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United States Department of Agriculture

Agricultural Research Service

Title: Estimating citrus rust mite densities on fruit: Some sampling considerations

Authors
item Hall, David
item Childers, C - UNIV OF FLORIDA
item Eger, J - DOWAGROSCIENCES

Submitted to: Citrus and Vegetable Magazine
Publication Type: Popular Publication
Publication Acceptance Date: March 30, 2005
Publication Date: April 1, 2005
Citation: Hall, D.G., Childers, C., Eger, J. 2005. Estimating citrus rust mite densities on fruit: some sampling considerations. Citrus and Vegetable Magazine. 69:8-9.

Interpretive Summary: Citrus rust mites continue to be key pests of citrus fruit in most Florida groves, particularly in fruit grown for the fresh market. In this article, sampling considerations for citrus rust mite are discussed. The effect on estimate accuracy of reducing the number of sample units examined is reviewed. If a rust mite sampling plan includes too few samples, sometimes mites will be present but not detected (especially if the true density is small) and other times the actual density may be grossly under- or over-estimated. If the management threshold for mites is low and only a small number of samples can be afforded then it may be best to select a sampling plan simply aimed at detection.

Technical Abstract: Citrus rust mites continue to be key pests of citrus fruit in most Florida groves, particularly in fruit grown for the fresh market. There are two different species, the citrus rust mite and the pink citrus rust mite, and the currently the same scouting and management programs are used to manage both. Scouting efforts made by citrus growers or their consultants to keep track of rust mite densities on fruit range from infrequent and simple to routine and more complex. In this article, sampling considerations for citrus rust mite are discussed. The effect on estimate accuracy of reducing the number of sample units examined is reviewed. If a rust mite sampling plan includes too few samples, sometimes mites will be present but not detected (especially if the true density is small) and other times the actual density may be grossly under- or over-estimated. Even if a moderate number of samples are taken, estimates could still occasionally be quite inaccurate. To guard against making an incorrect management decision based on an estimate, sample frequently and take at least a moderate number of samples. If a rust mite sampling plan involves counting the number of mites per sample, consider adopting an alternative method such as the HB method or presence/absence sampling to speed up the time required to take an individual sample, which will allow you to take more samples in the same amount of time. If the management threshold for mites is low and only a small number of samples can be afforded then it may be best to select a sampling plan simply aimed at detection.

Last Modified: 12/18/2014
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