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Italian ryegrass, cultivar Aberystwyth S22 and perennial ryegrass, CV.S321, grown for the production of seed in the A.D.A.S. S.E. Region and Wiltshire were surveyed for ryegrass mosaic virus (RMV). Visual leaf symptoms were used to assess infection; the diagnosis was checked using the electron microscope. RMV infection was widespread in both grasses and about 30 per cent of the fields carried an infection level greater than 10 per cent (based on number of plants infected/examined). Higher levels of infection were encountered in crops of Italian ryegrass than in perennial ryegrass. Out of 69 fields of Italian ryegrass, only 12 showed no infection whilst nine fields showed a level of infection greater than 30 per cent. Twenty-eight of the 61 fields of perennial ryegrass showed no infection and the highest level of infection found was 26 per cent. AU of the Italian and most of the perennial ryegrass crops were in their first harvest year. Since Italian ryegrass crops were occasionally encountered with more than 70 per cent of the plants infected, it is obvious that RMV can spread very quickly. In perennial ryegrass fields an increase in the amount of N fertilizer applied in the spring led to an increase in RMV; an increase from 100 to 200 kg N/ha led to an increase in the level of RMV from 9 to 37 per cent. By the first harvest year, fields sown in the spring of the previous year (usually under a cereal crop) were generally much more heavily infected than those sown in the autumn of the same year. [ABSTRACT FROM AUTHOR]

This article cites a study that determined the species of Rhynchosporium (R.) occurring on Lolium (L.) multiflorum, their relative frequency, and the host range of common isolates. The variation between and within cultivars was assessed with a view to increasing the level of resistance in L. multiflorum by breeding. R. orthosporum was isolated from L. multiflorum from breeders' plots at Aberystwyth, Wales twice as often as R. secalis. Of 20 genotypes of L. multiflorum, 17 ranked similarly for level of resistance to both pathogen species.

Growth of ryegrass (Lolium perenne) in a soil extremely deficient in available phosphorus, depended on conversion of most of the root system into endomycorrhizas by Rhizophzagus tenuis. A further growth increment could be obtained in infected plants by adding other nutrients, whereas uninfected plants responded only to phosphorus. Cocksfoot (Dactylis glomerata) and sweet vernal (Anthoxanthum odoratum) also relieved extreme phosphorus deficiency by symbiosis with Rhizophagus tenuis; but in slightly more fertile soil all three grasses grew better without the fungus. Then R. tenuis grew mainly in the rhizosphere of inoculated plants with much less penetration. [ABSTRACT FROM AUTHOR]

This article cites a study that described lolium (L.) mottle virus (LMV). A previously unrecorded virus with isometric particles 27 nanometer diameter had been isolated from L. perenne and Cynosurus (C.) cristatus from Eire and from C. cristatus from Yorkshire, England. Then this was named LMV. The virus could be inoculated into cultivars of wheat, oats, barley and rye, and Lagurus ovatus. It was symptomless in L. multiflorum and Phleum pratense. Some properties of LMV were reported. The virus, though readily sap transmissible, was not transmitted by two Oulema species or by three species of aphids.

A measurement of the effect of mildew and leaf blotch on both yield and quality of Lolium multiflorum (cv. Lior) was undertaken in two trials sown in 1966 and 1967. Plots were sprayed with a fungicide at 10-day intervals, and four cuts were taken during the season. Disease assessments were made at the time of cutting. Considerable differences in yield and quality were recorded which could be broadly related to the levels of disease infection in the treatments. [ABSTRACT FROM AUTHOR]

Studies the establishment of tall fescue and its subsequent growth and development when sown alone or in mixture with an aggressive grass species Lolium perenne at several densities. Several characteristics of agronomic value exhibited by tall fescue; Problems that deter the wider use of tall fescue in farming in Great Britain; Capability of the tall fescue to withstand severe climatic and soil conditions.

Presents a comparison of yields from plots sown with a single species or a mixture of grass species rye grass, meadow fescue and a triploid hybrid, under grazing and hay management. Conditions under which yields from mixed plots may exceed those from pure plots; Possible explanation for greater yields from mixed plots; Reason for decrease in the intensity of competition by mixing the grass species in plots.

Discusses the effect of management and competition on the phosphorus by rye grass, meadow fescue and their natural hybrid in pure and mixed plots. Reason for the difference between species in their capacities to absorb phosphate; Absorption of nutrients by established crops; Role of phosphate in the root penetration in plants.

Focuses on a study conducted on the growth of Italian ryegrass in New Zealand. Description of methods applied by researchers for conducting the study; Comparison of the mean radiation values with those of Great Britain; Seasonal changes in the interval between the appearance of successive leaves; Graphical representation of the dimension of mature leaf laminae; Decline in the number of live tillers in five months.

Summary. The major (Group I) allergen of rye grass pollen and two of its allergoids, adsorbed on alumina gel, were injected into three groups of non-allergic humans. In addition m inducing the anticipated blocking antibody (IgG) response, all individuals developed immediate skin hypersensitivity to the allergen and its allergoids characteristic of reaginic antibody-(IgE-)mediated reactions. At some time during the course of the study, virtually every individual's peripheral blood leucocytes were also found to release histamine when challenged in vitro with low concentrations of allergen and allergoids. Quantitatively, each person's skin and leucocyte sensitivities were not as well correlated as in naturally allergic people. Leucocyte responsiveness was generally shortlived, but could be restored by antigenic restimulation. Allergoid:allergen sensitivity ratios were greater in allergen- than allergoid-immunized individuals, but less than in naturally allergic individuals. Unexpectedly, allergoid-immunized individuals' leucocytes were more sensitive to allergen than allergoid. Despite the observed skin and leucocyte reactivities, none of the people showed clinical manifestations of hay fever following natural exposure to pollen. The skin sensitivity of the artificially sensitized individuals could be passively transferred to non-allergic humans by intradermal inject:ion of serum (P-K Test), thereby implicating the involvement of IgE antibody. Further proof of the role of IgE was obtained by blocking the P-K test, either by heating the serum or by adsorbing it using an anti-IgE immunosorbent. [ABSTRACT FROM AUTHOR]

A rat mast cell degranulation (R.M.C.D.) technique is described in detail. This method is shown to detect specific antibodies to rye grass pollen and purified factors thereof (rye Group I antigen). The antibody detected belongs to the IgE iramunoglobulin class as evidenced by specific degranulation when the rat mast cells are passively sensitized with the sensitive subject's serum and challenged with a monospecific rabbit antimyeloma IgE antiserum. No significant mast cell degranulation is observed with serum alone, antigen alone, or when anti-IgG, IgA or IgM are used in this system in an appropriate set of controlled experiments. [ABSTRACT FROM AUTHOR]

The highly purified major allergenic component of rye grass pollen (Group I) was used to investigate the possibility of destroying selectively the allergenic properties of an antigen, while largely retaining its original immunizing capacities. The allergen was treated under mild conditions with formalin alone or formalin plus a reactive low molecular weight additive. Certain derivatives (allergoids) showed well over 99 per cent reduction in allergenicity, determined by the histamine released from allergic human leucocytes in vitro, but were still able to combine with rabbit antibody against native antigen. Furthermore, the allergoids stimulated production (in guinea-pigs) of appreciable amounts of antibody able to inhibit native allergen-mediated human allergic histamine release in vitro and to cross-react with native antigen by PCA tests in normal guinea-pigs. Residual allergenicity and cross-immunogenicity (by the inhibition assay) of the different formalinized derivatives varied appreciably according to the additive used in formalinization, but the cross-reactivities of the different preparations in quantitative precipitin analysis against rabbit anti-native antigen serum were similar. The residual allergenicities of individual derivatives varied by up to 1000-fold in different cell preparations, suggesting a heterogeneity of allergenic determinants. Allergoid derivatives showed no hapten-like activity in that they were unable to inhibit allergen-mediated histamine release from leucocytes. The theoretical and practical application of allergoids is discussed, including their potential usefulness in improving the immunotheraphy of atopic humans. [ABSTRACT FROM AUTHOR]

A virus apparently indistinguishable from the ryegrass chlorotic streak virus in New Zealand has been found in Britain where it appears to be similar to, if not identical with, isolates of barley yellow dwarf virus transmitted specifically by Rhopalosiphum padi. [ABSTRACT FROM AUTHOR]

This article shows the resistance of a population of ryegrass (Lolium multiflora) to crown rust in a resistance breeding program in Italy. This pathogen was attacked by a rust during the spring and autumn and was identified as Puccinia recondita. When plants were grown in a glasshouse, the pustules became darker in color due tot e accumulation of orange-brown uredospores. Both natural and synthetic ryegrass populations varied markedly in their resistance to P. condita when scored for susceptibility on a 1-5 scale which is considered significance for resistance breeding.