of information on spatial variability in yield practically possible but the utility of this information for MZ delin-Unsupervised clustering has been proposed for developing geoeation remains largely unexplored. referenced agronomic information into management zones (MZs). Our objectives were to use fuzzy c-means clustering to identify yield-based

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The bionomics of the currant clearwing moth in a heavily infested Lincolnshire black currant plantation were investigated from 1951 to 1960. 95% of overwintered larvae pupate in May; the remainder, chiefly in the older wood, carry over until the following season. T h e mean number of eggs laid per bush was ninety and the mean number of larvae surviving until winter was forty-nine (59,ooo/acre). Pruning, parasitism and predation by tits reduced this to twenty by May, giving an overall loss of about 80% from egg to adult due to natural causes.Parathion, dipterex or gusathion, acting ovicidally, reduced surviving larvae by 80 yo compared with untreated controls, but a large-scale experiment showed no crop increase in the year following successful treatment and the net economic effect of high larval infestation was negligible.

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