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United States Department of Agriculture

Agricultural Research Service

Title: Perspectives on Sampling for Lygus in Cotton: Applications of Quadrat Based Sampling Schemes

Author
item Willers, Jeffrey

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: February 14, 1998
Publication Date: N/A

Interpretive Summary: By using the several ecological principles presented in this article along with the quadrat based sampling schemes, the author believes that an adequate assessment of the pest status of Lygus in cotton can be determined more reliably, more quickly and with fewer total samples than any other sampling plan currently available. The straightforward process of randomly choosing the baseline origin followed by the random placement of a perpendicular transect line on that baseline, is an appealing concept in row crops due to its simplicity. This procedure provides the randomization necessary to obtain unbiased sampling units, and thus unbiased estimates of row crop attributes like stand and plant bug number per acre. This study primarily demonstrates the use of line-intercept sampling (LIS) to estimate two row crop attributes; stand counts and populations of Lygus spp. in cotton.

Technical Abstract: Objective assessments of row crop attributes are necessary for optimal crop management. This study primarily demonstrates the use of line-intercpt sampling (LIS) to estimate two row crop attributes; namely, stand counts and populations of Lygus spp. in cotton. For either type of count, prior to canopy closure, transect lines of known length are randomly positioned at right angles to imaginary reference baselines that lie parallel to the rows. Ideally, the transect line and baseline lengths are selected to define a reference area that comprises one land acre, or for enhanced brevity of sample effort, quarter-fractions thereof. Sample information is collected from constant size quadrates intercepted by the transect lines. A quadrat is a small, rectangular area centered on a row that is bisected (i.e., encountered) by the transect line and corresponds to either the length of a yardstick or drop cloth. Attention is directed toward estimating crop attributes measured from a series of adjacent quadrats having fixed row distances; therefore, several transect statistics may be estimated using simple formulae. One particular statistic of interest discussed here is the attribute totals (i.e., the number of plants or plant bugs) per acre. Alternately, a visual technique for sampling plant bugs after canopy closure is also described.

Last Modified: 11/27/2014
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