bluuebunny/crossref_metadata_2025 huggingface dataset:
FIELD INVESTIGATIONS UPON THE CONTROL OF THE MUSTARD BEETLE, PHAEDON COCH‐LEARIAE F., ON WATERCRESS
Authors: EDWARDS E. E.
Published: February 2008

Summary

An account is given of field experiments in 1935 with pyrethrum and derris preparations for the control of Phaedon cochleariae F. on watercress plants.

Average infestations, judging by the beetle population on the untreated plots, were reduced by:

Pyrethrum emulsion of 0.01 % content of pyrethrin I to 37.9 %.

Derris wash of 0.004 % rotenone content to 22.4%.

Derris dust of 0.2 % rotenone content to 13.7 %.

Derris dust of 0.5 % rotenone content to 3.1 %.

The difficulties involved in the general application of insecticides for the successful control of the beetle in commercial culture of watercress are discussed.

A basis for controlling the beetle by means of direct measures is presented in the light of observations on extended trials by watercress growers in 1936, based upon a consideration of the results obtained from the 1935 field experiments and from a study of the life history of the insect.
THE DEVELOPMENT OF SAINFOIN IN ITS SEEDING YEAR
Authors: THOMSON J. R.
Published: February 2008

Summary

Evidence of delayed germination was obtained.

The number of leaflets in each of the firat six foliage leaves of sainfoin seedlings shows considerable variation. The mean number of leaflets in each of the second to the sixth foliage leaves is significantly greater in giant sainfoin than in common sainfoin.

Giant sainfoin tends to produce erect stam and flower in the seeding year, the amount of flowering being variable. Common sainfoin remains prostrate and never flowers.

Common sainfoin produces more tillers than giant sainfoin.

The origin of the giant and common varieties is discussed.
BIOLOGY OF OAT SMUTS
Authors: SAMPSON KATHLEEN , WESTERN J. H.
Published: February 2008

Summary

An attempt has been made to trace the history of six spore collections of the oat smuts during a 10‐year period of experimental work and to compare them in regard to stability.1

Evidence of change was found in three collections and the modifications, with one exception, were in a negative direction.

At an early stage in the work, collection L2 lost by screening the capacity to attack strigosa.

By monospore isolations, collection C2 was resolved into two types, one of which had a narrower range of infection than the parent collection.

Collection C4 also yielded two types, but both differed from the original collection. One was more pathogenic and the other less pathogenic than the collection as a whole.

Reasons are given for the view that the changes were due to heterozygous types in the collections.

No changes were detected in three collections.

One collection (L11) was outstanding in the uniformity of mono‐spore and monosporidial lines in culture.

Experiments designed to break down the resistance to smut in certain selected oat varieties met with no success.
PHYSIOLOGICAL RELATIONSHIPS BETWEEN INSECTS AND THEIR HOST PLANTS
Authors: EVANS A. C.
Published: February 2008

Summary

It is shown that under late summer conditions of light the rate of reproduction of the aphis, Brevicoryne brassicae, is positively correlated with the nitrogen content of the host plant and, in particular, with the protein content. The formation of winged forms is negatively correlated with the same factors.

The chemical composition of the plant affects the rate of growth, length of larval period and final pupal weights of Pieris brasscae. It also influences the amount of food eaten.
SOME APPLICATIONS OF LABORATORY BIOLOGICAL TESTS TO THE EVALUATION OF FUNGICIDES
Authors: MARSH R. W.
Published: February 2008

Summary

Laboratory sorting‐out tests on glass slides have shown the relative fungicidal value of a number of rubber accelerators and other organic sulphur derivatives. The most toxic of these materials, when tested on leaves, gave no promise of being of use in the field.

In laboratory leaf tests using spray supplements the adverse influence of sulphite lye on tenacity was illustrated by spore germination experiments. Loss of tenacity was similarly demonstrated in sprays including oils emulsified with sulphite lye.

A limited number of comparisons with field trials indicates that the laboratory leaf test may be used as an indicator of the fungicidal value of a spray material against Venturia inaequalis and V. pirina, but that in general it gives results less favourable to the fungicide than those from corresponding field trials.
THE TOXICITY OF ETHYLENE OXIDE TO CALANDRA ORYZAE, C. GRANARIA, TRIBOLIUM CASTANEUM, AND CIMEX LECTULARIUS
Authors: BUSVINE J. R.
Published: February 2008

Summary

The orders of resistance of four different species of insects are shown to be different towards hydrogen cyanide, ethylene oxide and sulphur dioxide.

The different circumstances to be considered in fumigation research are surveyed with a view to ensuring reliable results. They can be grouped as: (a) Factors which may influence absorption of poison. (b) Factors which may influence toxic processes and degree of poisoning.

These factors are assessed and each aspect of technique is described with an estimate of the extent to which it has been controlled.

The arrangement of experiments to provide as much information as possible is described and the limits of accuracy defined.

Details of the rearing and treatment of insects are given.

Difficulties of estimation of mortality are considered and a relation between severity of fumigation and incidence of death or recovery from stupefaction is demonstrated.

The dose‐kill data are treated by Bliss's Method of Probits and tables of statistics for each set of data are appended.

Various time‐concentration relations are considered, and from these the empirical formula cnt =W has been adopted. A statistical analysis shows no serious deviation from this relationship.

The need for uniformity in expression of toxicity is stressed, and the following criterion of resistance proposed: “The 5‐hr. concentrations (mg./l. N.T.P.) for 50 and 99% kill and the value of n”.

The values of the criteria for the four species used (Calandra granaria. C. oryzae. Triboliun castaneum and Cimea: lectularius) are given.
THE ECOLOGY OF THE LARGER FUNGI. III. CONSTANCY AND FREQUENCY OF GRASSLAND SPECIES WITH SPECIAL REFERENCE TO SOIL TYPES
Authors: WILKINS W. H. , PATRICK SHEILA H. M.
Published: February 2008

Summary

This paper is an investigation into the mycological flora characteristic of grasslands with particular reference to certain soil types.

Twenty stations were examined over a period of two years, the stations being representative of chalk, clay and sand soils.

The experimental method is briefly described and ecological notes on the twenty stations are given in detail.

Lists of the fungi found on grasslands in general and on each of the three soil types are given, and the constancy of species and frequency of individuals are discussed in relation to grasslands as a whole and in relation to each soil type.

The results are discussed and a comparison made between the fungi of grasslands and those of oakwoods and beechwoods.
NOTES ON THE PHOTOPERIODIC REACTIONS AND VIRUS CONTENTS OF SOME PERUVIAN POTATOES
Authors: DENNIS R. W. G.
Published: February 2008

Summary

Exposure of the Peruvian potato varieties to full summer‐day conditions at Cambridge resulted in a more uniform growing period, and increased the tendency to bloom. The effect on tuber production varied according to the variety. In most types the weight and number of tubers were not adversely influenced, but there was a tendency to elimination of the dormancy period and to conversion of the stolons into aerial shoots. In a few varieties there was no adverse influence, and in the members of one small group plants exposed to full‐day conditions formed no tubers.

Investigation of virus content showed that of fifty‐nine varieties only eleven were healthy. In the remaining forty‐eight varieties there were found viruses apparently identical with those known in this country as X, B, C, F, G and perhaps leaf roll.1 There was also evidence of the presence of other viruses, suggesting the existence in South America of a virus complex, only isolated members of which have hitherto been known in Europe. It follows that great caution should be exercised in introducing South American varieties into potato‐growing districts.
THE INTRACELLULAR INCLUSIONS OF SOME PLANT VIRUS DISEASES
Authors: BAWDEN F. C. , SHEFFIELD F. M. L.
Published: February 2008

Summary

The contents of healthy cells and those infected with a number of different, plant viruses are described. Some of these viruses apparently do not cause the production of intracellular inclusions; others cause the production of amorphous bodies only, and the remainder produce both amorphous and crystalline inclusions. The properties of the inclusions are compared with those of purified preparations of the viruses. It is shown that insoluble complexes of the viruses with protamines, histones and proteins which in many ways resemble the intracellular inclusions can be produced in vitro. Possible explanations for the formation and disappearance of the inclusions in infected plants are suggested.
A CANKER AND DIE‐BACK OF ROSES CAUSED BY GRIPHOSPHAERIA GORTICOLA
Authors: BROOKS F. T. , Alaily Y. A. S. el
Published: February 2008

Summary

A canker and die‐back of roses caused by Griphosphaeria corticola (Fckl.) v. Höhnel is described.

Conidial fructifications, which may be acervuli or ill‐defined pycnidia. precede the formation of perithecia. Conidial isolations are of slightly differing types as regards size and shape of spores, cultural behaviour and relative pathogenicity, but at present they are all referred provisionally to Coryneum microstictum B. & Br. Some of the conidial isolations have given rise to perithecia, but others have not.

Successful inoculations both with conidia and ascospores are described.

In Nature, infection by this parasite may occur through pruning wounds, dead buds, leaf scars, wounds made by thorns, and rust lesions.

The following varieties of roses appear to be particularly susceptible to the disease: Duchess of Atholl, Lady Inchiquin and Golden Emblem.

The pathological anatomy of the disease is described. Infection may occur at all times of the year except summer, when the rapid formation of “gum barriers” by the host tissues checks invasion.

The disease is not likely to become widespread unless neglected. Diseased shoots should be cut out; with some varieties normal pruning operations should sufficiently control the disease.
EXPERIMENTS AND OBSERVATIONS ON A VIRUS DISEASE OF WINTER SPINACH (SPIN ACIA OLERACEA)
Authors: STOREY I. F.
Published: February 2008

Summary

A disease of winter spinach common in the Thames Valley has been shown to be of a virus nature. It is characterized by a mottling and malformation of the leaves, stunting of growth and death of the plants. The causal agent has been shown to be identical with cucumber mosaic I of Ainsworth.

The disease is most prevalent in the earlier sown crops, and this appears to be correlated with their liability to be infested with aphides. Field observations on a number of farms indicated a correlation between intensity of aphis infestation and intensity of disease.

Seed‐borne infection, though possible, has not been proved.

Under field conditions in the Thames Valley it is suggested that a main source of contamination of winter spinach is the outdoor vegetable marrow crop.

Postponement of date of sowing until the latter half of September is suggested as a method of reducing the amount of disease.
AN APPARATUS FOR TESTING AND COMPARING THE BIOLOGICAL ACTION OF INSECTICIDES ON FLYING INSECTS AND A METHOD FOR SAMPLING THE CONCENTRATION OF THE ATOMIZED INSECTICIDE
Authors: POTTER C. , HOCKING K. S.
Published: February 2008

Summary

An apparatus and method for testing the effect of atomized sprays on flies and mosquitoes are described. The apparatus consists of a revolving wire gauze cage placed in a thermostatically controlled chamber, the whole of which may be easily cleaned and freed from toxic residues. The insecticide is sprayed into the chamber by means of an Aerograph MP gun and distributed by means of a slow‐moving fan. When the insecticide has been injected and an interval allowed for the initial rapid fall of concentration, the movement of the cage is stopped and the insects are introduced into it by means of a special tube and plunger. The time required for paralysis to take place is recorded. After a given interval the insects are removed from the gauze cage and kept to ascertain the mortality.

A technique for sampling the concentration of insecticide in the air space is described. The insecticide carrier is coloured with a dye, Sudan III for petroleum oil bases and methylene blue for water bases. The percentage of atomized material remaining in the atmosphere at any given time is determined by aspirating a known quantity of the atmosphere of the chamber through a sintered glass filter. The dye is retained in the filter, it is washed out with a measured quantity of liquid and compared with known standards. Reasons are given for the assumption that the dye molecules will behave in the same way as the insecticide molecules.

This sampling method has been used to study the behaviour of a light oil, a heavy white oil and water at different degrees of atomization. Tables and graphs are given which show that, except with a fine atomization where most of the insecticide remains suspended for a considerable time, there is an initial rapid fall, which varies in amount with the degree of atomization. This initial fall is followed by a much more gradual decrease of concentration. The experiments show clearly that oil bases of different physical properties cannot be compared adequately unless a sampling method is used to ascertain the quantities of material remaining suspended. Where water bases are used it is shown that the time concentration curve varies not only with the degree of atomization, but also with the degree of saturation of the atmosphere before spraying. The concentration remains higher in an unsaturated atmosphere than in a saturated one.
OBSERVATIONS ON APPLE CANKER
Authors: MUNSON R. G.
Published: February 2008

Summary

The fungus causing apple canker is described and its identity with Nectria galligena Bres. is confirmed.

The methods of dispersal of the spores of Ngalligena have been examined. The ascospores are discharged forcibly from the perithecium, the eight spores of each ascus typically being ejected simultaneously.

Field investigations have shown that spores are discharged during wet periods at all times of the year. Ascospore discharge reaches its maximum in January‐February and falls to a minimum in the summer months.

The dispersal of conidia occurs during wet periods in the spring and autumn.

Germination both of ascospores and conidia occurs over a range of temperature from 2 to 30°C, the optimum being at 20°C.
OBSERVATIONS ON APPLE CANKER
Authors: MARSH R. W.
Published: February 2008

Summary

Inoculations with N. galligena on unwounded shoots of apple show that canker infections through leaf scars may be initiated in October and April but not in November and January. Shoots sprayed before inoculation with a Bordeaux‐casein‐oil mixture gave a much lower proportion of infection than those unsprayed.

Inoculations with N. galligena on pruning cuts showed that freshly made pruning cuts on apple shoots are susceptible to canker infection throughout the dormant season. Pruning cuts made during autumn and winter acquire a natural immunity to infection within 2 months.

Several wound sealing materials applied to pruning cuts failed to give protection from canker when the treated surfaces were inoculated with N. galligena. The most promising wound protectant tested was a mixture of monohydrated copper sulphate, hydrated lime and linseed oil.
SUCCESSION OF FUNGI DECOMPOSING WHEAT STRAW IN DIFFERENT SOILS, WITH SPECIAL REFERENCE TO FUSARIUM CULMORUM
Authors: SADASIVAN T. S.
Published: February 2008

Summary

A study has been made of the sequence of fungi developing on wheat straw buried in four arable soils, an allotment soil, and a glasshouse compost. Both natural untreated straw, and straw autoclaved in a 2 % solution of sodium nitrate were employed. Fusarium culmorum and Mucor spp. appeared to be dominant organisms in the earlier stages of straw colonization, but these were replaced by Penicillium spp. in the latter stages of decomposition. The nitrogenous treatment of the straw favoured the development of Penicillium spp. at the expense of Fusarium culmorum and Mucor spp. The pathogenicity of the Fusarium culmorum isolates to wheat seedlings was established by inoculation experiments.

The data provided by this investigation are considered sufficient to justify the inclusion of F. culmorum in Reinking & Manns' (1933) group of soil‐inhabiting Fusaria, or true soil fungi.
THE HISTOLOGY AND PHYSIOLOGY OF ROTENOIDS IN SOME PAPILIONACEAE. I
Authors: WORSLEY R. R. LE GEYT
Published: February 2008

Summary

All available parts at all available stages of growth, of twenty‐two species of Papilionaceae have been examined microscopically for the presence of rotenoids: fourteen contain them, and Table V summarizes all the plant parts in which they occur.

The rotenoid content varies from mere traces in the seeds only of one species to appreciable quantities in nearly every organ of another species.

Seeds of twelve of the rotenoid‐containing species were available: all contained rotenoids. It appears to be the rule that if any species contains rotenoids in any tissue it will contain them in its seeds.

Roots of thirteen of the species were available: twelve contained rotenoids.

In general, rotenoid cells in the roots and stems are normal ones, but in all other tissues they are usually morphologically distinct, and frequently relatively very large.

Rotenoids occur in the seeds of species of Millettia and Derris not in cells but in iysigenous cavities.

In many species rotenoids are first detected in the cortex of the root opposite the protoxylem and primary medullary rays.

In general, the roots contain rotenoids in the xylem parenchyma, especially in the medullary rays, and in the cortex. In stems they occur mainly in the pith, when not lignified, and also in the phloem, especially in the rays, and in the cortex.

At nodes there is frequently an increase in the number of rotenoid cells, especially in the pith.

On germination, the seeds of Mundulea and Tephrosia species at first produce new rotenoid cells, accompanied by an increase in total rotenoid content, in the growing radicle and in the cotyledons. Later, the rotenoids diminish to nil in the radicle and to between 45% and nil. for different species, in the cotyledons. With Millettia. new rotenoid cavities are at first formed in the radicle, and later all rotenoids disappear from it: only a small reduction in the rotenoid content of the oetyledons, however, occurs. With Derris, no new rotenoids are formed in the radicle: the amount in the cotyledons in one species diminished to 62 %.

Rotenoids in the plumules of Millettia and Derris species disappear soon after germination.

Two instances only of lability of rotenoids have been proved: in the germinating seeds of all species, and in the lignifying pith of the stems of two species.

Derris elliptica plants placed in the dark until dead show no reduction in the amount of rotenone per plant: indicating that the rotenone is not available as a food reserve.

The application of the sap from Derris roots and stems to Derris cuttings produces no increase in percentage rooting or in the speed of rooting.

The results suggest that rotenoids are of some direct use to the germinating seed and seedling, but that they are probably waste products in all other tissues.
THE EFFECT OF CLIMATIC EXPOSURE ON TEXTILE FIBRES AND FABRICS
Authors: THAYSEN A. C. , BUNKER H. J. , BUTLIN K. R. , WILLIAMS L. H.
Published: February 2008

Summary

Various textile fabrics were exposed to a wide range of climatic conditions.

Those exposed to waterlogged conditions were destroyed rapidly. In the case of cellulose fabrics this destruction was due solely to bacteria, and not to fungi or actinomycetes. In the case of wool, the evidence of microbiological action was not conclusive.

Cellulose, wool, silk and cellulose rayon fabrics disintegrated on exposure in microbiologically active soils. The destruction was due to microbiological action, the rate being governed by the moisture content of the soil and, to a lesser extent, by the temperature. Cellulose acetate rayon was completely resistant.

Cellulose and wool fabrics exposed in the shade to very humid tropical conditions were damaged much less rapidly than in soil, although there was extensive “mildewing”.

“With fabrics exposed for a year in the shade at stations with subtropical or temperate climates, and with a rainfall of about 30 in., the microbiological damage suffered was insufficient to affect the strength of the fabric, but there was much”mildewing“. No microbiological damage or”mildewing“was observed in shade‐exposed fabrics in arid climates where the annual rainfall did not exceed 9·5 in.

Where fabrics were exposed to the action of sun as well as rain and wind, microbiological damage occurred when the moisture conditions were suitable for the growth of micro‐organisms. This damage was invariably less than that of fabrics exposed in the shade at the same station.

Exposure of cellulose fabrics both in sun and shade caused a lowering in viscosity, whereas soil exposure, which causes more extensive microbiological destruction, did not affect the viscosity. All sun‐ and shade‐exposed samples showed a lowering in pH value during the first 3 months, but subsequent exposure caused little further change. Soil exposure caused practically no change.

Inert substances such as glass, metals and rubber, when used as a covering for cellulosic fabrics, retard microbiological decay in soil and sea exposures. Some commercial protective substances owe their value to their shielding action. The parenchymatous and epidermal tissues surrounding the fibre bundles of jute exert no shielding effect. In a micro‐biologically active soil, flax, hemp and jute fabrics decay at approximately the same rate as cotton, which contains no protective tissue.

A provisional technique is described by which the relative merits of “mildew”‘ protective treatments may be evaluated. The only treatment which has been found to give permanent protection in the case of cellulosic fabrics is partial acetylation.
STUDY OF BYSSOCHLAMYS FULVA AND CONTROL MEASURES IN PROCESSED FRUITS
Authors: HULL R.
Published: February 2008

Summary

A survey of various fruit‐producing areas in England showed that fruit and foliage were liable to be contaminated with ascospores of Byssochlamys fulva. Contamination was most pronounced on mummified plums and on certain fruit refuse.

The thermal death point of ascospores is about 96°C., but only a small proportion of spores show this maximum heat resistance. Conidia are killed by exposure to relatively low temperatures.

The reaction and the sucrose concentration of the heating medium, and the strain of the fungus, are factors influencing the heat resistance of ascospores.

Ascospores germinate slowly and irregularly, but their germination is stimulated by previous heating to about 70°C. Ascospore germination and mycelial growth take place at relatively high temperatures, in high sucrose concentrations, in acid media, and in very high concentrations of carbon dioxide.

Ascospores are relatively insensitive to antiseptics and to desiccation.

Growth is accompanied by the production of a pectin‐destroying enzyme.

The results of laboratory experiments were applied to canning experiments and good agreement was obtained. Natural contamination on fruits could be overcome in cans by heating the contents to 195°F.

The amount of mycelial growth developing in an infected can depends upon the size of head space and the storage temperature.
THE INTERNAL TEMPERATURES OF FRUIT TREE BUDS
Authors: Grainger John
Published: February 2008

An account is given of the distributions of heat and relative humidity from three methods of orchard heating, together with the results of experiments with a simple type of humidified heating. Ignited balls of papier mache which had been soaked in crude oil, were humidified with saturated garden refuse, such as long grass or lawn clippings. This arrangement heats the air, and at the same time either maintains or enhances the relative humidity. No lowering of the internal temperature of the bud is produced, and the method helps to control a frost at its source, by diminishing radiation of heat from the earth to an open sky. Frosts may therefore be controlled in practice by the expenditure of about one‐third the fuel used in the flame‐type heaters.

Lateral distribution of heat from orchard heaters is not great. Suggestions are made for the alternate disposition of fruit trees and heaters upon a slope. Advantage may thereby be taken of the katabatic wind which occurs during a radiation frost, to direct the heated air towards the trees.
THE NUTRITION OF LETTUCES GROWN AS SAND CULTURES UNDER GLASS
Authors: Woodman R. M.
Published: February 2008

The effects of variations in the supplies of nitrogen, phosphorus and potassium on the appearance, growth and yield of the tinted lettuce May King have been studied by Woodman (1936, 1939a, b, c, d). The present experiments were designed: (i) to test the main findings of the previous experiments in a comprehensive experiment, (ii) to discover how far certain deficiency symptoms noticed in May King were common to a non‐tinted lettuce, and, (iii) and (iv), to ascertain what effects variations in the supply of calcium and magnesium respectively had on sand cultures of lettuce.
ON THE STEM AND BULB EELWORM (ANGUILLULINA DIPSACI KUHN) WITH SPECIAL REFERENCE TO ITS OCCURRENCE ON WEEDS OF ARABLE LAND
Authors: Johnson L. R.
Published: February 2008

The importance of wild hosts of Anguillulina dipsaci Kühn as carriers of infection needs no emphasis. The occurrence of the eelworm in the weeds, cleavers (Galium aparine) and duckweed (Stellaria media) taken in crops of oats and field beans which were themselves suffering from stem eelworm disease, was recorded by Johnson (1936) and Johnson & Thompson (1937); Walton (1937) confirmed the occurrence of infested cleavers plants in eelworm‐infested oats. Walton also stated that experiments indicated that seed oats failed to carry eelworm infection, and from circumstantial evidence similar to that recorded by Johnson (1936) stated that “infestations of oat crops which occur, even after the absence of the crop for more than six years, are in all probability attributable to weeds rather than to infested seed”. The present writer failed to obtain living eelworms from oat seed from infested crops in Yorkshire. This paper summarizes the results of field observations and experiments accumulated mainly during the past three years.
METABOLISM AND FLOWERING
Authors: Grainger John
Published: February 2008

Two earlier papers have established (1) that the late‐flowering chrysanthemum, a typical “short‐day” species, flowered in autumn because of a disability in nocturnal translocation which limited the amount of carbohydrate available at the growing‐point during the short nights of summer (Grainger, 1938), and (2) that many plants which flower in spring and early summer actually begin the formation of their flower initials in the autumn and winter of the previous year (Grainger, 1939). Such plants might conceivably be “short‐day” kinds, since the actual transformation from vegetative to floral organization of the growing‐point was accomplished when the days were short. It therefore appears necessary to investigate their relative diurnal carbohydrate metabolism, in order to discover whether it has any causal relationship with the time of actual flower initiation, as was demonstrated for the late‐flowering chrysanthemum. The present paper describes the results of such an investigation, and also of certain contributory studies as to the converse effect of flowering upon metabolism, the relative amount of energy used in flowering, and the possible inadequacy of nutrition in very floriferous plants.
OBSERVATIONS ON THE DISEASE OF SEA LYME‐GRASS (ELYMUS ARENARIUS L.) CAUSED BY USTILAGO HYPODYTES (SCHLECHT.) FRIES.
Authors: Bond T. E. T.
Published: February 2008

Ustilago Hypodytes was recorded by Berkeley & Broome (1841, 1850) and occurs on Elymus arenarius and Agropyrum species. A knowledge of its life‐history on these plants appeared desirable in view of the possibility of an extension in host range to nearly related cereals, added emphasis being given to this viewpoint by the recent production of perennial Triticum‐Agropyrum hybrids. Elymus arenarius is widely planted to prevent coastal erosion, and no knowledge was available of the effect of the fungus on its suitability for this purpose. The virtual absence of seed production by infected plants is known. In America, Ustilago hypodytes was described by Fischer (1938) as an increasing menace to the cultivation of Agropyrum cristatum (L.) Beauv. and other valuable forage grasses. The disease on Elymus was studied by Bornhövd (1936), who gave a full summary of the literature. She described the process of spore germination and the growth and nuclear behaviour of the fungus on artificial media, but dealt less adequately with the symptoms and spread of the disease and the histology of infection: her inoculation experiments were inconclusive.
THE NUTRITION OF LETTUCE
Authors: Woodman R. M.
Published: February 2008

In 1935, nutritional work on lettuce was started by the author. The investigations were divided into three sections: sand‐culture experiments, soil‐culture experiments, and field‐fertilizer trials. The results of the sand‐culture work have been published (Woodman, 1936, 1939 a, b, c, d, 1940 a, b); the present paper deals with the results obtained so far from soil cultures and field trials.
PRINCIPAL DECAYS OF BRITISH HARDWOODS
Authors: Cartwright K. St G. , Findlay W. P. K.
Published: February 2008

In previous publications the authors (1936,1938) brought together the available information about the rots of English oak and the principal decays of softwoods used in Great Britain. In this paper the principal decays of the British hardwoods other than those affecting oak are described. While the standardized form of the descriptions of the fungi and of the rots which they cause has been maintained, other aspects, particularly practical and economic recommendations, have been dealt with more briefly. The staining of hardwoods by fungi is not referred to here, since comparatively little work has been done in this country either on the fungi which cause the staining or on the conditions under which staining occurs.
THE USE OF TOXIC POLYNITRO DERIVATIVES IN PEST CONTROL
Authors: Wain R. L.
Published: February 2008

3:5‐Dinitro‐ortho‐cresol (d.n.c.) and stock emulsions of this substance in petroleum oil are available commercially and winter washes based on d.n.c.‐petroleum are becoming increasingly popular with the fruit grower. These washes can replace the separate application of tar and of petroleum‐oil emulsions, while the risk of bud injury which attends the use of combined tar‐petroleum washes is avoided (Kearns & Martin, 1941). In view of the increasing importance of d.n.c. the chemistry of this substance becomes of interest and further, suitable methods of analysis, both for the compound itself and as a constituent of oil emulsions, are urgently required. In this paper a number of molecular compounds and derivatives of d.n.c., and two simple methods of analysis are described. The application of the methods to the estimation of d.n.c. in compounded products will be communicated at a later date.
An investigation into the ‘stripe’ disease of narcissus
Authors: Caldwell John , Prentice Ian W.
Published: February 2008

Experiments on the transmission of the ‘stripe’ disease of the narcissus are described. It was found that the disease is not seed transmitted but that it is transmissible by grafting and by juice inoculation with the use of an abrasive such as carborundum powder. Under field conditions transmission of the disease takes place above ground and not through the roots. The identity of the vector has not been established. The effect of the disease in reducing bulb growth and vigour has been examined. Controlling the spread of the disease by roguing is recommended.
Behaviour of the fungus Rhizoctonia solani Kiihn in the soil
Authors: Blair I. D.
Published: February 2008

Rhizoctonia solani was found able to grow as a saprophyte through natural unsterilized soil. Its rate of growth under different soil conditions in glass tumblers was studied by the Rossi‐Cholodny soil‐plate method. Growth was most rapid at the lowest soil‐moisture content tested, viz. 30 % saturation, and was accelerated by forced aeration of the soil. The maximum distance to which mycelial growth could be supported on the food reserves of the agar inoculum alone was some 5 cm., as shown by extent of growth through tubes of moist sand, but in 23 days the fungus grew 21–24 cm through tubes of soil. Removal of the agar disk 2 days after inoculation of the tubes reduced growth through sand by more than half, but through soil by only a small proportion. In soil, Rhizoctonia was able to cause 100% damping‐off of radish seedlings planted at a radial distance of 4 cm. from the agar inoculum, and some 40 % damping‐off at a distance of 9 cm. The depressing effect of additions of 1 % ground‐wheat straw or dried grass to the soil upon growth of the fungus was attributed to (1) the negligible cellulose‐decomposing ability of Rhizoctonia, (2) nitrogen starvation of the mycelium, through rapid utilization of the available soil nitrogen by the cellulose‐decomposing micro‐organisms multiplying upon the fresh organic material, (3) fungistatic action on Rhizoctonia of the respiratory carbon dioxide produced by the cellulose‐decomposers.
Experiments to determine the effect of certain wood preservatives on the growth and cropping of the cultivated mushroom (Psalliota campestris)
Authors: Pizer N. H. , Glasscock H. H.
Published: February 2008

A small‐scale laboratory method of determining the effect of wood preservatives on growth and cropping of the cultivated mushroom is outlined. Experiments with a number of well‐known wood preservatives are described. According to these experiments wood treated with the following preservatives had no adverse effect on mycelial growth or on croppings: 5 % copper sulphate solution, green Cuprinol, 5 % Celcure solution, 2 % Triolith (Wolman salts) solution. On the other hand, wood treated with 2 % Chromel salt and coal‐tar creosote reduced the vigour of growth of mushroom mycelium to a depth of 1/2 in. in compost that was in contact with it. Under these conditions, however, the mycelium was not killed nor was the cropping reduced even when the treated wood was only 1 1/2 in in. below the casing soil. As in all experiments the treated wood was covered with compost, the chance of vapours from the preservatives coming into contact with sporophores was very small, and the possibility of harmful effect in mushroom houses from such vapours should not be ignored.

The experiments indicate that full‐scale trials in commercial mushroom houses could be undertaken with copper sulphate, green Cuprinol, Celcure and Triolith with negligible risk to the crop, but that it is advisable to carry out trials on a smaller scale with Chromel and coal‐tar creosote of known composition to determine whether these preservatives have any adverse effect on cropping. Owing to the great range in composition shown by coal‐tar creosote it is most important that the conclusions reached with the particular sample used in the above experiments should not be applied to creosotes in general.
Value of phloem necrosis in the diagnosis of potato leaf‐roll
Authors: Sheffield F. M. L.
Published: February 2008

In plants infected with leaf‐roll virus a type of phloem obliteration and necrosis occurs which is distinct from any abnormality produced by other pathogens or arising from physiological causes. The necrosis occurs in the primary phloem only of the bicollateral bundles. The affected tissue reacts with phloro‐glucinol in HCI. It was present in all of 179 plants of 33 varieties showing secondary leaf‐roll which were examined and was not found in any of 83 healthy plants of 20 varieties. The amount of necrosis varies in different plants. If the disease is severe, necrosis may extend to almost all parts of the plant except the stolon, tubers and roots. If the infection is mild it may be confined to a very few strands in two or three nodes near the base of the main stem. Phloem necrosis can always be found before leaf rolling is apparent.

In primary leaf‐roll, slight necrosis can be found in the stem near the bases of the lowest rolled leaves and sometimes in the petioles.

A technique is suggested for the use of this symptom in diagnosis.
Experiments on the poisoning of honeybees by insecticidal and fungicidal sprays used in orchards
Authors: Butler By C. G. , Finney D. J. , Schiele P.
Published: February 2008

Losses of bees by poisoning have been greatly increased in recent years by the growing practice of applying insecticidal and fungicidal sprays to fruit trees. Preliminary laboratory tests showed that, of the common constituents of spray mixtures, only lead arsenate and flowers of sulphur were likely to cause serious honeybee poisoning, though Derris emulsion may cause slight poisoning. Syrup containing lime sulphur, nicotine sulphate, or copper sulphate was strongly repellent to the bees.

It seemed possible that spray mixtures might be made repellent to the honeybee by the addition of suitable substances. Further trials showed that lead arsenate solution, at least in the concentrations normally used, was no more attractive to the bee than distilled water. Concentrations of 1/500 lime sulphur or 1/2000 nicotine sulphate were sufficient to reduce the uptake of M/1 sucrose to less than 10% of that of unadulterated sucrose solution, and very much lower concentrations appreciably affected the uptake. The presence of lead arsenate in these solutions seemed to make them even more repellent. The repellent effect was reduced, though not entirely destroyed, when the solutions were evaporated to dryness and taken up in distilled water again.

Creosote (0.13%), which has been suggested as a possible repellent, gave erratic results under laboratory conditions, and, in view of the danger of phytocidal action it is probably unwise to attempt to use its repellent property.

Open flowers of apple trees were sprayed with various spray mixtures in an orchard experiment, and counts of bees showed both lime sulphur (1%) and nicotine sulphate (0.05 % nicotine) to have retained their repellent value for at least 7 days, in spite of heavy rain. If bees can thus be deterred from visiting the open blossom, it should be possible to deter them even more thoroughly from collection of water contaminated by sprays applied at the correct time.

Data collected throughout the country during the last 3 years show calcium or lead arsenate to be the constituent of orchard sprays causing honeybee poisoning. Bees may collect arsenic when visiting fruit trees, or plants growing beneath or near the trees, for pollen or water, contaminated water apparently being the chief cause of poisoning; about 0.00005 mg. internal arsenic per bee has been found to be a lethal dose. When arsenical sprays alone are applied to trees, particularly if to the open blossom as is sometimes the case with gooseberries and cherries, severe poisoning from the pollen may be expected. On the other hand, much of the danger from contaminated water should be removed by the incorporation of lime sulphur (1% or more) or nicotine sulphate (0.05% nicotine) into sprays intended for application either before flowering or after petal fall, provided that alternative sources of water are available for foraging bees. Provision of water within the hive is suggested as a further safeguard.
Field experiments on the control of sheep maggots
Authors: Angus W. Rogie , Thomas I. , Williams O. G.
Published: February 2008

Field experiments on about 4700 sheep at about forty different farms in North Wales are discussed. Crutching is the most effective control measure for lambs. Regular dipping with commercial arsenic‐sulphur dips gives reasonable control except during adverse weather conditions. Dipping with zinc arsenite or with calomel proved, on the whole, less effective than dipping with commercial dip. Addition of calomel to commercial dip proved to be more effective than commercial dip alone. Preliminary observations are presented on the variation of the surface tension and viscosity of the dipping fluid as the number of sheep passing through the dip increased.
Black scurf and stem canker of potato (Corticium Solani Bourd. & Galz.)
Authors: Ph.D. T. Small
Published: February 2008

Black scurf and stem canker of the potato was investigated in field trials on infected soil at Warburton, Cheshire, to study the effect of planting clean and contaminated seed, and the relation between the dates of planting and lifting and the contamination of the crop tubers.

Black scurf was prevalent on crops grown from clean seed but was more severe on crops raised from contaminated seed. Under conditions favourable for the disease the yields from clean and contaminated seed were satisfactory and were not significantly different. Young shoots of plants from contaminated seed were severely attacked and tuber formation was checked; these results were not obtained on clean seed plots.

More black scurf occurred on late‐dug crops; on early‐dug plots the disease, although almost absent in 1941, was prevalent in 1942. Late planting failed to reduce appreciably the amount of black scurf.

Variety trials included Arran Banner, Kerr's Pink (two vigorous varieties), King Edward and Majestic (two less vigorous varieties). All were heavily infected and each recovered well from an attack on the young shoots.

Inoculation of the seed at planting time did not affect the results; in all trials, misses and wilted shoots caused by Corticium were rare and there was no relation between the yield and the amount of black scurf on the crop tubers.

The results indicate that the disease causes little, if any, loss under farm conditions.
Investigation into the production of bacteriostatic substances by fungi
Authors: Wilkins W. H. , Harris G. C. M.
Published: February 2008

A method is suggested for estimating the degree of potency and, to some extent, the specificity of bacteriostatic substances produced by fungi. It is based on the examination of several hundred fungi over a period of 2 years. It consists essentially of the placing of a few drops of the substance to be tested in the centre of a plate of bacteria‐incorporated agar with the consequent production of a zone of inhibition which varies in width in proportion to the concentration of the bacteriostatic substance. The test is made against two representative types of bacteria—Bact. coli and Staph, aureus. The permissible technical latitude in the application of the test has been summarized. By using a standard inhibitor (mercuric chloride) the accuracy of the method has been statistically proved. This ‘zonation’ method has been compared with the standard ‘dilution’ method and close correlation has been established.
The preparation of a standard pyrethrum extract in heavy mineral oil, with observations on the relative toxicities of the pyrethrins in oil and aqueous media
Authors: Martin J. T.
Published: February 2008

The preparation of a pyrethrum extract in highly refined heavy mineral oil, suitable for use as a basis of reference in the biological evaluation of commercial pyrethrum‐heavy oil preparations, is described. The solution was standardized with respect to colour, resin content and equal proportions of the pyrethrins. A standard solution containing pyrocatechol remained stable, when judged by the chemical determination of the pyrethrins, over a period of months.

When applied in a heavy mineral oil medium, pyrethrin II was shown to possess a toxicity to Tribolium castaneum Hbst. approaching, if not equal to, that of pyrethrin 1. When applied in an aqueous medium the toxicity of pyrethrin II was very much lower than that of pyrethrin I.
The natural cross‐pollination of crop plants with particular reference to the radish
Authors: Crane M.B. , Mather K.
Published: February 2008

Experiments were carried out to determine what degree of intervarietal cross‐pollination occurs when two radish varieties are grown at varying distances apart. The varieties chosen were Icicle and Scarlet Globe. Hybrids are distinctive; thus crossing is readily determined.

In closely planted experiments, where one half of the plot was Icicle and the other half Scarlet Globe, the amount of intercrossing ranged from 30 to 40 % at a distance of 9 in. to an average of about 1 % at 15 ft. Intercrossing decreased fairly regularly and rapidly with distance.

Single plants of Icicle were run out from plots of Scarlet Globe; in 1941 at distances from 9 in. to 95 ft. and in 1942 from 9 in. to 408 ft. In the plants near the red plots crossing was approximately 100 %. In 1941 there was a regular and rapid fall with distance and intervarietal crossing stopped at 95 ft. In 1942 the plots were closer to beehives; intercrossing was less regular and extended farther than in 1941, but beyond 240 ft. it was only 0.1%, and in an all‐white plot 360 ft. from a red plot with no intervening stringer plants it was nil.

Given a mass of plants and a profusion of flowers, bees confine their flower visiting to a small area. When radishes are grown in quantity 300 ft. guards against contamination of stock due to intervarietal crossing. If only small numbers are grown intercrossing is likely to occur over a greater distance.
Studies on the spread of certain plant viruses in the field
Authors: Smith Kenneth M.
Published: February 2008

Studies on the spread of potato viruses X and Y and cucumber mosaic virus in the field are described: tobacco was used as the experimental plant. The plants were set out in the form of a cross, one series with the leaves in contact and one with the leaves not touching. No spread of potato virus X was observed, but there was extremely rapid permeation of virus Y throughout the plots. The spread of cucumber mosaic virus was much slower than that of virus Y.