采用聚集度指数 ( I、C、M*、CA、K、Iδ)和 Iwao及 Taylor法 ,研究了稻粒黑粉病病株在稻田的空间分布型。结果表明 ,稻粒黑粉病病株在稻田的空间分布型呈聚集分布。在此分布型的基础上 ,通过调查病株密度 ,比较了平行线、单对角线、棋盘式及“Z”字型抽样法 ,最后肯定平行线抽样法最好。理论抽样数量通过 I-wao法计算公式得出不同发病率 ( X)所需最大的抽样稻丛数为 :n=3 .4 6/X+0 .71 The spatial distribution pattern of rice powdery mildew in paddy field was studied by means of aggregation index (I, C, M *, CA, K, Iδ) and Iwao and Taylor methods. The results showed that the spatial distribution pattern of rice powdery mildew in paddy field was aggregated. On the basis of this distribution pattern, parallel lines, single diagonal lines, checkerboard and “Z” shaped sampling methods were compared by investigating the density of the diseased plants. Finally, the parallel line sampling method was the best. The number of theoretical samples obtained by I-wao method formula for different morbidity (X ) the maximum number of sampled rice is: n = 3 .4 6 / X +0 .71