S U M M A R YPure swards of Lolium multiflorum. L. multiflorum var. westerwoldicum and L. perenne sown in August h a d " g r -o n areas treated with either 5 or 10 kn a.i./ha aldicarb than on untreated areas. Total annual drv matter , yields increased by iarger amounts where the greater rate of aldicarb wasapplied; throughout the trial, L. perenne was usually less affected by treatment than iiie other two grasses.Plant-parasitic nematodes were more numerous on untreated than treated plots and were fewest in areas receiving the larger application (except in the second harvest year). Number2 of Tylenchorhynchus and Helicotylenchus were affected most by treatments; abundance of Paratylenchus and Criconemella were little altered.Stem-boring Diptera invaded tillers of all three grasses but infection was least in L. perenne. Invasion occurred only on untreated plots in the establishment year and some yield benefit probably resulted from their control. In subsequent years invasion was similar on treated and untreated areas. Effects on other, non-target organisms were not assessed.Ectoparasitic nematodes multiplied more in L. multiflorum plots than in others during the first full-harvest year. The next year numbers of Paratylenchus only were greater in plots of L. perenne than in other plots.Sward persistence of L. multiflorum var. westerwoldicum was better on treated than untreated areas.It was concluded a) that aldicarb use greatly decreased nematode numbers and yields from treated areas were larger than from those untreated; b) that sward persistence was similarly improved following aldicarb use and c) that ryegrasses differed in their suitability as hosts to ectoparasitic nematodes.

The effects of irrigation, four fertiliser rates, fungicide, insecticide +

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