Call Prefix : PR-T

Call Suffix : 2003

Call Cutter : D - TrAg 2

Location : SEARCA Library

Format : TD

Publisher : Kasetsart University,

Publication Date : January 2003

Publication Place : Thailand :

Summary : Field experiments were conducted at Suwan Farm, Northeastern Thailand during dry and wet seasons of 2000 and 2001 to determine the species diversity of insect pests, natural enemies, weeds, and disease incidences of cotton. The randomized complete block design with four replicates was employed on four cotton varieties/lines, namely, AP1, AP2, SR60 (Si Samrong 60) and SD1 (Sarid 1). Shannon-Weaver diversity index was used for data analysis. It was found that 13-14 insect pests and 12-13 natural enemies appeared in cotton field regularly. The cotton leafhopper, Amrasca biguttula was observed to be the dominant species while the least abundant species was spiny bollworm, Earias sp. in both seasons. Various species of spiders were the most abundant natural enemy of dry season whereas antlike flower beetle, Anthicus ruficollis in wet season. Fusarium boll rot and leaf spot diseases were observed in dry season while damping-off and white rot in wet season. For weeds, approximate 14 species could occur in large numbers. Spatial distribution pattern and optimum sample size for cotton key pests. A bigutulla and the cotton bollworm, Helicoverpa armigera were analyzed using the variance to mean ratio, Morisita's index and the negative binomial parameter (k). While distribution of A. biguttula nymphs was found as clumped, H. armigera larvae exhibited mainly clumped but sometimes randomly disperse.