of the fungi tested grew reasonably well on the hemicellulose medium, the majority at least as well as on glucose, and a number better than on that sugar. In some cases there was production of a cleared zone round the colony due to an exo‐enzyme. It is likely that ability to ferment hemicelluloses will be found to be a general property of common fungi.

3. From soil, manure, and straw, twenty aerobic bacteria were isolated capable of utilising hemicelluloses. Three of these were thermophilic forms. Their morphological characters and biochemical reactions were determined.

4. All the organisms utilised a very wide range of sugars and poly‐saccharides; one group produced some acid and gas, the remainder little. Differentiation was obtained on saccharic acid and certain disaccharide acids.

5. Five of the mesophilic organisms agreed closely with the description of Achromobacter ubiquitum (Jordan). The remainder were aerobic spore‐formers, though not all Gram‐positive. The negative forms may represent new species.

6. None of the organisms in pure culture could validly be described as active in decomposing the isolated hemicellulose, or that in situ in straw.

7. Fungi seem to be more active and important in the natural decomposition of hemicelluloses than bacteria, unless when working in association the rather restricted individual fermentative powers of the latter are considerably enhanced.
OBSERVATIONS ON THE BIOLOGY OF THE LYCTUS POWDER‐POST BEETLES, WITH SPECIAL REFERENCE TO OVIPOSITION AND THE EGG
Authors: PARKIN E. A.
Published: February 2008

1. The life history and habits of the Lyctus powder‐post beetles have been described and the sex ratio determined.

2. External sex characters are given for six species reared from timber at the Forest Products Research Laboratory, Princes Risborough.

3. The male and female reproductive organs of various species are briefly described.

4. An account is given of copulation and oviposition.

5. A detailed description is given of the egg of different species, before and after being laid.

6. The changes in form which probably occur as the egg passes from the calyx to the exterior are described, and evidence is given to support the statements made.

7. The period of incubation of the egg has been determined and observations are recorded on embryonic development and the eclosion of the larva.

8. Special attention is given to the modification of Fisher and Clarke's pore‐size theory to fit the results of the present investigation.
ON THE BIONOMICS AND STRUCTURE OF SOME DIPTEROUS LARVAE INFESTING CEREALS AND GRASSES: II. OPOMYZA GERMINATIONIS L
Authors: THOMAS. I.
Published: February 2008

In the laboratory, the larval food plants of Opomyza germinationis L. are, oate, wheat, barley, Lolium perenne, L. italicum, Dactylis glomerata, Festuca rubra, Poa trivialis and Cynosurus cristata. In the field, only a few larvae were found in the cereals, the chief host plants being the grasses. The injury is similar to that caused by the larva of Oscinella frith.

There are three larval instars and pupation takes place inside the host plant near the ground. Adults emerge in mid‐June and live until early November.

In the laboratory eggs were laid in September and October either on the plants generally near the ground level or on the soil near the seedlings.

A description is given of the three larval instars, the egg and the puparium.