Effects of aphids on seedling growth of lucerne lines 3. Blue green aphid and spotted alfalfa aphid: a glasshouse study

Abstract

Seedlings of 23 lucerne (Medicago sativa) 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) and the spotted alfalfa aphid (Therioaphis trifolii (Monell) f. maculata) in separate experiments under glasshouse conditions. All lines were kept heavily infested from the unifoliate leaf stage, until the Hunter River controls died. The indices of resistance were plant mortality, suppression of plant height and dry matter production, and chlorosis of leaf veins (SAA experiment only). CUF 101 and WL 51 4, and to a lesser. extent, DK 185, AS 13R, WL 311, WL 508, PS 545, PS 581 and UC Cargo, were the most resistant to BGA, while AS 49, WL 600, Matador and Hunter River were the most susceptible. WL 508, PS 545 and PS 572, and to a lesser extent DK 185, WL 51 2, WL 51 4, CUF 101 and UC Cargo were the most resistant to SAA. While Hunter River was the most susceptible line, Falkiner, Amador, PS Victoria and AS 13 were severely debilitated.