Identifier

etd-07062006-174751

Degree

Doctor of Philosophy (PhD)

Department

Plant, Environmental Management and Soil Sciences

Document Type

Dissertation

Abstract

In field research conducted over two years, red morningglory control 35 days after treatment (DAT) was at least 90 % with atrazine at 3.36 kg ai/ha, diuron plus hexazinone at 1.57 + 0.44 kg ai/ha, flumioxazin at 0.14 kg ai/ha, sulfentrazone at 0.21 kg ai/ha, and metribuzin at 2.52 kg ai/ha. At 49 DAT, atrazine at 4.48 kg/ha provided only 70 % control, which was equivalent to that for diuron plus hexazinone and flumioxazin. Sulfentrazone at 0.21 kg/ha controlled red morningglory at least 93 % 49 DAT and by 77 DAT control was 78 %. From June through October, red morningglory seedling emergence was compared for no tillage and tillage treatments. Seedling emergence was equal for the tillage treatments in July, but more seedlings emerged in August and September where plots were tilled. Total seedling emergence for the growing season was 129 plants/m2 for the no tillage treatment and 195 plants/m2 where plots were tilled. Seed population in soil from June through October for the treatments decreased an average of 34.7%. When grown under 30 and 50 % shade, red morningglory seedling emergence decreased around 8% compared with full sun. Increasing shade to 70 and 90 % decreased seedling emergence around 40 %. Shade did not affect red morningglory height, but biomass per plant under 90 % shade decreased 48 %. Red morningglory produced more leaf area per plant under a shade environment. In the sugarcane (Saccharum spp. hybrids) and weed competition study, red morningglory infestation in November, based on the degree of wrapping of sugarcane stalks, was 24 % when plots were maintained weed free until late June and allowed to re-infest thereafter, but was no more than 9% when weeds were allowed to re-infest in July and August. In November, re-infestation was around 8% where plots were weedy until June or July and red morningglory was removed at that point, but weeds were not present in November for the August removal treatments. For the various weed removal treatments, sugarcane and sugar yield were equivalent to the season long weed free control, but yields were reduced around 27 % when red morningglory competed with sugarcane season long.

Date

2006

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

James L. Griffin

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