ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05564.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1The content of boron in the tissues of plants, grown in solutions of known concentration, has been ascertained in‐Vicia FabaandGossypium herbaceum.2The distribution of boron is regular and definite. The highest percentage, per unit of dry weight, is in the leaves, increasing regularly with the age of the leaf. The petioles and the stem apex are approximately equal in percentage content, and have both approximately double the stem concentration. The roots have much the lowest concentration, only 0–07 of that in the stem.3This distribution of boron does not appear to be entirely due to passive transportation in the transpiration current.4Boron is also present in seed grown on ordinary soil, but is confined to the cotyledons, the percentage content, inVicia,being 50 per cent, above that of the plant stems.5The amounts of boron absorbed are extremely small, though there is some storage in the tissues, and they are not directly dependent on the concentration supplied. The amounts are too small to allow of boron being regarded as a nutrient in the ordinary sense. Its importance is more probably that of an activator or regulator of metabolic proces

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05565.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1The progress of the mycelium of two forms ofUstilago Avenaewithin resistant and susceptible hosts has been described and attention drawn to differences between them.2Form LxonAvena strigosawas found to persist longer than form L11on the variety Potato, althouch both of these Oats failed to produce infected panicles with these smuts.3The response of the resistant variety, Markton, to attack by six collections ofUstilago AvenaeandU. Kolleriwas found to vary considerably. Forms C1and L11failed to penetrate, while form C2entered easily and the mycelium persisted for some time.4The types of sheathing structures around the penetrating tubes have been found in Markton inoculated with forms C1and C4. Their reaction to microchemical tests was investigated.5A hypersensitive reaction resulting in the formation of necrotic areas around the parasite hyphae has been found in Markton invaded by forms C4,L1and L2.6The varieties studied have been classified according to the grade of resistance offered to particular forms of smut. Five grades have been described.7In oats, resistance to smut is expressed in at least three ways, (i) a reaction of the epidermal cell wall which prevents penetration, (ii) necrosis of host cells, and (iii) a retarding effect on the growth of mycelium within the host.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05566.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1The type of seedling disease caused byPyihiumattack on swede seedlings is closely correlated with the temperature under which the plants are raised. Low temperature conditions favour the occurrence of the pre‐emergence phase of disease and produce no damping‐off. Medium temperatures also produce no damping‐off and result in a big reduction in the pre‐emergence phase. High temperatures show the pre‐emergence phase at a minimum but encourage damping‐off.2The disease in general is likely to be best evaded by germinating the seed under conditions of high temperature until the emergence of the seedlings. The temperature should then be lowered in order to encourage the production of sturdy seedlings not likely to be subject to damping‐off.3In these experiments the disinfection of the seed with an organic mercury compound prior to sowing did not secure any control of the disease.4The two varieties of swede used–Tipperary and Ideal–proved to be equally susceptib

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05567.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1Forty‐six collections ofPuccinia triticinahave been tested for the determination of physiologic forms. The majority of these were studied as single‐spore cultures. With the exception of three from Portugal the collections were made in various parts of England and Wales.2Ten new physiologic forms ofP. triticina(Forms 66–75 inclusive) are described for the first time. Forms 66–73 were obtained from collections in Britain, and Forms 74 and 75 from Portugal.3A mutation in pathogenicity is here recorded forP. triticinafor the first time, in the origin in the greenhouse of a variant of Form 10 from a culture of Form 66.4An apparently inherent instability in the behaviour of Form 66, as exhibited by an abrupt change in reaction on the variety Hussar from a resistant to a susceptible type, is discussed. This change cannot satisfactorily be correlated with environmental conditions or mixture of cultures. Such instability was not observed in cultures of any other physiologic form encountered in this investigation.5Changes in environmental conditions affected the reactions of some of the differential varieties to certain physiologic forms. For example:(a). Abnormal production of a type“x”reaction on certain of the differential varietieswasfound to be correlated in some forms with excessively high temperatures during incubation.Decrease,in light intensity, combined with decrease in temperature, was found to be responsible for the production of an abnormal type“”reaction by other forms.(b). Increase in resistance in normally susceptible reactions was found in many forms to be associated with low light intensity and low temperature. Eesults, however, low light intensity seemed in general to be the more important factor in bringing about this in susceptibility.(c). Increase insusceptibility in the normally resistantreactions of certain varieties to some physiologic forms wasfound to be correlatedwith increased temperature and light intensity. Increase towards susceptibility of normally resistant reactions was not usually of a very profound type. Resistant reactions were found on the whole to be less sensitive to environmental fluctuations than susceptible reactions.6Infection of certain varieties,e.g.Malakof, Webster and Democrat, byErysiphe graminisinduced the development of pustules of a susceptible type by some physiologic forms ofPuceinia triticinato which these varieties were normally resistant.7Form 66 appears to be the commonest and the most widely distributed form in Britain. This form was isolated fourteen times, Form 15 seven times, Form 67 five times, Form 68 three times, Form 70 twice, and Forms 10, 69, 71, 72 and 73 were each isolated once only.8Some variation in the annual distribution of physiologic forms was observed in the collections made near Cambridge, Newton Abbot, and Cardiff.9The fact that no previously describedforms,except Forms 15 and 10, have been encountered is discussed. The apparent absence of an aecidial host forP. trUidnain this country presents a problem as to the origin of the forms found here. It is suggested that mutation may account for the occurrence of some of these forms in view of the origin during the course of this investigation of a variant of Form 10 from a culture of Form 66, p

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05568.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1An organism has been isolated from fasciated sweet peas and found to reproduce the disease on inoculation into young seedlings.2Bacterial strains culturally similar to the sweet‐pea organism have been isolated from “leafy galls” on chrysanthemums, carnations andSchizanthus,and from “cauliflower” of strawberry. On inoculation all these strains produced marked fasciation in sweet‐pea seedlings, and also produced fasciation of sweet‐pea seedlings growing in inoculated sand cultures.3A preliminary description of the organism has been gi

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05569.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARYMunduleccbark from Moa district is as toxic to insects as Ammi Derris root containing 6.4 per cent. rotenone. That obtained from two other dietricts is only about half as toxic. The former tree may be a variety of theordinary M. suberosa.The powder dusted on cockroaches and flies, although having a much smaller initial effect than pyrethrum and not producing any rapid knock‐down, yet causes death in about half the time; Derris has the same action. The same remarks apply to paraffin extracts of these substances.Muduleaseeds are about three‐quarters as toxic as the bark, but are unlikely to be of any commercial value on account of their scarcity. Experiments are in progress in the cultivation ofM.suberosa from Moaseed,and it is hoped that the bark will h d a commercial out

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05570.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1A study has been made ofthe life history ofBrevicoryne brassicael.in the market‐garden areas of Bedfordshire, Cambridgeshire and Huntingdonshire from November 1933 to October 1935.2There was a variation in the behaviour of this pest in the two years. In 1934 the aphis over‐wintered only as eggs on cultivated cruciferous crops (and particularly Brussels sprouts), whereas observations strongly suggest that in 1935 it over‐wintered both as viviparous females and eggs. The hatching of the eggs was much later in 1934 than in 1935, but the first winged forms were produced at about the same date.3Predators and parasites were fairly abundant but not sufficiently so as to prevent serious damage.4It is suggested that control measures should aim at preventing the aphides from passing from old plants to newly planted ones. Nicotine sprays or nicotine dusts are suitable for this purpose. The pest is difficult to control on ordinary field

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05571.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1A brief review of the literature dealing with the history ofLepto‐byrsa rhododendriHorvath as a pest is given. The original home and subsequent dispersal are discussed.2The distribution of the insect in Great Britain, as known to the author, is given.3The bionomics of the insect are dealt with.4Detailed descriptions of the structure of the egg and its position in the leaf tissue are made, together with a short description of the egg gall and an account of the hatching process.5The external appearance of each of the four instars is described in detail. Comments upon the descriptions of the immature stages of previous workers are given.6The list of references contains all the more important papers which deal with the insect mainly from general economic and bionomic aspect

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05572.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY

摘要:

SUMMARY1The histology of the larval gut ofLyctusis described: owing to the absence of salivary glands and caeca, the digestive juices must be secreted by the midgut with doubtful contribution from the hindgut.2The mycetomes contain organisms which are apparently not symbiotic in relation to digestion.3The skeletal substance of wood passes through the larval gut unaltered, nourishment being derived from the cell contents.4A substance, soluble in water at 60oC, is necessary in oak sapwood for normal larval development.5Larvae are unable to develop in wood from which starch is absent.6Larvae living in wood containing relatively little starch may take two years to complete their development, instead of the normal one year.7Enzymes capable of hydrolysing starch, maltose, sucrose, lactose and protein were detected in tissue suspensions of the gut and its contents.8By feeding larvae on artificial diets it has been shown that starch, sugars and protein are necessary constituents of the larval food. Furthermore, larvae have been reared to the imaginal stage on a substrate which contains no wood.9The ability of the female beetles to determine the suitability of wood for larval development is demonstrated and the importance of the so‐called “tasting” marks discussed.10An account is given of the occurrence of starch in timber and the difficulties involved in its estimation and removal from the

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1936.tb05573.x

出版商:Blackwell Publishing Ltd    

年代:1936

数据来源: WILEY