Document Type

Thesis - Open Access

Award Date

1982

Degree Name

Master of Science (MS)

Department

Plant Science

First Advisor

David D. Walgenbach

Abstract

The northern corn rootworm, Diabrotica longicornis barberi, is a major pest of corn in South Dakota. It has one generation per year and overwinters in the soil as an egg. The eggs hatch in June and the larvae begin feeding on developing corn roots. The loss of roots reduces the uptake of water and nutrients, which can reduce yields especially under dry conditions. Root pruning by the larvae also weakens the brace root system, which may cause the plant to lodge, making harvesting difficult. Corn is the preferred host plant, although larvae have been reported surviving on several other species of grasses. After pupation in the soil, adults begin to emerge in mid-July and continue through August. The males emerge three to five days before the females. Mating occurs shortly after the females emerge and oviposition begins 14 to 20 days later. The oviposition period begins in early August and continues until the first killing frost. The adults feed on fresh corn silks and pollen but disperse to feed on various flowering weeds and crops when fresh silks and pol1en are no 1onger avai1ab1e. Recommendations for corn rootworm control include crop rotation or the use of a soil insecticide. Crop rotation is generally effective as a control measure because planting a crop other than corn results in larval mortality due to starvation. However, reports of the failure of crop rotation to control corn rootworms have occurred in corn following small grains and f1ax. The postulated reasons for this occurrence were re1aterl to the amount of weed growth in the stubble after harvest. Volunteer small grain and a number of weed species have been found attractive as feeding sites for adult corn rootworms and may also serve as oviposition sites. The environmental, edaphic and ground cover conditions responsible for attracting corn rootworms into these fields are not fully understood. The erratic occurrence of first year corn damage causes many farmers to treat first year cornfields with a soil insecticide as an insurance measure. This adds to the difficulty in obtaining an accurate estimate of first year corn damage in South Dakota. The objective of this study was to document the extent of northern corn rootworm damage to corn following small grains, flax and soybeans and to examine factors involved in its occurrence.

Library of Congress Subject Headings

Northern corn rootworm
Corn -- Diseases and pests
Corn -- Diseases and pests -- South Dakota

Format

application/pdf

Number of Pages

71

Publisher

South Dakota State University

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