A rapid method of sampling for aphids on strawberries

B. D. Frazer, R. R. McGregor


A rapid system of sampling for strawberry aphids, Chaetosiphon fragaefolii (Cockerell) was developed for use by pest management scouts. Regression equations relating mean numbers of aphids/leaf, variances of those means and the proportion of unifested leaves (Po) were developed from samples of aphids from single leaves. Using the equations, mean aphid density per leaf and standard errors can be estimated from Po and the sample size. The accuracy of the estimations were tested on data from 155 samples from commercial strawberry fields sampled by a professional pest management company. Means estimated from Po were sufficiently accurate for the intended purpose and only 2 hours were required to sample 300 leaves compared to 16 hours when all aphids on all leaves were counted from only 80 leaves. An electronic recorder was programmed to prompt an IPM scout for data entry, allow correction of errors and permit sampling from different subplots within a field.

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