Degree Name

Master of Science (MS)

Semester of Degree Completion

1980

Thesis Director

Grant G. Gray

Abstract

Three corn inbreds were grown in artificially inoculated, steamed greenhouse soil amended with atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) to determine the herbicide's effect on the severity of Gibberella zeae (Schwabe) Petch-induced seedling blight. Corn inbreds used were Gibberella-resistant (FR632), Gibberella-intermediate (FRMo17), and Gibberella-susceptible (C123HT). Soils were amended with atrazine at rates of 2, 15, and 30 ppm.

Susceptible inbred seedlings showed no response to the herbicide with symptims equally severe in controls and all 3 concentrations of atrazine. Intermediate inbred seedlings grown in all atrazine amended soils showed significantly more severe disease symptoms than controls. Soil amended with 15 ppm atrazine produced the most severely infected plants with 30 and 2 ppm showing less severe symptoms respectively. Resistant inbred seedlings showed significantly less severe symptoms than controls when grown in soils amended with 15 and 30 ppm atrazine, while soil amended with 2 ppm produced seedlings with symptoms significantly more severe than those in the control.

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