bluuebunny/crossref_metadata_2025 huggingface dataset:
THE HISTOLOGY OF THE NECROTIC LESIONS INDUCED BY VIRUS DISEASES
Authors: SHEFFIELD F. M. L.
Published: February 2008

About 12 hours after a leaf of Nicotiana glutinosa is inoculated with ancuba mosaic disease a band of necrotic material begins to form within the cell wall, usually between the lower epidermis and the spongy parenchyma. This band extends both laterally and towards the upper side of the leaf. At the same time, nuclear division is observed in the spongy parenchyma cells, but karyokinesis is not followed by cell division. As the necrotic mesh work extends the cells within it die and dry out. After about 3 days, the lesion consists of a meshwork of this necrotic material. The cells are all dead and the virus is isolated within the necrotic area, all interchange between the infected and healthy parts of the leaf having been prevented.

I am indebted to Fraulein Lina Cunow for assistance in making the preparations used in this study.
A NEW APPARATUS FOR SEPARATING INSECTS AND OTHER ARTHROPODS FROM THE SOIL
Authors: LADELL W. R. S.
Published: February 2008

The published methods for the separation of insects and other animals from the soil are briefly described.

None of these methods being sufficiently rapid or efficient for soil fumigation investigations, a new method has been devised.

The principle of the method is flotation by a dense liquid (a solution of magnesium sulphate sp. gr. 1.11) aided by stirring of the soil and a stream of fine air bubbles passing from the bottom upwards through the mixture of soil and solution. This produces a froth which contains all the animals, and by raising the level of the liquid in the cylinder the froth is swept over into a tank filled with magnesium sulphate solution; here is deposited any soil that has been carried over. The clear solution is then passed on to a Buchner funnel where the insects and other animals are retained. A black filter paper is used in order to show up Collembola and other colourless organisms.

The apparatus has many advantages:

Rapidity. The separation taking 30–40 min. from taking the soil sample of 6–7 lb. weight.

Cleanliness. The operation can be carried out in an ordinary laboratory.

Efficiency. All the organisms are concentrated in a small volume of residue, less than 1 per cent of the original soil, and are undamaged.

Non‐toxicity. The great majority of the insects come through alive, so that eggs and larvae may be bred out for purposes of identification.

A full account is given of the technique employed. The solution may be used again and again as the clay settles very quickly and the clear liquid may be syphoned or poured off.

Very high figures have been obtained for the soil population. These are much in excess of those recorded by most other workers with agricultural soils; for example, from fallow land 60‐6 million animals per acre were recorded and from new grass land, 121‐4 million per acre.1
THE PROBLEM OF THE EVALUATION OF ROTENONE‐CONTAINING PLANTS II. DERRIS ELLIPTIC A, DEBRIS MALACCENSIS AND THE “SUMATRA‐TYPE” ROOTS
Authors: MARTIN J. T. , TATTERSFIELD F.
Published: February 2008

The determinations of purified rotenone, ether extract, dehydro compounds, ether‐soluble resin after potash treatment, and of the rotenone plus “deguelin concentrates” are each shown to be inadequate as a means of assessing the relative insecticidal activities of the “Sumatra‐type”, D. malacceri&is, and D. elliptica roots.

The toxicarol present in the “Sumatra‐type” derris appears to play a small but definite part in the insecticidal activity of the root.

The resin recovered from the material precipitated by potash from an ether extract of the “Sumatra‐type” root is optically active, and appears to be rich in the precursor of inactive toxicarol.

Rotenone, if present, will separate readily from a carbon tetrachloride solution of “Sumatra‐type” resin from which the toxicarol has been removed. The possibility of a standard method of rotenone determination, dependent upon suitable pretreatment of the resins, is suggested.

We wish to express our indebtedness to the Copper Technical Bureau for their kindness in supplying us with samples of the “Sumatra‐type” root. We also wish to thank Dr S. Krishna of the Forestal Department of Northern India, for valuable assistance.
A DISEASE OF CULTIVATED HEATHS CAUSED BY PHYTOPHTHORA GINNAMOMI RANDS
Authors: OYLEE ENID , BEWLEY W. F.
Published: February 2008

A serious disease of the heaths Erica hyemalis, E. nivalis and E. Willmoreana has been investigated.

The causal organism was isolated and identified as Phytophthora Cinnamomi Rands.

This was shown to be capable of causing a similar disease in Antirrhinum, Calceolaria, Schizanthus and beech seedlings. It also rots apple and tomato fruits.

Infection was traced to (a) contaminated water tanks, (b) the “standing‐out” ground, and (c) plunging material.

The water tanks were cleaned by removing the debris, scrubbing with water and finally treating with formaldehyde.

The need for destroying the compost from discarded pots or alternatively of sterilizing it by heat before using it again is emphasized.
ON THE CONTROL OF GOOSEBERRY RUST
Authors: SAUNDERSON W. E. , CAIRNS H.
Published: February 2008

This investigation deals with the possibilities of controlling Aecidium Grossularia DC. (Puccinia Pringsheimiana Kleb.) on the gooseberry by means of fungicides or through the use of varieties resistant to rust.

From observations made on more than twenty varieties representative of the three types of gooseberry, red, green and yellow, no pronounced variation in resistance to the disease was found.

Very effective control of the disease resulted from spraying with fungicides: several concentrations of Bordeaux and Burgundy mixtures and proprietary colloidal preparations of copper and sulphur. Of these it is, suggested that Bordeaux mixture and the colloidal copper preparation may be recommended for general use against gooseberry rust.

The optimum time for spraying with a fungicide against rust was found to be about 2 weeks before the gooseberry commences to flower.

A single spraying gives very effective control of the disease, provided it is applied at this optimum time. Repeated spraying after this time does not appreciably increase the effectiveness of the treatment.

The results of these experiments seem to indicate that basidiospore discharge in Puccinia Pringsheimiana commences with, or soon after, the commencement of seasonal growth by the gooseberry, reaches a maximum several days before the gooseberry commences to flower and, normally, ceases some 4 or 5 weeks later.

Of the sedges present in the vicinity of the experimental centre at Galgorm, Puccinia was found on four species: Carex Goodenowii Gay., C. inflata, Huds., C. flava Linn., and C. panicea Linn. No attempt was made to correlate these with the Aecidium on the gooseberry.
THE USE OF NUMBERS OF INFECTIONS FOR COMPARING THE CONCENTRATION OF PLANT VIRUS SUSPENSIONS: DISTORTION OF THE DILUTION SERIES
Authors: BALD J. G.
Published: February 2008

A distinction is drawn between the types of infection‐dilution series given by unpurified samples of the tobacco mosaic group of viruses and viruses less resistant to loss of virulence.

Distortion of the series for the tobacco mosaic group, when inocula were diluted with distilled water or buffered near the neutral point, was shown to exist more in the concentrated than in the dilute end of the series.

An acid hydrogen‐ion concentration was found to change the form of the dilution series.

The addition of plant juices to the inocula tended to produce two opposing effects on the production of local lesions, a stimulation and a depression.

Unpurified samples of viruses less resistant to loss of virulence than the tobacco mosaic group gave low values for lesions at high dilutions.

The addition of concentrations of the order of 0.01 and 0.1 M of neutral potassium phosphate‐phthalate buffer to unpurified suspensions of X virus depressed the numbers of lesions produced.

Added in various concentrations to purified samples of X virus, the buffer produced high values for lesions at a concentration of about 0.00005 M, low values between 0.0001 and 0.001 M, a maximum between 0.001 and 0.01 M, and a decline at higher concentrations.

The presence of the buffer in inocula was shown to affect the dilution series of X virus.

A tentative hypothesis was advanced to explain the effects of salts on the production of lesions by X virus.
A BACTERIAL DISEASE OF APHIS RUMICIS LINN., APPARENTLY CAUSED BY BACILLUS LATHYRI MANNS AND TAUBENHAUS
Authors: NEEDHAM N. V.
Published: February 2008

An organism culturally resembling Bacillus lathyri Manns and Taubenhaus has been isolated from Aphis rumicis Linn. The aphides showed evidence of disease, in that they died within 24 hours of removal from the host plant. Bacteriological examination of healthy aphides indicated that they are remarkably free from bacteria; few colonies were found in cultures, even when made from the crushed insects.

The writer desires to express his gratitude to Dr F. Tattersfield, of Rothamsted Experimental Station, for the provision of a normal colony of A. rumicis; to Dr Mary Barratt, of the Lister Institute, for confirmation of certain of the cultural characteristics; and to his colleagues on the staff of the Cooper Technical Bureau, who have given him helpful advice.
SOIL FUNGI AND ACTINOMYCETES IN RELATION TO MANURIAL TREATMENT, SEASON AND CROP
Authors: SINGH JAGJIWAN
Published: February 2008

Quantitative

A direct correlation has been found between soil fertility as measured by crop growth, and the number of fungi and actinomycetes‐in Barnfield (permanent mangold) and Broadbalk (permanent wheat) at the Rothamsted Experimental Station.

Inconclusive or negative evidence has been obtained with regard to the phenomenon of periodicity in the fungi and actinomycetes in the soil. Evidence, on the whole, seems to suggest that numbers throughout the year scatter about a mean value with an indication of lower numbers in the winter.

No marked and dominant effect of the crop has been observed upon the numbers of fungi and actinomycetes beyond a suggestion that the wheat field, on the whole, contains a greater number of actinomycetes than Barnfield while the reverse is the case for the fungi.

Qualitative

The results do not favour the view that there exist specific soil fungus floras determined by particular manurial treatments. The more fertile plots contain, however, a greater variety of soil fungi.

In the two fields different soil forms exist in different quantities. Penicillium and forms of Dematium are more prevalent in Barnfield while Fusarium tends to predominate in Broadbalk.

Forms of Monilia occur fairly uniformly in the two fields. Species of Aspergillus and Mucor are scarce in the two fields.
A STUDY OF POLYPORUS BETULINUS (BULL.) FRIES
Authors: MACDONALD J. A.
Published: February 2008

An introductory survey is given of the distribution, synonyms, etc., of Polyporus betulinus (Bull.) Fries.

In an investigation of the parasitism of the fungus negative results were obtained from infection experiments, but field observations force the writer to the opinion that the organism is a wound parasite.

The effect of the fungus on attacked wood was traced in nature and in culture. The type of breakdown produced is regarded as a red‐brown cubical rot, attacking both sapwood and heartwood.

A study of the enzyme content of the fungus showed that it contained ferments capable of attacking lignin.

The characters of the mvcelium were investigated and the fungus is classified according to Fritz's work.

Black lines are formed in culture. They are frequently related in position to bulbils (sclerotia). It is suggested that here, as elsewhere, the hyphae of the black line may be regarded as forming the limiting layer of a resting stage of the fungus.

The fertile portion of the sporophore consists of a hymenium lining very numerous pores. The basidia form a continuous row of club‐shaped cells, interspersed with cystidia. These latter appear to be the terminal portions of fibre hyphae. The sequence of nuclear phenomena in the basidium was traced. The period of spore discharge was determined for the species and for individual sporophores.

The life of the fungus has been observed from spore to spore in culture during a space of 3 months.

Monospore cultures were obtained. The fungus is heterothallic. The spores were shown to fall into two groups when twelve monospore colonies were paired in every possible way. Monosporous mycelia have single nuclei and no clamp connexions. Mycelia which are polysporous in origin contain conjugate nuclei and bear clamp connexions.
EXPERIMENTAL SPAWN AND MUSHROOM CULTURE. I
Authors: CAYLEY DOROTHY M.
Published: February 2008

The wild grassland species Ps. campestris and Ps. arvensis show very different physiological characteristics from the cultivated varieties, and the wild haystack mushroom occupies an intermediate position, showing some of the characteristics of both.

The number of spores on the basidium is correlated with these physiological differences.

The two wild grassland species will not grow on stable manure compost or on any artificial medium fermented from 14 days onwards.

The wild haystack mushroom also fails to grow on stable manure compost, but will tolerate the by‐products of 14 days' high‐temperature fermentation (not longer), and a compost fermented at a low temperature for 1 month.

The cultivated varieties will grow on unfermented composts and also on high‐temperature composts up to 35 days, and on prolonged low‐temperature composts, but show varietal differences in the latter.

A standard unfermented compost for growing spawn of all forms is described.

In conclusion I wish to acknowledge my indebtedness to Dr D. A. Coult for his suggestion as to the effect of lime on the growth of the wild species; to Mr H. C. Osterstock for taking some of the photographs for the plates, and to the laboratory assistant, A. F. Emarton, for some of the photographs, and for his valuable assistance in the preparation of numerous artificial composts, and the manipulation of the large tube and battery jar cultures.
ONE‐YEAR STUDIES ON THE BIOLOGY OF THE HONEY‐BEE IN PALESTINE
Authors: BODENHEIMER F. S. , BEN‐NERYA A.
Published: February 2008

The aim of the study and the seasonal history of the apiary on which the observations were made are expounded.

The seasonal development of the vegetation is described so far as it affects nectar or pollen production.

The frequency and duration of visits of bees to flowering fruit‐trees is studied with regard to type of activity (nectar or pollen collecting), hour of day and distance from the hive.

The total flight‐activity of two hives throughout the year is studied (daily and monthly activity). The flight‐activity is correlated with conditions of temperature and humidity.

The brood distribution within the hive and its temperature is followed throughout one year.

The monthly egg production and the seasonal trend of the total population of a normal hive are described.

The seasonal changes in the weight of the beehive are followed.

The further correlation of the data observed with environmental conditions, the analysis of swarming conditions, etc. are left for a later study.
THE INFLUENCE OF BORON ON THE SECOND YEAR'S GROWTH OF SUGAR BEET AFFECTED WITH HEART‐ROT
Authors: BRENCHLEY WINIFRED E. , WATSON D. J.
Published: February 2008

Summary

Heart‐rot of sugar beet occurred on experimental plots at Rothamsted during 1935, the severity of the attack decreasing steadily with later sowing, but the effects of spacing of the rows and of treatment with sulphate of ammonia were not significant. Where the number of affected plants per row was high, a higher proportion of affected plants showed severe symptoms.

Unaffected sugar beets and others showing slight and severe symptoms of heart‐rot were transplanted to sand cultures and treated with light and heavy dressings of boric acid or with none.

In the absence of boric acid the characteristic signs of boron deficiency appeared in the shoots, the apices of the stems and the flower buds blackening and dying. This occurred even when no symptoms were present before transplanting.

In the presence of boric acid all plants produced healthy shoots, with no deficiency symptoms. Where heart‐rot was originally present and the main axis killed, a number of healthy, lateral shoots were produced.

A certain number of plants failed to survive transplanting, the proportion being greatest with the heavy dose of boric acid, with which one‐half of the plants died. This suggests a possible toxic action of the heavy dose which did not come into play if the plants were constitutionally able to withstand the initial poisoning and start away into growth.

The later addition of boron did not improve the condition of the roots of affected plants, as irremediable damage had been done before transplanting.

The possibility of producing healthy shoots in the second year from affected roots is important from the point of view of seed production, as considerable loss may be saved by the use of small amounts of boron compounds.
STUDIES OF THE BIOLOGY OF THE DEATH‐WATCH BEETLE,XESTOBIUM RUFOVILLOSUMDE G.: A SUMMARY OF PAST WORK AND A BRIEF ACCOUNT OF THE DEVELOPMENTAL STAGES
Authors: FISHER RONALD C.
Published: February 2008

Summary

The present paper is intended to form an introduction to a short series on studies of the biology of the death‐watch beetle,Xestobium rufovillosumDe G.

The status of the insect as a pest in this country is discussed, and a review is given of the literature and past work on its life history and habits.

A general description is given of the developmental stages (egg, larva, pupa, adult) and includes a short account of external sex characters in the pupa.

Special attention is devoted to the morphology of the reproductive organs and to their state of development at the time of emergence of the adult.

A brief account of the alimentary canal is also included.
THE INSECTICIDAL PROPERTIES OF SOME EAST AFRICAN PLANTS: MUNDULEA SUBEROSA BENTH. PART 3, VARIABILITY OF SAMPLES
Authors: WORSLEY R. R. le G.
Published: February 2008

Summary

Two types of Mundulea suberosa exist: smooth and corky barked. The differences may be botanical or due to periodic burning of the latter type.

Dry weather and calciferous soils appear to favour production of rotenone and other toxic principles in the plant.

No correlation exists between toxicity and the amount of ether extractable material in the plant.

A fair correlation was found between toxicity and rotenone content, the toxicity being about 1.6 times as great as for pure rotenone.

A correlation was found for all nine samples which had any toxic action between the content of “optical” dehydrocompounds in the barks and their toxicity. The formula for the regression line is

P= 5.03 + 1.98 (c̄ ‐ 1.30).

To prepare solutions of equal toxicity for the various Mundulea samples it is therefore necessary to take weights inversely proportional to their “optical” dehydrocompound contents.

No correlation existed between the content of “Takei” dehydrocompounds and toxicity.
THE ANTITHETIC VIRUS THEORY OF TULIP‐BREAKING1
Authors: McWHORTER FRANK P.
Published: February 2008

The term antithetic is suggested for viruses which are usually associated and which are physiologically antagonistic.

Tulip breaking results from the interaction of Tulip Virus I which inhibits flower and leaf colour and Tulip Virus II which adds flower colour but has no visible effect on chlorophyll distribution.

The established commercial broken tulips contain physiologically balanced mixtures of these two viruses.
THE RELATION BETWEEN POTATO BLIGHT AND TOMATO BLIGHT
Authors: SMALL T.
Published: February 2008

SUMMARY AND CONCLUSIONS.

1. In Jersey, potato and tomato crops are grown in close proximity in the open, and both suffer from severe attacks of blight (Phytophthora infestans). The disease appears first on the potatoes, and most growers assume that it passes from this crop to the tomatoes. To test this assumption, potato and tomato plants have been inoculated, using blight from either host plant.

2. In four out of five experiments, ordinary blight lesions developed on tomatoes inoculated with blight from glasshouse potatoes in January, February and March. The result suggests that tomato plants for the outdoor crop are liable to contract blight, if, as is often done, they are raised in glasshouses where diseased potatoes have just been, or are being, grown.

3. Blight from the early outdoor potato crop often failed to infect tomatoes. Where infection did occur typical symptoms of blight were not produced. When, under field conditions, early potatoes were interplanted with tomatoes, the former were quickly killed by blight while the latter remained almost healthy. The evidence indicates that early potato crops affected with blight are not so dangerous to neighbouring tomato crops as is commonly assumed.

4. Successful infection was established on all tomatoes inoculated with blight taken from outdoor potatoes in autumn, but ordinary blight lesions were not produced except in one experiment.

5. Blight taken from the leaves, stems, or fruits of the tomato infected the potato, and the disease so produced in the latter passed back readily to the tomato. This indicates that diseased tomato crops may be a serious menace to neighbouring potato crops.

6. The results of numerous inoculation experiments support the view that more than one strain of Phytophthora infestans exists.
OBSERVATIONS ON THE SPOTTING OF TOMATO FRUITS BY BOTRYTIS GINERE A PERS.
Authors: AINSWORTH G. C. , OYLER ENID , READ W. H.
Published: February 2008

Characteristic ring‐like spots caused by Botrytis cinerea on tomato fruits are described, with observations on certain factors which influence the spotting.

Evidence is presented to show that, under conditions of high humidity, Botrytis spores lying on the surface of immature fruits germinate, penetrating the epidermis, and that the spots result from the pectinase enzyme secreted by the germ tubes. With the return of drier conditions the spore‐lings die and no fungus can be isolated from mature spots.

It was found that similar spots could be produced experimentally by other species of Botrytis but not with various other fungi able to attack tomatoes.

The Botrytis spots are compared with aphid injury and notes are given on control.

We wish to thank Mr G. Cockerham, Mr E. E. Wallace, and Dr T. Small for material of blight, and Mr W. C. Moore for records of the disease.
EXPERIMENTAL SPAWN AND MUSHROOM CULTURE
Authors: CAYLEY DOROTHY M.
Published: February 2008

Methods for composting fermented and naturally rotted artificial composts consisting of straw, hay and dried lawn mowings for the growth of mushrooms are described.

The results of the tests in large pots and boxes on twenty‐four different composts are set out and show that previous high temperature fermentation is not absolutely essential for the growth of the cultivated mushroom, although the best results have been obtained from high‐temperature composts containing both lime and soil.

The effect of the addition of soil to both fermented and naturally rotted composts is described and discussed.

In conclusion I wish to express my indebtedness to Dr A. C. Fabergé for all the pH estimations, to Miss F. M. Durham for testing high‐temperature Compost I in the open, and to the laboratory assistant, A. F. Emarton, for the photographs for the plates and for his invaluable help with the preparation and manipulation of the various composts and cultures without which such a number of tests would not have been possible.
APPENDIX: The information supplied by the sampling results
Authors: COCHRAS W. G.
Published: February 2008

In any field experiment which involves sampling of a laborious nature, it is important to know as soon as possible what degree of accuracy in the treatment mean values will be reached with a given amount of work, how much work must be done to reach a given standard of accuracy and how best to distribute one's resources between the amount of sampling and the amount of replication.

The first sampling, whether it contains experimental treatments or is uniformly treated, can supply information on all these points if properly carried out. Ladell's fist wireworm sampling is taken as a simple numerical example of the way in which these questions can be answered with the help of an analysis of variance.

The sampling and experimental errors of Ladell's experiments are discussed. The sampling error accounts for a large proportion of the experimental error in most cases, as it is always advisable where the labour. involved in sampling is high.

Ladell's sampling errors agree well with those obtained under widely different conditions by Jones, and both may be recommended to other workers as an indication of the amount of variability to be expected in field sampling for wireworms.
INVESTIGATIONS INTO THE NUTRITION OF THE ASH‐BARK BEETLE, HYLESINUS FRAXINI PANZ.
Authors: HOPF H. S.
Published: February 2008

From investigations into the enzymes of the alimentary canal and a comparative analysis of ash bark and the frass of Hylesinus fraxini it appears that the food relations of the ash‐bark beetle are as follows:

Proteins are derived directly from the bark. The adult after emergence excretes more nitrogen than it consumes; this excess excretion may be regarded as representing waste‐products of metamorphosis.

The carbohydrates are derived from the following bark constituents: (a) The simple sugars.

Disaccharides, simple oligoses etc., probably all with α‐linkagee.

The α‐glucans up to starch, but with a definite preference for sugars of smaller chain‐length. Starch as such has disappeared from the bark of attacked trees.

The hexosan parts of the hemicelluloses.

The protein‐hydrolysing enzymes are of the tryptase and pepti‐dase type, in accordance with the alkaline pH of the gut.

The carbohydrate‐hydrolysing enzymes are of the following types: saccharase, a weak lactase, maltase, amylase (dextrinase), galact‐anase.

Cellulose is clearly not attacked. The same applies to all pentoaana.

The breakdown of starch in the attacked bark may serve as an attractant to the bark beetles, and may help to explain their preference for trees suffering from physiological or pathological disturbance.

A way has been shown in which the hemicelluloses are utilized by the insect in question, and the probable fate of the breakdown products of these substances in the frass has been indicated.
THE STEM AND BULB EELWORM, ANGUILLULINA BIPSACI (KUHN), IN STRAWBERRV IN BRITAIN
Authors: HODSON W. E. H.
Published: February 2008

SUMMAEY

1. Attention is drawn to the occurrence of Anquillulina dipsaci on strawberry in Britain and referenoe is made to litereture relating to such occurrence in the United States of America.

2. Recorded occurrencas in Britain are discussed in some detail and reference is made to the host range of the strains of nematode implicated.

3. Symptoms of attack am described.

4. Control measures are discussed, the principal suggestion being that on no account should runners be taken for propagation from infected plantationa.
COMPARATIVE EFFECTS OF COBALT, NICKEL AND COPPER ON PLANT GROWTH
Authors: BRENCHLEY WINIFRED E.
Published: February 2008

1. An account is given of the present position of our knowledge with regard to the distribution and the physiological importance of nickel and cobalt, in relation to plants and animals.

2. Experiments on barley and broad beans were carried out in water cultures with the sulphates and chlorides of cobalt, nickel and copper.

3. In every case a range of low concentrations did little or no damage, but toxic action occurred abruptly above a concentration which varied with the species and with the compound.

4. With barley, copper was the most poisonous element in either compound, but the differences were not striking. Low concentrations of the sulphate were innocuous, but parallel low strengths of the chloride caused a slight, significant depression in growth.

5. With broad beans, cobalt was much more poisonous than either nickel or copper, particularly with the sulphate. No slight depression with low concentrations of the chloride was noticeable with this species.

6. The morphological response to toxicity varied with the element concerned. Copper, in poisonous strengths, caused shortening and “bunching” of barley roots, whereas nickel and cobalt permitted the growth of elongated roots of a very attenuated nature.

7. The individuality of plant response to poison was frequently shown by the great variation in growth in the borderline concentrations just below those which caused marked depression of growth.
ROOT ROT, SHOOT ROT AND SHANKING OF TULIP CAUSED BYPHYTOPHTHORA CRYPTOGEAPETHYBR. & LAFF. ANDP. ERYTHRO‐SEPTICAPETHYBR.
Authors: BUDDIN WALTER
Published: February 2008

Phytophthora erythrosepticaandP. cryptogeahave been isolated on numerous occasions from diseased tulip plants on commercial nurseries, and the isolates, both in pure culture and in their effect on the host, have been compared with authentic cultures of these fungi. Both species have been proved to be, either separately or in conjunction, the cause of a serious root rot, shoot rot and shanking of forced tulips.

Infection, which takes place from contaminated soil through the roots, begins as soon as the first roots are produced from the basal plate of the bulb. The parasite passes directly through the basal plate to the base of the flowering stem, leaving the old bulb scales practically un‐attacked. According to the time, or rapidity, of infection an affected bulb may produce no visible shoot, or it may give a shoot bearing a flower bud that remains blind because the flower stem is rotted at the base (shanking). Sometimes a bulb with some of its roots attacked may produce a marketable flower of poor quality.

A very similar disease has been induced in outdoor tulips by contaminating the soil.

The disease, which may result in the total loss of a forced crop, has not yet been reported outside Great Britain, where it seems to be widely distributed.

There is no evidence that the disease is carried with the planted bulb in ordinary commercial practice, and the rate of spread in the glasshouse from one or more inoculated bulbs planted in the midst of healthy ones is comparatively slow.

The susceptibility of varieties of tulips to the two species ofPhytophthorais briefly discussed.

A contaminated water supply is a possibility, but appears to be relatively unimportant.

Partial sterilization of the contaminated soil by steam, or formaldehyde, combined with hygiene, is an effective method of controlling the disease, but soil treatment with Cheshunt Compound is unsatisfactory.

Certain strains ofPhytophthora cryptogeavar.Richardiaeand P.parasiticawere tested, but appear to be of little, or no, consequence as parasites of forced tulips.

A large proportion of the success of the present investigations has been due to the stimulus, and ever‐ready helpfulness, of Dr Geo. H. Pethybridge and Mr W. C. Moore. The credit for identifying the fungi concerned lies almost entirely with Mr S. F. Ashby. The writer also wishes to express his thanks to his Laboratory Attendant, Mr A. Sherval, for taking the photographs.
THE STERILIZATION OF LETTUCE SEED
Authors: WHITE H. L.
Published: February 2008

1. Since severe damage has followed the application by growers to lettuce seed of standard methods of sterilization recommended for cereals, trials of different methods of sterilizing lettuce seed have been carried out. Satisfactory sterilization free from seed injury is not effected by copper sulphate or formalin, while preparations containing mercury such as organo‐mercurial dusts are highly toxic to lettuce seed. Sterilization with calcium hypochlorite is a safe and efficient method.

2. Treatment with calcium hypochlorite prior to sowing has an accelerating effect, independent of germicidal action, upon the germination of lettuce seed. The viability of seed sown on filter paper or in soil is not appreciably affected but that of seed sown in contact with a film of agar, which shows exceptionally poor capacity to germinate, is notably increased. These effects are not attributable to germicidal activity and possibly result from increase of oxygen supply.

3. Susceptibility of lettuce seed to injury from germicides is a varietal characteristic.

4. Fresh seed with strong viability is more resistant to injury from germicides than older seed of less vigour.

Grateful acknowledgement is due to Dr G. C. Ainsworth for taking the photographs in Plate XXIX and for reading and criticizing the MSS.
VEIN CLEARING AND VEIN BANDING INDUCED BY HYOSCYAMUS III DISEASE
Authors: SHEFFIELD F. M. L.
Published: February 2008

The first symptom of Hy. III disease in tobacco is a clearing of the veins. This is followed later by vein banding. During clearing no anatomical or cytological abnormalities occur. The yellow colour is due to a retardation of chlorophyll formation.

When vein banding becomes apparent considerable hypertrophy is seen in the tissues near the veins and hypoplasia is apparent in the inter‐veinal areas. Intracellular inclusions are abundant in all tissues except the xylem.

Cleared tissue contains 6–11 times as much virus per unit volume as does the banded tissue. The latter also contains less than do the yellower parts of banded leaves.

I am indebted to Fraulein Lina Cunow who made most of the permanent preparations used in this study.
STUDIES ON EUROPEAN FOUL BROOD OF BEES
Authors: TARR H. L. A.
Published: February 2008

B. pluton will not grow on the chorioallantoin membrane of the developing chicken embryo or on medium made from minced embryos.

European foul brood is a purely intestinal infection of the bee larva, the causal organism being localized in the food mass within the peritrophic membrane.

Young larvae are readily infected with European foul brood by mixing relatively small numbers of B. pluton organisms, obtained from recently affected larvae, with the brood food surrounding them.
OBSERVATIONS OF THE EFFECT OF NITROGEN AND POTASSIUM ON THE FRUITING OF THE TOMATO
Authors: WHITE H. L.
Published: February 2008

Summary

The effect of nitrogen and potassium on the fruiting of the tomato under glass is studied by observations on plants grown on completely manured plots and plots from which nitrogen and potassium respectively have been omitted from the scheme of manuring over a period of years.

Nitrogen starvation reduces the number of blossom‐buds formed, the percentage of buds that open and the mean numbers of fruits per flower‐truss. Potassium starvation does not affect the number of blossom‐buds formed or the percentage of buds that open but reduces the mean numbers of fruits per flower‐truss.

An outstanding feature of nitrogen starvation is retardation of the rate of development of successive flower‐trusses. With potassium starvation the rate of development is accelerated. Growth, estimated from increase in height of plants trimmed to a single axis by continuous removal of incipient axillary shoots, is retarded by both nitrogen and potassium starvation.

The “maturation period” (between opening of the blossom and ripening of the fruit) is lengthened by potassium starvation, shortened by moderate nitrogen starvation and lengthened by severe nitrogen starvation. From the present results, in conjunction with data published previously, it is concluded that the “maturation period” is shortened by a high carbohydrate‐nitrogen balance and lengthened by a low carbohydrate‐nitrogen balance.

In mid‐season all plants suffer a check to growth and development demonstrated by (a) retardation of the rate of differentiation of leaves and flower‐trusses, (b) cessation of growth in height, and (c) the occurrence of a high proportion of fruit with arrested development. This “mid‐seasonal check” is accentuated by nitrogen and potassium starvation, especially the former, corresponds with the period of maximal weight of developing fruit, and is attributed to competition for nutrient supply between the fruits and vegetative parts of the plants, leading to apparent antagonism between these processes.

The fruiting and foliage symptoms of the potassium‐starved plants are attributed to the following effects:

(a) The potassium in starved plants is undergoing a continuous cycle, being translocated from older parts of the plant to the growing point, incorporated in young leaves and flower trusses and subsequently re‐translocated as these organs are approaching maturity.

(b) The level of potassium supply regulates nitrogen metabolism, a moderately low potassium supply being associated with high protein level and a greater degree of seventy of potassium starvation with low protein level.

The results are discussed in relation to the problems of overbearing and potassium manuring. The observed effects of potassium deficiency on fruiting (acceleration of development of flower trusses, failure of pollination and prolongation of the “maturation period” of the fruit) are those also associated with carbohydrate deficiency relative to nitrogen supply.
THE EFFECT OF MANURING UPON APPLE FRUITS
Authors: MUSKETT A. E. , HORNE A. S. , COLHOUN J.
Published: February 2008

Summary

Manurial treatment exercises a strong influence on the growth of apple trees, their time of blossoming, the amount of bloom, the foliage colour and the fruit colour. The effect is mainly due to nitrogen which induces increased growth, earlier flowering, more bloom, greener foliage and softer and greener fruit. Potash and phosphate have little effect on the growth of the trees, or on blossoming or foliage, but favour the production of more highly colonred fruit.

Nitrogenous manuring increases the nitrogen content of the fruit. Thus in 1930 the mean nitrogen content for the samples from plots receiving and not receiving nitrogen, was 0.0229 and 0.0550 respectively. In the following year the results for similarly treated pots were 0.0430 and 0.0745 respectively. Considering the results obtained in the years in question the mean nitrogen content for 1930 when there was a good yield was 0.0372 in contrast with 0.0587 for 1931 when the yield was poor. The control plot alone gave values of 0.0218 and 0.0343.

In 1930 the rates of radial advance (in mm. per day) of Cytosporina ludibunda for samples from plots receiving different treatments were K, 0.082; K+P, 0.118; X, 0.130; P, 0.150; C, 0.259; N+K+P, 0.456; N+P, 0.678; N, 1.213; and N+K, 1.249. The rate for the ample from the plot treated with N+K is fifteen times that calculated for the apples from the plot treated with K. The effect of nitrogenous as compared with non‐nitrogenous or no manuring has been studied in each of three years. The mean values for radial advance obtained for samples from plots receiving no nitrogen were 1930, 0.153; 1931, 0.33; 1932, 0.54, while for samples from plots receiving nitrogenous manuring the values were 1930, 0.889; 1931, 1.08; and 1932, 0.89. The values obtained in 1930 receive confirmation from observations on the radial spread of the fungus on the sterilized tissue from apples produced on trees in the various plots. The value γrm=+0.9112 was obtained for the correlation between radial advance (R) and radial spread (M). In 1930 the rate of growth of the fungus in the sample from the plot treated with K was one‐third of that in the sample from the control plot.

Radial advance is correlated with nitrogen content (N) of the fruit and this relationship is shown by the following values for the correlation coefficient: 1930, γRN+=0.8571; 1931, γrm=+0.7277.

Nitrogenous manuring increases the intensity of the attack of Venturia inaequalis on the fruit in the orchard. Evidence is produced in support of the suggestion that fruit resistant to attack by V. inaequalis may also be resistant to invasion by a rot producing fungus in storage. The value of the correlation between radial advance (R) and the percentage weight of scabbed fruit (S) was γRS+=0.6395. The percentage weight of scabbed fruit was shown to be correlated with the nitrogen content of the fruit and the value of the coefficient obtained was γSN;=+0.8292.
STUDIES IN POTATO STORAGE
Authors: SINGH B. N. , MATHUR P. B.
Published: February 2008

Summary

Tubers stored for 10–12 days at 18°C. lost considerably less weight during subsequent storage than those pre‐stored at 7°C. previous to permanent storage. This emphasizes the importance of pre‐storing potatoes for a brief duration at a higher temperature preparatory to permanent cold storage.

In the adolescent tubers the loss in weight during storage is high and decreases with increasing maturity of the tubers, the value for the total loss being about the same in mature and ripe tubers.

Although the magnitude of shrinkage during storage of mature and ripe potatoes is practically the same, the former are superior to the latter in that they keep longer in storage without sprouting.

During storage the loss in weight of potatoes due to respiration is very small in comparison with that caused by evaporation of water.
STUDIES IN POTATO STORAGE
Authors: SINGH B. N. , MATHUR P. B.
Published: February 2008

Summary

Adolescent, mature and ripe potatoes continue to be distinguished by their respiratory behaviour throughout the period of storage.

When potatoes are placed in storage there is a progressive increase in the concentration of internal carbon dioxide until the termination of the period of dormancy, the percentage of this gas falling rapidly with the commencement of sprouting.

Data concerning the composition of the atmosphere surrounding the tubers show that, in general, there is an accumulation of carbon dioxide in the surrounding air with increasing periods in storage.

There is a negative correlation between R.Q. and the percentage internal carbon dioxide during the stages of dormancy and sprouting.

Records concerning the composition of samples of air withdrawn from top, middle and bottom layers of potatoes show a slightly higher percentage of carbon dioxide in the bottom layer than in the middle and top ones.

Data concerning the permeability of the periderm of the potato to gas during storage indicate that the permeability of the superficial tissues decreases considerably during the dormancy of tubers.
COMPLEX FUNGAL ROTTING OF PEA SEEDS
Authors: PADWICK G. W.
Published: February 2008

Summary

Poor stands of peas due to fungal rotting were observed in field experimental plots in widely separated pea‐growing districts.

The rotting was not due to seed‐borne Ascochyta pisi or Mycosphaerella pinodes which were apparently absent from the seed.

Isolations from surface sterilized cotyledons of several varieties of peas grown in sterilized and unsterilized soil showed an abundance of common moulds and several pathogenic fungi, namely: a Fusarium of the section Roseum, Fusarium culmorum and Botrytis cinerea.

Isolations from surface sterilized rotting stems from five experimental centres at harvest time indicated the presence of a great variety of fungi including a number of species of Fusarium. Many of these, including all the common moulds such as Penicillium, were non‐pathogenic to the cotyledons. Fusarium avenaceum was found to be highly pathogenic to the cotyledons; F. solani var. Martii showed some signs of causing rotting; Botrytis cinerea was highly pathogenic. Several non‐pathogenic species of Fusarium were obtained.

Tests with numerous stock cultures show high pathogenicity of the following fungi to pea cotyledons:

Botrytis cinerea from Lactuca, Rosa and elsewhere.

Fusarium avenaceum from Triticum.

Fusarium culmorum from Triticum, Dianthus and Callistephus.

Fusarium species from Vicia faba and Tulipa.

Helminthosporium sativum from Triticum.

Ophiobolus heterostrophus from Oryza.

Sclerotinia species from Lactuca.

Fusarium Graminearum from Triticum.

It is suggested that loss of stand in pea crops due to rotting of the cotyledons by these and other fungi is probably more important than diseases caused by Ascochyta and Mycosphaerella and foot‐rots in the late stage.
A DISEASE OF THE VIOLA CAUSED BY RAMULARIA DEFLECTENS
Authors: CAMPBELL MARIE E.
Published: February 2008

Summary

Viola plants, of the variety Kate Blyth, which were badly infected with the fungus Ramularia deflecens, were received from Coventry in the early spring.

Sclerotium‐like bodies were found on the leaves.

Pycnidia containing pycnospores were obtained in culture.

By comparison it is seen that these sclerotium‐like bodies are really pycnidia which have not developed fully.

The formation of pycnidia in culture depends on nutrition.

Perithecia are found neither on the plant nor in cdture.

In the early spring positive results from infection experiments are obtained.
FACTORS AFFECTING THE FLUCTUATIONS IN THE POPULATION OF TOXOPTERA AURANTII BOY. IN PALESTINE
Authors: RIVNAY E.
Published: February 2008

Summary

The Citrus aphis reproduces parthenogenetically continuously throughout the year; sexual reproduction has not been observed.

The most favourable temperature for development and reproduction of the aphis is between 22 and 25° C. Between 18 and 22° C. the rate of reproduction and development is also suflicient to bring about heavy infestation.

The temperature below 18° C. is unfavourable for considerable increase of the population of this hisect. At 7° C. reproduction is barely taking place.

At 30–32° C. the mortality of the nymphs is almost 100%. At 34–35° C. reproduction ceases, and at 36° C. adult insects die within a short period.

The annual fluctuations of the population of the insect based on field observations are described.

Food as a factor in the increase of the population of the aphis is discussed.

The effect of the annual fluctuations of the temperature in Palestine upon the population of the aphis is pointed out.

The economic status of the insect is discussed.
STUDIES OF THE BIOLOGY OF THE DEATH‐WATCH BEETLE, XESTOBIUM RUFOVILLOSUM DE G.
Authors: FISHER RONALD C.
Published: February 2008

Summary

This paper, the second in a short series on biological studies of the death‐watch beetle, Xestobium rufovillosum De G., is concerned with the life of the adult, egg‐laying and hatching.

Times of pupation and emergence in the natural habitat of the insect in decayed parts of willow, and in timbers in buildings are discussed and compared.

The rate of development of the reproductive organs after pupation and until egg‐laying starts, is described.

The habits of the adults, activity, tapping, fight and mode of pairing are commented upon.

The major part of the paper deals with oviposition which has been studied out of doors and under controlled tempemture and humidity in the laboratory.

Out of doors forty to eighty eggs per female are laid during May and June over a period of 6–9 weeks. The egg stage lasts from 3 to 5 weeks, according to temperature conditions.

In the laboratory, oviposition and the hatching of the egg were studied at 15, 20, 25 and 30°C. and relative humidities of 23, 41, 53, 75, 86 and 95 %. The results are discussed in relation to the effect of temperature, relative humidity and saturation deficiency.

“Indices of suitability” for various combinations of temperature and humidity in relation to egg‐laying and hatching are calculated from the experimental data.

It is shown that an increase in temperature to a maximum between 25 and 30°C. is favourable but that the optimum conditions must include a low saturation deficiency. The data demonstrate an increasing tolerance, by the insect, of dryness associated with a rise in temperature.

The application of these findings to the occurrence and spread of Xestobium in buildings is briefly discussed.
ON THE BIONOMICS AND STRUCTURE OF SOME DIPTEROUS LARVAE INFESTING CEREALS AND GRASSES
Authors: THOMAS I.
Published: February 2008

Summary

In the field the chief larval host plants of Geomyza tripunctata Fall. are Lolium perenne and L. italicum; in the laboratory other grasses and wheat are readily attacked. The damage is similar to that caused by Oscinella frit L.; the larva feeds inside the grasses and kills the central shoot.