bluuebunny/crossref_metadata_2025 huggingface dataset:
YIELD STUDIES IN OATS: THE EFFECT OF THE PRE‐TREATMENT OF THE PARENT CROP UPON THE SEED PRODUCED, ITS GERMINATION AND SUBSEQUENT GROWTH
Authors: JONES MARTIN G. , TINCKER M. A. H.
Published: February 2008

The effect of the parent crop husbandry in the case of oats has been traced upon the seed, its germination and early growth and yield.

The beneficial effects of seed grading by weight are again emphasised, but it has been demonstrated that such mass selection does not cause an improvement of the seed qualities in every respect. More subtle characteristics than weight have a predetermining effect.

The relationship between environmental conditions and panicle characters has been discussed.

In spring oats grown under Welsh conditions the importance of establishment, which can be roughly gauged by laboratory tests, is emphasised. Heating the seed samples appears to be a suitable method by which further information can be obtained as to the seed's vigour.

It seems that an index to yield is likely to be found in this direction. Seed vigour is correlated with yield.

Plant to plant variation is so wide between spaced individuals that little indication of the graminaceous plant's capabilities were discernible in seedling behaviour.
OBSERVATIONS ON THE INSECT CARRIERS OF MOSAIC DISEASE OF THE POTATO.
Authors: SMITH KENNETH M.
Published: February 2008

An account is given of some preliminary experiments with insects as transmitters of potato mosaic disease. The various types of insect‐proof cage which have been used in these experiments are described.

The following insects were used in the inoculations:

Aphididae.

Myzus persicae.

Macrosiphum gei (=solanifolii).

Myzus Circumflexus.

Aleurodes, White‐fly.

Asterochition vaporariorum.

Capsidae.

Calocoris bipunctatus.

Lygus pabulinus.

Typhlocybidae, Leaf‐hoppers.

Zygina pallidifrons.

Eupteryx auratus.

The aim of the experiments is definitely to identify what insects of those normally attacking the potato are disseminators of virus disease.

Infected insects were placed both upon the sprouts of tubers and upon the haulm; the latter is the only satisfactory method for insects other than aphides.

Successful transmission of mosaic disease was obtained in 1925 by means of the aphides Myzus persicae and Macrosiphum gei. Some evidence of infection by means of Aslerochiton vaporariorum (greenhouse white‐fly) and the leaf‐hoppers Zygina pallidifrons and Eupteryx auratus wars also obtained; further work with these insects is required before definite conclusions are drawn. The capsid bugs Lygus pabulinus and Calocoris bipunctatw failed entirely to transmit the disease.
RHIZOCTONIA “FOOT‐ROT” OF THE TOMATO1
Authors: SMALL T.
Published: February 2008

A “foot‐rot” disease of young tomato plants from Guernsey caused by Rhizoctonia solani has been investigated.

The disease is least prevalent on dry open soils; it is most severe at temperatures ranging from 16°C.‐20°C

The degree of infection was increased by stable manure; slightly decreased by ammonium sulphate; apparently unaffected by lime, potassic and phosphatic manures.

Soil sterilisation by heat was the most effective and reliable means of controlling the disease. During the season the disease was checked by uspulun.

Control methods are suggested.
A STUDY OF HYLEMYJTA (CHORTOPHILA) RRAS‐SICAE BOUCHE, THE CABBAGE ROOT FLU AND ITS PARASITES. WITH NOTES ON SOMX OTHER DIPTEROUS PESTS OF CRUCIFEROUS PLANTS
Authors: SMITH KENNETH M.
Published: February 2008

A detailed account is given of the life history and parasites of Hylemyia (Chortophila) brassicae, the cabbage root fly. The various stages are described and figured. The egg is deposited in the vicinity of the roofs of Cruciferous plants, in the heads of cauliflowers, and in autumn on the leaves and cut stem of Brassicas. The period of the egg stage lasts from 3 to 5 days, the larva when full grown is smooth, white in colour, and possesses a caudal corona of well‐defined tubercles, one pair of which is bifurcate and serves as a means of identification. The maggots feed in the roots of Cruciferous plants, or in the heads of cauliflowers and turnips, while late in the autumn they may occasionally be found tunnelling in the midrib of Brassica leaves. The larval period lasts from 19 to 25 days. The puparium is reddish brown in colour and measures about 7 mm. in length. The length of the pupal stage is very variable and may occupy from an average of 16 days to 69 days. Pupation takes place in the soil in proximity to the plant. The adult is a dark grey insect somewhat resembling the home fly but is more bristly.

There are three generations in the season; as a general rule hibernation is in the soil in the pupal stage.

Four other types of larvae found associated with those of H. brassicae in Cruciferous plants are described, the most important being Phytomyza rufipes Meig.

A detailed description of the parasites of H. brassicae is given; these are the larva of the Staphylinid beetle Aleochura bilineata Gyll., the Cynipid Cothonaspis rapae Westw., the Braconid Dacnusa stramidpes Halid. and the Anthomyid fly Phaonia trimaculatu Bouché, the larvae of which are carnivorous and feed upon H. bassicue larvae. There are also described a Proctrotrupid, Emllonyx Eigatus Nees., which is parasitic upon the larva of Abochara bilinmta Gyll. and a Tachinid fly, One& agilis Meig., which is associated with H. brassicae, although the exact relationship has not been determined.

An unusual form of parasitism of the adult fly by some kind of micro‐organism is also figured and briefly described.
INVESTIGATIONS ON THE CONTROL OF WIREWORMS
Authors: MILES HERBERT W. , PETHERBRIDGE F. R.
Published: February 2008

A study of the wireworm problem in Great Britian shows that this pest is especially important in areas devoted to intensive agriculture and commercial horticulture.

In addition to most farm crops, strawberries, various flowers and tomatoes me particularly susceptible to wireworm attack and because these crops 60 often occur on new land, losses due to the activities of the pest are frequent, and serious. The nature and extent of wireworm attack, both in the field and in glasshouses, is described herein.

Examination of weeds growing in infested fields indicate that wire‐worms are found in numbers at the root of some plants such as couch‐grass, Agropyrum repens, and yarrow, Achillea millifolium, while very few occur at the roots of pants like chickweed, Stelkria media, gout‐weed, Chenopodium album and annual nettle, Urtica urens.

Field observations on the movements of wireworms in the soil throughout the autumn, winter and spring indicate that there is a definite downward migration in autumn and an upward migration in spring. Correspondingly wireworm activity in the surface soil was noted to be at its height in September and October, and March, April and May.

Expehents on the use of baits as a means of assembling wireworms, indicated that large numbers will collect to baits such as wheat, oats, and bran, and moreover these baits can be used to attract wireworms from the roots of crop plants, on which they are feeding. Because of the seasonal movements of wireworms, baiting is best carried out in autumn or spring.

Calcium cyanide in granular form has been found to be highly toxic to wireworms and used, in connection with the baiting, at the rate of 2–3 Ib. per 100 yd. of bait row, destroyed 75–100 per cent. of the wire‐worms assembled.

Based on the results of experiments conducted in Lincolnshire, Hertfordshire, and West Sussex, during the years 1925 and 1926, and involving 10,000 wireworms, recommendations are made for the control of wireworms by means of baits and the use of calcium cyanide.
THE BIOLOGY OF THYSANOPTERA WITH REFERENCE TO THE COTTON PLANT: 1. THE RELATION BETWEEN DEGREE OF INFESTATION AND WATER SUPPLIED
Authors: WARDLE ROBERT A.
Published: February 2008

Experiments concerning the degree of infestation of Thrips tabaci upon cotton plants under glasshouse conditions suggest that the infestation factor, or number of thrip stages per 100 sq. cm. of foliage surface, varies inversely with the weight of water supplied.

Plants receiving excessive water supply have a lower infestation factor and a lower number of thrip stages per leaf as compared with plants receiving sufficiency of water supply; plants receiving insufficient water supply have a greater infestation factor than plants receiving sufficiency of water supply but have not necessarily a greater number of thrip stages per leaf; owing to their smaller foliage area however they suffer more from thrip attack.

Irrigation is more effective in influencing the degree of thrip infestation than is rainfall.

Irrigation on a flat soil surface is more effective than irrigation on a furrowed soil surface.

The effect of excessive water supply does not appear to be due to mechanical removal of thrips stages from the foliage, nor an injurious effect of soil moisture or atmospheric moisture upon thrips stages, nor alteration of the osmotic concentration of cell sap, although all three factors may operate slightly.

It is suggested that one factor concerned is the influence of heavy water supply upon the texture of certain soils, in promoting surface caking which will act inimically to soil pupating species of Thysanoptera.
ANTAGONISM OF MICRO‐ORGANISMS AS THE CONTROLLING FACTOR IN THE: INHIBITION OF SCAB BY GREEN‐MANURING
Authors: MILLARD W. A. , TAYLOR C. B.
Published: February 2008

The “preferential food theory” as an explanation of the action of green manure in the control of scab is criticised.

Experiments are described in which potatoes are grown in series of pots containing soil only or soil mixed with grass cuttings. In each series the pots were inoculated with two Actinomyces species—the one, A. scabies (Thaxter) Güssow emend. M. and B., a virulent scab producer; the other, A. praecox, an obligate and prolific saprophyte. In Exp. 1, the inoculum of A. scabies was made to decrease and that of A. praecox to increase along the series. In Exps. 2 and 3 the inoculum of A. scabies was kept constant, and that of A. praecox was gradually increased along the series of pots.

In the absence of the saprophytic Actinomyces species, grass alone exerted no inhibitory action on scab.

A reduction of scab was obtained in all pots whether of soil or soil mixed with grass to which an inoculation of A. praecox had been given. This reduction was most marked in the case of the maximum inoculation with A. praecox.

Counts of the two Actinomyces species were made from soil samples taken from the pots during and after growth of the potato crops, and from these it was found that the presence of the saprophytic species had exerted a very strong depressing effect upon the parasitic species. This depressing effect was most marked after a whole season's growth as shown by Exp. 3. Here, on the millionth dilution platings from a pot inoculated with A. scabies alone, 225 colonies grew but no colonies of this species were found on the plates of the same dilution in the case of three pots to which inoculations of A. praecox had also been given.

The inhibitory effect of A. praecox on A. scabies is not due to the setting up of an unfavourable soil reaction but is probably caused by a starving out of the weaker organism in competition for the available food supply of the soil.

It is suggested that the beneficial effect of green manuring on scab under field conditions is due to similar competitive action and that in this competition the bacteria as well as the Actinomyces may play a part.

The cases in which green manuring has apparently failed to inhibit scab have been considered from this fresh point of view.
ON THE CONTROL OF GLASSHOUSE INSECTS WITH CALCIUM CYANIDE
Authors: MILES.M.Sc. HEEBERT W.
Published: February 2008

Experiments on glasshouse fumigation with calcium cyanide in Great Britain during 1925–26 indicate that this material is a satisfactory source of hydrocyanic acid gas, and can be used to control a number of the usual pests infesting glasshouse plants. Trialeurodes vaporariorum Westw. was held in check with dosages of 1/12–1/5 oz. per 1000 cu. ft. and effectively controlled with dosages from 1/4–3/4 oz. per 1000 cu. ft. according to the conditions prevailing.

At least six species of greenhouse aphides were controlled with dosages varying from 1/1 oz. to 1/2 oz. per 1000 cu. ft.

Thrips, of which four species were dealt with, were more difficult to control, apparently only the adults being affected by the hydrocyanic acid gas. Dosages of 1/3 to 11/2 ozs. per 1000 cu. ft. killed varying percentages of the adults and a series of fumigations were found to give satisfactory control.
THE EFFECT OF SOIL STORAGE AND WATER CONTENT OX THE PROTOZOAN POPULATION
Authors: CUTLER D. WARD , DIXON. A.
Published: February 2008

Experiments are described showing that it is possible to conduct laboratory experiments on micro‐organisms in stored soil, providing the surface of the soil is large relatively to its volume.

Experiments on the influence of moisture on the soil protozoa show that active forms are found in soils containing a very low per centage of water.

The flagellate Cercomonas crassicauda was found to excyst and reproduce in air‐dried soil brought to 1/6 the water‐holding capacity. The numbers of the bacteria also in this experiment nearly doubled their numbers in 24 hours.

Four common soil protozoa were found to behave normally in soil of 1/2 and 1/3 the water‐holding capacity, which previously had been air‐dried and then brought to the desired water content

Field soils having water contents of 6 per cent, in one case and 4 per cent. in another corroborated the laboratory experiments In all of these samples active Cercomonas were found, other protozoa being present only in the form of cysts.
STUDIES IN BACTERIOSIS. XV A DISEASE OF SWEDES AND TURNIPS
Authors: PAINE SYDNEY G. , NIRULA RAM. L.
Published: February 2008

A disease of swedes is shown to be related to the presence of bacteria.

Certain features of the disease lead the authors to reserve their opinion as to whether bacteria are wholly responsible until opportunity for further investigation shall have presented itself.

An organism has been isolated and described.

The organism has been shown to be identical with one isolated contemporarily from cauliflower in France by Dufrenoy and Szymanek.

The identity of the organism with Pseudomonas campestris has been discussed and it has been suggested that it is probably a saltant strain of this species, though the authors reserve the question of actual identity until farther evidence is available.

The strain possesses more than one flagellum.
ON THE LIFE‐HISTORY OF “WIREWORMS” OF THE GENUS AGRIOTES ESCH.: PART IV.
Authors: ROBERTS A. W. RYMER
Published: February 2008

The most reliable characters for distinguishing the larva of Agriotes lineatus from the closely similar larva of A. obscurus have been found in the spiracles. The spiracles of A. lineatus are longer and more parallelsided than those of A. obscurus and also bear a noticeably larger number of teeth bordering the orifices.
THE GROWTH OF FUNGI IN SOIL1
Authors: McLENNAN E.
Published: February 2008

Sterile soil was inoculated with a known quantity of spores of four different fungi, incubated at 9°C. and at intervals representative samples were plated out by the dilution method and an analysis of the. plate population made. Results showed that high plate counts were not in any way connected with vegetative growth and supported Conn's idea that in such a case one is simply measuring the sporing capacity of the forms used.

Samples of moist soil and of soil which had been dried in a vacuum desiccator over calcium chloride were plated out by the dilution method and the number of fungal colonies per plate compared. A marked decrease was noted with the dried sample. The reduced pressure was found to have no effect as drying under ordinary air‐pressure gave comparable results.

Suspensions in soil, and in sand, of fragmented mycelia and of a mixture of fungal spores, were in turn plated out directly and after drying. No colonies developed from the sample in the desiccator containing only mycelia, whereas the sample containing spores was in no way affected. It is suggested therefore that the decrease obtained after drying is due to the desiccation of the vegetative mycelium in the soil and since the reduction in the number of colonies per plate is very pronounced after this treatment, it. is thought that the normal fungal constituents of the soil are present extensively in the mycelial condition.

In conclusion I should like to acknowledge my indebtedness and gratitude to Sir John Russell for offering to me the hospitality of the Rothamsted Experimental Station and to Dr W. B. Brierley, Head of the Department of Mycology, for placing at my disposal all the facilities of the Department and for his encouragement and helpful eritieism during my work at the Station.
EXPERIMENTS WITH A MOSAIC DISEASE OF TOMATO
Authors: SMITH J. HENDERSON
Published: February 2008

A description is given of a mosaic disease produced in tomato by a virus, possibly identical with Johnson's Tobacco Virus 6, which differs from that of ordinary tomato mosaic in the brilliance and intensity of its leaf‐symptoms, but in other respects is indistinguishable from it by the characters investigated.

The filtered juice of infected plants transmits the disease in dilutions in water up to 1 in 10,000, retains its activity for a year or more at room temperature, and withstands heating for 10 minutes at 80°C. but is inactivated at 90°C.

It is not inactivated by alcohol up to 90 per cent. The virus comes down with the precipitate, and is not destroyed when the formation of precipitate is prevented by the addition of NaOH.

Attempts at cultivation of the virus outside the living plant are described; all were unsuccessful. The methods employed in filtration, inoculation, etc. are given in detail.
ON CLADOSPORIUM HERBARUM: THE QUESTION OF ITS PARASITISM, AND ITS RELATION TO “THINNING OUT” AND “DEAF EARS” IN WHEAT
Authors: BENNETT F. T.
Published: February 2008

The only types of Cladosporitun found occurring on our four cereals were strains of C. herbarum, not different species.

Five strains of C. herbarum, tentatively termed “prevalent strains” of wheat, barley, oats, cabbage and broccoli, were isolated from these plants respectively.

The bud‐spore forms, or so‐called Hormodendron stages, of these strains do not differ in parasitic capacity from the normal Cladosporium forms; they do not cause perforation of leaves.

None of these strains of C. herbarum, and they may be regarded as typical of the species, is parasitic in any stage or form on brassicas or cereals; they are all “semi‐parasitic,” establishing themselves on, and thereafter hastening the death of, dying tissues.

C. herbarum is not the cause of “thinning out,”“premature ripening (whiteheads),” or “deaf ears” in wheat.
THE BIONOMICS OF APION ULICIS FÖRST. (GORSE WEEVIL), WITH SPECIAL REFERENCE TO ITS ROLE IN THE CONTROL OF ULEX EUROPAEUS IN NEW ZEALAND1
Authors: DAVIES W. MALDWYN
Published: February 2008

The present study of Apion vlicis Först. is in reference to the use of this weevil in the control of Ulex europaeus in New Zealand: its synonymy and geographical distribution are dealt with.

The external morphology of the egg, larva, pupa and imago of Apion ulicis have been studied, special attention being devoted to the mouth parts of both adult and larva. The male and female reproductive organs are also described and figured.

The details of its life‐history and feeding habits are given and an account of the damage caused by both adult and larva is included.

A survey of 62 districts in Great Britain has been organised and as high as 92 per cent. pod infection has been observed.

Primary attention has been given to the possibility of Apion ulicis attacking economic plants. It was found that only leguminous plants need be considered, and of these oviposition only occurred in pods of Ulex europaeus. Tests to ascertain the ability of Apion ulicis to thrive on other leguminous plants gave entirely negative results.

A parasite identified as Splintherus leguminum, Ratz. has been bred, a 4 per cent. parasitism was estimated. Three other records of parasites of Apion ulicis are quoted.
THE GERMINATION AND EARLY GROWTH OF WHEAT TREATED WITH COPPER CARBONATE AND TILLANTIN R.
Authors: SAMPSON KATHLEEN , DAVIES D. WALTERS
Published: February 2008

From a review of recent literature the authors conclude that the supposed “stimulating effect” of such substances as uspulun tillantin, and copper carbonate, is in most cases clearly to be attributed to the fungicidal properties of these compounds.
THE COMMON GREEN CAPSID BUG (LYGUS PABU LINUS)
Authors: PETHERBRIDGE F. R. , THORPE W. H.
Published: February 2008

The capsid bug Lygus pabulinus has become a serious pest of currants, gooseberries, strawberries, potatoes and dahlias, and is also present on apples, pears, plums, cherries and peaches, and a large number of cultivated plants and weeds.

A detailed account is given of the characteristics and measurements of the various stages which will serve the purpose of identification, and also of the genitalia.

Diagnostic characters are given for the purposes of distinguishing it from the P. rugicollis which causes similar damage on currants and apples.

There are two generations per annum. Eggs are laid in the autumn in woody plants such as currants, gooseberries, apples and roses and then migration to herbaceous hosts usually takes place where the summer eggs are laid, the second generation returning to the woody host to lay their eggs.

In the first generation a secondary migration from strawberries to other herbaceous hosts takes place. Details are given of the damage done to the more important host plants and of the habits of the bug in its various stages. Control measures are given.
On Two Cases Of Recovery From A Mosaic Disease Of Tomato Plants, Lycopersicum Esculentum
Authors: VERWOERD LEN
Published: February 2008

Experiments are recorded which indicate that from a number of tomato plants raised from mosaic‐diseased cuttings, two plants were free from mosaic disease.

These two plants showed no symptoms of mosaic disease and neither was the active principle of the disease present in the juice obtained from these plants.
STUDIES ON POTATO VIRUS DISEASES V. INSECT TRANSMISSION OF POTATO LEAF‐ROLL
Authors: SMITH KENNETH M.
Published: February 2008

Inoculation experiments with seven different species of insects carried out in 1927 gave negative results, except in the case of the aphis Myzus persicae Subs, which gave a high percentage of positive infections.

Further inoculation tests with this aphis in 1928 proved it to De an efficient carrier of the leaf‐roll virus.

Experiments carried out during two years on the question of the inheritance of the leaf‐roll virus by the progeny of Effective aphides proved negative. It is therefore assumed that the virus is not hereditary in the offspring of the aphis.

One or two virus‐bearing aphides are capable of infecthg a healthy potato plant with leaf‐roll. Such infection when achieved differenced in no degree of severity from that induced by 18 aphides. The incidence. of infection was greatest among plants colonised with groups of 18 infective aphides.

Colonisation of virus‐bearing aphides upon non‐solanaceous hosts such as cabbage for periods varying from 24 hours to 7 days did not affect the subsequent infective power of such aphides.

M. persicae, when colonised upon plants affected with combinations of viruses of which leaf‐roll was one constituent, transmitted only leaf‐roll to healthy potatoes. The combinations used were leaf‐roll and streak, and leaf‐roll and mosaic. In the latter case the aphis was shown, by its infection of tobacco with a mottling disease, to be picking up both viruses of which only leaf‐roll developed in the potato.

The incubation period of the leaf‐roll virus' in the plant averaged about 30 days under glasshouse conditions. In some cases the disease was found to develop in 18–20 days.

Seven varieties of potato have been infected with leaf‐roll by means of M. persicae. There existed no apparent difference in degree of resistance to leaf‐roll.

The leaf‐roll virus can be disseminated by the feeding of M. persicae, either on the sprouts of the tuber, on the leaves and shoots of the growing plant, or on the stem alone.
THE BIOLOGY OF THYSANOPTERA WITH REFERENCE TO THE COTTON PLANT IV. THE RELATION BETWEEN THE DEGREE OP INFESTATION AND SURFACE CAKING OF THE SOIL
Authors: MACGILL ELSIE I.
Published: February 2008

Results of experiments on the effect of water supply on the infestation of a plant by thrips suggested that the surface caking of the soil has an important influence on the degree of infestation.

Plants grown in pots in which the surface of the soil was tilled showed a higher infestation by thrips than plants in similar pots, but in which the soil was allowed to cake, although both sets of plants were receiving an equal water supply, and all other conditions were the same.

The difference in the infestation factors for the two groups was largely due to differences in the numbers of larval thrips, but it is pointed out that the number of larvae forms a more reliable factor than the number of adult insects.

The present experiments support the suggestion put forward that surface caking of the soil acts inimically to soil pupating species of thrips.
ADDITIONAL HOSTS OF SYNCHYTRIUM ENDOBIOTICVM (SCHILB.) PERC
Authors: MARTIN MARY S.
Published: February 2008

Infection of numerous species of Solanaceae by Synchylrium endobioticum has been obtained using Glynne's “green wart” method. Plants grown in contaminated soil did not show infection. The following new hosts are recorded: Solanum dulcamara var. villosissimum, Nicandra physalodes, Solanum dulcamara alba, Solanum nodiflorum and Solanum villosum.

In certain hosts the fungus may occur in the tissues with little or no external sign of its presence.

I am indebted to Dr W. B. Brierley for helpful criticism and suggestions received during the course of this work; and to the Director, Research and Experimental Station, Cheshunt, Herts, The Director. Royal Botanic Gardens, Kew, Surrey, The Regius Keeper, Royai Botanic Gardens, Edinburgh, and Martin H. Sutton, Esq., Erlegh Park, Whiteknights, Reading, for seed and tubers used in the experiments.
THE CONTROL OF CUCUMBER AND TOMATO MOSAIC DISEASES IN GLASSHOUSES BY THE USE OF CLEAN SEED
Authors: BEWLEY W. F. , CORBETT W.
Published: February 2008

Summary.

Evidence is submitted to show that mosaic disease of both the cucumber and the tomato is transmitted by the seed.

Stocks of infected seeds have been cleaned by early and careful roguing of diseased plants.

There is every reason to believe that in this country the incidence of this disease in glasshouses can be reduced to small proportions, if not entirely prevented, by the use of clean seed.
INSECTS FOUND ASSOCIATED WITH CACAO, SPICES AND DRIED FRUITS IN LONDON WAREHOUSES
Authors: RICHARDS O. W. , HERFORD G. V. B.
Published: February 2008

Summary.

The pests found in certain cacao, spice and dried fruit warehouses in London have been enumerated. Reference has been made to some of the more important papers in which the food, habits or distribution of the species have been described.

To make the identification of some of the pests more easy we have made new keys to the species met with in the following genera:Carpophilus, Laemophlaeus, Dermestes, Gnathocerusand allies,EphestiaandDrosophila.

The following insects appear to be recorded from Britain for the first time. Those marked with an asterisk have only been found dead. Coleoptera: Plochionus pallens F. (Carabidae), Carpophilus flavipes Murr. (Nitidulidae), Tenebroides oblongus Shp.* (Trogositidae), Laemophlaeus janeti Grouv. (Cucujidae), Dermestes cadaverinus F. and D. carnivorus F. (Dermestidae), Cyclocephala tetrica* Voert., Diplognatha silacea* Moel. and phileurus didymus* L. (Scarabaeidae), corynetes analis Kl. (Cleridae), Catorama herbarium Gorh. (Anobidae), Monomma brunneum* Thoms.(Monommidae), Sitophagus hololeptoides Casteln. (Tenebrionidae), Anthicus australis* Lea (Anthicidae), Caulophilus latinasus Say (Curculionidae), Stephanoderes busckii* Hopk. (Ipidae). Hymenoptera: Holepyris hawaiiensis Ashmd. and Cephalonomia carinata Kieff. (Bethylidae), Campoplex prytanes Cam. (Ichneumonidae), Zeteticontus laeviscutum Thoms. (Encyrtidae). Diptera: Drosophila immigrans sturt. (Drosophilidae).
THE PHYSIOLOGY OF VIRUS DISEASES IN PLANTS
Authors: CALDWELL JOHN
Published: February 2008

Summary.

In this paper the movement in the plant of the causative agent of virus disease is discussed. The relevant data in the literature are summarised.

A method is described whereby a portion of the stem in the middle of a tomato plant was killed either by chloroform or by steam. In this way the living upper and lower portions of the plant were connected by a bridge of dead tissue. It is shown that the symptoms appeared in that part of the plant in which the inoculation was made. The virus agent did not travel across the dead region.

The xylem tracts were not materially affected by this treatment, and water travelled across the region. Evidence of this is the fact that the distal portion remained turgid and sometimes continued growth for a considerable time. If the stem were removed above the ground level and put into eosin solution, this travelled readily over the dead tissue. That the vessels were not occluded by protein plugs is shown by the fact that particulate substances were carried up the xylem tracts past the dead region.

No evidence of adsorption of the virus agent to the cell remains could be adduced, so it is assumed that it was not travelling in the xylem stream.
THE RÔLE OF THRIPS TABACI LINDEMAN IN THE TRANSMISSION OF VIRUS DISEASES Of TOMATO
Authors: JARRETT PHYLLIS H.
Published: February 2008

Summary.

A description is given of experiments designed to show the rôle of Thrips tabaci Lindeman in the transmission of tomatoes.

The diseases tested were tobacco mosaic and glasshouse streak singly, and the viruses of each of these two combined with a potato mosaic virus to give a disease termed experimental streak.

The source of the materials used and the methods employed are described in detail.

In no case was transmission of any of the viruses recorded, although the insects had fed freely on all the plants. It is concluded that Thrips tabaci does not transmit virus diseases of tomatoes under all conditions. The importance of this insect as a vector of these diseases in commercial glasshouses in England is therefore doubtful.
THE INFLUENCE OF ENVIRONMENTAL CONDITIONS ON THE DEVELOPMENT OF THE ANGULAR LEAF‐SPOT DISEASE OF COTTON. II. THE INFLUENCE OF SOIL TEMPERATURE ON PRIMARY AND SECONDARY INFECTION OF SEEDLINGS
Authors: STOUGHTON R. H.
Published: February 2008

Summary.

Experiments on the angular leaf‐spot disease of cotton carried out under controlled conditions lead to the following conclusions:

Seed derived from diseased plants may give rise to infected seedlings.

This infection is due to bacteria carried on the outside of the seed and in the fuzz.

Thorough disinfection of the exterior of the seed results in healthy seedlings.

The amount of primary infection resulting from infected seed decreases at soil temperatures above 30° C., but infection is not inhibited at 40° C.

Soil temperature has little or no effect on secondary infection resulting from spray inoculation of the plants.

Plants diseased in the seedling stage grow out free from disease, if no further inoculation occurs.
THE RELATION BETWEEN THE NUMBERS OF A SOIL BACTERIUM AND THE AMMONIA PRODUCED BY IT IN PEPTONE SOLUTIONS; WITH SOME REFERENCE TO THE EFFECT ON THIS PROCESS OF THE PRESENCE OF AMOEBAE
Authors: MEIKLEJOHN JANE
Published: February 2008

Two sets of experiments on ammonia production from peptone were carried out, one with “YB” bacteria in liquid cultures, and another comparing “YB” and Hartmanella with “YB” alone in sand cultures.

In liquid cultures an inverse linear relation was found to hold between bacterial numbers and efficiency.

The greatest rate of production of ammonia was found to correspond to a bacterial content of about 500 million per c.c, any increase in bacterial numbers above this lowered the rate of ammonia production.

The effect of diluting the inoculum ten times was to increase the “lag” period, both for bacterial growth and for ammonia production, to a week or more; after this extended “lag” period the cultures then followed a normal course.

In sand cultures the presence of amoebae, while lowering the bacterial numbers, appears to increase the rate of ammonia production.

It is suggested that the amoebae reduce the bacterial numbers from too high a valua to a value nearer the optimum for ammonia production, and so increase the rate of ammonia production.

I should like to express my thanks to Mr Woolf, of the Sir William Dunn Institute of Biochemistry, Cambridge, for demonstrating the details of his method to me, and also to Dr Wishart and Dr Fisher, of the Statistical Department, Rothamsted, for help in the analysis of the results, and especially to Mr D. Ward Cuder, in whose department the work recorded in this paper was carried out, for his constant help and encouragement.
ON THE LIFE‐HISTORY OF BLASTODACNA ATRA HAW., THE PITH MOTH OF THE APPLE
Authors: MILES MARY
Published: February 2008

A study has been made of the life‐history and habits of the pith moth of the apple.

The adults, which are described, emerge during the latter part of July.

The eggs, a description of which is included, are laid singly on the twigs, usually near the base of the buds. Incubation requires 14 to 17 days.

Immediately on hatching, in the first half of August, the larvae tunnel into the bark of the twigs, without first feeding on the leaves.
THE RELATION OF ATMOSPHERIC TEMPERATURE AND HUMIDITY TO TOMATO LEAF MOULD (CLADOSPORIUM FULVUM)
Authors: SMALL T.
Published: February 2008

Summary

A study of the relation of atmospheric temperature and humidity to tomato leaf mould (Cladosporium fulvum) has been made with a view to assisting growers to control the disease by cultural methods.

The optimum temperature for the various stages of leaf mould is about 22° C. At 10° to 15° C. severe infection occurs under humid conditions, but the disease develops very slowly.

Humidities exceeding 90 per cent, are very favourable. At 22° C. infection is severe at 80 per cent, humidity but is rare at 70 per cent. At 18° C. infection and subsequent development are considerably retarded at 80 per cent, humidity.

Experiments indicate that seasonal variations in the severity of leaf mould are related to temperature.

Data are given which show that humid conditions obtain in large glasshouses for several hours each night and that these conditions are largely responsible for the severity of leaf mould.

Wetting of the foliage caused by overhead watering does not appear to favour the disease. Excessive watering produces turgid, susceptible plants.

A basis for controlling leaf mould by cultural methods is suggested.
POLYSULPHIDE SULPHUR IN RELATION TO THE FUNGICIDAL EFFICIENCY OF CERTAIN SPRAY MATERIALS
Authors: GOODWIN WILLIAM , MARTIN H. , SALMON E. S.
Published: February 2008

Summary

The results of a prolonged investigation of the fungicidal properties of solutions containing sulphur in polysulphide form upon the hop powdery mildew (S. Humuli) have been classified and summarised. During the course of this work the fungicidal efficiency of various lime sulphurs, liver of sulphurs, and solutions containing sodium, potassium, ammonium, calcium and barium polysulphides have been compared and it has been shown that, in all cases, the effect upon the fungus, when growing under similar biological and external conditions and provided that the sprays are applied under standardised conditions, is determined solely by the content of polysulphide sulphur of the spray fluid. The estimation of the amount of polysulphide sulphur present provides, therefore, a measure of the efficiency of these materials against S. Humuli.
Studies In Bacteriosis XVIII. A Bacterial Canker Of Apple Trees
Authors: LACEY MARGARET S. , DOWSON WALTER J.
Published: February 2008

Summary.

A bacterial canker of apple trees is described and compared with cankers previously described by Rose and Hopkins, and with fire blight. The causal organism bears a certain likeness to B. amylovorus, but it is regarded as identical with Ps. papulans Rose. The suggestion is made that the latter organism should be considered as a weak parasite producing disease only where some physiological condition renders the trees liable to be attacked.
YIELD STUDIES IN OATS: III. The Inter‐Relationship Of The Parts Of The Oat Plant During Development
Authors: Tincker M. A. H. , Jones Martin G.
Published: February 2008

Summary.

1. This paper is the third report of a series dealing with the oat crop, and is concerned with the inter‐relationship of the developing parts of the plant in the field.

2. Experiments are reported in which the various component parts of the sub‐aerial growth of spaced plants growing at stated intervals were removed at successive stages of development. The after‐effect of such treatment was observed upon the rate of growth of both the roots and shoots.

3. Whilst the removal of lateral branches in their developmental stages, during which they are dependent upon the parent branch, resulted in an acceleration of the rate of growth of the parent axis, the removal of any part of the sub‐aerial growth which is actively engaged in photosynthesis caused a reduction of the rate of growth of the plant as a whole. Such changes in the rate of growth are reflected in the root system and the ratio of root to shoot.

4. The influence of the removal of part of the shoot system is a lasting one. It can be traced out upon the time of flowering, and its effect noticed upon the rate at which the remaining parts ripen.

5. These Considerations are closely related to the previous agronomic observations dealing with the relative yield of grain and straw obtained from a variety. The late, multi‐tillered varieties, are the straw yielders par excellence. In them the relationship of the parts of the plant more closely corresponds to that observed under conditions of wide space than under limited space. The early varieties in general behaviour more closely resemble the plants grown at close intervals and those plants grown at wide intervals from which the side tillers were removed.

The authors desire to express their thanks to Prof. R. G. Stapledon, the Director of the Welsh Plant Breeding Station where this work was carried out, for so kindly providing the facilities necessary, but more particularly are they indebted to him for his enthusiastic interest and the encouragement given at all stages. To the members of the technical staff we are indebted for assistance in the cutting, counting, and weighing of the large number of plants.
Further Results Of An Investigation Into The Resistance Of Basket Willows To Button Gall Formation
Authors: Barnes H. F.
Published: February 2008

Summary.

1. Twelve commercial varieties of S. triandra have been proved, under experimental conditions, to be very susceptible to attack by the button top midge (R. heterobia).

2. Three varieties of S. purpurea, one variety of S. viminalis, three hybrids of S. viminalis and purpurea and S. alba var. vitellina have proved to be totally immune. Notwithstanding eggs sometimes being laid and the larvae hatching, no galls or side‐branching have occurred.

3. From field observations a closely allied gall midge, R. terminalis, is known to attack S. alba var. vitellina, but has not been known to attack any variety of S. triadra.

4. Reference has been made to a similar phenomenon with regard to attacks on willows by the Chrysomelid beetles; viz. to Galerucella lineola which appears to be confined to varieties of S. triandra; and to Phyllodecta vitellinac which is known to attack S. alba var. vitellina and S. purpurea and its varieties, while it is not known to attack any variety of S. triandra.

5. It is suggested that hybridisation of S. triandra×S. purpurea or ×S. viminalis or ×S. alba should be attempted. Mention is made of three aspects of host plant, preference needing special attention in connection with willow gall midges.

In conclusion it is desired to express the indebtedness the writer owes to Mr Hutchinson, who was responsible for the choice of the varieties of willows to be tested in the various trial beds and the supply of sets. Dr Walton, of the Long Ashton Research Station and Mr Kearns of Bristol University have taken part in several very helpful conversations. Thanks are also due to Dr Imms for the generous aid he has given throughout the period of the investigations.
Studies IN Bacteriosis: XIX. Researches on the Group of Green‐Fluorescent Bacteria, Part I; Bacterium Trifoliorum (Jones ET AL.) AS THE Cause OF A Disease OF Vicia Faba
Authors: Lacey. Margaret S.
Published: February 2008

Summary

A disease of Vicia faba is described and the causal organism identified as B. trifoliorum. This species is compared with other members of the green‐fluorescent group of bacteria.
The Biological Decomposition OF Plant Materials: Part IV. The Biochemical Activities on Straws of Some Cellulose‐Decomposing Fungi
Authors: Norman A. Geoffrey
Published: February 2008

Summary

1. A number of common soil fungi isolated from rotting straw were inoculated into sterile straw with the addition of available nitrogen.

2. The amount of decomposition effected, the losses of various straw constituents, and the immobilisation of nitrogen which took place, were all determined, and compared with mixed flora decompositions at various temperatures.

3. Though none of the organisms develop appreciably on a cellulose‐agar plate, all were found to decompose cellulose to a considerable extent.

4. Certain minor differences in ability to utilise the carbohydrate constituents were noted, but in general all substances but lignin were attacked to a degree relatively proportional to the apparent total loss of organic matter.

5. The “nitrogen factor” or nitrogen immobilised by 100 gm. straw rotting with a particular organism was determined in each case. There is no correlation between the “nitrogen factor” and the loss of organic matter or of any particular straw constituent. The differences appear to be varietal.

6. Some indication of the relative efficiencies of the organisms was obtained from a factor for which the name “nitrogen equivalent” is proposed. This represents the nitrogen immobilised as microbial protein in the course of the removal of 100 gm. organic matter from any given plant material.

7. Attention is drawn to difficulties which restrict the absolute value of the “nitrogen equivalent” as a measure of efficiency in decomposition.

8. The value of single factor studies as a preliminary to the synthetic method of investigation of such a process as biological decomposition is discussed.

The author‐is indebted to Sir John Russell, F.R.S., Director of the Rothamsted Experimental Station, for placing at his disposal the facilities of that Station, and to the Department of Scientific and Industrial Research for a Senior Research Award, during the tenure of which this work has been carried out.

Especially are his thanks due to Dr W. B. Brierley, and Mr E. H. Richards, Heads of the Departments of Mycology and Fermentation, for their ready assistance and advice.
A Botanical Study of Pasture Formation
Authors: Fenton E. Wyllie
Published: February 2008

Summary.

Where summer drought is liable to occur it is impossible to form a satisfactory turf in pasture without Wild White Clover. White or Dutch Clover cannot replace Wild White Clover except during the first year of grazing.

Italian Rye Grass is of considerable value, not merely on account of its early growth, the shelter afforded slower‐growing species and helping to conserve surface moisture, but it greatly assists Wild White Clover by competing against Red Clover.

The two most successful plots were those with Italian Rye Grass in the seeds mixture.

The addition of Rough‐Staked Meadow Grass was a distinct success and it should be included in seeds mixtures for long leys or permanent pastures in South Devon.

With sound mixed grazing, all the plots—except No. III—gradually developed a flora of very similar proportions, in spite of initial differences.

The chief feature of the best plots was the Wild White Clover— Perennial Rye Grass association plus Cocksfoot, and in one case plus Rough‐Stalked Meadow Grass.

Timothy was not successful in the pasture owing to severe grazing by sheep and the effect of summer drought. It was much more successful and permanent in the hay sub‐plots.

Cocksfoot is a splendid drought resister and invaluable where summer drought is usual.

Perennial Rye Grass, Wild White Clover, and Rough‐Stalked Meadow Grass tend to hold Cocksfoot in check and prevent any coarseness in its growth.

The marked fluctuations in growth, as measured by the percentage ground covered, by the leading species in the plots is an annual occurrence of considerable regularity, the inter‐specific competition being well shown by the graphs.

The close resemblance in results between the pastures and experimental pasture plots previously considered is a point of considerable importance.
The Susceptibility Of Certain Potato Varieties To Leaf‐Roll And Mosaic Infection
Authors: WHITEHEAD T. , CURRIE J. F.
Published: February 2008

Summary.

1. A trial planned to ascertain whether any differences in susceptibility to leaf‐roll and mosaic infection existed in seven varieties—two of which had been included in a revious trial—was laid down in 1929. It consisted of four replicated plots for each disease; the varieties being randomised in the plots to secure uniform chances of infection. Sources of infection were provided by drills of diseased plants alternating with varieties under test.

2. Mosaic was generally transmitted but with such faint symptoms that percentage infection could not be determined. The apparent loss of vigour was very slight, but losses ascertained by weighing the crop, against that given by normal plants, ranged from 0·8 to 24·4 per cent.

3. Leaf‐roll infection was very heavy; most varieties showing from 90 to 100 per cent. infection of the plants. Tuber infection on the infected plants was also heavier than in 1924, and ranged from 77·3 to 99·9 per cent. Both haulm (or plant) infection and tuber infection thus showed a marked dependence upon seasonal factors which affect the breeding of insect vectors.

4. The loss in yield due to leaf‐roll was found to be the most reliable guide to the susceptibility of a variety. This loss cannot be estimated from the degree of stunting or the number of rolled leaves on a plant, but only by weighing and grading the crop. Some evidence is presented to show that loss in yield of an infected plant is less dependent upon seasonal factors than percentage haulm or tuber infection, and that, therefore, figures showing such losses have a more general applicability to other localities and seasons. On this assumption a table of susceptibility of fifteen varieties has been constructed.

5. Although the variety Field Marshal suffered little from leaf‐roll infection, heavy losses occurred when mixed leaf‐roll and mosaic viruses entered the plant. In large tubers receiving mixed infection the effect was to produce neither leaf‐roll nor mosaic symptoms, but “crinkle.” The small tubers, however, gave apparently pure leaf‐roll.

6. The value to be attached to field trials of this kind, and their applicability to other conditions, is discussed in detail. Suggestions are offered for improvement in the technique for such trials.