Browsing by Author "Storey, H.H."

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A Bark Disease of Coffee in East Africa
(1932) Storey, H.H.; East African Agricultural Research Station, Amani
A disease of the bark of young leader shoots of arabica coffee 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 lateritium Nees var. longum Wr., 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 arabica alone, 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 plantation.
Basic Research in Agriculture - A Brief History of Research at Amani 1928-1947
(East African Agriculture and forestry Research Organisation, 1928/1947) Storey, H.H.; East African Agriculture and forestry Research Organisation
In 1927 the British and East Mriean Governments reopened the old German research institute at Amani as a centre for " long-range and widerange" research. Under the direction of William Now~ll to 1936 and A.G.G. Hill thereafter, research proceeded for some twenty years until Amani's identity became merged into a new research organisation. The following brief account of these researches is presented iJ:t order that the reader may understand something of the aims and methods of the research worker, of the kind of results he obtains, and of the way thatthese results ean influence agriculture.
East African Work on Breeding Maize Resistant to the Tropical American Rust, Puccinia Polysora
(1957) Baldwin, B.J.T.; Audrie, K.H.; Storey, H.H.; Dixon, G.E.; Hemingway, J.S.; Jameson, J.D.; Thorpe, H.C.; East African Agricultural and Forestry Research Organization: Tanganyika Agricultural Corporation: Uganda Department of Agriculture: Kenya department of Agriculture
Since 1952 Puccinia polysora under has become widespread in maize in the tropical areas of East Africa, and severe attacks have been shown to reduce yield greatly. Two physiologic races have been recognized, 'EA.I' being today the prevalent race in the field and 'EA.2' being known as yet only in the Muguga glasshouses. Experimental infection trials in glasshouses at Muguga, Kenya, failed to demonstrate resistance in any African maize variety; but among maize’s imported from Central America and the Caribbean plants were found that showed the hypersensitive type of resistance. From these, lines were bred that were pure for either of two genes: Rppl. conferred high resistance to Race EA.I but none to EA.2; while Rpp2 conferred a lesser, but effective, resistance equally to both rust races. Field breeding at three stations in East Africa was successful in incorporating each of these genes separately in locally adapted maize varieties; and considerable bulks of pure-breeding resistant maize’s were expected to become available during 1957 and later years.
The Inheritance by an Insect Vector of the Ability to Transmit a Plant Virus
(1932) Storey, H.H.; East African Agricultural Research Station
The leaf hopper, Cicadulina mbila Naude, is normally an efficient vector of the virus of streak disease of maize (Storey, 1925). I have, however, encountered exceptional individuals of this insect-species which were unable to transmit the virus (Storey, 1928). An attempt to discover the reason for their anomalous behavior led me to undertake studies of the breeding of this species. The results so obtained, which show that the ability to transmit is an hereditary character, have been briefly reported (Storey, 1931), and I now present a full account of this work. Since these studies introduce a new conception into pathology, I find it necessary to give my definition of certain current terms and to utilize two new ones. I employ transmission in the restricted sense of the act of transfer of a virus by a vector from a diseased to a healthy plant in the natural process of that vector's feeding. I introduce the term activity to denote an insect’s inherent potentiality to transmit a virus; inactivity to denote the absence of that inherent potentiality. An insect is viruliferous or non-viruliferous according as it is, or is not, actually carrying a virus in such a way that it inoculates that virus into a plant on which it feeds, and in consequence causes the plant to develop the symptoms of the disease.
Inheritance of resistance in maize to the virus of streak disease in East africa
(1967) Storey, H.H.; Audrie, K.H.; East African Agriculture and Forestry Research Organization
Maize plants selected from lines raised in South Africa, and resistant to an East African isolate of streak virus, gave rise on selfing to lines that bred true for resistance through four generations. Heterozygotes from crossing resistant by susceptible lines reacted to infection by inoculation with the vector in a manner intermediate between the parents; neither allelomorph was fully dominant. The F2 generation from the cross segregated in the expected 1: 2: 1 ratio. Backcrosses segregated 1: 1. The evidence is interpreted as showing …
Investigations of t plant III 632.388:591.67 612.313.3:595.753 e mechanism of the transmission of iruses by insect vectors the insect's saliva
(1939) Storey, H.H.
For the type of virus transmission characteristic of leafhopper vectors, there is convincing evidence at the virus passes through the insect's body. The manner in which it emerges from the insect and comes to be inoculated into a plant is much is certainly known. It has generally been assumed that the saliva is the vehicle of the inoculation. For this assumption there is even now little dire t evidence.
Investigations of the Mechanism of the Transmission of Plant Viruses by Insect Vectors
(1939) Storey, H.H.; East African Agricultural Research Station Amani
The studies here described aim at the elucidation of the action of a plant virus within the insect that is its specific vector. It is widely held that insect transmission is not normally a mechanical process; but of the nature of the biological relation, into which virus and insect are supposed to enter, little is definitely known. By the use of the method of mechanical inoculation of the virus into the insect I have obtained certain direct evidence bearing upon this problem. The virus studied is that which causes streak disease in the maize plant. A single strain has been used, maintained in the course of my experiments by repeated transfers to maize seedlings in the greenhouse. Conceivably this strain is a complex of viruses, but if so it has shown no sign of splitting into its components during the period of the work now described.
Investigations of the Mechanism of the Transmission of Plant Viruses by Insect Vectors II. The Part Played By Puncture in Transmission
(1938) Storey, H.H.; Amani;
In an earlier paper (Storey 1933) I showed that, after Cicadulina mbila Naude had fed on a source of the maize streak virus, this virus appeared externally to the intestine in the insect's blood. The next stage, it may be supposed, is the collection of the virus at some centre whence it becomes available for ejection into a plant. It seems hardly possible to doubt that this centre is the salivary gland, and that the saliva is the vehicle whereby the virus is transferred into the plant. Nevertheless, my attempts to demonstrate a virus in the saliva have met with almost uniform failure.
Investigations of the Mechanism of the Transmission of Plant Viruses by Insect Vectors II. The Part Played by Puncture in Transmission.
(1938) Storey, H.H.; Storey, H.H.; East African Agricultural Research Station
In an earlier paper (Storey 1933) I showed that, after Cicadulina mbila Naude had fed on a source of the maize streak virus, this virus appeared externally to the intestine in the insect’s blood. The next stage, it may be supposed, is the collection of the virus at some centre whence it becomes available for ejection into a plant. It seems hardly possible to doubt that this centre is the salivary gland, and that the saliva is the vehicle whereby the virus is transferred into the plant. Nevertheless, my attempts to demonstrate a virus in the saliva have met with almost uniform failure. The problem of the mechanism of inoculation is thus not simply solved. As one step towards its solution, I now present evidence bearing upon the factors that decide whether an insect succeeds in causing the infection of the plant. In a later paper I shall consider the process of excretion of saliva and attempt to relate the facts so obtained to the conclusions of the present studies.
Investigations of the mechanism of the transmission of plant viruses by insect vectors III. The insect's saliva
(1939) Storey, H.H.
For the type of virus transmission characteristic of leafhopper vectors, there is convincing evidence that the virus passes through the insect's body. The manner in which it emerges from the insect and comes to be inoculated into a plant is much less certainly known. It has generally been assumed that the saliva is the vehicle of the inoculation. For this assumption there is even now little direct evidence.
A New Virus of Maize Transmitted by Cicadulina Spp.
(1937) Storey, H.H.; East African Agricultural Research Station, Amani
Of the means available for the differentiation of plant viruses, the specificity of the insect vector has been regarded as one of the most reliable (4). More particularly has this been true of those viruses that are transmitted by species of leafhoppers. It is therefore of some interest to record the occurrence of an apparently new virus transmitted by the same species of Oicadulina that are the vectors of the streak virus of maize. Such a virus, producing in maize a disease that I have termed "Mottle", has been found in Tanganyika Territory.
The Photodynamic Action of Methylene Blue on the Virus of a Plant Disease
(1934) Storey, H.H.; East African Agricultural Research Station, Amani
The results of the author's experiments very briefly described in this note are interpreted to indicate that the virus of maize streak [R.A.M., xiv, p. 146] is inactivated by adding to it sufficient methylene blue ('medicinale' of Meister Lucius and Brüning) and then irradiating the mixture for 3 to 4 0.5 hours in diffused daylight at an open window [ibid., xiv, p. 186]. The virus agent was not inactivated, on the other hand, when the virus plus methyiene blue mixture prepared in a dark room was kept for a similar period in total darkness, or when the virus fluid alone was irradiated as in the first series. These results are correlated with recent work by Perdrau and Todd [loc. cit.] on animal viruses as well as on certain races of bacteriophage.
Research On Agriculture In Semi-Arid Regions
(1949) Glover, J.; Storey, H.H.; Agriculture and Forestry Research Organisation, East African High Commission, Nairobi, Kenya.
There is need to extend agriculture in the semi-arid regions of Africa. It can only succeed if special methods and crop plants are used. We suggest that an assessment of our present knowledge on these points and of the directions in which research should proceed is desirable. Lines of research indicated are studies by plant physiologists and soil physicists on water-soil-plant relationships and by plant-breeders on drought-resisting or -evading grain plants and grasses. Certain initial work bearing on both has been done by the East African Agriculture and Forestry Research Organisation and a programme on the former is being planned. Con- currently, technological research will be needed on new or existing dry-land experimental stations. The world demand for food and living space is everywhere increasing the pressure on the marginal agricultural lands. Among these are the vast, empty "semi-arid" regions which cover so much of Africa. It has often been suggested that these semi-arid regions should be used for agriculture; and the idea is attractive since they often have high average annual rainfall by comparison with some regions where agriculture is successfully practised.
Resistance to the Maize Rust, Puccinia polysora
(1954) Storey, H.H.; Ryland, A.K.
DURING 1953 we have studied resistance in maize to the form of the rust fungus, Puccinia polysora Underw., that recently appeared in East Africa1• Our results augment the information given by Stanton and Cammack
Studies of the Mosaic Diseases of Cassava
(1938) Storey, H.H.; Nichols, R.F.W.; East African Agricultural Research Station, Amani, Tanganyika Territory
The symptoms of mosaic disease in cassava, although generally typical of the mosaic group, show wide variations, due in part to the varietal reaction of the plant, to its stage of development and to the environment. The most important cause of variations however is differences in the strains of the virus, of which we have recognized, through the study of symptoms, two groups of severe and mild strains. The viruses are transmitted across a graft, but we have failed to obtain mechanical transmission by needle or hypodermic injection. A Bemisia sp. can transmit both groups of strains. It can inoculate the plant only through immature leaves, less than about one-quarter of their full length. The virus so inoculated does not pass out of the leaf until about 8 days have elapsed. On the basis of this knowledge a convenient and reliable single-leaf cage technique has been developed. After the virus has entered the stem it passes rapidly to the base of this stem, but odp slowly into side branches from it or into other stems arising from the same original cutting. Infection of a plant with a mild strain of virus failed entirely to confer immunity from infection by severe strains introduced by grafting. If the severe strains were inoculated by insects there was an indication of some conferred resistance but insufficient to make the procedure practically useful in control.
Studies of the Mosaic Diseases of Cassava
(1938) Nichols, R.F.W.; Storey, H.H.; East African Agricultural Research Station
The symptoms of mosaic disease in cassava, although generally typical of the mosaic group, show wide variations, due in part to the varietal reaction of the plant, to its stage of development and to the environment. The most important cause of variations however is differences in the strains of the virus, of which we have recognized, through the study of symptoms, two groups of severe and mild strains. The viruses are transmitted across a graft, but we have failed to obtain mechanical transmission by needle or hypodermic injection. A Bemisia sp. can transmit both groups of strains. It can inoculate the plant only through immature leaves, less than about one-quarter of their full length. The virus so inoculated does not pass out of the leaf until about 8 days have elapsed. On the basis of this knowledge a convenient and reliable single-leaf cage technique has been developed. After the virus has entered the stem it passes rapidly to the base of this stem, but odp slowly into side branches from it or into other stems arising from the same original cutting. Infection of a plant with a mild strain of virus failed entirely to confer immunity from infection by severe strains introduced by grafting. If the severe strains were inoculated by insects there was an indication of some conferred resistance but insufficient to make the procedure practically useful in control.
Studies of the Mosaic Diseases of Cassava
(1938) Storey, H.H.; Nichols, R.F.W.; AMANI
The symptoms of mosaic disease in cassava, although generally typical of the mosaic group, show wide variations, due in part to the varietal reaction of the plant, to its stage of development and to the environment. The most important cause of variations however is differences in the strains of the virus, of which we have recognized, through the study of symptoms, two groups of severe and mild strains. The viruses are transmitted across a g~aft, but we have failed to obtain mechanical transmission by needle or hypodermic injection. A Bemisia sp. can transmit both groups of strains. It can inoculate the plant only through immature leaves, less than about one-quarter of their full length. The virus so inoculated does not pass out of the leaf until about 8 days have elapsed. On the basis of this knowledge a convenient and reliable single-leaf cage technique has been developed. After the virus has entered the stem it passes rapidly to the base of this stem, but only slowly into side branches from it or into other stems arising from the same original cutting. Infection of a plant with a mild strain of virus failed entirely to confer immunity from infection by severe strains introduced by grafting. If the severe strains were inoculated by insects there was an indication of some conferred resistance but insufficient to make the procedure practically useful in control.
Transfer of resistance to the Streak Virus into East African Maize
(1967) Audrie, K.H. ; Storey, H.H.; E.A.A.F.R.O., Kikuyu, Kenya
Streak disease is caused by infection with a virus that is prevalent in maize and some grasses in many parts of Africa. It has been frequently described (eg Storey, 1925; McClean, 1947); typically it results in leaves developing with a nearly uniform pattern of chlorotic and green areas; in its most severe form some half or more of the total leaf area may be chlorotic, and in this form the disease causes a marked reduction in the growth and productivity of the plant. Because the virus is transmissible only by a specific insect vector of the genus Cicadulina (Storey, loc. cit.) and by no other known means, prevalence of the disease in the field is dependent not only on the presence of the virus but also on the frequency with which the vector occurs. In consequence, outbreaks of streak disease may vary from season to season and from place to place. Nevertheless, in aggregate the disease can cause large losses in productivity of maize; and a search for resistant maize types is justified. Glasshouse studies of streak resistance in maize have been prosecuted over a number of years at EAAFRO That this resistance existed had been recognized in the early thirties in South Africa, but owing to difficulties inherent in studies of this problem under field conditions, research workers there had been unable to arrive at any hypothesis for the manner in which resistance was inherited (Rose 1938; Gorter, 1959). The purpose of the work at EAAFRO was to see whether a genetic hypothesis would emerge from studies carried out under the more exact, more reliable and more rapid conditions provided by
Transmission of Groundnut Rosette Virus
(1955) Storey, H.H.; Ryland, A.K.
The rosette virus was transmitted to groundnut plants, if previously etiolated, bymechanical inoculation of juice with ‘Celite’ addition; but only a small proportion of the inoculations succeeded. Aphis craccivora (Koch), the known vector, transmitted the virus by feeding on germinating groundnut seeds; and from this fact we developed an experimental technique that is convenient and flexible. Different races of this species appeared to vary in inherent efficiency in transmission, and one failed ever to transmit. Within races that could transmit, all larval forms and alate and apterous adults might transmit; but alatae were sometimes significantly more efficient than apterae, and at other times the converse held. A field experiment showed that wingless forms, moving over the soil surface, might play a predominant part in secondary spread around a rosetted plant. comparative tests with groups of I, 2, 3 and 4 infective aphids supported the hypothesis that infections by this vector are individual and independent.....
Transmission of Plant Viruses by Insects
(1939) Storey, H.H.; Amani
Insects, as a general rule, play an essential part in the survival of the viruses that cause plant disease. It is true that a virus will pass from scion to stock, or the reverse, across a graft in those species of plants where organic union is possible. I t is also true that by vegetative reproduction of a diseased plant the virus is perpetuated in its progeny. But every living plant owes its origin ultimately to sexual reproduction; and the real problem, from a theoretical and a practical point of view, is how a virus can become established in a sexually produced plant.

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Browsing by Author "Storey, H.H."

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