Influence of Annual Spring Seeding of Alfalfa on Alfalfa Weevil Populations12

Abstract

Research was conducted on Ames Plantation at Grand Junction, Tennessee to determine if Hypera postica (Gyllenhal) infestations could be prevented or reduced by a change in cultural practice. It was postulated that if alfalfa were grown as an annual crop seeded each springinstead of as a perennial, weevil populations might be minimal because of the absence of the host crop during critical periods in the insect’s biology. The research was conducted at Ames Plantation because it comprised 18,000 acres where planting could be controlled and perennial alfalfa could be eliminated. It was found that spring-seeded alfalfa will escape serious in festation by the alfalfa weevil in Tennessee and probably as far north as the counties bordermg on the Ohio River in Indiana. This is because most weevil oviposition in the South occurs before the newly seeded crop emerges. It was found also that nonhardy varieties of alfalfa do not always winter kill. Therefore, to prevent weevil infestation by reseeding each spring with nonhardy varieties, fields should be rotated between other crops annually, or be plowed in the fall so that no plants survive to serve as reservoirs of infestation in the field.