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A survey of perennial ryegrass seed lines received for testing in 1982 revealed different Lolium endophyte infection level characteristics for different cultivars. Grasslands Ruanui had low infection levels, Ellett had high and Grasslands Nui and other perennial ryegrass samples had variable infection levels. Differences in infection levels are ascribed to the infection status of the original cultivar material and the storage period between harvest and sowing during the seed multiplication process. The problems associated with providing a seed testing service for Lol ium endophyte are also discussed. INTRODUCTION The discovery of an association between the Lolium endophyte and ryegrass staggers (Fletcher & Harvey, 1981) prompted the need for a reappraisal of the incidence of Lolium endophyte in perennial ryegrass (Lolium perenne L.) seed lines. Previous surveys (Neill, 1940; Lloyd, 1959) have shown a variable incidence of infection, depending on the source and age of the seed concerned. A preliminary survey of perennial ryegrass seed samples from the 1981 harvest confirmed the presence of infection in many seed lines. However, these tests were carried out at least six months after harvest and it was considered that the results did not accurately reflect the levels of viable infection which would have been present immediately after harvest. A further survey was initiated early in 1982 to determine the levels of viable infection present in freshly harvested perennial ryegrass seed, and to determine if there were any differences in levels of seed infection between different-pergnnial r.yegrass-cultivars. MATERIALS AND METHODS In February and March 1982, samples of perennial ryegrass seed received at the Seed Testing Station for routine purity and germination tests were set aside for Lolium endophyte tests. All samples of Government certified pre-basic (breeders) and basic seed of named cultivars received during this period were tested as a first priority. In addition, a proportion of samples of certified first generation and uncertified seed were tested as necessary to ensure that approximately equal numbers of seed lines of different cultivars were tested. The testing was discontinued once a clear trend in results became apparent. A similar test method to that described-by-Neill-(-1940)-was-used-in-this-sur= ~__ vey. Seeds were germinated on blotting paper substrate at 20°C for 16 days, after which time 50 seedlings per sample were prepared for examination. From each seedling a five millimetre length of leaf, cut off just above and below the end of the leaf sheath, was used. On each microscope slide three lengths of leaf were mounted in l-2 drops of staining fluid (50 ml of lactic acid to 100 ml of 0.1% aqueous aniline blue). The lengths were punctured and flattened using a needle, 2 5 4 then covered with a coverslip and left overnight. The preparations were examinedfor the presence of endophytic hyphae using a compound microscope.

LOLIUM ENDOPHYTE LEVELS IN COMMERCIAL PERENNIAL RYEGRASS SEED LINES