Publication Date
1989
Description
Fusarium wilt of alfalfa (Medicago sativa L.) was first described in 1927 (Weimer, 1928) in the United States and has since been reported from many other areas of the world. The causal agent is Fusarium oxysporum Sehl. f. sp. medicaginis (Weimer) Snyd. & Hans. Shoots of infected plants become yellow and wilt ; often only one side of the plant is affected. The outer root xylem tissue turns reddish brown, and infected plants usually die within one season (Leath et al., 1988). The fungus is soil-borne, survives in organic debris, and can persist up to 10 years as chlamydospores in the soil. During the past 15 years, Fusarium wilt has increased in severity and prevalence in the northeastern U.S. The disease is of such consequence in some areas that resistant varieties are needed to provide satisfactory stap.d longevity. The clover root curculio (Sitona hispidulus L.) (Manglitz and Ratcliffe, 1988) causes severe injury to roots of alfalfa in much of the northeastern U.S. Generally, adults enter fields in the fall of the seeding year and lay eggs. Larvae hatch the following spring and feed on nodules and roots until pupation. Following emergence, adults again lay eggs on the soil around the plants, and this cycle repeats during each year of stand life. As larvae increase in size through five instars, they feed on successively larger roots, with later instars feeding on the taproots. Larval feeding injury has been recognized as serious on red clover (Trifolium pratense L.) for many years, but only within the past 15 years has it become serious on alfalfa. This research was undertaken to determine the importance of feeding activity by larvae of S. hispidulus in the infection of alfalfa roots by F. oxysporum f. sp. medicaginis.
Citation
Leath, K T. and Hower, A A., "Feeding Sites of Sitona Hispidulus Larvaw as Infection Foci for Fusarium oxysporum F. SP. Medicaginis in Alfalfa Roots" (2025). IGC Proceedings (1989-2023). 19.
https://uknowledge.uky.edu/igc/1989/session6/19
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Feeding Sites of Sitona Hispidulus Larvaw as Infection Foci for Fusarium oxysporum F. SP. Medicaginis in Alfalfa Roots
Fusarium wilt of alfalfa (Medicago sativa L.) was first described in 1927 (Weimer, 1928) in the United States and has since been reported from many other areas of the world. The causal agent is Fusarium oxysporum Sehl. f. sp. medicaginis (Weimer) Snyd. & Hans. Shoots of infected plants become yellow and wilt ; often only one side of the plant is affected. The outer root xylem tissue turns reddish brown, and infected plants usually die within one season (Leath et al., 1988). The fungus is soil-borne, survives in organic debris, and can persist up to 10 years as chlamydospores in the soil. During the past 15 years, Fusarium wilt has increased in severity and prevalence in the northeastern U.S. The disease is of such consequence in some areas that resistant varieties are needed to provide satisfactory stap.d longevity. The clover root curculio (Sitona hispidulus L.) (Manglitz and Ratcliffe, 1988) causes severe injury to roots of alfalfa in much of the northeastern U.S. Generally, adults enter fields in the fall of the seeding year and lay eggs. Larvae hatch the following spring and feed on nodules and roots until pupation. Following emergence, adults again lay eggs on the soil around the plants, and this cycle repeats during each year of stand life. As larvae increase in size through five instars, they feed on successively larger roots, with later instars feeding on the taproots. Larval feeding injury has been recognized as serious on red clover (Trifolium pratense L.) for many years, but only within the past 15 years has it become serious on alfalfa. This research was undertaken to determine the importance of feeding activity by larvae of S. hispidulus in the infection of alfalfa roots by F. oxysporum f. sp. medicaginis.
