ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04311.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYIt has been shown that the symptoms induced by aucuba or yellow mosaic of tomato in certain other members of the Solanaceae (notablyN. glutinosaandD. stramonium)differ markedly from those in tomato. Neither formation of intracellular inclusions nor systemic infection occurs in these plants. InN. glutinosa, the symptoms appear only on the rubbed portion of the leaves and little multiplication of the virus takes place. InD. stramonium, although no mosaic symptoms appear on the host, the virus travels through the tissues and can infect susceptible grafts. Holmes' work on the use ofN. glutinosaas a ready means of demonstrating the presence of the virus agent in a juice has been confirmed and amplified.It has also been shown that it is possible to inject the intercellular spaces of the leaf ofN. glutinosawith virus juice and that no infection occurs unless cells have been ruptured.

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04312.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYThe results of the second series of bulb manipulation experiments have confirmed previous results as to the infectious nature of the agent or virus which brings about “breaking” in tulips.“Breaking” can be transmitted by grafting and plugging bulbs with tissue from “broken” bulbs, but injections with filtered sap expressed from “broken” bulbs have given negative results.All attempts to induce parrotting by grafting have been unsuccessful.There appears to be no correlation between the type of “break” of the transmitter and the type of “break” induced.Transmitters vary in potency on different hosts, and different hosts vary in degree of susceptibility towards the same transmitter.Tulipaspecies have been observed to “break” naturally under garden conditions, and “breaking” has also been induced in the same by grafting with “broken” garden varieties.The bi‐colour variety Keizerskroon has been proved not to be an infectious “break,” but a true bi‐colour; “breaking,” however, can be induced in the red areas of the perianth by grafting with other “broken” varieties.The effect of the virus on the colour plastids and the distribution of the anthocyanin sap pigment is discussed.It is suggested that a knowledge of the translocation of the virus in the bulb is of practical importance to bulb growers.The experiments indicate the importance of aphis control by means of spraying in the growing season and the advantage to be gained by lifting and storage under aphis‐free conditions in the autumn.In conclusion, my thanks are due to Sir D. Hall for information with respect to the initial “breaking” of Zomerschoon and the “breaks” inTulipaspecies, and to the laboratory assistant E. F. Emarton for taking the photographs for the plates and for his valuable

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04313.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYA disease of the bark of young leader shoots ofarabicacoffee occurs in the Usambara Mountains of Tanganyika Territory. The disease may be important when “stumping” is practised in the regeneration of old plantations. A brown sunken lesion, formed of dead extra‐cambial tissues, usually gradually extends and rings the shoots; after a period varying from a few days to several months after complete ringing the foliage above wilts and dies. A leaf spot is also due to the same cause.The fungus,Fusarium lateritiumNees var.longumWr., among several isolated from lesions, has been shown to be capable of reproducing the disease by pure culture inoculation. A proportion of the experimental inoculations resulted in the ringing and death of the shoots; many of the lesions, however, after a time ceased to advance and became callused at the margin. Similar recoveries from the disease were observed in the field.Field observations and experiments demonstrated that a common mode of entry of the fungus into the stem tissues was through freshly exposed leaf scars, and occasionally from a leaf‐spot down the petiole of a leaf. Many shoots also in the field became diseased as the result of the fungus passing to them through the tissues of a stump from the base of a dead shoot.Coffea arabicaalone, of a number of coffee species tested, was susceptible to any extent to this disease.Excision of the affected bark of a stump was effective in checking the spread of the fungus through the stump. The operation, however, is not considered to offer a practicable means of control in the pla

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04314.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1Tomato‐leaf mould may be held in check by attention to atmospheric temperature and humidity.2Varieties resistant to this disease are known, but they are not suitable for commercial work. Attempts are being made to breed varieties combining resistance with crop excellence.3The disease has been controlled by spraying with salicylanilide paste, sold under the name of “Shirlan Paste,” combined with a sul‐phonated oil sold as Agral I.4The above spray mixture has also proved effective against certain other d

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04315.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYDiseases of potato tubers, lettuces and seeds ofMedicago lupulinacaused by bacteria belonging to the green‐fluorescent group are described and the identity of the pathogens is discussed. The cultural characters of thirty‐six strains isolated from various plant lesions are given and compared with those of thirty‐two known species of the green‐fluorescent group, and a discussion on cultural variations

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04316.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARYThe changes in botanical composition of closely cut turf (such as that of lawns) which result from the periodic applications of heavy dressings of ammonium sulphate have been followed at five centres during a period of 3 years. These dressings were applied at the rate of 3 lb./1000 sq. ft. (1–2 cwt. per acre) every 2 weeks during the spring and summer months. The applications were “watered in” to avoid injury from a solution of high concentration.A method of botanical analysis by means of randomly selected quadrats was employed. The changes in botanical composition are expressed as changes in the area covered by each individual species. The data have been treated statistically where possible.As a result of the treatment the areas covered by the weeds (i.e.all species other than the Gramineae) were greatly diminished. Some species such asTrifolium repensandAchillea Millefoliumwere more susceptible than others. As an illustration of the order of magnitude of this effect it was found at one centre that there was a decrease in “total weeds” (i.e.the sum of the areas covered by individual species) from 17‐0 to 3–7 per cent., between April and September, of the total area examined. On the control plots the changes were slight.A reduction in the “total weeds” was associated with an increase in the area covered by the grasses, the dominant species in each case showing the greatest expansion.In addition to trials with ammonium sulphate, two experiments were carried out, one with ferrous ammonium sulphate and the other with an equivalent mixture of ferrous and ammonium sulphates. It was found that both these treatments produced greater reductions than ammonium sulphate alone. In one case ferrous ammonium sulphate at 10 lb./1000 ft.2reduced the “weed area” from 12‐5 to 0–3 per cent., while ammonium sulphate applied at an equivalent nitrogen rate, reduced the area from 10‐6 to 5‐0 per cent, during the same period.The changes of soil reaction show that the view that soil acidity is a pre‐requisite for weed diminution by ammonium sulphate is untenable.It is suggested that the effect of the ammonium sulphate is due to a differential action of the ammonium ions, which are toxic to the majority of the weeds while increasing the growth of the grasses.The writer wishes to thank the Secretaries of the Bishop's Stortford, Royal Worlington, Gog and Magog and Stoke Poges Golf Clubs for their help, and also to express his gratitude to Sir Frederick Keeble and Mr Page for their suggestions. Finally, he is indebted to Mr Marmoy of Jealott's Hill for

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04317.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1An explanation is provided of the causation byL. italicumof delayed establishment inF. pratensis, Phleum pratenseandPoa trivialis.2The presence of seeds or seedlings ofL. italicumis not detrimental to the germination of the other species under conditions thought likely to occur in the field, except in the case ofPoa trivialis, the seeds of which grass are extremely susceptible to the presence of carbon dioxide and hence to root‐respiration.3Under certain conditions, seedlings ofL. italicuminhibit completely the growth of seedlings of the other three grasses, the latter being deprived of light and soil nutrients. At the same time, seedlings suffering suppression in this way are remarkably persistent and are capable of immediate recovery on the removal of competition.4The significance of this behaviour, ecologically and to agricultural practice, is discussed.5The effeet of different physical factors on germination in the same four species of grass is described. The action of low temperatures in depressing the germination ofF. pratensis, PhleumpratenseandPoa trivialisto a greater extent than that ofL. italicumis considered an important factor in interspecific competitio

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04318.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1The bionomics of the bat willow gall midge(Rhabdophaga terminalisH.Lw.), which does serious damage to certain willows grown for basket making and the cricket bat willow grown for sets, have been studied.2The midge exhibits a distinct host‐plant preference, choosing the bat willow(S. coerulea)when possible. But it also breeds readily on a golden willow,S. albavar.vitellina.It will not attack Black Maul (S triandra), Long Skin (S. viminalis) and Dicky Meadow (S. purpurea).3It is shown to be a species which sometimes occurs in epidemic numbers. Intensive cultivation is suggested as a contro

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04319.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY

摘要:

SUMMARY1Preliminary data is reported as to the insecticidal properties of three tropical fish‐poison plants(Tephrosia macropodaHarv.,Mundulea suberosaBenth. andNeorautanenia (Rhynchosia) fisifoliaC.A.Sm.).2A list is given of other plants (most of them known to be fish poisons) from many different countries, which have been tested but appear to have little or no toxicity toAphis rumicisL.3Extracts of the stems of black Haiari(Lonchocarpussp.) are shown to be toxic as contact insecticides to young larvae of two species of moths. Older larvae are much, more resistant.4All the plants so far tested which are toxic both to fish and to insects are members of the natural order Leguminosa

ISSN:0003-4746    

DOI:10.1111/j.1744-7348.1932.tb04320.x

出版商:Blackwell Publishing Ltd    

年代:1932

数据来源: WILEY