bluuebunny/crossref_metadata_2025 huggingface dataset:
The Physiology of Potato Leaf‐Boll
Authors: WHITEHEAD T.
Published: February 2008

1. A comparative study of the rates of respiration, as measured by the weight of carbon dioxide evolved, has been made with healthy and leaf‐roll infected potatoes at all stages in the life cycle, under anaerobic as well as aerobic conditions.

2. Except for a short period covering the end of dormancy of the tuber to the first unfolding of the leaves, the infected plant respires at a much lugher rate than does the healthy one. This is true also when the conditions of light, temperature, and external carbon dioxide approximate to those present in the field.
The Effect of Mosaic Disease Upon Certain Metabolic Products in the Tobacco Plant
Authors: CORDINGLEY H. , GRAINGER J. , PEARSALL W. H. , WRIGHT A.
Published: February 2008

1. Analyses of healthy leaves and of leaves infected with mosaic disease (N. tabacum) show that the diseased leaves contain higher proportions of nitrogen and lower proportions of carbohydrate, these differences being apparently increased during photosynthesis.

2. In leaves kept in the dark for 68 hours, carbohydrate losses are similar but fall chiefly on insoluble carbohydrate in healthy leaves and on disaccharides in the diseased leaves.

3. In diseased leaves, protein breakdown is retarded and insoluble substances are less readily hydrolysed.

4. The diseased leaves resemble older leaves in their metabolism.
The Movement of Tobacco Mosaic Virus Within the Plant
Authors: SAMUEL GEOFFREY
Published: February 2008

By means of extensive cutting‐up test's on tomato plants inoculated with tobacco mosaic the following points have been determined:

1. Confirming the work of Holmes, there is no movement of virus from the inoculated leaf for the first 3 or 4 days. This period is slightly less or considerably more according to the greater or less activity of growth of the plant.

2. When the virus passes out from the inoculated leaf it travels first to the roots of the plant with such speed that it can seldom be intercepted at intervening positions.

3. Usually about a day later it travels with equal rapidity to the top of the plant.

4. In the earliest stages of entering the stem virus particles may be separated by considerable distances (at least several centimetres), since successive samples taken from the stem may yield lengths of 21/2 cm. (the length of the cuttings) free from infection. interspersed irregularly between portions containing the infection.

5. The presence of developing fruit trusses on the stem may cause part of the virus to travel upwards as far as these trusses at the same time that the initial downward movement is occurring.

6. The virus enters developing fruits at the same time as it travels through the stem, whereas adjacent leaves remain uninfected for days or weeks.

7. In pot plants, after the initial rapid infection of the developing leaves at the top of the plant. the more mature leaves become successively invaded from the top downwards and from the bottom upwards until the plant is completely invaded by the virus. Complete invasion occurs very quickly in small vigorously growing plants; it may take 3 weeks or more in medium sized plants (Text‐fig. 2); and as much as 2 months in large fruiting plants (Text‐fig. 3).

8. Complete invasion never occurs when large field plants of tobacco or tomato bearing a number of mature leaves are inoculated. The mature leaves remain free from virus, apart from a limited movement along the mid‐ribs, for periods of more than 3 months following inoculation (Text‐fig. 4).
Aphides as Vectors of “Breaking” in Tulips. II.
Authors: D.I.C. A. W. McKenny HUGHES,
Published: February 2008

Three types of “breaking” are distinguished—full, “self and “clotted.”

The evidence points to “full break” being the product of two viruses.

“Self breaking” may be selectively transmitted by the aphis vectors Myzus persicae Sulz and Macrosiphum gei Roch.

“Self break” tulips only transmit “self breaking.”

“Clotting” is an expression of “full break” in certain varieties.

Anuraphis tulipae B. de Fonsc. is a definite vector in the bulb store but not on the growing plant.

At a certain stage of growth tulips cease to be susceptible to infection.
Some Common Species of the Genus Thrips (Thysanoptera)
Authors: SPEYER E. R.
Published: February 2008

1. The economic importance of the Thysanoptera as an order of insects and the necessity for a revision in the classification of the order are pointed out.

2. The past confusion between some common and destructive species of the genus Thrips is unravelled and the reasons for this confusion are set out.

3. The range of variation, within the species, of characters which have in the past been used for the separation of species in the genus Thrips is illustrated, this relating especially to measurements of the antennal joints and of setae upon the body. New structural characters of true specific value, especially relating to the chaetotaxy of the abdomen, are illustrated by examples.

4. Variation in colour and the shape of the head are referred to.

5. Characters of a constant nature for the species and of value in determination are set out, together with some account of the abdominal structure.

6. Quick and reliable methods for the mounting of specimens for microscopic examination are given.

7. Specific characters, which enable them to be distinguished from one another, and from other species, are given for some common British species of the genus Thrips.

8. A general account of the biology and a more detailed account of that relating to some common species is given.

9. Lines upon which a sounder classification of the Thysanoptera than at present exists are outlined.
Some Factors Affecting the Inactivation Rate of the Virus of Tomato Spotted Wilt
Authors: BALD J. G. , SAMUEL GEOFFREY
Published: February 2008

Tomato spotted wilt inoculum stirred in the process of inoculation lost its virulence more rapidly than inoculum standing undisturbed.

The rate of inactivation of the virus was increased by bubbling air through the inoculum.

When all but traces of free oxygen were excluded by bubbling nitrogen through the inoculum loss of virulence was slightly delayed but the final rate of inactivation was practically unchanged.

The addition of two oxidising agents, chloramine T and hydrogen peroxide, increased the rate of inactivation.

Of six reducing agents tested, one, sodium sulphite, retarded inactivation very markedly. In one experiment at a temperature of 22° C. the virus remained active for more than 36 hours in a 0.2 per cent, solution of the anhydrous salt while control inoculum prepared at, the same time with distilled water was completely inactivated in less than 5 hours.

Sodium nitrite retarded inactivation slightly.

The remaining four reducing agents—ferrous sulphate, tannic acid, hydroquinone and cysteine hydrochloride—hastened inactivation, but the oxidation‐reduction potentials existing in the virus‐containing systems were not known.

These results are briefly discussed in their bearing on the possibility that the normal rapid inactivation of spotted wilt virus which occurs in the standing juice is due to an oxidation reaction.
The Physiology of Virus Diseases in Plants: Vi. Some Effects of Mosaic on the Metabolism of the Tomato
Authors: CALDWELL JOHN
Published: February 2008

The literature dealing with the effect of virus diseases on the metabolism of the host plants is briefly summarised. Results are presented of work which has been carried out on the aucuba or yellow mosaic in tomato. The effect of time of inoculation has been studied in some detail. It has been found that the plant is generally reduced by the disease, and that the carbohydrate and dry‐matter content of the diseased plants is less than that of the controls. The stage of development of the plant is not apparently affected by the disease; the diseased plants, though reduced in size, have the same number of leaves and flower trusses as the controls. The nitrogen content is not materially affected by the disease. The effect of the disease on the respiratory mechanism of the host tissues has been examined, and it has been established that the CO2, output of these tissues is higher than that of the controls. This is found when the output is expressed in mg. of CO2, per three‐hour period in terms of the initial fresh weight, the residual dry‐matter content or of the residual nitrogen content. The higher CO2, output is also found ill respiration in oxygen or in nitrogen. This has been attributed to all increase in the efficiency of the enzyme system of the diseased plants.
The Sheep Blowfly Problem in North Wales
Authors: DAVIES W. MALDWYN
Published: February 2008

1. Early writings indicate that attack by sheep blowflies was common and well known in the early sixteenth century, prior to the establishment of sheep farming in North Wales.

2. A survey of North Wales has shown thatLucilia sericataMg. isthesheep blowfly of the province. In two advanced cases only were larvae ofCalliphora erythrocephalaMg. present, and then only in small numbers.

3. Sheep are attacked from May until October. The degree of attack as indicated in a summary of seasons regarded as severe was as follows:Upland districts—10–15 per cent. of sheep attacked;Lowland districts exposed—20–25 per cent.;Lowland wooded—35–40 per cent.

4. The complete absence of parasitism among larvae taken fromlivingsheep was a signscant result of the survey. Such a source of unparasitised larvae will mitigate success in the biological control of blowflies.

5. The life history ofLucilia sericataunder North Wales conditions has been investigated. Four generations are recorded. The normal mode of hibernation is in the prepupal stage, which hibernates in late September or October and returns to the soil surface from mid‐March onwards, when the soil temperature at 8 in. approaches 45° F. and when in the upper layers is slightly higher.

6. Shepherds, normally, “rub out” larvae from infested sheep, assuming that starvation and death results in the soil. Over 90 per cent, of such larvae produced imagines, and such infestations are pure cultures ofLucilia sericataMg. with an absence of competitive secondary species. Experiments, combined with a morphological study, showed that at the temperature of the sheep's body, larvae attain the third instar in 24 hours. They are then only half‐size, but can successfully produce imagines despite subsequent starvation. The present practice, therefore, should be changed, and a larvicide applied before the larvae are removed from the wool.

7. There is clear evidence of the greater susceptibility of lambs to attack, and the factors involved are being studied.

8. Observations have been made on the relative susceptibility to attack of six different breeds of sheep and their crosses. The degree of attack ranged from the Wiltshire breed, which is only rarely attacked, to the Southdown breed, which is frequently subject to heavy infestations.
THE INSECTICIDAL PROPERTIES OF SOME EAST AFRICAN PLANTS. I
Authors: WORSLEY R. R. Le G.
Published: February 2008

A number of East African plants, mostly indigenous, has been tested for insecticidal value as contact poisons.

No new insecticide equal in toxicity to nicotine has been discovered.

Two plants, Cassia didymobotrya and Barringtonia racemosa, have toxic properties slightly less than half that of nicotine used as sulphate. The plants, which grow dd, should be of value for making insecticides on those farms where they are already growing: they would not, however, be worth cultivating. No definite chemical compounds were obtained from these two plants.

The toxicity of extracts of Tephrosia vogelii has been found to be of the same order as that of nicotine in the form of sulphate, and these extracts should be able to replace nicotine in all sprays against soft‐bodied insects such as aphis and thrips.

Nearly all parts of this plant contain tephrosin, the seeds having the largest content at 0.35 per cent., whilst the leaves contain 0.18 per cent. Methods are given for the easy extraction of tephrosin from the various parts of the plant. The product obtained has been called “crude tephrosin ” by the author, and in this form is suitable for the preparation of insecticides.

Crude tephrosin contains about 20 per cent. of a substance crystallising in he yellow needles with a melting‐point of 227° C., which is probably dehydrodeguelin and is non‐toxic. The remaining 80 per cent, forms white tabular crystals with a melting‐point of 187° C., and is undoubtedly identical with Hanriot's tephrosin. So far it has resisted separation into two or more constituents, either by repeated recrystal‐lisation or by oxidation. This crystalline substance accounts for the toxicity of the crude tephrosin and of the plant itself.

Resins were obtained from most parts of the plant but, contrary to Tattersfield's results, they were found to be only slightly toz.

It is considered that in view of the fact that Tephrosia vogelii grows both widely spread and vigorously in East Africa it should be able to replace the use of nicotine almost entirely. On a small scale home‐made solutions could be easily and cheaply prepared, and the extraction of crude tephrosin on a larger scale is also worth consideration.

9. As a paraffin spray agarnst Antestia and Lygus, Tephrosia vogelii extracts proved useless compared with pyrethrum, but as a domestic spray against flies, mosquitoes, etc., paraffin extracts were found to be as effective as pyrethrum and should be able to replace it, at least for local use.

10. The finely powdered pod of T. vogelii has some value as an insect powder, due probably to the tephrosal in it, but cannot compare with pyrethrum powders.

11. The seeds contain 12 per cent. of fixed oil from which a soft soap can be made, suitable, according to preliminary tests, for a spreader but not for domestic purposes. The oil is a non‐drying one.

12. Further work on many of these points is continuing.
THE EFFECT OF ENVIRONMENTAL CONDITIONS UPON PYRETHRUM (CHRYSANTHEMUM CINERARIAEFOLIUM). II.
Authors: MARTIN J. T. , TATTERSFIELD F.
Published: February 2008

The effects of light, temperature and dormancy upon pyrethrum have been studied. The partial shading of the plant during the five months preceding flowering resulted in the production of smaller flowers with a reduced pyrethrin content.

The successful flowering of the plant was largely dependent upon the relative temperatures experienced throughout the year. A dormant period, dependent upon sufficiently low winter temperatures, was shown to be necessary for the normal production of large numbers of flowers.
AN APPARATUS FOR TESTING CONTACT INSECTICIDES
Authors: TATTERSFIELD F.
Published: February 2008

A description is given of the design of two atomisers for use in quantitative laboratory spraying for testing contact insecticides.

Tables and graphs are given showing the weights of spray delivered by each form upon known areas placed in different positions inside the spray jars, and an examination is made of the change in the distribution of the spray with the progressive closure of the orifice and increase in the distance from the orifice of the surface sprayed.
POTATO BLIGHT (PHYTOPHTHORA INFESTANS) INVESTIGATIONS IN JERSEY. PREVENTION OF DISEASE IN EXPORT PRODUCE
Authors: SMALL T.
Published: February 2008

Summary.

In Jersey the loss due to potato blight (Phytophthora infestans) in crops grown for export may be divided into:

Loss in transit caused by contamination of the tubers by spores at digging time and by packing tubers which are infected, but not obviously, when dug.

Loss in the field, which includes diseased potatoes left on the ground at harvesting time.

These losses, excepting those caused by contamination, occur when the disease on the haulms has reached an advanced stage before harvesting. The remainder occurs when disease is active on the haulms at digging time.

It is shown that blight may spread from diseased or contaminated tubers during transit and that there is little or no danger in using barrels which have previously contained diseased produce.

Ventilation or fumigation of the packages reduced the disease in transit.

Control methods are suggested and discussed.
SOME OBSERVATIONS UPON THE “RED SPIDER”, TETRANYCHUS TELARIUS L., ON HOPS AND ITS CONTROL, WITH NOTES ON SOME PREDATORY INSECTS
Authors: JARY S. G.
Published: February 2008

Summary.

Treatment of the soil around hops in November, with crude naphthalene at the rate of 300 lb. per acre, did not prevent infestation by Hop Red Spider in the following summer.

Examination of hop poles showed that large numbers of mites may hibernate in deep cracks in the poles.

h emulsion containing 5 per cent. of a high‐boiling neutral tar oil, sprayed with force into the cracks of poles, killed the great majority of mites. It was1 more effective in this respect than an emulsion containing 5 per cent. of a semi‐refined petroleum oil.

Of a number of washes applied in the summer to infested hops, emulsions of a highly refined (water‐white) petroleum oil at 1 and 2 per cent. oil concentrations, were effective in killing the mites. Lime sulphur a t concentrations of 1 in 30 and 1 in 60 also gave a complete control. A Derris wash of 0.0056 per cent. rotenone content appeared to give a complete control at the second applicabion whereas it failed to do so at the first. 'There is evidence that the toxicity of a Derris wash of the type used increasies up to a point with time after water is added to the powder. Liver of sulphur and colloidal sulphur a t the concentrations used showed no marked toxicity and the two spreaders used were also non‐toxic.

The petroleum‐oil emulsions and lime sulphur caused some injury to foliage when applied in late June and the first three weeks in July.

Lime sulphur caused no injury to foliage or “burr” on the varieties Fuggles, Cobbs and Early Birds, when applied during late July and early August, a t concentrations ranging from 1 in 60 to 1 in 150. Concentrations smaller than 1 in 100 were not markedly toxic to the mites, but at 1 in 60 and 1 in 80 lime‐sulphur wash was completely effective in killing all forms other than eggs.

Notes are added on three insect predators of the Hop Red Spider.
STUDIES ON APHIDES INFESTING THE POTATO CROP
Authors: DAVIES W. MALDWYN. , WHITEEEAD T.
Published: February 2008

Summary.

Field observations show that migrating alatae are the main source of the initial infestation of Myzus persicae Sulz. on the potato crop. They arrive in quantity, during June and July, from various cruciferous plants on which they have hibernated, or to which they migrated in early spring.

In 1934 the main migration at a selected centre occurred during a week which contrasted with other periods, since the wind, which was slight, changed from the north‐west to the south‐east, tbe temperature rose from about 67d̀ F to 80d̀ F. and the relative humidity dropped from 68 to about 30 per cent.

The hot, dry conditions not only facilitated flight but also greatly increased the proportion of alatae by causing the cruciferous weeds to wilt and die, when alate forms were produced in abundance.

The proportion of alate M. persicae was found to be much higher in a district where virus infection of the stocks had been rapid compared with a district where such was negligible.

The proportion of migrating alate M. persicae infected with virus diseases, in a district where the spread is rapid, proved to be particularly small. In eighty‐one experiments involving 1178 alatae only four instances included vectors; possibly only a single vector in each of the four experiments.

It is concluded that the introduction of virus diseases into a healthy stock by migrating alatae is slight, but this small amount is subsequently spread by apterous forms moving within the crop.
THE PROBLEM OF THE EVALUATION OF ROTENONE‐CONTAINING PLANTS
Authors: TATTERSFIELD F. , MARTIN J. T.
Published: February 2008

Summary.

Seven samples of Derris root have been examined chemically and the following determinations carried out: rotenone (crude and recrystallised), ether extract, methoxyl content, and dehydro compounds. The importance of using standard methods of analysis is stressed.

Insecticide tests have been carried out and comparisons made between pairs of samples tested on the same day.

When comparisons were made between pairs belonging to different species of Derris, the determinations of rotenone by the present methods, ether extract or methoxyl content did not express accurately the relative insecticidal potencies of the pairs of samples. When comparisons were made between pairs of the same species, all these determinations appeared to give a closer measure of their relative activities.

In our samples, the estimation of the dehydro compounds, or of rotenone plus the dehydro compounds in the resin, gave a better assessment of the relative potencies than the other determinations, whether comparisons were made between samples of the same, or of different species. Further work is, however, needed.
THE INFLUENCE OF SEASON AND OF THE APPLICATION OF LIME ON THE BOTANICAL COMPOSITION OF GRASSLAND HERBAGE
Authors: BRENCHLEY WINIFRED E.
Published: February 2008

Summary.

The botanical composition of the herbage of grassland under constant manurial treatment varies considerably from year to year.

With complete fertilisers including nitrogen and minerals the relative proportions of the three main groups of species, i.e. grasses, leguminous and miscellaneous plants, are not usually much affected by season, though the individual species do vary, but with one‐sided fertilisers and on unmanured areas wide fluctuations occur in the percentage of these groups. No correlation can be traced between the annual variations in the yield and the botanical composition of the herbage, except for some suggestion of association between high yield and high percentage of leguminous plants with long‐continued mineral manuring.

The variations of individual species occur on all plots. They may be caused by direct or indirect response to season and are much influenced by the type of manuring. It is often difficult to determine whether a marked increase or decrease of a species in any year is due to climatic conditions being beneficial or detrimental to that particular species. It may be that the real effect is on other constituents of the herbage which change so much that the proportion of the species under consideration is radically affected [cf. Alopecurus in 1922). In some cases, especially with organic fertilisers, the main groups and also certain species [as Alopecurus, Arrhenatherum, Dactylis] show a tendency to rhythmic changes with season, rising and falling over a period of years. In other cases the fluctuations are more abrupt and irregular, sometimes being exaggerated in the presence of lime.

The application of lime to plots with long‐established manurial treatment does not affect the balance of the three main groups with complete fertilisers, but with one‐sided manures a definite bias in one direction appears sooner or later. Individual species usually respond to lime at once, showing a change of proportion at the first succeeding cut, but under certain soil conditions a delay may occur until a second dressing has been given. It would appear that the maximum effect of liming is reached within a few years from the first application, after which fluctuations with season may again become more obvious.

Shade is also a factor which influences the balance of species in herbage. The available data is limited to a single plot, but indicates that certain species may be greatly increased or decreased as a result of shading, whereas the proportion of other species may not be affected.
NOTES ON THE TIMOTHY GRASS FLIES (AMAUROSOMA SPP.)
Authors: BARNES H. F.
Published: February 2008

Summary.

 A short account of the systematic position of the Timothy flies (Amaurosoma armillatum Zett. and A. flavipes Fall.) is given and the literature concerning them is reviewed.

 Their distribution is stated and notes are given on their bionomics as observed at Harpenden on material obtained from Slough, Buckinghamshire.

 The parasites Microbracon exhilarator Nees and Lamprotatus sp. are recorded.

 Efforts have been made to see whether the earliness or lateness of Timothy grass strain has any effect on the incidence of attack. There are indications that a dwarf strain which is an early one is less liable to attack, though this may be due to a varietal resistance rather than to the time of flowering.

 It does not appear feasible to get limits of flowering wide enough to cover the period of attack, so that further investigations in this direction need not be pursued.

 Indications were obtained that the effect of manuring the grass may be to lower the attack, but further work in this direction ia required.
SHEEP BLOWFLY INVESTIGATIONS
Authors: HOBSON E. P.
Published: February 2008

Summary.

 Various putrefying substances attract Ludlia sericata to oviposit on sheep in the field. Other blowflies do not respond.

 Excreta of Ludlia larvae are extremely attractive; faeces from scouring sheep, stale urine and bacterial cultures are also effective.

 Ludlia does not oviposit on these substances unless they are placed close to the skin of a live sheep; neither sheep skin, wool, nor other live animals can take the place of sheep.

 The attraction is not due to chemical or bacterial changes in the fleece, since actual contact with the skin or wool is not necessary.

 It is therefore concluded that the sheep itself plays an essential part in attracting Ludlia. The natural odour may be responsible.

 These results are discussed in relation to the origin and control of sheep strike.
THE CHLOROTIC DISEASE OF THE HOP
Authors: SALMON E. S. , WARE W. M.
Published: February 2008

Summary.

In 228 seedlings raised from hop plants affected with chlorotic disease, transmission of the disease occurred in twenty‐eight plants (12.3 per cent.) in the first year and, of the remaining 196 healthy seedlings,1 thirty‐three plants (16.8 per cent.) showed the disease in the second year. Thus, of the 228 seedlings raised, sixty‐one (26.8 per cent.) eventually showed chlorotic symptoms.

In the authors' opinion, transmission of the disease was through the seed.
OBSERVATIONS ON THE SHEEP BLOWFLY (LUCILIA SERICATA MEIG.) IN SCOTLAND
Authors: RATCLIFFE F. N.
Published: February 2008

Summary.

 It is suggested thai; a limited temperature tolerance in the early stages of Calliphora erythrocephala, as compared with Lucilia sericata, is the reason for this species not being a serious pest of sheep.

 Experiments to discover the numbers of eggs laid by females of Lucilia sericata, and the length of the larval, prepupal, and pupal stages are described.

 The detailed records of strikes in an Aberdeenshire flock throughout the 1933 and 1934 seasons are analysed; and the figures shown to agree with results obtained in other parts of Britain.
PREVENTION OF BLIGHT (PHYTOPHTHORA INFESTANS) IN SEED POTATOES
Authors: SMALL T.
Published: February 2008

The loss of seed potatoes through blight (Phytophthora infestans) in Jersey may be subdivided into (a) loss in the field at digging time, and (b) loss in the seed boxes subsequent to harvesting.

It is shown that the loss in the field may be prevented in most seasons by regular and thorough spraying, whilst that in the boxes may be reduced by scorching or removing the diseased haulms before digging, or by immersing the tubers in a fungicide.
TWO VIRUSES OF THE CUCUMBER MOSAIC GROUP ON TOBACCO
Authors: HOGGAN ISMÉ A.
Published: February 2008

A “yellow cucumber mosaic virus” is described, which appeared to develop spontaneously during experiments with ordinary cucumber mosaic on tobacco. This form is readily distinguishable from the ordinary cucumber mosaic virus by the conspicuous bright yellow mottling produced on tobacco and other hosts. In modes of transmission, properties and host range, the virus appears to be identical with ordinary cucumber mosaic virus, and is hence regarded as a strain variant of this form.

A second virus is described on tobacco which appears to belong to the same general group, although showing differences of greater magnitude from the ordinary cucumber mosaic virus. This form is distinguished chiefly by the milder type of symptoms produced upon various common hosts, and by its somewhat lower thermal death‐point, tolerance to dilution and longevityin vitro.

Additional evidence is thus offered of strain variation in the cucumber mosaic group, similar to that already recognised in certain other groups of plant viruses.
ON THE GALL MIDGES INJURIOUS TO THE CULTIVATION OF WILLOWS
Authors: BARNES H. F.
Published: February 2008

The species of gall midges whose larvae live in the stems of willows have been briefly reviewed.

It is pointed out that, in the past, the so‐called “shot hole” midge damage on willow stems and branches has been frequently ascribed to R. saliciperda Dufour without considering either the insect itself or the species of willow.

This study has shown that several species of gall midges are responsible for this type of damage and that, so far as can be ascertained from an examination of cultivated species of willows, with S. fragilis in addition, each species of midge is restricted to one (in one case three) species of willow.

The adults, pupae and larvae of R. saliciperda Dufour, R. triandraperda sp.n., R. purpureaperda sp.n. and R. justini sp.n. have been described.

The bionomics of these species have been worked out. It has been found that, while all multiply by means of unisexual families, the first three species are single brooded but that R. justini sp.n. has two broods a year. R. saliciperda Dufour lives on S. caerulea, S. fragilis and S. alba (Cecconi), R. triandraperda sp.n. will only attack S. triandra, while R. purpureaperda sp.n. and R. justini sp.n. are restricted to S. purpurea.

The nature of the damage caused by the larvae of these midges has been described and control measures have been discussed. Tarring the stubs has been mentioned. It is suggested that cutting down the new growth in May, where practicable, would reduce the midge infestation. This latter treatment has the additional advantage of getting rid of initial caterpillar and frost damage which result in dead terminals and so produce side‐branching close to the stubs. Wild Crack willow (S. fragilis) should be destroyed as it can act as a reservoir for R. saliciperda Dufour.

Keys have been drawn up for the identification of the midges using host plants, larval, pupal and adult female characters.

The following parasites are recorded—Torymidae: Torymu ssp., near auratus Fonsc; Eurytomidae: Eurytoma aciculata Ratz., E. saliciperdae. Mayr.: Pteromalidae: Tridymus salicis Nees; Eulophidae: Pleurotropis? caenus Walk., Tetrastichus flavovarius Nees, T. roesellae De Geer; Platygasteridae: Platygaster cecidomyiae Ratz., P. sp. (?philinna Walk.).
PHYTOPHTHORA INFESTANS (MONT.) DEBARY AND CLADOSPORIUM FULVUM COOKE ON VARIETIES OF TOMATO AND POTATO AND ON GRAFTED SOLANACEOUS PLANTS
Authors: BOND T. E. T.
Published: February 2008

Experiments are described which are concerned with the possibility of an increase or decrease in susceptibility to pathogenic fungi, induced or transmitted by grafting. Two diseases are investigated, namely, potato blight, caused by Phytophthora infestans (Mont.) dc By., and tomato leaf mould, caused by Cladosporium fulvum Cke.

Preliminary inoculation experiments were carried out on eleven large‐fruited varieties of tomato, eight varieties of potato, various small‐fruited tomatoes, and other Solanaceous plants, with the following results:

Phytophthora infestans. All the varieties of potato were equally susceptible, but certain varieties only of tomato, viz. Giant Red, Golden Queen. Detached leaves of the currant tomato were also infected.

Cladosporium fulvum. Only tomato varieties and certain smail‐fruited tomatoes were susceptible. Giant Red and Golden Queen were particularly susceptible, Stirling Castle and Maincrop were relatively resistant. The currant tomato (Lycopersicum racemigerum Lange or L. pimpinellifolium Dun.) was immune. No support can be given to Schmidt's suggestion that immunity depended on the presence of a substance termed “prohibitin”, capable of inhibiting spore germination. It is suggested that the identity of Schmidt's cultures was mistaken.

About fifty grafts were made involving various combinations of resistant and susceptible plants. The grafts were inoculated, in most cases, after new growth had developed from stock and scion. Without exception, the results of these experiments were the same as on the ungrafted material, both stock and scion retaining their characteristic reaction to infection unaltered. Although negative results cannot be conclusive in themselves, they indicate that resistance and susceptibility are either genotypic properties of the protoplasm or else are due to some factor that is not, as such, transmissible from stock to scion or vice versa.
GLOMERELLA PHACIDIOMORPHA (CES.) PET. ON PHORMIUM TEN AX IN BRITAIN
Authors: KINGHOKN W. O.
Published: February 2008

Glomerella phacidiomorpha (Ces.) Pet. has been found to be the cause of a disease of Phormium tenax in England. This is the first record of the fungus in Britain.

The fungus is only weakly parasitic, and is of danger only to plants of lowered vitality.

The imperfect fungus Colletotrichum rhodocyclum (Mont.) Pet. is shown to be a conidial stage of Glomerella phacidiomorpha.

I wish to express my indebtedness to Mrs N. L. Alcock, Plant Pathologist to the Department of Agriculture for Scotland, who supplied the material of Phormium tenax, and to Dr M. Wilson, Mycology Department, University of Edinburgh, who supervised the work.
BIOLOGIC STRAINS OF OPHIOBOLUS GRAMINIS SACC.
Authors: PADWICK G. W.
Published: February 2008

Isolates of Ophiobolus graminis compared were obtained in England, Canada and Australia from the following hosts: Triticum vulgare, Agropyron tenerum, A. repens and Hordeum murinum.

The optimum for growth of all isolates studied on carrot dextrose agar was in the neighbourhood of 25o C. They varied in their ability to grow at temperatures above and below the optimum.

Isolates vary in type of growth on carrot dextrose agar, the most noticeable difference being in the production of macrohyphae.

Saltation leading to the abundant production of black strands of macrohyphae by a culture producing very few was observed.

There are distinct differences in ability to survive desiccation over calcium chloride or 60 per cent, sulphuric acid. There seems to be some relation between the presence of macrohyphae and ability to withstand desiccation.

Isolates exhibit marked differences in general pathogenicity, but these differences are not specific towards certain hosts. Those causing greatest reduction in length of plants of Triticum spelta also caused greatest injury to T. dicoccum, T. monococcum, T. vulgare varieties and Hordeum vulgare. Conversely, hosts most resistant to one isolate were also those most resistant to the others.
SOME NOTES ON THE MORPHOLOGY OF THE IMMATURE STAGES OF SOME BRITISH CHAFER BEETLES
Authors: FIDLER J. HAVELOCK
Published: February 2008

From the foregoing morphological descriptions of the main genera of the British Melolonthinae, it will be seen how much more closely allied Amphimallus is to Melolontha than is Serica. In nearly all details where the former species differs only slightly from Melolontha, Serica is found to differ more widely. This therefore gives support to the practice of separating this subfamily into the two tribes of Sericini and Melolonthini.

Since Scarabaeid larvae other than those of the Melolonthinae are also found damaging crops in the British Isles, a table for the rough identification of the most common genera is appended. All species of the Scarabaeoidea are not however included, and since genera such as Geotrupes and Aphodius may be found at the roots of crops, confusion may occasionally arise in their identification, although they are not known to cause damage to plants. In such cases therefore reference should be made to the foregoing descriptions for exact identification.

(2) Body club‐shaped at caudal end, antennae long with joints of unequal length. 3.

(1) Body thickest at middle, antennae short with joints of equal length.Cetonia.

(4) Spines of radula arranged in two longitudinal rows 5.

(3) Spines of radula arranged in one transverse row Serica.

(6) Longitudinal rows of spines on radula parallel or slightly converging at ends 7

(5) Longitudinal rows of spines on radula diverging especially at caudal end.Amphimallus.

(8) Caudal aspect of mandibles with stridulating area made up of small pits.Melolontha.

(7) Caudal aspect of mandibles with stridulating area made up of transverse file‐like ridges Phyllopertha.
THE DISTRIBUTION AND SAMPLING OF INSECT POPULATIONS IN THE FIELD WITH SPECIAL REFERENCE TO THE AMERICAN BOLLWORM, HELIOTHIS OBAOLETA FABR.
Authors: MARSHALL JOSEPH
Published: February 2008

The problem associated with estimation of insect activity is discussed.

A precision experiment, undertaken to investigate the nature of the egg‐laying of the American bollworm, is described. The nature of the distribution is investigated.

Correlation trials between the two counts show that the same portions of the crop retain their relative attraction to the bollworm moth over short periods.

The effect of subdivision of the area on the sampling error is analysed.

Both egg as well as plant number figures per 3‐yard length show a greater variation between than within rows.

Correlation and regression coefficients prove a very close relationship between plant number and eggs laid.

Eliminating the effect of plant number eliminates this greater variation for the first egg‐count figures. In the second count the variation between rows is still significantly greater. The reason for this is discussed.

Considerations affecting the sampling technique developed from the precision data are discussed.

The sampling method is explained and two examples are given. From the analysis of these the system is shown to sample adequately the fields and fulfills the requirements of the survey.
TRIALS OF MERCURIC CHLORIDE FOR THE PREVENTION OF POTATO SICKNESS
Authors: JOHNSON L. R.
Published: February 2008

An investigation of the effect on potato sickness of mercuric chloride applied as a soil dressing is described.

It has been found that mercuric chloride applied 3–6 weeks prior to planting has a depressing effect on the early growth of potatoes. The variety Great Scot withstands this effect better than the varieties Majestic and Eclipse. This toxic effect is prevented by applying the chemical 3 or 4 months before planting.

The degree of infestation of the plants by the eelworm is decreased by dressing the soil with mercuric chloride. The reduction in infestation is greater the nearer the application is to the time of planting.

The reduction in eelworm infestation is accompanied by an increased yield of tubers except where plants cannot properly recover from the direct toxic effect due to mercuric chloride.

Evidence has been obtained to show that mercuric chloride does not kill the eggs within the cysts.

Mercuric chloride treatment of soil effectively prevents the fungous diseases common scab and collar rot.

The writer wishes to acknowledge with thanks the assistance given by many of his colleagues, and especially to Mr W. E. Gelling and Mr J. Strachan for their help in arranging the field trials, and to Mr S. Burr and Dr W. A. Millard for their help with the mycological aspect of the investigation.
METHODS OF DETECTING MUSKRATS
Authors: WARWICK TOM
Published: February 2008

In this article natural signs left by muskrats and various artificial aids in detection are described and discussed. Houses and the so‐called “push‐ups” are in marshes obvious and characteristic signs. With few exceptions it is hard to state definitely whether food traces found in the field have been made by muskrat or not. Willow shoots and the stems of bulrush (Scirpus) are however bitten off in a characteristic manner. The finding of burrows is very important from the practical standpoint. Where the burrows are not superficial the Fangerstock or probing bar is employed in locating them. The footprints of the muskrat are unmistakable.

A method for the identification of muskrat dung is given. This depends on the measurement of the ratio of medulla width to hair width in hairs obtained from the faeces and its comparison with that of similar hairs from water vole and brown rat. Far more hairs of the muskrat lie in the ratio limits 0–30‐0‐50 than do those of water vole and brown rat– the reverse being true of the ratio limits 0–70‐0‐90.
OBSERVATIONS ON THE LIFE HISTORY AND CONTROL OF THE CABBAGE APHIS, BRE VICORYNE BBASSICAE L.
Authors: PETHERBRIDGE F. R. , MELLOR J. E. M.
Published: February 2008

A study has been made ofthe life history of Brevicoryne brassicael. in the market‐garden areas of Bedfordshire, Cambridgeshire and Huntingdonshire from November 1933 to October 1935.

There was a variation in the behaviour of this pest in the two years. In 1934 the aphis over‐wintered only as eggs on cultivated cruciferous crops (and particularly Brussels sprouts), whereas observations strongly suggest that in 1935 it over‐wintered both as viviparous females and eggs. The hatching of the eggs was much later in 1934 than in 1935, but the first winged forms were produced at about the same date.

Predators and parasites were fairly abundant but not sufficiently so as to prevent serious damage.

It is suggested that control measures should aim at preventing the aphides from passing from old plants to newly planted ones. Nicotine sprays or nicotine dusts are suitable for this purpose. The pest is difficult to control on ordinary field crops.
STUDIES ON THE APHIDES INFESTING THE POTATO CROP
Authors: DAVIES W. MALDWYN
Published: February 2008

The results are given of laboratory experiments on the effect of variation in wind velocity upon the flight of Myzus persicae Sulz.

When no wind passed through the experimental chamber, twenty‐five winged aphides averaged 154‐8 flights per minute. The incidence of flight in a range of wind velocities is recorded. Low wind velocities had a marked influence on flight which ceased when the speed of the wind was increased to 3–75 m.p.h.

The aphides remained stationary on the glass surface of the chamber when high winds of 20 and 30 m.p.h. passed through the chamber and even when the full force of the wind, equivalent to a gale of 70 m.p.h., passed over them the aphides adhered to the surface with ease. Microscopical observation showed that the aphides possess a small membranous pad between each claw and another at the base of each tarsus; these are adpressed to the surface and facilitate adherence.

The literature on the subject of the dissemination of aphides by wind is reviewed and the phenomenon of voluntary migration as compared with involuntary transportation is discussed.
REPORT OF THE HON. TREASURER FOR THE YEAR ENDING DECEMBER 31. 1935
Authors: SMITH J. HENDERSON
Published: February 2008

Hon. Treasurer.
ZONE LINES IN PLANT TISSUES
Authors: CAMPBELL A. H. , JUnNSQN; R E.
Published: February 2008

The black lines of Polyporus squamosus have been found in the wood of elms. Isolations were made from these lines and an account of the development of P. squamosus in artificial culture is given. Particular mention is made of the formation of black plates, or lines as they appear in section, in culture media and of the appearance of abnormal fructifications. Pure cultures of the fungus on sterilized wood blocks have produced black lines in the wood, similar to those occurring in nature.

From a consideration of the structure and formation of the black plates, the suggestion is made that they form the limiting layer or rind of sclerotium‐like bodies buried in the attacked wood.

A review is given of sclerotium formation and structure in several species of Polyporus, and analogies are made between these sclerotia and the sclerotium‐like body of P. squamosus. It is decided to distinguish the P. squamosus body from these sclerotia by naming it a pseudo‐sclerotium, on the criteria previously advanced for Armillaria mellea(8).
THE VIRUSES CAUSING TOP NECROSIS (ACRONECROSIS) OF THE POTATO
Authors: BAWDEN F. C.
Published: February 2008

It is shown that top necrosis can be produced in different potato varieties by a number of viruses. The reactions of these viruses on a large number of commercial varieties are given, together with certain of their properties and methods by which they can be transmitted. By grafting and needle inoculating infected potatoes to the four varieties Epicure, Arran Victory, President and Up‐to‐Date, and noting the type of necrotic disease produced on these differential hosts, it has been found possible to distinguish with a fair degree of accuracy between six viruses. The necrotic reactions of these varieties are given below.

The writer has great pleasure in expressing his gratitude to Dr D. R,. Salaman for permission to make use of the virus material, and for many valuable suggestions.
THE ROLE OF PLASMODESMS IN THE TRANSLOCATION OF VIRUS
Authors: SHEFFIELD F. M. L.
Published: February 2008

Although intracellular inclusion bodies may occur in every cell over large areas of the epidermis, they have not been found in the guard cells of the stomata. No protoplasmic connexions could be shown to exist between the guard cells and the surrounding tissues. These findings suggest that, owing to the absence of plasmodesms, the virus is unable to reach the guard cells. Support is lent to the view that, when the virus moves in the ground tissue of the host, it is carried from cell to cell along the protoplasmic bridges.
THE CHARACTERS OF SOME COLIFORM BACTERIA ISOLATED FROM GRASS AND GRASS SILAGE
Authors: ALLEN L. A. , HARRISON J.
Published: February 2008

The species of coliform bacterium predominant on fresh grass was found to be a capsulated type growing well at 30o C. but unable to grow at 37o C. For this reason it will not be detected by the presumptive test in bile salt‐lactose broth at 37o C. The name Bacillus (Aerebacter) aerogenes graminis is proposed for this species.

It is possible that conforms of the above type contribute to a small extent to the initial fermentation of the silage. Those coliforms giving the presumptive test at 37o C. were found in such small numbers in the silage investigated that their influence was concluded to be negligible.

This work forms part of some research carried out under grant from the Research Council of Imperial Chemical Industries, Ltd., to whom the authors wish to make due acknowledgement. Valuable help was also received from Dr S. J. Watson, who supplied samples of grass and silage‐
FURTHER EXPERIMENTS ON THE CONTROL OF THE HOP RED SPIDER MITE, TETRANYCHUS TELARIUS L
Authors: JARY S. G.
Published: February 2008

Small‐scale experiments with a number of spray fluids gave the following results against Tetranychus telarius on hops:

Lime sulphur at a concentration of 1/80 proved very toxic to the mites, but a second application had to be made to deal with those which hatched subsequently from eggs.

Emulsions of a “water white” petroleum oil at 2 and 1 per cent. Concentrations were very toxic to the mites but caused marked oedems.

Whale oil‐potash soap at 1 and ½ per cent. Concentration; cotton‐seed oil emulsion, 6 pints of il per 100 gallons of wash Derris extracts of 0.005 per cent. Rotenone and0.002 per cent. Rotenone content, and pyrethrum extract of 0.0025 per cent. Content of pyrethrins 1 and 2 were all without appreciable toxic effect upon the mites.

Lime sulphur at 1/80, to which a wetter of the sulphonated lorol type was added proved successful in the field for the control of T. telarius on hops. No injury to the plants resulted from the use of Bordesux mixture on the same plants.