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Variability in initial spray deposit in apple trees in space and time
Author(s) -
Xu Xiangming,
Wu Pihong,
Thorbek Pernille,
Hyder Kieran
Publication year - 2006
Publication title -
pest management science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.296
H-Index - 125
eISSN - 1526-4998
pISSN - 1526-498X
DOI - 10.1002/ps.1262
Subject(s) - spatial variability , orchard , sampling (signal processing) , tracer , fruit tree , environmental science , pesticide , soil science , hydrology (agriculture) , biology , agronomy , atmospheric sciences , horticulture , mathematics , statistics , geology , physics , geotechnical engineering , filter (signal processing) , computer science , nuclear physics , computer vision
Variation in pesticide residues in space and time has not been investigated systematically in spite of the large variability found at single scales (e.g. between trees or orchards). Information on variability at different scales will support the development of sampling methods and more reliable prediction of residues. Experiments were conducted to quantify the spatiotemporal variability in initial spray deposit on apple leaves and fruit using a substitute tracer (zinc EDTA chelate). Five hierarchical spatial scales were defined as (1) between orchards, (2) between plots within an orchard, (3) between trees within a plot, (4) between zones within a tree and (5) between leaves/fruit within a zone. Similarly, two temporal scales were defined as (1) between applications within a single year and (2) between years. The initial zinc concentration was approximately log‐normally distributed; the variability in initial deposit concentration was greater on leaves than on fruit. The average initial zinc deposition was significantly greater in the top and outside zones than in the middle zones within individual trees. The most important scale for driving residue variability is the within‐zone unit‐to‐unit variation, contributing to 71 and 49% of the observed variability for leaf and fruit samples respectively. Variability at other scales was related to the variation in the tree architecture. The results indicated that stratified sampling on the basis of within‐tree zone structures, with the effort focused on within‐zone sampling, should be used for the determination of pesticide residues. Copyright © 2006 Society of Chemical Industry