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Title: GIANT RAGWEED EMERGENCE AND DEVELOPMENT UNDER DIFFERENT CROPPING SYSTEMS

Author
item MAERTENS, KURT - UNIV OF ILLINOIS
item SPRAGUE, CHRISTY - UNIV OF ILLINOIS
item WAX, LOYD

Submitted to: North Central Weed Science Society US Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 12/14/2001
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: In 2001, a field experiment was conducted at the University of Illinois Northern Illinois Agronomy Research Center in DeKalb. The objectives of this study were to: 1) evaluate giant ragweed emergence under three cropping systems, and 2) monitor growth and seed production of selected giant ragweed plants in these cropping systems. The experiment was set up as a randomized complete block design with four replications of 6.1 m by 9.1 m plots in a heavy natural infestation of giant ragweed. The cropping systems were soybeans, and corn planted in 76.2 cm rows, and no crop. Giant ragweed emergence was monitored weekly in two 1.0 m2 fixed quadrats from April 10 through mid-July. After giant ragweed emergence, plots were kept weed-free, except for one plant per plot every two weeds to monitor growth and seed production. Peak emergence occurred in the first two weeks and accounted for 50% of the total plants; however, emergence continued into July. Different cropping systems did not significantly affect the rate of giant ragweed emergence. Emergence time and cropping system did have an effect on giant ragweed's ability to compete. Competition with corn greatly suppressed dry weight and seed production of later emerging giant ragweed plants. Giant ragweed plants with no competition produced significantly more dry matter than plants grown in soybeans or corn. Emergence time significantly affected giant ragweed biomass for all three cropping systems; however, emergence time did not have a significant affect on seed production when grown in soybeans. This research shows that different cropping systems do not affect the rate of giant ragweed emergence, but do affect growth and seed production.