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|Title:||The life history and control of bigroot morning glory (Ipomoea pandurata)|
|Author(s):||Horak, Michael Joseph|
|Doctoral Committee Chair(s):||Wax, Loyd M.|
|Department / Program:||Agronomy|
|Degree Granting Institution:||University of Illinois at Urbana-Champaign|
Biology, Plant Physiology
|Abstract:||Bigroot morningglory is a large rooted perennial weed which can be difficult to control due to a late emergence time, a large tap root which occurs below the plow layer, and the ability to reproduce from root cuttings or seed. Studies on bigroot morningglory germination, emergence, and growth and on herbicide efficacy, absorption and translocation in this weed, were conducted with the goal of developing effective control measures.
Studies showed increased seed germination with chemical or mechanical scarification. The optimum temperatures for germination were 20 or 25 C, while the best pH range for germination was between 6 and 8.5. Plant establishment was greatest at the 2 to 4 cm planting depth and decreased at greater depths. The emergence sequence of bigroot morningglory did not fit the models of hypogeal or epigeal germination. Plant establishment was rapid with 85% of 11 day old seedlings able to sprout after shoot removal.
Emergence of bigroot morningglory occurred 75 growing degree days (GDD) after seeding. Flowering and seed production began 630 GDD after emergence and continued until the first killing frost. Massive accumulation of dry matter occurred after 600 GDD for shoots and 900 GDD for the roots. First year plants became true perennials within six weeks of germination.
Excellent seedling control was obtained with triclopyr (99%), fluroxypyr (91%) and 2,4-D (95%). In field studies on established populations, the best season long suppression was obtained with 2,4-D or triclopyr at an early June application, or triclopyr at an early July application. Ratings taken the spring following treatment showed that glyphosate resulted in the best long term control.
Herbicide efficacy studies revealed that clopyralid, a compound with similar chemical and physiological characteristics to triclopyr, was ineffective on bigroot morningglory. Studies on these two compounds in bigroot morningglory were conducted to determine if absorption and translocation differences could account for differential control observed. Both compounds were readily absorbed (60% absorbed of total recovered at 144 h). Triclopyr was readily translocated, and at 24 h 15% of the herbicide absorbed had moved to the roots. Clopyralid translocation was also rapid and within 24 h, 20% had moved to the roots. It was concluded that absorption and translocation differences could not account for the differential efficacy.
|Rights Information:||Copyright 1990 Horak, Michael Joseph|
|Date Available in IDEALS:||2011-05-07|
|Identifier in Online Catalog:||AAI9026208|