bluuebunny/crossref_metadata_2025 huggingface dataset:
ON THE CAUSES OE SWARMING IN THE HONEY BEE (APIS MELLIFERA L.): AN EXAMINATION OF THE BROOD FOOD THEORY
Authors: MOBLAND D. M. T.
Published: February 2008

Summary

The influence of nitrogenous food in the hive is discussed in its bearing on the question of swarming.

Theories of the origin of the brood food are examined.

The division of labour among the bees of various ages is considered in its relation to the brood rearing cycle.

A critical surplus of nurse bees is found to be associated with the formation of queen cells in preparation for swarming.

Eecognised swarm control measures are reviewed in the light of the brood food theory.
Studies On Potato Virus Diseases VIII. On A Ringspot Virus Affecting Solanaceous Plants
Authors: Smith Kenneth M.
Published: February 2008

A ringspot virus affecting solanaceous plants is described. This is the first record of the disease in the British Isles.

The reactions of the following solanaceous plants to the ringspot virus are described S. capsicastrum. S. tuberosum (potato). S. laciniatum. S. nigrum (black nightshade). S. nodiflorum. Lycopersicum (tomato). Nicotiana tubacum (var. (a) White Burley, (b) Virginia). N. glauca. Datura stramonium (jimson weed). Capsicum spp.

The close parallels in the behaviour of the ringspot to the viruses of the potato mosaic group are emphasised. The virus is able to exist in a variety of symptom expressions according to species of host plant and degree of virulence. “Ringspot” is thought to be an alternative symptom expression for a number of mosaic viruses, the development of the ringspot symptoms probably depending upon the degree of virulence of the virus, the type of host plant and the method of infection of that host plant.

A marked difference in receptivity of the various solanaceous plants to the ringspot virus when transmitted by the aphis M. persicae is shown to exist. The virus was transmitted by means of this aphis to D. stramonium and Capsicum and not to the other species.

The phenomenon of temporary recovery of tobacco plants affected with the ringspot in its virulent form is well illustrated. Plants die down and then re‐grow for a period, temporarily symptomlees, only to succumb once more to a severe attack. This may happen two or three times before the plant finally remains in a necrotic and moribund condition.

In no case was the virus transmitted through the seed of affected plants.
Pasture Production In Areas Liable To Infection By Oncopera Intraicata (Walder) In Tasmania
Authors: Nelson Alexander
Published: February 2008

Summary.

The replies to a questionnaire sent out to a large class of sheep owners and pastoralists in Tasmania indicate: (1) that Oncopera intricata (Walker) is a pest of first‐class economic importance in the State of Tasmania, precluding as it does successful pasture production over large areas of the country; (2) that grasses with a mechanism for natural vegetative propagation, e.g. stolons, etc., are likely to persist through a severe attack and by their recovery after the pupation of the grass‐attacking larvae provide some return rather than allow the ground to go out of production or be covered by unprofitable weeds; (3) the replies plus external evidence show that a sward of creeping grasses and clovers will be likely to be most useful.
The Stem And Buld Eelworm, Tylenchus Dipspaci (Kuhn) Bastian. A Further Conteribution To Our Knowledge Of The Biologic Strains Of The Nematode
Authors: Hodson W. E. H.
Published: February 2008

Summary.

1. The significance of the occurrence of biologic strains in T. dipsaci is discussed and reference made to previous work on the subject,

2. The technique by which the nematode may regularly be induced to set up an infestation in a favoured host plant is described, as is its application to the experiments made.

3. Experimental results obtained when fourteen strains of the nematode, of known history, are given facilities for entering alien host plants are presented in detail.

4. The conclusions arrived at are, that biologic strains of T. dipsaci occur, but that these strains are in some cases able to attack more than one host plant. Further, some affinity appears to exist between strains occurring in the narcissus and in the common plantains.

5. The practical application of our knowledge, in the event of a crop being attacked by the nematode, is discussed.
Gibberella Saubinetii (Mont.) Sacc. on British Cereals: II. Physiological AKD Pathological Studies
Authors: Bennett F. T.
Published: February 2008

Summary

G. Saubinetii (Mont.) Sacc., the conidial stage of which is known as Fusarium graminearum Schwabe, produces mature perithecia on natural and artificial substrata, given ample moisture and a uniform temperature of 21° to 22°C. British summer shade temperature does not suffice for this.

The minimum temperature for the germination of conidia and ascospores is about 6°C. Between 5° and 10°C. both kinds of spores develop mycelia, and the fungus can infect cereal seedlings. The optimum temperature for vegetative growth of the fungus and the production of mature perithecia is about 24° C.; the maximum temperature for growth is about 37°C.

In its vegetative and perithecial stages this fungus can withstand prolonged exposure to a temperature range of — 1° to — 20°C. and in its vegetative stage it persists through the winter in this country.

Under storage conditions it retains its vitality for at least two years in its vegetative stage, and for at least one year (probably much longer) in its perithecial stage.

Heating to 100°C. for five minutes under dry conditions kills G. Saubinetii on or in diseased grains, but this treatment of seed grain is not a practicable way of controlling the disease.

G. Saubinetii causes “seedling blight” and “foot rot” of cereals, but is much less virulent than .F. culmorum and F. avenaceum in this respect. All three fungi attack the ears in a similar way, with similar virulence and with similar results.

G. Saubinetii occurs throughout England and in Ireland, but full details of its frequency of occurrence in the British Isles have not yet been obtained.
Extracts of Pyrethrum: Permanence of Toxicity and Stability of Emulsions
Authors: Tattersfield F. , Hobson. R. P.
Published: February 2008

Summary.

1. Pyrethrum flowers (Chrysanthemum cineraraefolium) both as whole heads and as powder retain their insecticidal properties at ordinary temperatures and at 28°C. for considerable periods if stored in closed vessels. If exposed to the atmosphere in a thin layer as finely ground powder there is risk of loss of toxicity.

2. Alcohol and petroleum extracts of pyrethrum retain their toxicity in temperate climates over many months. Alcohol extracts readily give permanent emulsions when added to water; petroleum extracts require the incorporation of an emulsifier.

3. Water‐miscible petroleum extracts of pyrethrum can be prepared by the addition of certain materials, such as ammoniated Agral W.B. and neutral turkey‐red oil.

4. A study has been made of the degree of permanence of the active principles in alcoholic and water‐miscible petroleum extracts at ordinary British temperatures and at 28°C. and also in emulsions of these extracts in alkaline spray fluids of varying PH. The active principles proved more permanent than has been usually supposed.

5. The readiness with which water‐miscible petroleum extracts disperse in the aqueous phase and the stability of the emulsions formed under a variety of conditions have been investigated.
Experiments on Potato Sickness
Authors: Cheal W. F.
Published: February 2008

Summary.

Following results already published of the effect of inoculations on potato plants with Heterodera schachtii and Corticium Solani in 1928 and 1929, further pot experiments were carried out in 1930 with an additional organism Colletotrichum atramentarium. The results showed a definite effect, the fir& year of inoculation, in those pots where Heterodera schachtii was present.

There was not enough evidence to support the view that the absence of Colletotrichum atramentarium in the 1928 inoculations accounted for the slight symptoms of potato sickness produced that year compared with results obtained in 1929 (the second year).
The Formation Of Intracellular Inclusions In Solanaceous Hosts Infected With Aucuba Mosaic Of Tomato1
Authors: SHEFFIELD F. M. L.
Published: February 2008

Summary

A description is given of the mode of formation of intracellular inclusions produced by aucuba mosaic of tomato in Solanum nigrum, S. nodiflorum, S. lycopersicum, Nicotiana tabacum and Hyoscyamus niger.

Soon after infection the rate of streaming of the cytoplasm is increased, then minute particles of protein appear in the cytoplasm which carries them passively about the cell. These particles aggregate and fuse to form large masses which are still carried passively but more slowly about the cell. These fuse until all the protein material is contained in one or occasionally more granular masses. In the three Solanum species examined this mass becomes rounded and it may lose its granular appearance and become vacuolated. In N. tabacum the body does not always round off and in H. nip it very seldom does so but remains as an irregularly shaped granular mass which may, however, become vacuolate.

There is no evidence at any time of autonomous movement, the particles and the fully formed body being carried, as are the cell nucleus, mitochondria, etc., of the normal plant, in the cytoplasmic stream.

After the spherical body is formed spike‐like crystal appears in the cell.

The cell remains at rest for the space of several weeks. Often the rounded inclusion body and the nucleus are juxtaposed, but there is no special significance in this, it is merely the accidental result of the mode of formation of the body. Particles tend to accumulate where number of strands of plasm meet; usually several strands converge on the nucleus.

Ultimately the body breaks down giving number of protein crystals. After some months these dissolve. In H. niger the inclusion bodies are confined to the chlorotic areas where they are abundant in all tissues. In the other species studied they are distributed over green and yellow tissues. They are very abundant in the hairs, less so in the epidermis and very rare in the palisade and spongy tissues. In H. niger the development of the palisade tissue is arrested, in the other species the development is not so obviously affected although growth is retarded.

These inclusions appear not to be organismal in nature; they seem to be products of reaction of the host cell to the virus, but they may contain the etiological agent of the disease.
Some Experiments On Inoculating Methods With Plant Viruses, And On Local Lesions
Authors: SAMUEL GEOFFREY
Published: February 2008

Summary.

It is shown by means of dilution tests that a light rubbing with virus, in which no visible wound is produced on the leaf, is a more effective method of mechanical inoculation than scratching with a needle in the case of the five viruses: cucumber mosaic, spot necrosis, tobacco ring spot, petunia mosaic, and yellow tobacco mosaic, all inoculated on to tobacco. The contentions of Holmes with regard to inoculating methods with tobacco mosaic are thus extended to these other viruses.

Some of these viruses form local lesions of a definite type which may prove to be of value in quantitative work. It is shown that temperature, age of the leaf inoculated, and other factors influence the character and the number of the local lesions formed.

The development of the virus in the inoculated leaf (the “primary phase” before systemic symptoms become visible), as well as certain later stages, can be followed particularly well in the case of yellow tobacco mosaic, using the iodine method for demonstrating the areas of normal starch formation (Holmes, 1931). In an area closely corresponding to where the virus has spread, starch formation is inhibited, so that the path followed by the virus shows up as a light‐coloured area in the treated leaves. An intimate relation between the vascular system and the path of travel of the virus is made strikingly evident by this treatment.
The Biology Of Thysanoptera With Reference To The Cotton Plant: VII. The Relation Between Temperature and Relation and the Life Cycle
Authors: MACGILL ELSIE I.
Published: February 2008

Summary.

1. It is found that in the development of T. tabaci the degree of atmospheric humidity is of great importance in the question of the survival of the larva.

2. At high temperatures a relatively high degree of atmospheric humidity (over 70 per cent.) is necessary if the insects' are to reach maturity.

3. Although temperature has a most marked effect on the length of the life cycle of T, tabaci, the degree of relative humidity appears neutral, neither accelerating nor retarding the development of this insect.
Pyrethrum Flowers: A Quantitative Study Of Their Development
Authors: TATTERSPIELD F.
Published: February 2008

Summary.

An account is given of the examination of the flowers of pyrethrum plants (C. cinerariafoolium) grown upon a bed in Harpenden. The plants were divided into blocks and randomised, the flowers being harvested from a dozen plants each week over a period of 81/2 weeks, the flower heads ranged from the small bud stage in the first week to the overblown stage in the last week. The categories into which the flowers were divided to indicate maturity are defined and illustrated.

The yield in numbers and weight of heads per plant, the diameters of the receptacles and the content of pyrethrin I and II were determined. There was a considerable amount of variation in all these factors in the flowers from different plants.

A statistical analysis showed in this experiment:

That there was no significant variation in the numbers of the flowers with time, but that position of the plant in the bed had a significant effect.

That the time of harvesting had a significant effect upon the content of the pyrethrins whether taken separately or together and whether expressed in percentages, parts per flower head or parts per plant. The effect due to‐ position was only definitely significant in the case of pyrethrin I when expressed in parts per flower head.

That there was on the different dates a significant correlation between the contents of pyrethrin I and II expressed in parts per flower head or plant.

That there was, for the blocks of material examined, a significant correlation between the contents of pyrethrin I and II, whether expressed in percentages, parts‐per head or parts per plant, but that owing to the heterogeneity of the material the correlation was only significant for individual plants when the pyrethrias were expressed in parts per plant.

The data in this experiment indicate that for the material examined, there is a quantitative development of the active principles in the flower heads from the small bud stage up to the time of maturity of the flowers, which more than keeps pace on the whole with the increase in weight of the flowers. Thus the content of pyrethrins, both relatively and absolutely, rises to a maximum at the maturity of the flowers. The mean percentage content of pyrethrins fell after pollination and the fading of the flowers; this corresponds with the rapid increase in weight of the heads on the formation of seed. There would thus appear to be a loss, which might be serious, both in percentage content of active principles and in yield of flowers if harvested before being fully open. There seems to be no useful purpose served in leaving the flowers to the overblown condition.

I wish to express my great indebtedness to Dr R. A. Fisher and Dr J. Wishart for carrying out the greater part of the statistica.1 analyses incorporated in this paper and for much helpful advice. I am also indebted to Mr J. T. Martin for checking many of the analyses by an alternative method.
THE FILTRATION OF THE VIRUS OF STREAK DISEASE OF MAIZE
Authors: STOREY H. H.
Published: February 2008

Experiments have been carried out in the feeding of leafhoppers timragh membranes upon the juice of streak‐diseased maize plants after passage through various filters. Tests of these leafhoppers have shown that at a pH of about 6 the virus passes through Chamberland LI, Berkefeld V and N niters, and less freely through Chamberland L3. Hie virus does not pass a Seitz E.K. filter disc.
THE CHLOROTIC DISEASE OF THE HOP. II
Authors: Salmon E. S. , Wake W. M.
Published: February 2008

Further experiments are recorded in which the transmission of the recently described chlorotic disease of the hop was obtained by means of grafting and budding.

Transmission was obtained also by rubbing healthy leaves with macerated chlorotic tissue in such a way that.bruising of the lamina resulted.

In all the experiments described, with one exception (see above, p. 6), no symptoms of disease appeared until the year following that in which the inoculations were made.
THE RELATIVE RESISTANCE OF SOME WHEAT VARIETIES TO TILLETIA CARIES (DC.) TUL. (—T. TBITIGI (BJERK.) WINT.)
Authors: WESTON W. A. R. DILLON
Published: February 2008

Some factors influencing the relative susceptibility of a wheat variety to Tilletia caries are recorded, and it is shown that infection varies with the spore load and with the date of sowing. The relative resistances of certain wheat varieties to bunt when contaminated separately with Little Joss bunt, their own bunt and bunt spores from other varieties are shown.

Rye is susceptible to Tilletia caries, but no infection is recorded on Hordeum nudum and Avena nuda.

Hybridization experiments between resistant and susceptible wheat varieties are described.

The general trend of the experiments indicates that several of the so‐called immune or highly resistant varieties are susceptible when they are contaminated with bunt spores that are produced on those varieties. They indicate that the passage of the pathogen through the host increases the virulency of the disease. These phenomena are accounted for because Tilletia caries is not a single system of one identity but is composed of physiologic forms and the passage of the parasite through the host increases the virulency because this process leads to the selection of a particular form or forms well adapted to the environmental conditions. It is thought that resistance depends not on one single factor but on at least three, namely, the physiologic form of the parasite and its environment, and the strain of the host and its environment.
ON ATOMARIA LINEARIS STEPHENS (COLEOPTERA, CRYPTOPHAGEDAE) AND ITS LARVAL STAGES
Authors: NEWTON H. C. F.
Published: February 2008

A brief survey is made of the history and habits of Atomaria linearis Stephens, the Pigmy Mangold Beetle, and some new observations recorded.

The egg and the external structure of the larva are described for the first time.
STUDIES UPON THE COPPER FUNGICIDES
Authors: MARTIN HUBERT
Published: February 2008

The initial product of the interaction ol cupric sulphate and calcium hydroxide solutions, at ordinary temperatures, is the 4CuO. S03 basic sulphate.

With amounts of calcium hydroxide in excess of 0–75 equivalent, the 4CuO. S03 salt is slowly decomposed with elimination of the sulphate radicle and the formation of a blue hydrated cupric oxide or cupric hydroxide, a product called, for convenience, the hydroxide.

The cupric hydroxide formed retains, by adsorption, part of the sulphate radicle. Direct evidence by analysis of the precipitate, which might be considered to indicate the formation of a basic copper‐calcium complex, is therefore unreliable.

In the analogous interaction of calcium hydroxide with cupric chloride, the formation of cupric hydroxide in the presence of amounts of calcium hydroxide in excess of 0–75 equivalent, is indicated by the dehydration of the precipitate to form nigger brown hydrated cupric oxide, and by the definite point of inflection on the hydrogen‐ion concentration curve which corresponds to equimolecular amounts of calcium hydroxide and cupric chloride.

The hydrogen‐ion concentration curve for the cupric sulphate‐calcium hydroxide reaction shows that permanent alkalinity is not‐reached until equimolecular amounts of calcium hydroxide have been added.

The cupric hydroxide, formed from the 4CuO.SO3 basic sulphate by the action of calcium hydroxide, is stabilised by adsorbed sulphate ions. If the adsorbed sulphate and excess calcium hydroxide be removed by continued washing with carbon dioxide‐free water, the Bordeaux mixture precipitate undergoes dehydration to form the nigger brown hydrated cupric oxide.

Dehydration of the Bordeaux mixture precipitate when sprayed upon foliage, is therefore prevented by some chemical or physical change of the precipitate which occurs on drying.

Dehydration is not prevented by physical changes which occur on drying.

Carbon dioxide is a factor in the process whereby dehydration is prevented.

It is suggested that the formation in situ of the protective copper‐containing deposit by the action, primarily, of carbon dioxide, accounts for the excellent adhesive properties of the Bordeaux mixture precipitate; that inertness towards the chemical changes which occur after spraying may be the cause of failure of some Bordeaux substitutes; that these changes may profoundly affect the value of sedimentation tests as criteria for the fungicidal efficiency of various Bordeaux mixtures.
STUDIES IN THE PHYSIOLOGY OF VIRUS DISEASES IN PLANTS
Authors: CALDWELL JOHN
Published: February 2008

It has been shown that the symptoms induced by aucuba or yellow mosaic of tomato in certain other members of the Solanaceae (notably N. glutinosa and D. stramonium) differ markedly from those in tomato. Neither formation of intracellular inclusions nor systemic infection occurs in these plants. In N. glutinosa, the symptoms appear only on the rubbed portion of the leaves and little multiplication of the virus takes place. In D. stramonium, although no mosaic symptoms appear on the host, the virus travels through the tissues and can infect susceptible grafts. Holmes' work on the use of N. glutinosa as a ready means of demonstrating the presence of the virus agent in a juice has been confirmed and amplified.

It has also been shown that it is possible to inject the intercellular spaces of the leaf of N. glutinosa with virus juice and that no infection occurs unless cells have been ruptured.
“BREAKING” IN TULIPS. II
Authors: CAYLEY DOROTHY M.
Published: February 2008

The results of the second series of bulb manipulation experiments have confirmed previous results as to the infectious nature of the agent or virus which brings about “breaking” in tulips.

“Breaking” can be transmitted by grafting and plugging bulbs with tissue from “broken” bulbs, but injections with filtered sap expressed from “broken” bulbs have given negative results.

All attempts to induce parrotting by grafting have been unsuccessful.

There appears to be no correlation between the type of “break” of the transmitter and the type of “break” induced.

Transmitters vary in potency on different hosts, and different hosts vary in degree of susceptibility towards the same transmitter.

Tulipa species have been observed to “break” naturally under garden conditions, and “breaking” has also been induced in the same by grafting with “broken” garden varieties.

The bi‐colour variety Keizerskroon has been proved not to be an infectious “break,” but a true bi‐colour; “breaking,” however, can be induced in the red areas of the perianth by grafting with other “broken” varieties.

The effect of the virus on the colour plastids and the distribution of the anthocyanin sap pigment is discussed.

It is suggested that a knowledge of the translocation of the virus in the bulb is of practical importance to bulb growers.

The experiments indicate the importance of aphis control by means of spraying in the growing season and the advantage to be gained by lifting and storage under aphis‐free conditions in the autumn.

In conclusion, my thanks are due to Sir D. Hall for information with respect to the initial “breaking” of Zomerschoon and the “breaks” in Tulipa species, and to the laboratory assistant E. F. Emarton for taking the photographs for the plates and for his valuable help in the manipulation of the large number of bulbs treated.
THE CONTROL OF TOMATO‐LEAP MOULD
Authors: BEWLEY W. F. , ORCHARD O. B.
Published: February 2008

Tomato‐leaf mould may be held in check by attention to atmospheric temperature and humidity.

Varieties resistant to this disease are known, but they are not suitable for commercial work. Attempts are being made to breed varieties combining resistance with crop excellence.

The disease has been controlled by spraying with salicylanilide paste, sold under the name of “Shirlan Paste,” combined with a sul‐phonated oil sold as Agral I.

The above spray mixture has also proved effective against certain other diseases.
STUDIES IN BACTERIOSIS
Authors: LACEY MARGAHET S.
Published: February 2008

Diseases of potato tubers, lettuces and seeds of Medicago lupulina caused by bacteria belonging to the green‐fluorescent group are described and the identity of the pathogens is discussed. The cultural characters of thirty‐six strains isolated from various plant lesions are given and compared with those of thirty‐two known species of the green‐fluorescent group, and a discussion on cultural variations follows.
THE OPERATION OF INTERSPECIFIC COMPETITION IN CAUSING DELAYED GROWTH OF GRASSES
Authors: CHIPPINDALE H. G.
Published: February 2008

An explanation is provided of the causation by L. italicum of delayed establishment in F. pratensis, Phleum pratense and Poa trivialis.

The presence of seeds or seedlings of L. italicum is not detrimental to the germination of the other species under conditions thought likely to occur in the field, except in the case of Poa trivialis, the seeds of which grass are extremely susceptible to the presence of carbon dioxide and hence to root‐respiration.

Under certain conditions, seedlings of L. italicum inhibit completely the growth of seedlings of the other three grasses, the latter being deprived of light and soil nutrients. At the same time, seedlings suffering suppression in this way are remarkably persistent and are capable of immediate recovery on the removal of competition.

The significance of this behaviour, ecologically and to agricultural practice, is discussed.

The effeet of different physical factors on germination in the same four species of grass is described. The action of low temperatures in depressing the germination of F. pratensis, Phleumpratense and Poa trivialis to a greater extent than that of L. italicum is considered an important factor in interspecific competition.
THE INSBCTICIDAL PROPERTIES OF TEPHROSIA MAGROPODA HARV. AND OTHER TROPICAL PLANTS
Authors: TATTEKSFIELD F. , GIMINGHAM C. T.
Published: February 2008

Preliminary data is reported as to the insecticidal properties of three tropical fish‐poison plants (Tephrosia macropoda Harv., Mundulea suberosa Benth. and Neorautanenia (Rhynchosia) fisifolia C.A.Sm.).

A list is given of other plants (most of them known to be fish poisons) from many different countries, which have been tested but appear to have little or no toxicity to Aphis rumicis L.

Extracts of the stems of black Haiari (Lonchocarpus sp.) are shown to be toxic as contact insecticides to young larvae of two species of moths. Older larvae are much, more resistant.

All the plants so far tested which are toxic both to fish and to insects are members of the natural order Leguminosae.
A STUDY OF PAXILLUS PANU0IDE8 FR. AND ITS EFFECTS UPON WOOD
Authors: FINDLAY W. P. K.
Published: February 2008

An account is given of the occurrence and distribution of Paxillus ?panuoides Fr.

The fruit bodies of the fungus produced naturally and on artificial media and the appearance of the fungus in culture are described and the microscopic details of the hyphae figured.

The effect of temperature, of different hydrogen‐ion concentrations and of antiseptics upon the growth of the fungus are examined.

The growth of the fungus upon sawdust and upon blocks of sound and of already partially decayed wood are investigated and a description given of the details of the hyphae in the cells of the wood and their effect upon the walls thereof.

Means of recognising decay caused by P. panuoides and suggestions for controlling damage by this fungus are given.
THE INFLUENCE OF ENVIRONMENTAL CONDITIONS ON THE DEVELOPMENT OF THE ANGULAR LEAF‐SPOT DISEASE OF COTTON
Authors: STOUGHTON E. H.
Published: February 2008

Experiments carried out in the Rothamsted control chambers on the influence of atmospheric humidity on the angular leaf‐spot disease of cotton, resulting from spray inoculation of young plants, show that high humidities favour the development of the disease. Maximum infection occurs at humidities exceeding 85 per cent, and at humidities below this the degree of infection decreases rapidly.

The relation of these results to the experiments on the influence of air temperature is discussed, and it is concluded that the importance of humidity is mainly physical in nature, by affecting the time during which the infection droplets persist.
THE TOXICITY OF THE VAPOURS OF VOLATILE ORGANIC COMPOUNDS TO THE “RED SPIDER” MITE (TETRANYCHUS TELABIUS L.)
Authors: READ WILFRID H.
Published: February 2008

With the exception of methyl formate the toxicity towards the “red spider” mite of the normal aliphatic alcohols and their formates at first increases as the series is ascended.

Methyl formate is an exception to the above rule and is the most toxic of the formates tested.

The normal compounds are more toxic than their isomers, the toxicity decreasing with increased branching of the chain.

The above decrease is greatest when the branching is at the a position to the hydroxyl or carboxyl group.

The relative effects of the compounds on plants are similar to their effects on the mite, but the differences due to molecular structure are more pronounced.

Control of the mite cannot be obtained on tomato plants without injury by the use of any of the substances tested.
ACTINOMYCES IN CACAO‐BEANS
Authors: BUNTING E. H.
Published: February 2008

The presence of Actinomyces within cacao beans is discussed, and descriptions by Waksman of three strains of a new species–Act. cacaoi– are given.
THE CHLOROTIC DISEASE OF THE HOP. III
Authors: SALMON PROF. E. S. , WARE W. M.
Published: February 2008

Three further cases of the occurrence of the chlorotic disease of the hop, hitherto known from only one hop‐yard (of the Fuggle variety) in Worcestershire, are recorded from hop‐yards in the same county on the varieties Fuggle, Early Bird and Tutsham.

The chlorotic disease has been transmitted by grafting to the commercial varieties Tutsham,. Cobbs and Mathon. With one doubtful exception, all the affected plants showed as well the symptoms of mosaic disease.

The chlorotic disease has been transferred by grafting to three new seedling varieties (M. 45, p. 13 and GG. 45).

In three instances, individuals of symptomless mosaic carriers (of two varieties), to which chlorotic disease had been transmitted by grafting or budding, exhibited eventually marked symptoms of mosaic disease.

Two further cases are recorded of the appearance in scions of chlorotic symptoms in the same year in which the scions were grafted on the infected stocks.
VIRUS DISEASES IN RELATION TO COMMERCIAL SEED POTATO PRODUCTION
Authors: WHITEHEAD T. , CURRIE J. F. , DAVIES W. MALDWYN
Published: February 2008

Under a scheme, begun in 1927, and supported by a special grant from the Ministry of Agriculture since 1928, an attempt is being made to test the value of certain localities in North Wales for the production of seed potatoes.

Evidence is produced to show that out of fifteen farms originally selected for this purpose, eight have maintained their stocks without increase of virus diseases, three have shown only a slight increase, whilst four have been discarded from the scheme. Replicated yield trials at the College Farm proved that seed mixed from these eleven farms was equal to Scotch “stock” seed, and the value of this Welsh seed was confirmed by trials in a number of Welsh counties in which it was tested against ordinary T.S. Scotch seed.

Concurrently with this, a study has been made of the aphid population on the potato crops at these centres, which has led to the following conclusions:

The absence of increase of virus diseases, and of leaf‐roll in particular, at the more successful centres is not due to the scarcity of aphides, nor to the absence of known vectors of the diseases, such as Myzus persicae. Neither can it be attributed to the non‐infective condition of the aphid vectors present at these centres since representative samples, taken from potato crops, transmitted leaf‐roll to healthy plants under glass. With one exception no transmission occurred with any of the species of aphides when taken from apparently healthy plants in a partially diseased crop. In samples taken from leaf‐roll plants transmission only occurred when they included Myzus persicae.

The accumulated data suggest that the maintenance of health in potato stocks is influenced not merely by the relative abundance of aphides, but rather by the relation between the date of maximum infestation and the stage of maturity of the foliage. The more successful centres, each year, showed either a delayed maximum infestation and/or the foliage was cut down earlier than at the less successful centres. The relative movement of aphides within the crops at the different centres is certainly of importance, but this is conditioned by many factors which are still under investigation.
THE APPEARANCE AND BEHAVIOUR OF PIGMENT IN THE SUFFOLK BREED OF SHEEP
Authors: BOYD EVLYN
Published: February 2008

The results of a microscopic study made of the colour transition shown by the fleece of the Suffolk from birth to maturity are given. It is demonstrated that the physical structure of the fibre cuticle obviates the possibility of pigment inclusions.

An explanation for the sporadic occurrence of coloured fibres in an otherwise white 3eece is attempted, and it is pointed out that, however else the pigmentary system of the Suffolk sheep may be stimulated, thresholds of irritation conditioned by temperature need not he considered as possible stimuli.
STREAK IN TOMATOES ASEPTICALLY GROWN
Authors: SMITH J. HENDERSON
Published: February 2008

From the necrotic tissues of tomato plants suffering from streak, a virus disease, it is possible regularly to obtain bacteria which belong to one or both of two definite types. The same bacteria are to be found in tobaccos infected with the same disease.

If the plants are grown from sterile seed under aseptic conditions throughout and inoculated with bacteriologically sterile virus‐holding streak juice, these bacteria do not appear although the plants develop well‐marked signs of the disease.

“No evidence has been found that the bacteria are derived from the virus or the virus from the bacteria.
ZONE LINES IN PLANT TISSUES I. THE BLACK LINES FORMED BY XYLABIA POLYMORPH A (PERS.) GREV. LN HARDWOODS
Authors: CAMPBELL ALEX. H.
Published: February 2008

A brief account is given of the literature on zone lines in wood, and a preliminary attempt is made to classify the zone lines into groups in order to provide a basis for systematic research and to facilitate the statement of results. A single fungus, X. polymorpha, suspected of causing black lines in hardwoods, is dealt with morphologically and culturally. The development and stromatal production of the fungus on artificial media and wood blocks are described. X. polymorpha is established as a black line producing fungus by its production of black lines in inoculated wood blocks. The morphology of the black lines is described in detail and their actual formation has been observed in cotton‐wool. As a result the Suggestion is made that the black lines are the marginal zones of entostro‐mata in the substratum comparable to those occurring in the Diaporthe. The black lines produced by the genera Nummularia, Ustulina, Hypoxylon and Daldinia in the substratum are stated to be of similar structure and significance.

An account is given of a X. polymorpha black line superimposed upon the zone line formed by the attack of Fomes applanatus on beech wood. The confusion existing in the literature on the zone lines of F. applanatus is partly attributable to this not uncommon phenomenon. The value of zone lines as criteria in the diagnosis of wood rots is discussed and some of the difficulties in the identification of a zone line in a typical rot are pointed out.
THE NITRIFICATION PROCESS IN SOILS AND BIOLOGICAL FILTERS
Authors: BARRITT N. W.
Published: February 2008

An extensive review of the literature on nitrification shows that the workers in this subject may be divided into three groups, viz. (a the Winogradsky or purely autotrophic group, (b those who include growth in organic media, (c those who exclude autotrophic growth.

The process of nitrification in soils and filter beds is essentially the same and the organisms concerned exhibit the same cultural characteristics, viz. autotrophic growth in purely mineral solution containing carbonates and low thermal death‐point (56° C).

In the absence of carbonates heterotrophic organisms can supply the necessary carbon, dioxide by the decomposition of organic matter, a process which accounts for nitrification in acid soils and filter beds. In the absence of a salifiable base the oxidation of ammonia is arrested by the formation of free acid and at a pH of 5.5 the nitrous acid is spontaneously oxidised to nitric acid.

The inhibitive action of organic matter on nitrification can be accounted for by accumulation of carbon dioxide and ammonia and deficient aeration. Removal of any of these factors results in increased nitrification.

Increased nitrifying power of soil after passage through earthworms is recorded and accounted for.

The restrictive influence of Winogradsky's ideas on autotrophism ara discussed, and the possibility of nitrifying bacteria being a phase in the life cycle of heterotrophic organisms is suggested.
THE EFFECT OF SOME ‐CHEMICALS ON GERMINATION IN COCKSFOOT (DACTYLIS QLOMERATA L.)
Authors: CHIPPINDALE H. G.
Published: February 2008

Attempts to accelerate the germination of cocksfoot seeds by treating them with solutions of several chemical compounds have been unsuccessful.

A pronounced acceleration of germination can be produced by soaking the seeds in water and drying for an indefinite period before sowing.

No evidence has been obtained that with any condition of the soil is such treatment undesirable.

The author wishes to thank Professor R. G. Stapledon, to whom he is indebted for criticism and at whose suggestion the work was begun.
GIB BE BELLA SAUBINETII (MONT.) SACC. ON BRITISH CEREALS III. OCCURRENCE UNDER NATURAL CONDITIONS.
Authors: BENNETT F. T.
Published: February 2008

Gibberella Saubinetii (Mont.) Sacc. occurred in its perfect stage under field conditions on wheat ears in 1932. The meteorological conditions are compared with those of a season when perithecia were not developed outdoors.

Single ascospore growths in culture are normally of the Fusarium type, with a characteristic modification on salts‐glycerine agar. The ascigerous type of growth may arise from ascospores developed under abnormal conditions.
AN INVESTIGATION OF TOMATO VIRUS DISEASES OF THE MOSAIC “STRIPE,” STREAK GROUP
Authors: AINSWORTH G. C.
Published: February 2008

Virus diseases of tomato of the mosaic, “stripe,” streak type as occurring in glasshouses in the British Isles have been examined.

Ordinary or mild mosaic (tomato mosaic) has been identified with true tobacco mosaic and found not to be implicated in most of the “stripe” disease.

The symptom picture generally known as “stripe” may be due to several causes, and in this paper the diseases have been distinguished as follows: stripe when attributed to Bacillus lathyri, glasshouse streak when caused by a single virus (the most frequently occurring form), and streak when due to a mixed virus infection (typically tomato mosaic and potato mosaic).

Descriptions are given of tomato mosaic, glasshouse streak, and streak, and they are compared with each other and with spotted wilt.

The author wishes to express his best thanks to Dr W. F. Bewley for helpful criticism and advice.

The work has been carried out with the aid of a grant from the Empire Marketing Board.
ON THE BIOLOGY OF THE PLUM SAWFLY, HOPLOGAMPA FLAVA L.1, WITH NOTES ON CONTROL EXPERIMENTS
Authors: PETHERBRIDGE F. R. , THOMAS I. , HEY. G. L.
Published: February 2008

Observations on the biology of Hoplocampa flava L. are given.

Reasons are given for stating that all records of plum sawfly damage in England referred to H. fulvicornis should be referred to H. flava L.

Observations are given showing the variation in intensity of attack during 1925–32.

Control experiments with the object of killing the larvae were promising in 1929, but yielded no control in 1932.

The authors are indebted to Dr H. W. Miles and Mr H. Kingston, who were associated with us in the above observations in 1926, and to Messrs M. H. Ivatt and G. H. Cannon, on whose plantations the observations were made.
ON THE BIOLOGY OF GACOEGIA CRATAEG ANA HUB. (LEPIDOPTERA: TORTRICTDAE) ON FRUIT TREES IN THE WISBECH AREA
Authors: HEY G. L. , THOMAS. I.
Published: February 2008

An account has been given of the life history and habits of the moth Cacoecia crataegana, in the Wisbech area, where it attacks fruit trees.

The egg and egg‐laying habits have been described and the external anatomy and biology of the larva and pupa have been studied.

The measurement of the larval head capsule in relation to Dyar's hypothesis has been discussed.

The effect on the egg and on the larva of routine control measures has been observed.

The parasitism of the moth has been studied. One Dipterous, and five Hymenopterous parasites have been bred out, and the biology of one of these, the egg parasite Trichogramma evanescens Westw., has been studied in detail.

The writers wish to acknowledge their indebtedness to Mr P. R. Petherbridge, under whose supervision the work has been carried out, and to Dr A. D. Imms and Mr J. C. F. Fryer for criticism of the manuscript. They also wish to thank members of the staff of the British Museum of Natural History, for identification of the moth and its parasites, and for supplying references to the literature, and to Mr M. H. Hey, of the Mineralogical Department, for the analysis of the egg‐masses. Thanks are also due to Messrs J. Lefevre, E. G. Davison, and G. E. Munday, for reporting, the presence of egg‐masses at the various centres, and to the growers in whose orchards the observations were made.
A CAMBIUM MINER, OF BASKET WILLOWS (AGROMYZIDAE) AND ITS INQUILINE GALL MIDGE (CECIDOMYIDAE)
Authors: BARNES H. F.
Published: February 2008

1. A brief resume is given of the information available concerning Dipterous cambium miners (Agromyzidae).

2. The morphology of the egg, larva, pupa and adult of Dizygomyza barnesi sp.n. Hendel is described.

3. The bionomics of this fly receive detailed attention. There is only one brood a year and the larvae mine in the cambium of different species of Salix. Pupation takes place in the soil. While S. viminalis is attacked most commonly, S. triandra, S. purpurea, S. viminalis×purpurea and S. triandra×viminalis occasionally suffer. In addition the larvae can live on S. caerulea. The damage caused by the larvae is considerable. The Braconids, Symphia ringens Halid. and S. hians Nees, are recorded as primary parasites.

4. Two gall midges are described, the larvae of one living as inquilines in the burrows of the Dizygomyza larvae. The bionomics of this species are described.
STUDIES IN THE PHYSIOLOGY OF THE VIRUS DISEASES OF THE POTATO
Authors: BARTON‐WRIGHT EUSTACE , ALAN M.
Published: February 2008

The present investigation is concerned with the differences between the nitrogen metabolism of healthy and leaf‐roll affected potato plants.

Diurnal estimations were made of the total nitrogen as well as the following nitrogen fractions, ammonia N, asparagine N, amino‐acid N, nitrate N, residual N and protein N in the leaves and petioles of healthy and leaf‐roll infected Arran Victory and President. Weekly determinations of total nitrogen and the above nitrogen fractions were also made in the laminae of Arran Victory and President throughout the growing season.

Evidence is presented to show that there is apparently no fundamental difference in the nitrogen metabolism of healthy and leaf‐roll plants, and that the formation of nitrogenous compounds proceeds along the same lines in the two cases.

A theory is put forward to account for protein synthesis direct from nitrate N, and not via amino‐acids. The problem of translocation is also discussed, and it is considered that the residual N fraction plays an important part in nitrogen transport.

We wish to express our indebtedness to Mr William Robb. F.E.S.E., for reading the manuscript and making a number of suggestions. We would also like to take this opportunity of thanking Dr W. H. Pearsall, of the Botany Department, The University, Leeds, for his help and assistance in a number of different directions. This work was carried out at the Station of the Scottish Society for Research in Plant Breeding, Corstorphine, Edinburgh, under a scheme supported by a grant from the Empire Marketing Board.
ON THE OCCURRENCE, PERPETUATION AND CONTROL OF GRAM (CICER ARIETINUM L.) BLIGHT CAUSED BY ASCOCHYTA RABIEI (PASS.) LABROUSSE, WITH SPECIAL REFERENCE TO INDIAN CONDITIONS
Authors: SATTAR A.
Published: February 2008

1. The importance and distribution of blight of gram are described.

2. The field appearance of blight, and the influence of environmental factors such as rainfall, temperature, wind and cultural practices on its incidence and development have been studied. The occurrence of blight in various parts of India is shown to be highly correlated with the amount of rainfall during the flowering and fruiting periods of the gram crop.

3. It is shown that the gram plant increases in susceptibility with age and is most susceptible at the flowering and fruiting stages. This susceptibility has been found to be directly proportional to the amount of malic acid secreted by the plant on its surface.

4. Germination of spores of A. Rabiei has been studied in some detail, and it has been found that they are favoured in their germination by the presence of N/50‐N/25 malic acid or acidified carbon food (pH 2–5).

5. Modes of transmission of blight from one year to another are described.

6. Measures to control blight are given and some new lines of attack have been indicated.

The writer wishes to record his indebtedness to Prof. Luthra and to Mr Zafar Alam of the Agricultural College, Lyallpur, Punjab, for their assistance in providing diseased specimens and healthy seeds of the gram plant, and to Prof. W. Brown of the Imperial College of Science and Technology, London, for help and advice given during the period of two years' study leave which the author spent in England.
GNARLED STEM CANKER OF TEA CAUSED BY THE CAPSID BUG (HELOPELTIS BERGROTHI REUT.)
Authors: LEACH K. , SMEE COLIN
Published: February 2008

1. Gnarled stem canker of tea is shown to be caused by the tea mosquito bug (H. bergrothi Reut.).

2. An account is given of the development of the canker from the time that the insect starts feeding.

3. The measurements of cankers found occurring in the field and those caused by different stages of the insect are given.

4. The path of the stylets in the tissues of the stem is described. The cause of the collapse of the affected tissues is discussed.

5. Control measures are considered in brief.