A line transect survey method for rice tungro disease

Bottenberg H., . and Litsinger J.A., . and Kenmore P.E., . (1990) A line transect survey method for rice tungro disease. [Proceedings Paper]

We investigated the potential of a new sampling method that is sensitive to low incidence levels of tungro the major virus disease of rice in South-east Asia yet can cover large rice areas in a relatively short period. Perpendicular distance data of tungro infected rice hills detected visually by an observer walking on rice field bunds were collected from 19 fields sampled randomly within a 1 km radius in two contiguous rice areas in the Krian Irrigation Scheme Malaysia in November 1983. Distance data were grouped into intervals of 4 rows for analysis to compensate for variation in planting distance. At low incidence levels spatial distribution of tungro was assumed not to be related to proximity to rice bunds. Each field represented a replicate line segment. Distance data were pooled to get one estimate of tungro incidence for each site. Fourier series models with one term were fit to perpendicular distance data collecte from each site. The Fourier estimators did not differ significantly from the frequency distributions of distance data. Tungro incidence was estimated at 5.9-2.1 infected rice hills/ha in Parit Hussein CV35.8 percent and 11.3-2.9 infected rice hills/ha in Parit Kasa CV25.6 percent. More reliable results can be obtained with longer transect lines and precise measurements of distance. In compliance to the basic assumptions of line transect theory scanning effort should be intense along the rice bund and decrease with distance into the field

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Abstract

We investigated the potential of a new sampling method that is sensitive to low incidence levels of tungro the major virus disease of rice in South-east Asia yet can cover large rice areas in a relatively short period. Perpendicular distance data of tungro infected rice hills detected visually by an observer walking on rice field bunds were collected from 19 fields sampled randomly within a 1 km radius in two contiguous rice areas in the Krian Irrigation Scheme Malaysia in November 1983. Distance data were grouped into intervals of 4 rows for analysis to compensate for variation in planting distance. At low incidence levels spatial distribution of tungro was assumed not to be related to proximity to rice bunds. Each field represented a replicate line segment. Distance data were pooled to get one estimate of tungro incidence for each site. Fourier series models with one term were fit to perpendicular distance data collecte from each site. The Fourier estimators did not differ significantly from the frequency distributions of distance data. Tungro incidence was estimated at 5.9-2.1 infected rice hills/ha in Parit Hussein CV35.8 percent and 11.3-2.9 infected rice hills/ha in Parit Kasa CV25.6 percent. More reliable results can be obtained with longer transect lines and precise measurements of distance. In compliance to the basic assumptions of line transect theory scanning effort should be intense along the rice bund and decrease with distance into the field

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Item Type:	Proceedings Paper
Additional Information:	Summary En
AGROVOC Term:	ORYZA SATIVA
AGROVOC Term:	VIGILANCIA DE ENFERMEDADES/ VIRUS DE LAS PLANTAS
AGROVOC Term:	MUESTREO
Geographical Term:	MALAYSIA
Depositing User:	Ms. Norfaezah Khomsan
Last Modified:	24 Apr 2025 05:26
URI:	http://webagris.upm.edu.my/id/eprint/15317

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