bluuebunny/crossref_metadata_2025 huggingface dataset:
THE BIOLOGY OF THYSANOPTERA WITH REFERENCE TO THE COTTON PLANT
Authors: WARDLE ROBERT A. , SIMPSON ROBERT
Published: February 2008

Observations and experiments concerning Thrips tabaci on cotton and other plants suggest that plant injury from thrip attack is in this case due entirely to premature and excessive defoliation, and is dependent in extent and severity upon the value of the infestation factor, or number of thrip stages per unit area of foliage surface. Differences between plant species, plant varieties and plant individuals as regards susceptibility to injury arise chiefly through variations in thickness of the epidermal cell layer.

Leaf injury consists essentially of necrosis of a patch of meso‐phyll cells lying immediately below a gash in an epidermal cell. Such necrosed patches are scattered and isolated when the infestation factor is low, but are confluent and form extenaive rusty areas when the infestation is high. Such areas consist of dead cells of the superficial meso‐phyll layers; the deeper layers, palisade tissue and epidermal layers remain intact, except for the initial gashes made in epidermal cells. In later stages of leaf injury, such necrosis involves the whole leaf, all the layers become disorganised, and premature shedding occurs. There is no evidence that the insect salivary secretion is toxic.

The insect does not puncture or rasp the epidermis but gashes an epidermal cell by pickaxe‐like movements of the single mandible, induced by a slight rocking movement of the head. In most cases, the mandible can only gash the outer epidermal wall, the inner wall and the lateral walls of the mesophyll cells being broken down by similar movements of the longer protruded maxillary laciniae. There is no evidence of attack through the stomata. Suction of the chloroplasts into the pharynx is aided probably by the partial vacuum established within the mouth cone when applied closely to the leaf surface.

The preference shown by thrip stages for the lower surface of leaves is believed to be. due rather to differences in thickness of epidermis between the lower surface and the upper surface, than to negative phototropism. In plants where such differences are slight, such as cotton plants, thrip stages readily invade the upper leaf surface. On Cajanus indicus, the upper surface is the more favoured, the lower surface being unsuitable owing to the close spacing of numerous fine hairs. The more widely spaced hairs on cotton leaves do not act as a deterrent, the hairy American and Indian varieties being more heavily attacked than the smoother leaved Egyptian varieties of cotton.
THE STRAWBERRY DISEASE IN LANARKSHIRE
Authors: WARDLAW C. W.
Published: February 2008

In the field two aspects of the “Lanarkshire Straw‐berry Disease” are apparent, namely, the devastation en masse of the strawberry beds. and the diseased condition of individual plants.

Soil conditions as a whole are unfavourable, and this tells against the development of an extensive and healthy root system.

The roots are weak and lax. consequent on the excessive stiffness of the soil. This renders them liable to fungal attack.

Roots of all kinds were found to be penetrated by fungal hyphae. and to have hyphae associated with them.

Eighteen separate extractions of fungi were made, and on twelve occasions a species of Pythium was the only fungus obtained.

When inoculated into pots in which strawberry plants had been grown under sterile conditions, the Pythium attacked young and old roots: and produced all the symptoms of the disease.

The Pythium was isolated again in the laboratory from inoculated plants.

This evidence demonstrates that the Pythium is capable of producing the strawberry disease as it occurs in field conditions. It is concluded that Pythium is an important factor in exploiting the root system on which the general health of the plant depends.

The problem appears to be an agricultural rather than a mycological one. The main factor involved appears to be the general health of the plant. The fungal attack is to be regarded as an important accessory to the main Factor. It is, however, a factor which has become increasingly aggressive owing to the accentuation of certain soil conditions.

Experimental work on the soil is being carried out side by side with the mycological studies.
THE ROSETTE DISEASE OF PEANUTS (ARACHIS HYPOGAEA L.)
Authors: STOREY H. H. , BOTTOMLEY A. M.
Published: February 2008

Rosette is a destructive disease of peanuts in South Africa, characterised by chlorosis of the young leaves and extreme stunting. Similar conditions in this plant have been reported from tropical Africa, Java and India.

Experimental evidence is advanced to show thali rosette is not carried in the seed of the peanut nor in soil which has borne a diseased crop. It was successfully transmitted to healthy plants by grafting, but not by inoculation of juice from diseased plants.

Insect transmission studies demonstrated the ability of Aphis leguminosae Theo. to act as a vector of rosette. Thirteen species of leaf‐hoppers in a limited series of tests failed to transmit the disease.

Aphis lguminosae was shown to obtain the virus of rosette by feeding upon a diseased plant. Winged and wingless adults, when feeding singly, were shown occasionally to transmit the disease.

An infrequently occurring mosaic‐like form of the disease is considered to be due to an exceptional reaction of individual plants to infection by the same virus as that causing typical rosette.

In the field this disease is believed to overwinter in diseased plants, which germinate in the late autumn and survive the drought and frost of winter. Upon these plants the aphides may spend the winter. It is thought that in the spring winged aphides become disseminated from the overwintering plants and cause localised infections in the peanut fields. Later in the season epidemic spread of rosette frequently occurs. The evidence of six years of peanut‐growing indicates that spring infection of rosette is most severe in seasons following winters of exceptional rains.

Rosette disease is likely to be largely escaped in the average season if the crop be planted at the earliest favourable date. Precautions recommended for control are the destruction of surviving plants during the winter and the removal of the diseased plants which develop in the new crop. The best prospect of practical control of rosette however is thought to lie in the discovery of resistant varieties.
ON THE CONTROL OF RED SPIDER BY MEANS OF NAPHTHALENE VAPORISED OVER A SPECIAL LAMP
Authors: PARKER. THEODOEE
Published: February 2008

Naphthalene vapour having been shown by other investigators to be toxic to Red Spider, Tetranychus telarius L., it was thought that better control of the fumigation would be obtained if the substance was vaporised by means of a lamp. A suitable lamp was designed and is described herein. It has been used under commercial conditions and has given satisfactory results.

Carnations and tomatoes have been fumigated with naphthalene and satisfactory control of Red Spider has been secured as shown by data given herein.

Fumigations on a variety of glasshouse plants in addition to the foregoing have been conducted and general observations and recommendations on naphthalene fumigation for the control of Red Spider are included.
THE EFFECT OF PHENOL, CARBON BISULPHIDE AND HEAT ON SOIL PROTOZOA
Authors: DIXON. ANNIE
Published: February 2008

Experiments made to discover the death‐point of protozoa by phenol, carbon bisulphide and heat showed that phenol has a greater lethal effect than carbon bisulphide.

Heating the soil in a steamer for thirty minutes is usually sufficient to kill off the protozoa, and the treatment of glass‐house soil by steam destroys the majority of the protozoa and has a depressing effect on their numbers for a long period.
ON TWO SPECIES OF FUSARIUM, F. CULMOBUM (W. G. SM.) SACC. AND F. AVENACEUM (FRIES.) SACC., AS PARASITES OF CEREALS
Authors: BENNETT F. T.
Published: February 2008

Fusarium disease of wheat, common in the north of England, is due mainly to F. culmorum (W. G. Sm.) Sacc. and F. avenaceum (Fries.) Sacc. occurring either separately or together.

Both species cause “seedling blight,”“spring yellows,” and “foot‐rot”; the foot‐rot results in “thinning out” between earing and harvest, and in “premature ripening” or “whiteheads” with “deaf ears.”

Both species cause a “blight of the ears” by casual external infection, resulting in sterility of florets, or diseased grain; F. culmorum is the more frequent cause of this phase.

Barley, oats and rye show corresponding phases of the disease.

The pathogens overwinter in diseased material in the granary or in the field; under storage conditions they retain vitality for considerably more than one year.

The cultural and diagnostic characters of the fungi are given, and control measures are discussed.

The writer is indebted to Mr F. T. Brooks for advice on the preparation of this paper.
ATTEMPTS TO CONTROL BUNT (TILLETIA TRITICI, WINT.) IN WHEAT WITH A FORMALIN‐GYPSUM DUST
Authors: STIRRUP H. H. , CRANFIELD H. T.
Published: February 2008

A series of experiments over a period of four years is described in which attempts are made to control Bunt in wheat by dressing heavily infected seed with a dry powder or dust composed of formaldehyde and calcined gypsum.

Good control was obtained in the first two years when clean seed, artificially infected with bunt spores obtained from crops of different varieties, was used.

In the last two years the seed was heavily infected naturally by bunt spores obtained from the same crop. Under these conditions, the formalin‐gypsum powder exercised little or no control of Bunt.

The experiments seem to provide some evidence to support the view that Tilletia tritici is a fungus comprising a number of biologic forms.

While going to press, attention has been drawn to a paper by J. D. Sayre and R. C. Thomas, which appeared in the October, 1927, number of Science (Vol. LXVI, No. 1713). In this paper the authors give the results of one year's experiments on the control of oat smut using a dry powder incorporating formaldehyde with charcoal or infusorial earth.
THE USE OF TETRACHLORETHANE FOR COMMERCIAL GLASSHOUSE FUMIGATION
Authors: PARKER. THEODOEE
Published: February 2008

Various methods for the application of tetrachlorethane as a fumigant for the control of White Fly under commercial horticultural conditions are discussed.

The lowest concentration that appears to give a control has been suggested.

The fumigant appears to be selective in its action upon White Fly and Mealy Bug. Certain species of Aphides seem to be unaffected.

Certain plants show a varietal susceptibility to the action of the fumigant.
ON THE LIFE‐HISTORIES AND ECONOMIC STATUS OF CERTAIN CYNIPID PARASITES OF DIPTEROUS LARVAE, WITH DESCRIPTIONS OF SOME NEW LARVAL FORMS
Authors: JAMES H. C.
Published: February 2008

Cothonaspis rapae (Westd.) was found to be an effective parasite of the Cabbage Root Maggot (Hylemyia brassicae Bouche) in the Cambridge district. Twenty‐five per cent. of the total of host maggots and puparia examined were found to be parasitised by this cynipid.

The average duration of a life cycle of C. rapae is 92 days and the length of the larval stage is about 55 days. There are two generations in the season; the first appears in May and the second in August and September.

The winter is passed in the larval stage.

Hypermetamorphosis occurs in the life cycle, the primary larva being eucoiliform with three long pairs of thoracic processes, a long cauda, and suctorial mouth parts. The full grown larva is a typical mandibulate hymenopterous grub without cauda or appendages of any kind.

The life‐histories of Figites anthomyiarum Bouché, Kleidotoma marshalli (Marshall) and an undetermined Kleidotoma are described.

They are all effective parasites during the early larval stages of carrion feeding Diptera such as the Calliphora erythrocephala, Sarcophaga carnaria, Lucilia sericata, etc. The writer estimates that saprophagous maggots are reduced in numbers by 30 per cent. owing to parasitisation by various Cynipid parasites during the early larval stages.

These three parasites have each two broods per season. The duration of the Figitids' life cycle is about 60 days, but that of both Kleidotomids takes from 10 to 20 days longer. There does not appear to be any definite period of emergence, but one generation overlaps another.

The primary larva of F. anthomyiarum is a modified eucoiliform. No primary larva of a figitine species has been hitherto described. The primary larvae of the two Kleidotomids are eucoiliform but with short thoracic processes. These types of primary larvae are each succeeded by an entirely new type of endoparasitic larva which bears pronounced affinities to the polypod embryonic stage. The writer has termed this type of larva the polypodeiform larva. The polypodeiform larva of both F. anthomyiarum and Kleidotoma marshalli are figured and described.

The early stage forms of parasitic Cynipid larvae are reviewed and compared.

Several experiments were conducted to test whether Cynipids parasitising saprophagous maggots would oviposit in phytophagous maggots and vice versa. Under suitable conditions F. anthomyiarum was induced to oviposit in the maggots of H. brassicae (phytophagous) but the eggs did not develop.

C. rapae, however, could not be induced to oviposit in saprophagous Anthomyid larvae.
THE INFLUENCE OF ENVIRONMENTAL CONDITIONS ON THE DEVELOPMENT OF THE ANGULAR LEAF‐SPOT DISEASE OF COTTON
Authors: STOUGHTON R. H.
Published: February 2008

The serious disease of cotton caused by Bacterium malvacearum E. F. S. is associated with unfavourable climatic conditions.

A description of an apparatus for controlling air temperature and humidity within a chamber is given.

At humidities above 80 per cent. relative saturation the limiting temperature for attack by B. malvacearum was 32°C., above which infection did not occur.

At 70 per cent. relative humidity infection was slight at 25°C.

At lower humidities no infection was obtained at a temperature of 28°C.
INOCULATION EXPERIMENTS WITH THE DOWNY MILDEWS OF THE HOP AND NETTLE (PSEUDOPERONOSPORA HUMULI (MIY. ET TAKA.) WILS. AND P. URTICAE (LIB.) SALMON ET WARE)
Authors: SALMON E. S. , WARE W. M.
Published: February 2008

The evidence now available indicates that the Downy Mildew of the hop, Pseudoperonospora Humuli (Miyabe and Tak.) Wils, is a distinct species coming from Japan, or possibly North America, into Europe about 1920. The views advanced by us in 1924 that this species might be co‐specific with P. Urticae and that it is endemic to England, are abandoned.

Inoculation experiments have shown that P. Humuli is capable of infecting and producing spores on Urtica urens. No evidence was obtained, however, as to whether it can establish itself permanently on this host‐plant.

Spores produced on U. urens as the result of inoculation with P. humuli can infect fully the hop.

Zoospores of P. Humuli placed on leaves of Urtica dioica and Parietaria ramiflora produced phenomena approaching sub‐infection.

Since P. Humuli in its native countries has been observed only on species of Humulus, the fact that in Europe a species of Urtica can be artificially infected, may indicate a widening of its host range.

Spores of P. Humuli, taken from cultivated hops, failed to infect fully Humulus japonicus.

Spores of P. Urticae (Lib.) Salmon et Ware, taken from Urtica dioica, were found to infect fully Urtica urens.
ON DEMATIUM PULLULANS De B. AND ITS ASCIGEROUS STAGE
Authors: BENNETT F. T.
Published: February 2008

The fungus Dematium pullulans de Bary, is in its perfect stage Anthostomella pullulans (de B.) comb. nov. The mature ascigerous stage occurs in nature, and in immature form has been obtained in pure culture from both the conidium and the ascospore of the organism.

A. pullulans retains vitality through all periods of natural drought and cold in this country by chlamydospores and microsclerotia; the perithecial stage is not essential for its continued existence, and appears to be formed intermittently only.

Six strains of this one species, A. pullulans, are described, showing the extent to which variation by transitional stages may occur within the species.

The fungus is saprophytic, or weakly parasitic, but non‐pathogenic, and is of promiscuous habit as regards host material.
THE PRODUCTION OF POWER ALCOHOL FROM WASTE VEGETABLE MATERIALS, SUCH AS GRASS, STRAW AND HUSKS
Authors: THAYSEN A. C. , GALLOWAY L. D.
Published: February 2008

It has been established that the hemicelluloses of various waste vegetable materials can be hydrolysed by acids to yield extracts fermentable by alcohol forming bacteria.

A study has been undertaken of the conditions under which Bac. acetoethylicus Northrop can be utilised for the fermentation of the extract obtained by the hydrolysis of various vegetable materials and the conditions have been ascertained under which the fermentation may be technically applied.

A method is described for carrying out this fermentation without the application, for the preparation and sterilisation of the mashes, of temperatures exceeding those of boiling water.
OBSERVATIONS ON THE DISEASE OF OATS CAUSED BY THE STEM EELWORM ANGUILLULINA DIPSACI (KÜHN, 1857)
Authors: ROBERTSON DAVID
Published: February 2008

The life‐history of the nematode is described.

The numbers of eelworms occurring in infected soils is discussed.

The external symptoms of diseased oat plants are described in detail.

It has been definitely proved that A. dipsaci can infect the oat panicle and grains and remain in a quiescent state within the harvested seed.
THE TRANSMISSION OF POTATO MOSAIC TO TOMATO
Authors: SMITH J. HENDERSON
Published: February 2008

Inoculation by leaf‐mutilation with the foliage of normal potatoes produced no disease in tomato. Nine varieties of potato were tested.

Similar inoculation with foliage of mosaic potatoes produced a characteristic disease in tomato. Five varieties of potato were used, of which three had been tested in the experiments with normal foliage.

The characters of the disease are described. It is transmissible back to potato again and to other solanaceous plants. The virus is filterable, is still infectious after high dilution of the extracted juice, and remains active on keeping for several months. It is less resistant to heat and alcohol than ordinary tobacco mosaic.

The disease resembles closely the spot‐necrosis disease described by Johnson as obtained by inoculation of tobacco with foliage of normal potatoes, the chief difference being the greater resistance of the potato mosaics here described.

It is probable that there exist several strains, differing in resistance, of the virus causing mosaic in the potato.
“BREAKING” IN TULIPS
Authors: CAYLEY D. M.
Published: February 2008

“Breaking” in Tulips is infectious and can be induced by bringing the internal tissue of a normal bulb in contact with tissue from a “broken” bulb during the resting stage.

 The degree of “breaking” appears to be proportional to the amount of infected tissue introduced.

 The phenomenon of “parrotting” has appeared in the “broken” flowers from bulbs infected with a small amount of “broken” tissue.

 Injections of filtrate from “broken” tissue have given negative results so far.
THE BIOLOGY OF OAT SMUTS: I. VIABILITY OF THE CHLAMYDOSPORES
Authors: SAMPSON KATHLEEN
Published: February 2008

The viability of the chlamydospores of V. avenae and U. levis has been under investigation since 1925. Samples of spores were tested dating back to 1921. The results are expressed in terms of percentage germination. Tests were carried out for the most part on 2 per cent. cane‐sugar solution or on an extract made from the pales of oats.

 Samples of U. levis showed a short “after ripening” period. They reached a maximum germination figure about two months after harvest and showed no loss in viability during a period of 2 to 21/2 years. Some samples were viable after 51/2 years.

 Panicles of U. avenae collected soon after exsertion yielded immature spores which quickly lost their viability. Mature samples, collected by covering the panicles with pollen‐proof bags, showed only a slight loss in viability after nearly 2 years in storage.

 The influence on viability of several methods of storage was investigated.

 The data emphasise the importance of maturity as a critical factor in the viability of samples. Divergent results obtained with the same species from time to time are probably to be explained by differences in the maturity and age of the samples tested.

 The significance of the results in connection with the different methods of contamination and infection current in the two species of oat smut is discussed.
AUTOCATALYSIS AND GROWTH
Authors: COPEMAN P. R. v. d. R.
Published: February 2008

The autocatalytic equation in the form log x/(a ‐ x) =K (t‐t1) may be used to express closely the changes which occur during growth.

The constant k, as given by K = ka, is not a constant which is independent of environmental conditions.

The changes in growth may be more suitably expressed by means of the equation dx/dt= (k1+ k2x) (a ‐ x). In this case k1 may be regarded as a constant, dependent upon external conditions, while k2 is a measure of the internal factors governing the growth processes.
SOME EXPERIMENTS WITH CALCIUM CYANIDE AS A CONTROL FOR PLANT PARASITIC NEMATODES
Authors: HODSON W. E. H. , GIBSON GORDON W.
Published: February 2008

Considerable diversity of opinion has existed regarding the practicability of controlling plant parasitic nematodes by means of granular calcium cyanide.

 Previous experiments with this substance have invariably been directed against eelworms of the genus Heterodera.

 The experiments described in this paper were carried out in South Devon and in the Isles of Scilly and with the exception of one with Heterodera radicicola, in tomato, relate to Tylenchus dipsaci, in narcissus.

 Doses of granular calcium cyanide, ranging from 300 lbs. to 2000 lbs. per acre, were employed under various conditions. Only with doses of from 1500 lbs. to 2000 lbs. per acre was any real indication of satisfactory control of T. dipsaci obtained, while H. radicicola remained unaffected by similar doses.

 In the opinion of the writers the successful use of granular calcium cyanide for the control of plant parasitic nematodes, on a commercial scale, is not possible under conditions pertaining to this country. At the same time, where expense is of no account, small areas of soil may be rid of nematodes by means of exceedingly heavy doses of the substance.
LABORATORY EXPERIMENTS WITH NON‐ARSENICAL INSECTICIDES FOR BITING INSECTS
Authors: GIMINGHAM C. T. , TATTERSFEBLD F.
Published: February 2008

A convenient technique for experiments with insecticides for biting insects is described.

 The silicofluorides of sodium, potassium, aluminium and calcium, used in the form of spray‐fluids, showed considerable toxicity to young larvae of several species of moths. The degree of resistance varies with different species and is greater with older larvae. Considerable, but irregular, injury to foliage was noted, and much further work is required to establish the conditions under which these compounds could be safely used.

 Foliage sprayed with extracts of certain tropical plants is extremely repellent to young larvae. Even with high dilutions of the extracts, the foliage remained uneaten and the larvae eventually died of starvation.

 A short review of some recent work on laboratory experiments with non‐arsenical insecticides for biting insects is given.
INVESTIGATION ON HETERODERA SCHACHTII IN LANCASHIRE AND CHESHIRE PART I. THE INFESTATION IN CERTAIN AREAS AS REVEALED BY CYST COUNTS; AN ESTIMATION OF THE ERRORS INVOLVED IN THE TECHNIQUE AND A CORRELATION WITH INTENSITY OF DISEASE
Authors: SMITH A. M. , PRENTICE E. G.
Published: February 2008

Heterodera schacJitii has been identified in many parts of Lancashire and Cheshíre where severe losses have resulted from failure of the potato crop.

A detailed study of the errors involved in the technique of a method for estimating the infestation has been made.

The degree of infestation, as determined by cyst counts, has been compared with records of crop failure.

The conclusions that have been drawn are to the effect that: (a) where “eelworm disease” has been noted recently there is a positive association of intensity of disease and cyst content of the soil; b) where the disease was observed three or four years ago, disease and crop failure are always associated with a high cyst content of the soil, but there may be a moderately high infestation without apparent diminution of crop yield.
INVESTIGATIONS ON HETERODERA SCHACHTII IN LANCASHIRE AND CHESHIRE PART II. THE RELATIONSHIPS BETWEEN DEGREE OF INFESTATION AND HYGROSCOPIC MOISTURE, LOSS ON IGNITION AND pK VALUE OF THE SOIL
Authors: SMITH A. M.
Published: February 2008

Soil samples taken for the purpose of measuring the infestation of Heterodera schachtii have been further examined for any association between cyst concentration and those physico‐chemical properties relating to the moisture, temperature and acidity of the soil.

The hygroscopic moisture and loss on ignition have been determined for three typical series of ten samples having significant variations in cyst counts. There is no simple association of the observations within any of the series. It appears improbable, therefore, that the rate of reproduction of Heterodera schachtii is influenced to a marked degree by the normal variations in the physical condition of the soil.

The pH of seventy‐eight samples has been measured electro‐metrically. When the samples are divided into two groups according to soil type, there is found to be a significant negative correlation between pK and cyst count for fifty‐three peat soils. There is not, however, a significant correlation in the case of the other twenty‐five sandy soils.
THE MOSAIC DISEASE OF THE HOP; GRAFTING EXPERIMENTS, II
Authors: MACKENZIE D. , SALMON E. S. , WARE W. M. , WILLIAMS R.
Published: February 2008

When scions of varieties susceptible to mosaic disease were grafted on German, American, Danish, English and Seedling varieties, they developed typical mosaic disease. It appears, therefore, that “carrier” varieties are common amongst commercial varieties of hops. Certain male hops also proved to be “carriers.”

In a few cases susceptible scions grafted on “carrier” stocks remained healthy. These anomalous cases require further investigation.

As a rule, the “carrier” varieties show no trace whatever of mosaic disease; the leaves are of normal colour and the plant shows normal growth with high fertility.

A case is recorded where one “carrier” variety (Red Vine Canada) exhibited in one season nascent symptoms of disease. The term “masked mosaic” is suggested for the appearance shown.

Scions of the commercial variety Fuggles, when grafted on “carrier” plants, invariably remained healthy.
A MOSAIC VIRUS OF GRASSES, NOT VIRULENT TO SUGAR CANE
Authors: Stokey H. H.
Published: February 2008

This paper records studies of a mosaic disease observed in maize and Sorghum spp. in the Transvaal, South Africa. In these hosts the signs produced were not distinguishable from those produced by the common sugar cane mosaic virus. Leaf‐cage experiments showed that Aphis maidis Fitch was capable of transmitting the virus to maize.

In the part of the Transvaal where the mosaic was found all sugar cane seen was free from mosaic. Sugar cane failed to contract the disease, both in a field experiment extending over three years in the Transvaal and in large cage experiments in Natal. The method employed in the Natal experiments was always successful in transmitting mosaic to sugar cane when the source of infection was either diseased cane or diseased grasses collected in the neighbourhood of diseased cane.

It is concluded that the Transvaal virus is not virulent to sugar cane and is therefore different from the common sugar cane mosaic virus.
POLLINATION OF HARDY FRUITS: INSECT VISITORS TO FRUIT BLOSSOMS
Authors: WILSON G. FOX
Published: February 2008

It was considered necessary to carry out observations on the insects concerned in the pollination of hardy fruit flowers over long periods in order to arrive at definite conclusions as to what insects may be considered essential for the carrying out of the work.

The result of five years' work has shown the usefulness of th3 hive bee as a pollinating agent, yet the important work of pollination, under certain conditions, may be carried out entirely by wild insects, principally humble and other wild bees (Bombus and Andrena) and flies (Eristalis, Syrphus, Sciara, Anthomyiids and Calliphora).

The district and the position of orchards govern to a large extent the numbers of wild insects, and the plantations at Wisley are favoured in this respect by their close proximity to open country and pasture land.

The factors, other than the presence of pollinating agents, which influence fruitfulness in orchards are considered.

The transference of pathogenic organisms by anthophilous insects is discussed.

The species of insects taken on the various fruit flowers are listed together with data as to their individual habits and abundance.

A census of the chief pollinating agents of hardy fruit flowers at Wisley is appended and the meteorological data covering the period over which observations were made.
THE LARVA AND PUPA OF SCATOPSE FUSCIPES MG. AND A COMPARISON OF THE KNOWN SPECIES OF SCATOPSID LARVAE
Authors: LYALL EDITH
Published: February 2008

The larvae of Scatopse fuscipes were found in decaying green ginger at a London dock in 1927. The necessity for descriptions of larvae occurring in stored products is pointed out.

The previous literature is discussed. General descriptions of the larvae and pupae are given, especial attention being paid to the mouth‐parts of the larvae, which have in common with larvae of several Dipterous families, “premandibles.”

A short comparison of the larvae of S. fuscipes, S. notata and S. subnitens is made and the most important differences between them are emphasised. No other species have yet been described.

I have to express my indebtedness to Mr O W. Richards for material and references and to Dr J. W. Munro for his assistance and advice.
SOME ASPECTS OF THE MORBID ANATOMY OF PLANTS
Authors: BUTLER E. J.
Published: February 2008

Summary.

The anatomical modifications in the tissues of plants caused by the action of gall‐inducing fungi and insects are illustrated by a number of examples, and compared with those produced by various processes of regeneration and wound healing or by factors that lead to anatomical changes without the intervention of wounds, such as nutrition, humidity, and the like. It is concluded that all living cells have the potentiality to react to various stimuli by hypertrophy, hyperplasy, or the development of meristeroatic tissues, and that the pre‐existing meristems are not, of necessity, primarily implicated in gall formation.
INTRACELLULAR INCLUSIONS IN MOSAIC OF SOLANUM NODIFLOBUM
Authors: SMITH J. HENDEESON
Published: February 2008

Summary.

A description is given of the intracellular inclusions found in S. nodi‐florum after inoculation with the virus of the yellow (aucuba) mosaic of tomato. In this plant these inclusions are unusually conspicuous and can be observed in the living cell with exceptional ease. They are of two main types, crystalline spikes and amoeboid bodies, the latter corresponding to the X‐bodies found in other plants. A detailed account is given of their appearance, structure, position in the cells, relation to the nucleus etc. The X‐bodies may be either coarsely granular, looking like aggregates of particles, or more homogeneous; and they have a pronounced tendency to crystallise into the forms commonly seen in protein crystals. They are vacuolate, and occur in all the tissues of the leaf.
THE CHLOROTIC DISEASE OF THE HOP
Authors: SALMON E. S. , WARE W. M.
Published: February 2008

Summary.

A description is given of a new virus disease of the top characterised by weakness of growth and by the presence of yellowish (chlorotic) markings on the leaves, accompanied by distortion of the lamina. The name “chlorotic disease” is proposed.

Two instances are recorded where the disease has been transmitted artificially, in one to a healthy plant by budding with a diseased bud, and in the other to a healthy scion by grafting it on to a diseased stock.
NOTES ON THE CULTURING OF INSECTS FOR VIRUS WORK
Authors: HAMILTON MARION A.
Published: February 2008

Summary.

A method for keeping pure and uninfected cultures of aphides for virus work is described; it involves the use of cellophane and bolting silk on a metal framework.

Specially constructed glass capsules are described in which aphides can be fed on artificial media, plant extracts or dyes.
THE EFFECT OF CERTAIN TREATMENTS ON THE GERMINATION OF TOMATO SEEDS1
Authors: JOZEFOWICZ MARY
Published: February 2008

Summary.

The effect of soaking tomato seeds in certain compounds and of exposing them to varying periods of wet and dry heat has heen investigated.

Good seeds (germination power 98–99 per cent.) withstood solutions of formaldehyde, not stronger than 2 per cent. (1 part per volume 38–40 per cent, commercial formaldehyde to 19 parts water) for 10 minutes, and not stronger than 1 per cent, for 15 minutes, followed by drying at 15–18° C. A 5 per cent, solution for 10 minutes, which was without effect when seeds were sown wet, retarded the germination after drying but did not affect the seeds' vitality.

Seeds of an inferior quality (80 per cent, germination) withstood solutions of formaldehyde not stronger than 1 per cent, for 5 minutes when sown wet, and were affected even by 0.1 per cent, formaldehyde for 5 minutes when dried after treatment.

100, 50, 35, 10, 5 and 1 per cent, solutions of hydrogen peroxide (commercial 20 vols. hydrogen peroxide) for 10 and 30 minutes, followed by drying, retarded germination, which was more pronounced with stronger solutions, the vitality of the seeds being practically unaffected.

An 0.05 per cent, mercuric chloride solution for 10 minutes proved harmless, but higher concentrations and longer treatment either checked the germination of dried seeds or retarded it markedly.

The vitality of seeds was not affected by copper sulphate solutions as follows: 10 per cent, for 15 minutes, 5 per cent, for 20 minutes, 2 per cent, for 50 minutes, 1 per cent, for 100 minutes and 0.5 per cent. for 200 minutes, but the germination in some cases was markedly retarded. A 5 per cent, solution of copper suphate for 10 minutes proved practically harmless.

Good air‐dried seeds withstood hot water at 35–46° C. for 15 hours and at 50.5° C. for 1 hour without any important injury. Higher temperatures decreased the percentage germination markedly even after 10 minutes' soaking.

Air‐dry seeds were not affected by exposure to dry heat of 30–50° C. for 72 hours. They withstood dry heat up to 79.5° C. even for 72 hours, the germination, however, being more retarded as the temperature and time of exposure increased. Temperatures above 79.5° C. proved very injurious at 10 minutes' exposure.
SOME OBSERVATIONS ON TOMATO PLANTS FROM SEED SUBMITTED TO HIGH TEMPERATURES1
Authors: JOZEFOWICZ MARY
Published: February 2008

Summary.

The results of pre‐drying seeds prior to heating at high temperatures and a description of abnormalities in tomato seedlings caused by heat are given.

Commercial tomato seeds withstood 90° C. and 88–100° C. for 1 hour better when previously dried at lower temperatures, their germination being, however, markedly retarded.

Part of the heated seeds germinated abnormally, and the developing plants were more or less abnormal. The primary root did not develop, the cotyledons were misshapen, and the plumule failed to develop into a normal shoot.

The longer the period of pre‐drying, the higher the rate of germination, and the less the degree of abnormality.

The basal growing point of a tomato embryo is least resistant to heat, the apical growing point, the hypocotyl, the inner and, lastly, the outer cotyledons following in order of resistance.

Embryos unable to push through the seed‐coats can grow for a certain period within them and develop chlorophyll.
THE TRANSMISSION OF STREAK DISEASE BETWEEN MAIZE, SUGAR CANE AND WILD GRASSES
Authors: STOREY H. H. , McCLEAN A. P. D.
Published: February 2008

General summary.

This paper describes experiments in the transmission of streak disease between maize, sugar cane, D. horizontalis Willd. and E. indica Gaert. The leafhopper, Cicadulina (Balclutha) mbila Naude, acted as the transmitting agent and was usually manipulated by the single‐leaf cage method.

The virus of maize streak disease is incapable of causing permanent infections of sugar cane. This conclusion is based on a considerable series of leaf‐cage experiments, in the greenhouse and in the field, and upon a large‐cage experiment. It is confirmed by certain field observations.

The maize virus frequently caused transitory infections of Uba cane, in the form of a few large chlorotic streaks on the leaves. From these streaks the virus was re‐transferred to maize. All evidence indicated that the cane plant made a complete recovery from this transitory infection and ceased to harbour the virus.

The virus from Uba cane readily infected Uba cane. When transferred to maize it produced in this species only a mild form of streak disease, distinguishable with certainty from normal maize streak. Repeated passage of the cane virus through maize failed to enhance its virulence to maize. Infection by the cane virus afforded no protection to a plant from infection by the maize virus; nor were hoppers similarly protected.

Streak disease was discovered in the cane variety P.O.J. 213, hitherto regarded as immune. The virus from these plants produced normal streak in Uba cane and the mild form of streak in maize. After many failures the disease was transmitted experimentally to this variety from Uba cane and from P.O.J. 213 naturally infected in the field. Cuttings taken from diseased plants of P.O.J. 213 frequently produced entirely healthy plants.

Lists are given of cane varieties which have been proved to be susceptible to streak disease and of those provisionally regarded as immune.

A list is given of species of wild grasses believed to contract streak disease in the field.

Streak in D. horizontalis has been transmitted from D. horizontals and to and from maize, but not from cane. The virus from a naturally diseased Digitaria plant, however, showed a virulence to cane greater than the maize virus.

E. indica was not successfully infected from maize or Uba cane. It was once mildly infected from P.O. J. 213, and was temporarily infected from Eleusine.

In experiments infective leafhoppers survived in the open through the winter at Durban and infected maize in the following spring. The infection of maize in the spring in Natal is thought to be caused usually by survival of the virus in overwintering leafhoppers and not in perennial host‐plants.
OBSERVATIONS ON LEAF FALL IN THE DOUGLAS FIR WHEN INFECTED WITH RHABDOCLINE PSEUDOTSUGAE SYDOW
Authors: BROWN A.B.
Published: February 2008

Summary.

In the Douglas fir the abscission layers and associated tissues are laid down early in the development of the leaf.

The extent of development of the protective layer has no causal relationship with leaf fall.

Infection with R. Pseudotsugae brings about a marked decrease in the water content of infected leaves.

The abscission mechanism is efficient at an early stage in the life of the leaf, provided the necessary physiological conditions are present and R. Pseudotsugae is capable of providing these conditions.

The author wishes to express his indebtedness to Dr Malcolm Wilson for his valuable supervision of the work and criticism of the manuscript.
CARBON DIOXIDE IN RELATION TO GLASSHOUSE CROPS
Authors: WHITE H. L.
Published: February 2008

Summary.

Data are given showing that the process of enriching the atmosphere with carbon dioxide affects the tomato plant slightly in many different ways, the sum of these tending to an increased yield of fruit.

These effects include (1) shortening of the period between opening of the flower and picking of the fruit, (2) high percentage of blossom developing into fruit, (3) lower percentage of fruit retarded in ripening,(4) better development of the truss normally most poorly developed,(5) earlier development and ripening of trusses in the later part of the season, (6) better swelling of the fruit at the end of the season.

Conclusions are drawn from the data that the results of an increased concentration of carbon dioxide are most beneficial to the plant at periods of low fruit‐production. These periods are discussed as occurring in the life of the commercially grown tomato plant.

The greatest percentage increases in weight of fruit of the treated plants over the controls are picked from the trusses which develop at such periods in the life of the plant.

In conclusion the writer is indebted to Dr W. F. Bewley, Director of the Cheshunt Experimental Station, and Dr F. G. Gregory, of the Imperial College, for valuable suggestions in connection with the text.
FIELD EXPERIMENTS ON THE DETERIORATION OF SCOTCH POTATO SEED IN ENGLAND
Authors: BROWN W. , BLACKMAN V. H.
Published: February 2008

Summary

An experiment with three varieties of potatoes (Great Scot, Kerr's Pink and King Edward) was carried out during the period 1922–24 in order to test the physiological theory of potato deterioration by determining whether the cropping power was influenced by early lifting or affected by shading the growing plants and so protecting them from overheating. The main results of this experiment were as follows:

In the absence or very limited presence of virus disease, neither early lifting nor shading produced any significant effect on crop yield. All the types of seed (one‐year grown, two‐year grown, early‐lifted, etc.) gave yields which were not significantly different from that of fresh Scotch seed.

When considerable infestation with virus disease was shown, all the types of English‐grown seed showed a significant falling off in yield as compared with Scotch seed. In such cases the falling off in yield was not so great with seed which had been lifted at a very early date. Thus, with virus disease present, an advantage may be gained by early lifting of the seed.

In one case, evidence was obtained that very immature seed is intrinsically inferior in cropping power to seed lifted at the normal time, i.e. apart from the effects due to the unequal distribution of virus disease.

In two cases the greater cropping power of one‐year grown English seed as compared with fresh Scotch seed was demonstrated. This difference is probably to be explained on the ground of the unequal sprouting at the time of planting.

A general correlation was observable between the amount of virus disease present in the various plots and the falling off in cropping vigour.

No effect of a purely physiological nature arising from early lifting or from shading was indicated. Though such an effect could not be disproved, it was clear that it was of minor account and quite subsidiary to the effects of virus disease.

An experiment was carried out over the period 1925–8 to determine whether, by a process of rogueing, the cropping vigour of a deteriorated stock could be restored. The weight tests carried out in 1928 showed that certain English‐grown stocks, some of which were in their seventh year from Scotland, yielded as heavily as Scotch seed.

The experiments were carried out in such a way that the statistical significance of the data obtained could be assessed. In thirty‐three such experiments, where the yield of English‐grown types of seed was compared with that of Scotch seed, the percentage drop in cropping power which was significant varied from 7.0 to 20.0. Over the whole series, the average figure was 11.8 per cent., corresponding to a falling off in yield of about 1.2 tons per acre.

In conclusion we wish to record our thanks, for facilities offered for this work, to the Director of the Rothamsted Experimental Station and to the Principal of the South‐Eastern Agricultural College, Wye, and the Principal of the Harper‐Adams Agricultural College, Newport, Salop.
APHIS AS A POSSIBLE VECTOR OF “BREAKING” IN TULIP SPECIES
Authors: HUGHES A. W. McKENNY
Published: February 2008

Summary

Myzus persicae Sulz. is suggested as a vector of the virus of transmissible variegation known as “breaking” in tulips.

“Red‐streak break” is associated with Myzus persicae.

Macrosiphum gei Koch possibly carries “break” in a lesser degree and is associated with “white streak.”

Anuraphis tulipae B. de Fonse. and Rhopalosiphoninus tulipaella Theo. have both so far shown negative results.
GIBBERELLA SAUBINETII (MONT.) SACC. ON BRITISH CEREALS
Authors: BENNETT F. T.
Published: February 2008

Summary

The occurrence of Gibberella Saubinetii (Mont.) Sacc. on wheat and barley grown in England is recorded, but the extent to which it occurs in this country is not known.

The methods by which it was isolated and grown in pure culture are described.

The complete life cycle of this “strain” has been carried through from single‐conidium and single‐ascospore pure cultures.

The diagnostic characters are given, and the identification verified.

The writer tenders thanks to Dr G. H. Pethybridge for assistance rendered.

(Since writing the foregoing article the writer has isolated G. Saubinettii from the bases of wheat, barley and T. monococcum plants grown in the Eastern Counties. 23/12/29.)
BACTERIAL “BLIGHT” OF WALNUTS IN BRITAIN
Authors: WOEMALD H.
Published: February 2008

Summary

An organism has been isolated from lesions on leaves, shoots, and fruit of young walnut trees at the East Mailing Research Station, Kent.

This organism was proved to be pathogenic by positive results obtained from inoculation on walnut leaves and shoots.

It corresponds closely to descriptions of Pseudomonas juglandis and is therefore referred to that species.
CARBON DIOXIDE IN RELATION TO GLASSHOUSE CROPS
Authors: SMALL T. , WHITE H. L.
Published: February 2008

Summary

The effect on the tomato crop of atmospheres enriched in respect of carbon dioxide liberated by two methods with possibilities of commercial application, (1) a fermentation process, and (2) a portable stove, is compared with that of carbon dioxide liberated by acid from sodium bicarbonate.

The concentration of carbon dioxide obtained from the fermentation process was insufficient to give any increase in yield. Using the stove method, which gave a concentration of at least 18 parts per 10,000 for 1.5 hours twice daily, the average increase in crop was 16 per cent. where plants were treated throughout the season and was 9 per cent. where they were treated for the first half of the season only.

Relatively high concentrations of carbon dioxide are shown to be normally present in cucumber houses. It is suggested that, under the weak light conditions prevailing in such houses, the concentration is sufficient for the requirements of the crop.

Mechanical mixing of the carbon dioxide and air is not essential from the standpoint of crop production.

In the case of tomatoes grown in enriched atmospheres, the cultivation of two crops, planted January and June respectively, was not profitable under the experimental conditions.

The stove method of treatment is discussed in relation to commercial practice.
APPARATUS FOR THE GROWING OF PLANTS IN A CONTROLLED ENVIRONMENT
Authors: STOUGHTON R. H.
Published: February 2008

Summary

An account is given of the construction of tanks and chambers for the growing of plants under independently controlled soil and air conditions. The plants are grown in soil tins sunk in a water tank, the temperature of which is automatically controlled. Double‐walled glass chambers fit over the tanks, and within these the conditions of temperature and humidity are independently controlled. Artificial illumination is provided by two floodlights over each chamber, with 500‐watt gas‐filled lamps in each providing an illumination of the order of 1000 foot‐candles. The chambers were erected under a grant from the Empire Marketing Board for research on the bacterial disease of cotton.