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Document Type

Thesis - University Access Only

Award Date


Degree Name

Master of Science (MS)

Department / School


First Advisor

Robert W. Kieckhefer


In South Dakota, winter wheat, Triticum aestivum (L.), is normally sown in. September. After emergence, the plants are frequently infested with cereal aphids. They will survive and reproduce on the seedling wheat until killing, subfreezing temperatures occur, typically in mid-November. The bird cherry oat aphid (BCO), Rhopalosiphum padi (L.), is a major species involved in these autumn infestations. Infestations in the autumn by BCO are known to reduce yield in winter wheat. In addition, BCO is a known vector of the barley yellow dwarf virus (BYDV) which can cause substantial yield losses in wheat. Winter survival is a major limitation to growing winter wheat in the state. Since winter-hardy cultivars tend to yield less than nonwinter-hardy cultivars under mild growing conditions, growers throughout the state plant cultivars with an array of winterhardiness levels in an attempt to maximize winter survival and yield. The interaction of level of winterhardiness a cultivar possesses with tolerance to fall aphid feeding and BYDV inoculation is not known for yield and other agronomic traits. The objective of this research was to assess the effect of fall aphid feeding and BYDV inoculation on seed and plant yield, tiller number, and mature plant height in winter wheat cultivars differing in level of winterhardiness.

Library of Congress Subject Headings

Aphids as carriers of disease

Winter wheat -- Diseases and pests

Rye -- Diseases and pests

Barley yellow dwarf viruses



Number of Pages



South Dakota State University