Survey Methods for Assessment of Citrus Tristeza Virus Incidence When <i>Toxoptera citricida</i> Is the Predominant Vector

Phytopathology - Tập 89 Số 6 - Trang 487-494 - 1999
G. Hughes1,2, T. R. Gottwald
1E-mail Address: [email protected]
2E-mail address:

Tóm tắt

Citrus tristeza virus (CTV) incidence may be assessed by sampling groups of citrus trees, recording the groups as CTV positive (one or more infected trees) or CTV negative (no infected trees), and then calculating disease incidence at the scale of the individual tree by means of a formula involving incidence at the group scale and the number of trees per group. This procedure works well when the CTV status of a tree can be regarded as independent of the CTV status of other trees in the same group. This is the case when the main vector species is Aphis gossypii and the groups comprise four adjacent trees, because the spatial pattern of CTV incidence at the within-group scale can be regarded as random. However, when the main vector species is Toxoptera citricida, this simple procedure is not appropriate, because the spatial pattern of CTV incidence at the within-group scale cannot be regarded as random. Using field data and computer simulation, an alternative procedure for assessment of CTV incidence when the main vector species is T. citricida was devised and tested. In the alternative procedure, the sampling scheme is operationally identical to that used when the main vector species is A. gossypii, but the calculation of CTV incidence at the scale of the individual tree is based on incidence at the group scale and an effective sample size. The analysis of CTV-incidence data collected from a number of citrus blocks in reasonable geographical and temporal proximity and the use of CTV-detection methods more sensitive than the enzyme-linked immunosorbent assay used here are also discussed.

Từ khóa


Tài liệu tham khảo

Bennett S., 1989, GLIM Newsl., 17, 12

Central California Tristeza Eradication Agency. 1998. Field Procedures Manual. CCTEA, Tulare, CA.

10.2307/2532446

10.1007/BF02853501

10.2307/2532039

Cochran, W. G. 1977. Sampling Techniques, 3rd ed. John Wiley & Sons, Inc., New York.

Collett, D. 1991. Modelling Binary Data. Chapman & Hall, London.

Colquhoun, D. 1971. Lectures on Biostatistics. Clarendon Press, Oxford.

10.2307/2532625

10.1002/sim.4780111206

Garnsey, S. M., and Cambra, M. 1991. Enzyme-linked immunosorbant assay (ELISA) for citrus pathogens. Pages 193-216 in: Graft Transmissible Diseases of Citrus. C. N. Roistacher, ed. FAO (Food Agric. Organ. U.N.), Rome.

10.1094/Phyto-86-45

10.1094/PHYTO.1998.88.7.621

Gottwald, T. R., Garnsey, S. M., Cambra, M., Moreno, P., Irey, M., and Borbón, J. 1996. Differential effects of Toxoptera citricida vs. Aphis gossypii on temporal increase and spatial patterns of spread of citrus tristeza. Pages 120-129 in: Proc. Conf. Int. Organ. Citrus Virol., 13th. J. V. De Graça, P. Moreno, and R. K. Yokomi, eds. IOCV (Int. Organ. Citrus Virol.), Riverside, CA.

Healy, M. J. R. 1988. GLIM: An Introduction. Oxford Science Publications, Oxford.

10.2307/2533075

10.1093/jee/85.6.2234

10.1093/jee/85.6.2240

10.1093/jee/89.2.386

10.1094/PHYTO.1998.88.7.715

10.1111/j.1365-3059.1992.tb02549.x

10.1094/Phyto-83-759

10.1111/j.1365-3059.1995.tb02651.x

10.1094/PHYTO.1997.87.5.542

Kish, L. 1965. Survey Sampling. John Wiley & Sons, Inc., New York.

10.1146/annurev.py.33.090195.002525

Mathews, D. M., Riley, K., and Dodds, J. A. 1995. Comparison of ELISA and PCR for the sensitive detection of citrus tristeza virus (CTV) in pooled leaf samples from sweet orange groves with a low incidence of infection. Pages 12-16 in: Proc. Conf. Int. Organ. Citrus Virol., 13th. J. V. De Graça, P. Moreno, and R. K. Yokomi, eds. IOCV (Int. Organ. Citrus Virol.), Riverside, CA.

10.1094/PDIS.1997.81.5.525

10.1093/jee/89.6.1468

10.1093/jee/79.6.1421

10.2307/2532311

10.1094/PD-79-0437

10.1094/Phyto-75-882

10.2307/2265776

10.2307/2347977

Thông tin
Thông tin xuất bản

Phytopathology

Tập 89 Số 6

487-494

Thông tin tác giả