Effects of aphids on seedling growth of lucerne lines. I. Blue-green aphid in field conditions (Acyrthosiphon kondoi Shinji)

Abstract

Twenty-three lucerne lines introduced into Australia from the United States of America and two Australian cultivars (Hunter River and Falkiner) were screened for resistance to the blue-green aphid (Acyrthosiphon kondoi Shinji) (BGA), in the seedling stage under rain grown field conditions. Considerable tolerance to BGA was shown by seedlings of all lines infested at the 2-3 trifoliate leaf stage, as no seedling mortality occurred in the presence of high aphid populations. Using the suppression of both plant height and dry matter production as indices, six imported lines exhibited greater resistance than the others. These were DK 167, AS 49, WL 31 8, AS 13, WL 51 4 and CUF 101. There was no relation between the resistance expressed and the aphid population carried.