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This article examines the use of Atriplex hortensis L. as a useful test plant for several viruses. The following viruses gave distinctive reactions: arabis mosaic, carnation mottle, carnation vein mottle, hydrangea ring spot, pea mosaic, potato virus X, raspberry ring spot, sugar beet mosaic and tobacco mosaic. Tomato ring spot, tomato spotted wilt and turnip crinkle also showed distinctive reactions. The following viruses did not infect A. hortensis: bean yellow mosaic, broad bean mottle, carnation etched ring, carnation latent, cauliflower mosaic, celery yellow net, chrysanthemum stunt, chrysanthemum vein mottle, cucumber green mottle mosaic, dahlia mosaic, henbane mosaic, iris mosaic, lettuce mosaic, potato virus Y (one isolate), and tulip breaking viruses.

This article describes the use of Torenia Fournieri as a test plant for plant viruses. The plant has proved susceptible to most of the viruses. The plant as infected by Anemone mosaic, Arabis mosaic, Cabbage black ring spot, Carnation Italian ring spot, Carnation mottle, and other viruses. All in all, the plant was infected by 46 isolates of 31 viruses out of the 64 isolates of 49 viruses tested. Several viruses, such as anemone mosaic and turnip crinkle, induced diagnostic symptoms.

This article examines the use of Chenopodium (C.) quinoa as an indicator plant for carnation latent virus. The reactions of C. quinoa to carnation latent virus are usually sufficiently distinct from those of other carnation viruses to provide a diagnostic indicator plant for routine testing of carnation. These reactions might sometimes be confused with those of vein mottle virus, but the latter is seldom seen in British carnation stocks. In sap-rubbing inoculation, C. quinoa reacted to carnation latent virus with indefinite local yellowish spots, followed by systemic interveinal yellowish spotting-mottle, puckering, and rugosity.

This article presents the result of an experiment on the use of Emilia Sagittata L. as a test plant for plant viruses. Emilia sagittata was infected by 32 isolates of 25 viruses, out of 55 isolates of 44 viruses tested by sap rubbing inoculation. No infection occurred after grafting with chrysanthemum or dahlia scions containing three chrysanthemum, or dahlia mosaic, viruses. Emilia sagittata was a satisfactory host plant from which viruses were readily transferred to other plants, or from which purified virus preparations were obtained.

This article focuses on a study that examined the preservation of plant viruses by freeze-drying. Material was freeze-dried by the centrifugal vacuum freezing method of Greaves in a slightly-modified Edwards Model L.5 freeze-drier, using phosphorus pentoxide as a desiccant. No quantitative comparison was made to show the proportions of infectivity lost during drying and storage, but local lesion host plants were used where possible, and the numbers of lesions produced were assumed to give a good indication of the infectivity of the preparation. Of the forty-six isolates of thirty-nine viruses tested only one, potato virus A, was not infective when freeze-dried in this way. Although the viruses in the trials were dried in groups of three, no instance of cross-contamination has been observed.

This article focuses on the investigations that were done in the 1950s to measure and compare virus spread in the seed potato growing areas of England and Wales. The pattern of aphid infestation differed in three years. In 1955, M. persicae was first detected in the crops in late June in Cotswolds, Devon, North Wales and the East Riding of Yorkshire. Exceptionally early immigration occurred in 1957, when large numbers of M. persicae and other species were flying in the early part of May, often before any potato plants had emerged. Calculation of the angle of colonization proved to be a much more sensitive method of detecting the presence and activity of aphids in seed areas than was trapping, at some sites, quite high angles of colonization were obtained although no alate M. persicae was trapped.

This article emphasizes the usefulness of Nicotiana clevelandii Gray in acting as indicator host for different plant viruses. Tests in the Plant Pathology Laboratory in Harpenden, England have indicated that N. clevelandii has many advantages. It is susceptible to several viruses, such as pea mosaic, that are unable to infect the commonly-used member of the Solanaceae. The leaves contain plenty of sap which is readily clarified and is suitable for serological work. The plants occupy less space than tobacco for maintaining stock cultures of viruses and most viruses could readily be isolated even from old plants.

The article focuses on the symptoms and pathology of anemone brown ring as a virus disease. The symptoms consisted of a number of brown rings with pale tan centres, on the older leaves. As the disease seemed likely to be due to virus infection, mechanical inoculations from leaves showing conspicuous rings were made to anemone seedlings, previously checked by inoculation to Chenopodium amaranticolo. The virus concentration in the younger, almost symptomless, leaves of infected anemones was very much lower than that of the older leaves or the roots.

This article highlights a study on the reactions of Chenopodium amaranticolor to a number of additional plant viruses. Virus symptoms on the plant include anemone brown ring, barley false stripe and bean yellow mosaic. No reaction could be detected after inoculation with viruses such as carnation latent, chrysanthemum ring pattern, chrysanthemum vein mottle, potato veinal necrosis and one isolate of potato virus C. However, a previous isolate of potato virus C induced numerous local chlorotic dot lesions after about a week, these lesions being indistinguishable from those of potato virus Y.

This article focuses on the use of Chenopodium amaranticolor as a test plant for plant viruses. The plant has reacted with local lesions to a number of viruses which fail to infect the more commonly used test plants, and in many cases the lesions are distinctive and diagnostic of the virus. Dilution curves have been prepared for several viruses, and have shown the plant to be very suitable for quantitative work. For diagnostic tests, the plant has usually shown symptoms within a few days, and has maintained a greater susceptibility over a longer period than most other test plants. It has proved susceptible to a wide range of plant viruses, some of which previously appeared to be restricted to one or two species.

This article presents a study on the cause of physiological ring pattern in some Gesneraceae. From all the experiments it is clear that sudden chilling of the leaves of these plants in sunlight is the cause of the ring and line patterns, and of the more severe total yellowing and necrosis that can be developed. The damage is done almost immediately after contact with the chilling agent, but may not become visible until later. Damage is apparently cumulative, since repeated daily watering under slight shade conditions result in progressively more severe damage, whereas a single watering may have no visible effect. Only slight markings are produced by chilling under conditions of moderate shading, and none occurs under heavier shade. No exact figure can be given for the threshold of light intensity necessary to induce susceptibility, but no markings could be produced in shade conditions where the incident light did not exceed 30 foot-candles.

This article presents the results of experiments on aphid movement and virus spread in the seed potato areas of England and Wales from 1950 to 1953. In 1950, aphids entered the crop early and caused considerable spread. In comparison, 1951 was an easy year for seed production, with very late aphid immigration and very little virus spread in seed areas. In 1952, aphids came into the crop quite early, and the spread was severe, though generally less than in 1950. In 1953, aphids did not arrive in the crop until fairly late in the season, and though sizable migrations occurred later, blight destroyed the tops early, and virus spread was slight.

This article provides information on new or uncommon plant diseases and pests discovered in Great Britain. The first is the development of stem and inflorescence galls on yarrow caused by nematode Anguina millefolii. The infested yarrow plants were originally supplied from Starcross, Devon. The second reported incident was the spread of tomato ringspot virus in North America. The virus was initially cultured in Chenopodium amaranticolor and purified by phosphate buffer-butanol extraction. The isolate caused severe symptoms in several glasshouse crop plants including lettuce, tomato and cucumber and in several ornamental plants. Another fungal disease caused by coniothyrium fragariae was also discovered during an investigation of a necrotic condition in strawberry crown in Scotland. It appears to be the first record of C. fragariae in Great Britain.