비트 흰띠명나방의 경제적 피해수준 설정

Abstract

Abstract This study was carried out to determine the economic injury level and economic threshold levelon beet (Beta vulgaris L.) infested with Spoladea recurvalis in the plastic greenhouse condition in 2010. Thesecond instar larvae of S. recurvalis were inoculated with 7 different density levels on the each 10 beet plantsas a replication. Injury levels of beet leaves and density of S. recurvalis were increased with the inoculationdensity of S. recurvalis. However, yield and marketable commodity of beet were decreased. Linearrelationship between the percent yield reduction (Y) of beet leaves and different infestation densities of S.recurvalis (X) was estimated by the following equation Y = 1.226x + 3.36. Based on the relationshipsbetween the densities of S. recurvalis larvae and yield index of beet leaves, the number of second instarlarvae which caused 5% loss of yield, economic threshold level was estimated as 1.1 larvae/10 plants for theplanting 10 days. The percent yield reduction (Y) of beet roots infested with different densities of S.recurvalis (X) estimated by the following equation Y = 1.537x + 1.4634 after inoculation for 10 days at 3rdharvesting of leaves. Based on the relationships between the densities of S. recurvalis larvae and yield indexof beet roots, the number of second instar larvae which caused 5% loss of yield, economic threshold levelwas estimated as 6.4 larvae/10 plants for the planting 10 days. Key words Beet, Economic injury level, Economic threshold level, Spoladea recurvalis