bluuebunny/crossref_metadata_2025 huggingface dataset:
Further investigations on the biology and control of the carrot fly (Psila rosae F.)
Authors: Petherbridge F. R.
Published: February 2008

Records were obtained for the emergence of the first and second generation flies at Chatteris and Cambridge. There is a correlation between the age of the carrot crop and the commencement of the emergence of the second generation from it. The first generation was successfully controlled by killing the flies with a poison bait sprayed on the dikesides of the carrot fields. This treatment reduced the popúlation of second generation flies and also their attack. Spraying the dikesides and/or the headlands of eight maincrop carrot fields in August and September greatly reduced the second generation damage. Very high kills of carrot fly were obtained on the headlands of treated fields. Poor results were given by the treatment on three very weedy fields which were incompletely treated. A marked increase in attack occurred in three untreated areas in 1942 as compared with the previous year.

Application of the poison bait spray in the field is discussed. Creosote‐treated string gave promising results in small‐scale experiments for the control of the second generation. Calomel dust (4°) with and without grass cuttings caused no reduction in attack.

In hot sunny weather the flies shelter in the vegetation around carrot fields from about 10 a.m. until about 5 p.m. In the cooler conditions of early morning and evening there is a movement of flies into the field. This rhythm is not maintained in dull warm weather

Seedling carrots may be attacked in the field any time after the cotyledon stage. This enables the first generation of flies to propagate on main crop carrots. Soil sections about carrot rows showed that pupae of the overwintering generation are closely congregated around the carrots. Various insecticides were tested for the destruction of pupae in the soil. A creosote‐sawdust mixture gave the best results.

Storage experiments showed that clamped carrots deteriorate much less than those unlifted. The population of flies is greatly increased by allowing attacked carrots to remain unlifted throughout the winter or by ploughing in.
Materials for a study in animal competition
Authors: Lloyd LL.
Published: February 2008

The incidence of the sewage fly, Psychoda alternata Say, breeding almost free from other insect competitors in a bacteria bed at Huddersfield is examined. Its general seasonal trend is marked by periods of peak output explained on the theory that there are two successions of generations running persistently and alternating with one another. Such behaviour has previously been demonstrated for another sewage fly, Spaniotoma minima, and has been shown to be instituted by irregular temperatures in autumn and spring. In Psychoda alternata a special type of intraspecific competition is set‐up in the warmer months when the cycles are rapid, for the larvae of one succession must start life in a bed just depleted of food by the other. Therefore large and small outbursts of the fly tend to alternate. The discharges of solids from the bed have a detailed periodicity corresponding to the alternations in the successions of the fly.
The effect of a chemical soil sterilizing agent on the subsequent development of tomato plants
Authors: Western J. H. , Stewart R.
Published: February 2008

An account is given of the effect on the development of tomato plants of a chemical soil sterilizer containing orthodichlorbenzene and an emulsifying agent of the sulphonated oil type. The symptoms are described and an account is given of an experimental study of the effect of the treatment on growth and yield: the latter showed a considerable decrease. The injurious ingredient was shown to be orthodichlorbenzene.
The nutrition of the pea
Authors: Woodman R. M.
Published: February 2008

Sand‐culture experiments with the pea plant demonstrated that 8.24–32.96 p.p.m. of available nitrogen was the optimum range of concentrations for yield of peas, with a bias in favour of the lower half of the range; adequate supplies of nitrogen appeared to cause branching of the tops into two or more main stems. The best range of concentrations of available phosphorus was 2.73‐10.92 p.p.m., while that for available potassium was 5.61‐44.88 p.p.m. Deficiency of potassium caused marginal scorch followed by general scorch and death of the foliage progressively up the stem. Absence of boron had not a great effect with this plant, probably because the large seed possibly contains an appreciable amount of boron.
An unusual correlation between insect damage and crop harvested
Authors: Gadd C. H.
Published: February 2008

An experiment is described by which an attempt was made to determine the effect of manurial treatments on the damage caused by the shot‐hole borer of tea. Increases in yields of the plots were accompanied by increases in the damage caused by the beetles as measured by the number of broken branches‐an unusual correlation between pest damage and harvest (r=+0.9267). The experiment failed to indicate clearly the cause of increased damage following manuring, but possibly it results from an increase in the number of galleries formed (r=+0.6547).
Studies of wireworm populations
Authors: Salt George , Hollick F. S. J.
Published: February 2008

A method has been developed, and is here briefly described, by means of which all the wireworm larvae of all stages can be collected from soil samples. By use of that method, complete wireworm populations have been obtained from soil samples of three types, two of which provide large homogeneous populations for detailed study while the third gives information about the seasonal and spatial infestation of fields. These collections show that the wireworm population of English pasture land is on the average about three times as large as has been commonly supposed. Populations have been found ranging up to ten millions per acre in the top 12 in. of soil. In two pastures studied intensively throughout the year, the wireworm population has been found to consist of large numbers of small larvae, decreasing numbers of larger larvae, and comparatively few of the very large larvae that have usually been allowed to represent the population. Such a composition is shown to be characteristic of wireworm populations under old grass at all seasons of the year and in several fields in different parts of the country. This result suggests that in research on the wireworm problem it is desirable to take into consideration the whole wireworm population throughout the year, not merely the large larvae during the cropping season.
Influence of certain soil factors on chocolate spot of beans
Authors: Glasscock H. H. , Ware W. M. , Pizer N. H.
Published: February 2008

In the summer of 1941 chocolate spot of beans was widespread in the South‐Eastern Agricultural Province and caused much damage to the crop. Soil samples were collected from forty‐nine affected fields on a variety of soil types, and the relation between the severity of attack by chocolate spot and the texture, pH, available potassium and available phosphorus determined. Severity of attack was classified into three grades: ‘slight’, in which only spotting of the foliage occurred; ‘moderate’, in which death of leaves and blossoms on the three or four lowest nodes occurred; and ‘severe’, in which there was generally a total loss of crop. No significant relation between severity of attack and soil texture, pH or available potassium was found. A highly significant relation was found to exist between the severity of attack and the amount of available phosphorus in the soil as determined by the method of soil analysis used in this Province. Damage by chocolate spot was generally slight on soils containing ‘medium to medium high’ or higher amounts of available phosphorus, and generally severe on soils containing low amounts of available phosphorus.
Mould deterioration of feeding‐stuffs in relation to humidity of storage: Part I. The growth of moulds at low humidities
Authors: Snow D. , Crichton M. H. G. , Wright N. C.
Published: February 2008

The literature relating to the growth of moulds at different humidities is surveyed.

Observations were made on the development of mould growth on six widely different types of feeding‐stuffs for storage periods extending over some 3 1/2 years. The main factors controlling mould growth were found to be:

1. The relative humidity rather than the moisture content of the food.

2. The length of the storage period. Mould growth took place relatively quickly on all feeding‐stuffs stored at 100‐75% R‐H. Below 75% R.H. mould growth, while not prevented, only developed after a very prolonged latent period. Mould development was observed on locust beans exposed to a humidity as low as 65 % after a latent period of over 2 years.

3. The balance and type of nutrients provided by the various feeding‐stuffs was shown to influence the latent period as well as the extent of mould deterioration. This was confirmed by experiments on artificially dried grass fractions and by experiments on starch, protein and fibre mixtures.

4. The temperature of storage was found to affect the rate of mould development; mould growth developed sooner on samples stored at 22d̀C. than at 15.5d̀C.

5. The type of mould species present. At high humidities all mould species grew rapidly: at low humidities, only a few types were capable of growth.
Mould deterioration of feeding‐stuffs in relation to humidity of storage: Part II. The water uptake of feeding‐stuffs at different humidities
Authors: Snow D. , Crichton M. H. G. , Wright N. C.
Published: February 2008

The water uptake of a wide variety of feeding‐stuffs was determined over a range of fixed humidities. It was shown that the level and shape of the water uptake curves are closely related to the amounts of soluble carbohydrate and protein present. Fibre exerts a depressing effect on the water uptake, while the value is also lowered by the presence of inert fats and non‐hygroscopic ash constituents. These conclusions were confirmed by direct experiments on the water uptake of samples of pure starch, protein and fibre.

The results of the investigations have enabled safe limits of moisture content to be laid down, for both short‐ and long‐period storage, below which mould growth will not normally take place. These limits vary for each individual feed, representative figures being included in the paper in tabular form.
Stability of the microbial populations of the caecum of guinea‐pigs and rabbits
Authors: Baker Frank
Published: February 2008

The microbial population of the caecum of rabbits and guinea‐pigs, respectively, normally exhibits distinctive features which can be tabulated precisely, and which persist when the animals are kept in the same cage and fed on the same diet. A pronounced resistance, therefore, opposes cross‐infection and tends to secure the stability of the population whose characteristics afford useful criteria for the microbiological control of in vitro incubation experiments.
Chafer damage to grassland in north Wales in 1942‐1943 by Phyllopertha horticola L. and Hoplia philanthus Fuess. I. Notes on population, life history and morphology
Authors: Thomas I. , Heal Gwen M.
Published: February 2008

An account is given of a severe attack to grassland by chafer‐beetle larvae in some north Wales valleys in the years 1942‐3. The species concerned were Phyllopertha horticola L. and Hoplia philanthus Fuess. Estimations of the populations of both species were made and notes are given on the biology and comparative morphology of their immature stages. Both species have a one‐year life cycle; all stages of Hoplia philanthus occur somewhat later than Phyllopertha horticola.
Inert dust insecticides: Part I. Mechanism of action
Authors: Alexander P. , Kitchener J. A. , Briscoe H. V. A.
Published: February 2008

The mode of action of inert dust insecticides on the grain weevil (Calandra granaria L.) has been investigated by determination of mortality‐time curves and by a detailed study of the influence of dusts on the water relations of the insects. It has been found that dusts do not depend for their action on any chemical reactivity, some highly inert substances such as diamond and carborundum being very effective. A physical process is therefore indicated.

Dusts do not penetrate into the respiratory system, and although large amounts are ingested these seem to have little harmful effect.

It has been demonstrated that effective dusts increase the rate of evaporation of water from insects to the air, and that the relative killing powers of different dusts run parallel with their capacities for promoting evaporation. The results are in harmony with the view (proposed by earlier workers) that inert dusts kill insects by inducing death by desiccation.
Factors influencing infection of the tomato by Verticillium albo‐atrum. II
Authors: Roberts F. M.
Published: February 2008

Tomato plants receiving adequate supplies of mineral nutrient acquired great resistance to infection byVerticillium albo‐atrumif the leaf‐shoot ratio was reduced; this effect is attributed to reduction in carbohydrate content of the host. Wide variation in potash manuring did not affect susceptibility of tomatoes toVerticillium.
Factors influencing the development of cotton diseases
Authors: Ling Lee
Published: February 2008

The observations and experiments reported in the present paper were carried out in Suinin, Szechuan Province, West China, through the period 1938‐41. Under local conditions, the incidence of most cotton diseases was observed to be influenced chiefly by air humidity. No matter whether it attacks the seedlings, mature plants, or bolls, such a disease requires a humid condition preceding the occurrence of an epidemic. For sore shin disease, soil moisture and soil temperature, however, have a more profound influence. Cyrtosis, which is a disorder caused by leafhopper injury, responds to the climatic factors in a different way. During the period of rapid reproduction of the leafhopper, higher temperatures result in the earlier appearance of the disease, while heavy rainfalls reduce the intensity.

Modification of the environmental conditions by varying the time of sowing influences the incidence of diseases occurring in both the seedling and mature stages of the cotton plant. Among seedling diseases, anthracnose is further proved to be influenced chiefly by air humidity in its prevalence. Sore shin disease, on the other hand, requires a moist soil condition for its spread and development. In the mature plant, late sowing increases the intensity of cyrtosis but reduces that of bacterial blight and anthracnose.

Modification of several cultural practices was also tested. Nitrogenous fertilizers generally increase the incidence of most diseases. Denser stand and closer spacing bring about a heavier infection in stem and leaf diseases but not in boll diseases. A mixed cropping system appears to have no effect on the fungal and bacterial diseases but reduces the intensity of cyrtosis when the crop interplanted with cotton is not susceptible to the infestation of leafhopper.
Diseases of the gladiolus: I. Control of hard rot, due to Septoria gladioli Passer., by fungicidal treatment of the corms
Authors: Hawker Lilian E.
Published: February 2008

Losses from hard rot, measured by an arbitrary disease index, were reduced by treating the dehusked corms before planting with mercuric chloride (with or without the addition of 10% hydrochloric acid), mercurous chloride (calomel), three proprietary mercury compounds (Aretan, Uspulun and Ceresan) and one proprietary non‐mercury compound (Folosan). Calomel was the least effective. All the treatments were relatively less effective when corms with definite lesions were treated.

The weight of clean corms produced per old corm planted (weight index) was usually increased by all the fungicides tried, but calomel and Ceresan were less satisfactory than the others.

Mercuric chloride (3 hr. steep in a 0.1% solution) was not rendered more effective by the addition of hydrochloric acid nor by a preliminary dip in methylated spirits to facilitate wetting, while the addition of a proprietary wetting compound (Agral) was definitely harmful to the corms and usually less effective than mercuric chloride alone. Increase in time of steeping or concentration of mercuric chloride was not beneficial and was sometimes harmful. Reduction in time of steeping to 1 hr. gave promising results.

Treatment in November had some advantages over treatment in March.

All the mercury compounds tended to delay flowering, this being most marked in the presence of the wetting compound. Stunted foliage and poor quality flowers resulted from the use of Ceresan.
Studies of fluctuations in insect populations: XI. The interrelationship of the wheat blossom midges and their host plant
Authors: Barnes H. F. , Weil J. W.
Published: February 2008

The date of wheat blossom midge emergence in an insectary some distance away from the growing wheat can give as reliable an estimate of the forwardness of the crop as field observation of the date of ear emergence. The percentage grain attacked by the wheat blossom midges, which can be assessed by routine workers without any special experience of wheat, can give in early July a useful first estimate of the crop yield.
A further note on an unusual correlation between insect damage and crop harvested
Authors: Gadd C. H.
Published: February 2008

The unusual positive correlation between the yield of tea and damage caused by shot‐hole borer beetles persisted during the third year from the pruning of the bushes even though the beetle attack fell to a low level. The diminished insect injury during the third year enabled a significant yield response to nitrogenous manures to be demonstrated. Methods of measuring beetle infestation are discussed, and the view is put forward that factors favouring growth, as reflected by crop, also favour the multiplication of the beetle.
Investigation into the production of bacteriostatic substances by fungi VI. Examination of the larger Basidiomycetes
Authors: Wilkins W. H. , Harris G. C. M.
Published: February 2008

The present paper, the sixth of the series, gives the results of testing some 700 species of the larger Basidiomycetes for bacteriostatic properties. Initially, the ‘juice’ extracted from the sporophore was tested and this was followed in certain cases by a test of the metabolism solution produced by the fungus in culture. The results indicate that the larger Basidiomycetes are among the more promising fungus groups which produce antibiotics and that they compare favourably in this respect with the Aspergilli and the Penicillia. Of the 700 species tested approximately 70 are strongly and approximately 100 weakly positive against Staphylococcus aureus and/or Bacterium colt.
Dry rot of potato [Fusarium caeruleum (Lib.) Sacc.]. Investigation on the sources and time of infection
Authors: Small T.
Published: February 2008

Inoculation with soil samples proved that the fungus causing dry rot is frequently present in field soils in Cheshire and in soil adhering to imported seed tubers. The fungus was viable in soils having a wide range of pH values and in fields which had not grown potatoes for 5‐6 years. Other sources of infection include lofts, used sacks, seed boxes, diseased tubers, and knives used for cutting seed potatoes.

Bruised tubers stored in heavily contaminated boxes developed much dry rot; far less disease occurred in unbruised tubers. In boxes containing own‐saved seed, healthy tubers in contact with diseased ones remained sound. Bruised tubers in contact with, or contaminated by, diseased tubers contracted dry rot. Cutting seed with a contaminated knife increased the disease seven‐fold.

Inoculation of tubers attached to the parent plant showed that little or no infection occurred before lifting. In field trials severe dry rot developed in several varieties 6‐8 weeks after lifting.

The results are discussed in relation to seed treatment.
The ‘phloem necrosis’ virus disease of tea in Ceylon II. Field observations and effect on yield
Authors: Bond T. E. T.
Published: February 2008

After a brief discussion of the methods and accuracy of diagnosis of the ‘phloem necrosis’ disease in the field, the results of plot records taken over a number of years are presented. These are compared with the figures supplied from estates for the removal of non‐productive diseased bushes, which is undertaken as a routine measure of control and regeneration of affected fields. Taking all the evidence together a frequency of at least 25% diseased bushes is suggested for the aggregate acreage of tea above 6000 ft. At lower elevations no reliable estimate is possible.

Despite the pronounced effect on individual bushes there appears to be no general tendency for the yield of affected estates to decline. Two estates, believed to be representative, are dealt with in which a decline in yield occurred from 1929 to 1930, followed by a recovery some 4 or 5 years later. The fields judged to be most heavily affected in each of the two properties, respectively, show a decline in yield relative to the estate as a whole, not exceeding 19 1b. made tea per acre per annum, which is only 33% of the mean yield during the last 10 years. The great variability in individual bush yields is stressed, and the conclusion is drawn that the elimination of unproductive bushes and their replacement by supplies of a type which, so far, has remained unaffected (although possibly ‘carrying’ the virus) will more than counteract the effect of the continued and gradual deterioration of the necrotic bushes remaining.

The distribution of diseased bushes in the field is irregular, and records from observation plots have mostly given positive results on examination by Cochran's geometric series ‘aggregation’ test and the X2 test for ‘neighbour infection’. The rate of spread of the disease in the different areas is highly variable, and doubling of the incidence of infection may occur in periods ranging from 3 1/2 to less than 1 year. Two ‘rogueing’ experiments are described, the results of which lend further emphasis to the importance of bush‐to‐bush spread. The course of the disease in these experiments has been expressed by means of the Verhulst‐Pearl logistic curve, whence it appears that complete rogueing of all ‘necrotic’ and ‘suspected’ bushes at 6‐monthly intervals has reduced the rate of spread to about one‐third of the value for the unrogued plots.
The transmission of the virus of the ‘woodiness’ disease of passion fruit (Passiflora edulis) by single leaf grafts
Authors: Nattrass R. M.
Published: February 2008

A method is described of transmitting the virus of the ‘woodiness’ disease of passion fruit by means of single leaf grafts. The grafts can be made from one species to another in the genera Passiflora and Tacsonia and from these genera to species of Adenia and vice versa.
Influence of earthworms on larval emergence in the potato‐root eelworm, Heterodera rostochiensis Wollenweber
Authors: Ellenby C.
Published: February 2008

Hatching experiments were carried out with potato‐root eelworm cysts (a) from plant pots containing different numbers of earthworms, and (b) from worm casts. Cysts from these sources differed from controls in the following ways: (1) more larvae emerged, per cyst; (2) the larvae emerged sooner; (3) more cysts produced larvae; (4) the number of emerging larvae, per cyst, increased with the number of earthworms.

Examination of the contents of cysts isolated from worm casts showed that, compared with controls, 145% more eggs hatched; it also indicated some of the limitations of the ‘per‐cyst’ basis of expressing results.
The behaviour of mercury compounds in soil*
Authors: Booer J. R.
Published: February 2008

The uses of inorganic compounds of mercury for the control of plant pests is reviewed, and a summary of the relevant chemical and physical properties of the compounds concerned is given. On chemical evidence a working hypothesis is propounded showing that all compounds may be expected to decompose into metallic mercury.

A pot technique is described by means of which a correlation can be obtained between the effective mercury content of a given soil sample and the rate of growth of wheat seedlings. The mathematical treatment of the results is described, and the validity of the pot technique is verified by statistical analysis of results. Using the pot technique it is shown that volatilization losses are insignificant but that mercury is slowly rendered ineffective by the formation of mercuric sulphide. The effect of sulphur‐reducing bacteria is considered and the influence of Vibrio desulpkuricans on mercury is studied in detail.

Experimental evidence obtained by the pot technique is produced to show that mercurous chloride slowly decomposes in the soil giving mercury and mercuric chloride, mercuric chloride rapidly decomposes into mercury and mercurous chloride, and other inorganic compounds decompose directly into mercury. The working hypothesis is substantiated in all major aspects.

The uses and properties of the organo‐mercury compounds are then discussed. Type compounds selected are ethyl mercury phosphate, phenyl mercury acetate and methoxyethyl mercury acetate.

Using the pot technique it is shown that the formation of organo‐mercury clays takes place and that these clays decompose giving metallic mercury. A mechanism is suggested.
The parasitism of Striga hermonthica Benth. on Sorghum spp. under irrigation: I. Preliminary results and the effect of heavy and light irrigation on Striga attack
Authors: Andrews F. W.
Published: February 2008

Investigations were carried out at the Gezira Research Farm in the Anglo‐Egyptian Sudan. The greater majority of the seeds of Striga hermonthica can only be germinated by excretions from roots of certain plants not all of which can act as hosts for this parasite. Unless it becomes attached to a host plant, the Striga seedling dies. The growing of those plants whose roots can stimulate the germination of Striga seed but cannot be parasitized by it, may be a means of ridding infested land of this parasite. Green ovaries picked from flowering plants produce viable seeds if left to dry. Sorghum is sown in the field during the rainy season, viz. June to October: the earlier the sowing date within this period the greater is the Striga attack. In the field Striga seeds are distributed in the soil to a depth of at least 15 in. When Striga seeds are evenly distributed through the soil, the number of Striga seedlings attached to a sorghum root is proportional to the root's development. Size of sorghum seed has no effect on the root size of a sorghum plant and consequently no effect on the degree of parasitism. The effect of severe Striga attack on the sorghum plant is to produce a reduction of about 60% in leaf and root weight. No reduction of Striga attack is obtained when various micro‐elements are coated on sorghum seeds before sowing. Field and laboratory experiments show that light irrigation of the sorghum crop during the normal sowing period increases the Striga attack and heavy irrigation decreases it. This result was not obtained in laboratory experiments when sorghum was sown out of season. Striga attack is lessened when conditions favouring growth of the sorghum crop are improved.
The influence of date of lifting and method of storing on loss of onion bulbs harvested in 1943
Authors: Wallace E. R. , Hickman C. J.
Published: February 2008

Date of lifting experiments with four varieties of onion at two centres are examined in relation to the incidence of losses in store, and at one centre the effects of indoor and outdoor storage are compared. Losses due to Botrytis, eelworm infection and sprouting are treated separately, and the practical significance of the results is discussed.
Black scurf and stem canker of potato (Corticium Solani Bourd. & Galz.): Further field studies on the use of clean and contaminated seed potatoes and on the contamination of crop tubers
Authors: A.R.C.S. T. Small, Ph.D.,
Published: February 2008

Black scurf and stem canker of the potato were investigated in field trials in contaminated soil at Warburton, Cheshire, to determine the effect of planting clean and contaminated seed (vars. Arran Banner and Majestic) on crop yield and on the contamination of the crop tubers.

Black‐scurf contamination was prevalent on crops grown from clean seed and was not significantly different from that occurring on plots planted with contaminated seed. It was severe on early‐dug tubers, but was more severe on late‐dug tubers. Produce grown with and without stable manure was heavily contaminated.

Contaminated seed caused a check to tuber formation and an appreciable increase in stem canker and in the number of primary shoots killed. Nevertheless, the yields from the manured, contaminated seed plots were satisfactory and were not lower than those from the clean‐seed plots. There was no relation between the yield and the amount of black scurf on the produce.

The results of a trial made in a field which had been in grass for at least 43 years, suggested that the soil contained little, if any, Corticium Solani. Heavy contamination occurred on tubers grown under relatively dry soil conditions.

In all the trials misses and wilted shoots caused by Corticium were rare and there was no premature yellowing or death of the haulms on the clean or contaminated seed plots.

The evidence obtained in the four seasons from 1941 to 1944 indicates that in this country satisfactory yields of early maincrop and maincrop varieties may be obtained despite the prevalence of C. Solani in the soil and on the seed, provided the soil and cultural conditions are reasonably good.
Experiments on the control of white rot (Sclerotium cepivorum Berk.) in onions
Authors: B.Sc. J. R. Booer, Ph.D.,
Published: February 2008

Experiments‐made during 1943 and 1944 on the use of mercurous chloride (calomel) for the control of Sclerotium cepivorum in spring‐sown onions are described. The application of 4% calomel dust to the seed drill at sowing time gave better results than seed treatment. 1 lb. of dust per 25 yd. of seed drill gave good disease control in bulb onions, and 1 lb./so yd. may suffice for salad onions.

The relation between disease control and the effective mercury content of the treated soil is discussed.
Studies in the dynamics of disinfection: IV. The reaction between phenol and Bact. coli: the true shape of the probit‐log survival‐time curve
Authors: R. C. Jordan, Ph.D.  , S. E. Jacobs, Ph.D.
Published: February 2008

The results of numerous experiments on the disinfection of standard cultures of Bact. coli with phenol, under rigidly controlled conditions, have been combined and used to elucidate the true shape of the probit‐log survival‐time curve. It is concluded that the true shape is that of a very asymmetrical sigmoid curve. When the disinfection is slow, the curve approximates closely to a bilinear form with one line of small and one of large slope up to high probit values, but in faster disinfections the curvature of the steeper line is evident, especially above the probit value of 8.
The incidence and distribution of some diseases of the adult honeybee (Apis mellifera L.) in England and Wales
Authors: Butler C. G.
Published: February 2008

Although epidemics of bee disease have been repoited in Europe for hundreds of years it was not until recent times that detailed notes on the incidence and distribution of one of these epidemics, the so‐called ‘Isle of Wight disease’ epidemic, were made.

Since 1918 four complaints of the adult honeybee, acarine disease, Nosema disease, Amoeba disease and bee paralysis, have been recognized in this country.

Surveys in England and Wales to determine the incidence and distribution of acarine disease, Nosema disease and Amoeba disease were carried out during the winters of 1941‐2 and 1943‐4. These surveys showed that none of these diseases is clearly confined to any definite areas of England and Wales. Acarine disease is, however, apparently more abundant in the west and south‐west; and Nosema disease appears to be most prevalent in Buckinghamshire, Hertfordshire, Middlesex and Surrey, and also has other areas of heavy infection in Leicestershire and Cumberland, Lancashire and Yorkshire.

Sufficient cases of Amoeba disease have not yet been recorded for it to be possible to conclude that any one area is more heavily infected than another. It is estimated that approximately one out of every five or six of the colonies of bees in England and Wales is suffering from acarine disease. Less than 1% are likely to be suffering from Nosema or Amoeba disease. Bee paralysis is both common and widespread, but probably does little serious harm.
A comparative study of onion varieties in relation to bolting and yield when grown from sets
Authors: Holdsworth M.
Published: February 2008

Two trials are described, each of twenty‐five varieties tested during two seasons and the intervening winter storage period. Sets were produced from seed in the‐first season and planted to produce mature bulbs in the second. In the second seasons of both trials, the effects of time of planting of sets were also investigated as part of a factorial experiment. In the later trial the effects of set size were also tested. Data are presented of varietal differences in bolting, yield, earliness and of behaviour of the sets in storage. The effects of set size and of late planting on these characteristics are also recorded. Some practical recommendations are made: thus, among those tested, varieties were found which bolted little and gave high yields when grown from sets, but it is emphasized that names of varieties as listed in seedmen's catalogues may not be reliable. Efforts are being made to maintain and improve by selection the most satisfactory of these strains. Late planting of sets is not recommended, for, although bolting was effectively controlled by this means, the yields were much reduced. Plants grown from large sets tended to bolt more than those from small, as has been shown by earlier workers; while on the contrary the yields from large and small sets were on the average alike. Comparing different varieties, the highest gross yields of all were produced from the large sets of non‐bolting varieties; but for highest yields of bulbs free from flower stalks small sets should be used and this is advisable for all varieties. During storage the large sets lost less percentage weight than the small but they sprouted much more, and this is considered the more serious defect. The storage data demonstrate an additional disadvantage of late planting, for this involves longer storage and both sprouting and weight losses increase rapidly during late spring.
The prevention of seed‐borne diseases of flax III. The dusting, short wet and fixation methods of seed disinfection in relation to storage of the seed
Authors: Colhoun John
Published: February 2008

Flax seed containing up to 10% of moisture was disinfected with a proprietary dry fungicide containing tetramethylthiuram disulphide (Nomersan) at the rate of 12 oz./cwt. of seed, and stored for periods of up to 18 months, without its germination being impaired.

Experiments were made with samples of seed the moisture content of which, before treatment, varied within the range of 5‐8‐13‐2% and which were kept in a commercial store after disinfection. Treatments were carried out with an 8% solution of a soluble organo‐mercurial (Ceresan U. 564) at the rates of 0‐67 and 0‐9 gal./cwt. applied by the short wet method, and with an organo‐mercurial powder (Ceresan UT. 1875 A) at the rate of 12 oz./cwt. applied by the fixation method using 0‐9 gal. of separated milk per cwt. The results obtained show that treatment by either method has the effect of lowering the percentage of viable seeds during subsequent storage and that the higher the moisture content of the seed before treatment the earlier this effect becomes apparent. It is suggested that seed to be treated by the short wet method on a commercial scale should be dried to contain about 5% of moisture, that not more than 0‐67 gal./cwt. of liquid be applied and that the seed should not be stored for longer than 3 months after treatment. Following upon these suggestions, 10‐ton lots of seed were treated commercially by the short wet method using a Kontramix machine and no ill effects on the crop were observed.
Chemical changes in beech litter due to infection by Marasmius peronatus (Bolt.) Fr
Authors: Harris G. C. M.
Published: February 2008

The chemical effect of Marasmius peronatus on beech litter is described, with particular reference to the ecological relation between fungus and substrate. Beech leaves, some infected, and others uninfected by this fungus, were analysed and the results compared.

Analysis shows that a vital process involving loss of carbon is at work, and that the fungus decomposes lignin, converting it into soluble products by the action of exoenzymes. It is suggested that by this process it is contributing to conditions favourable for beech regeneration.

The fact that this fungus can more successfully colonize hardwood litter (e.g. beech) than other types of substrate, is explained by consideration of its physiology.
The use of cobalt salts as indicators of humidity and moisture
Authors: Solomon M. E.
Published: February 2008

To meet the need for a simple method of measuring humidity in small spaces, a new method of using paper impregnated with cobaltous salts has been developed. Cobalt chloride paper is blue at low and pale red at high humidities, with a series of lilac colours between. There is a close correspondence between colour and relative humidity, although the colour is influenced slightly by temperature. It is shown that the colour is determined chiefly by the relative quantities of cobalt chloride and water in the paper. The paper is impregnated by dipping in a solution of CoCl2.6H2,O. The time required for a piece of CoCl2, paper to reach equilibrium with the atmosphere depends chiefly on humidity and temperature; up to 2 hr. exposure is allowed. Colour standards for the matching of test papers are prepared by exposing papers over constant humidity solutions and then sealing them up in liquid paraffin between opal and clear glass. It is possible to measure humidities from 40 to 70% R.H. to the nearest 2% R.H., and above this range to the nearest 5%, except for low humidities at low temperatures.

Various colloid substrates other than paper, including mercerized cotton, cause the blue colour to persist at somewhat higher humidities; possible uses of this are suggested. Certain salts, such as potassium thiocyanate and sodium thiosulphate, produce a similar, but much greater effect, and also produce stronger colours. The method can thus be adapted for accurate use at higher humidities. Alternatively, the addition of zinc chloride or certain other salts adapts the method for use at low humidities.

Papers more suitable for use at high humidities have been prepared with cobalt thiocyanate solution. A further improvement is the use of pure cotton tissue paper. Methods of impregnating the paper are described, also the above‐mentioned method of preparing standards. Approximate corrections for temperature are given. The influence of temperature and humidity on the time taken to reach colour equilibrium is described. An exposure of 30 min. is sufficient except at very high humidities, where up to 2 hr. may be necessary. Corrections are given for use when exposures other than 30 min. are allowed. The standards cover humidities above 50% R.H. at intervals of 5% R‐H.; teat papers can be estimated to about the nearest 1% R.H. But under unfavourable conditions, errors may amount to as much as ± 5% R.H., unless the corrections are used.
The effect of sulphanilamide and other bacteriostatic drugs on the growth of moulds
Authors: Snow D. , Watts P. S.
Published: February 2008

Some fifty isolates of moulds, mainly Aspergillus spp. and Penicillium spp., were tested for their reaction to sulphanilamide, sulphonamide E.O.S., sulphapyridine, sulphamezathine, sulphaguanidine, propamidine and phenamidine.

The moulds showed a high degree of specificity in their reaction to the drug concentrations: Aspergillus spp. were more susceptible to the drugs than were Penicillium spp. Most of the species included in the Aspergillus glaucus group were inhibited by concentrations of 1/8000 (125 p.p.m.) of sulphanilamide, sulphonamide E.O.S. or propamidine. Similar concentrations of sulphapyridine, sulphamezathine, sulphaguanidine and phenamidine had only a slight inhibitory effect on mould development. A. versicolor and A. sydowi showed very similar reactions to the drug concentrations, which is in keeping with their relationship on morphological grounds. In general, Penicillium spp. were not affected by small concentrations (1/2000 or less) of the drugs and were only partially inhibited by higher concentrations (up to 1/125) of sulphonamide E.O.S. Propamidine was more effective against certain Penicillium spp. though not all were susceptible. Some of the moulds were slightly stimulated by small concentrations of the drugs. No difference in the fungistatic effect of sulphonamide E.O.S. was apparent at different pH levels between 4 and 8.

Different strains of the same species sometimes showed different degrees of resistance or susceptibility to the drug concentrations. This was particularly noted for strains of Aspergillus ruber, two of which showed marked resistance to propamidine when incorporated in beer‐wort agar while four other strains of the same species were susceptible to the drug when incorporated in this medium. The two resistant strains, however, were susceptible to propamidine when incorporated in the synthetic Czapek‐Dox medium.

4 p.p.m. of p‐aminobenzoic acid was found to annul the fungistatic action of sulphonamide E.O.S. at concentrations of 250 p.p.m. The addition of p‐aminobenzoic acid to a synthetic medium incorporating propamidine did not annul the inhibitory action of this drug.
Certain aspects of resistance of plum trees to bacterial canker: Part II. On the nature of the bacterial invasion of Prunus sp. by Pseudomonas mors‐prunorutn Wormald
Authors: Erikson Dagnt
Published: February 2008

A detailed histological study was made of the necrotic areas induced in the stem of a resistant and a susceptible variety of plum as the result of artificial inoculations of Ps. mors‐prunorum Wormald. The pathogen was found to penetrate the tissues intercellularly, causing plasmolysis of cell contents, followed by disintegration of cell walls, and gradual invasion of the bacteria. The seasonal progress of infection was followed, the maximum cankers caused by winter inoculations in the susceptible host appearing in spring. Limitation of necrosis occurs in summer, generally accompanied by the production of new tissue composed of xylem elements. Viable bacteria were isolated in autumn from those cankers in which the area of necrosis had extended into the wood cylinder beyond the limiting periderm. The difference in the nature of the injury to the tissues of the resistant trees is quantitative rather than qualitative. The significance of the apparently more efficient host mechanism of periderm production in this variety is considered. Lesions similar in histological aspect were obtained as the result of the injection of cell‐free filtrates of cultures of the causal organism.
Certain aspects of resistance of plum trees to bacterial canker: Part III. The action of cell‐free filtrates of Pseudomonas mors‐prunorum Wormald and related phyto‐pathogenic bacteria on plum trees
Authors: Erikson Dagny , Montgomery H. B. S.
Published: February 2008

A technique for introducing 2‐3 c.c. liquid into the bark of plum trees is described. Parallel injections with dyestuff throughout the spring failed to afford a reliable index of the invasive powers of the various test fluids introduced in this manner.

A susceptible variety of plum (Giant Prune) showed greater injury by cell‐free filtrates of Ps. morsprunorum than did a resistant variety (Warwickshire Drooper), which showed negligible injury. The greatest injuries were caused by filtrates of cultures 5 weeks old, and over, especially when concentrated.

Of other bacteria tested Ps. prunicola, Ps. syringae strains, Syringa 3, Ap. No. 1, Ap. No. 2, and Bact. pruni, yielded damaging filtrates, whereas Ps. syringae, strains pear 6 and 7, Ps. tabaci, Ps. fluorescens, Ps. marginalis, Ps. phaseolicola, Ps. tumefaciens, Ps. pisi and Ps. cerasi failed to do so.

Some evidence is advanced for the view that the deleterious activity of Ps. mors‐prunorum may be due in part to an endotoxin of protein nature obtainable from the dried bacterial cells by acetic acid extraction.
Evaluation of materials for louse control
Authors: Aschner M. , Mager J.
Published: February 2008

A simple procedure for evaluation of the effectiveness of different louse‐killing substances is described. Factors likely to influence the results are discussed, and it is shown to what extent differences in age, mode of application and interaction of carriers are able to influence the insecticidal effect. A number of substances was tested by the methods described and their potency against lice determined by comparison of the minimum time of exposure necessary to give 100% kill.
The occurrence of Anguillulina dipsaci (Kühn.) on weed hosts, including new host records in fields of oats affected by ‘tulip‐root’
Authors: D.I.C. L. N. Staniland, A.R.C.S.,
Published: February 2008

The examination of eighteen weeds in three fields of oats affected with ‘tulip‐root’ is described. Cleavers, common chickweed, mouse‐ear chickweed and sandwort, were found to be hosts of A. dipsaci, the last two weeds being new host records. Successful transferences of A. dipsaci have been made from chickweed to oats and from oats back to chickweed. Transference of A. dipsaci has also been made from cleavers and sandwort to oats.
Some causes of chlorosis and necrosis of sugar‐beet foliage
Authors: Hale J. B. , Watson M. A. , Hull R.
Published: February 2008

The symptoms and characteristics of two virus and one fungus disease and four nutritional disorders of sugar beet which cause chlorosis and necrosis of the foliage are described. The causes of the diseases and methods of distinguishing between them have been investigated by analytical, pathological and field experimental methods.

Experiments in which diagnosis was confirmed by serological and spectrochemical methods show that the two often easily confused diseases, sugar‐beet yellows virus and magnesium deficiency, can be visually distinguished.

Sugar‐beet yellows virus reduces the potassium, but slightly increases the magnesium content of the leaves.

Magnesium deficiency symptoms are associated with a low magnesium content of the foliage, but may be induced by salt applications without greatly affecting the magnesium analysis.

‘Potash’ deficiency symptoms are often, but not necessarily, associated with a low potassium analysis and may actually be caused solely by a deficiency of sodium. In the field, symptoms are induced by sulphate of ammonia and phosphate applications and may be prevented in some cases by the application of either salt or muriate of potash, in others by salt only. Some interchangeability of the functions of potassium and sodium in the plant is suggested.

Manganese deficiency symptoms are associated with a low manganese content of the leaves, which can be readily increased by spraying or injection with manganese sulphate solution, but a high concentration of manganese in the foliage, such as sometimes occurs naturally on acid soils, has a toxic effect.