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ARS Home » Research » Publications at this Location » Publication #86435

Title: EMERGENCE CHARACTERISTICS OF FOUR ANNUAL WEED SPECIES

Author
item HARTZLER, ROBERT - IOWA STATE UNIVERSITY
item Buhler, Douglas - Doug

Submitted to: Weed Science Society of America Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 2/12/1998
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Two thousand seeds of giant foxtail (Setaria faberi Herrm.), woolly cupgrass (Eriochloa villosa (Thumb.) Kunth), velvetleaf (Abutilon threophasti Medik.), and common waterhemp (Amaranthus rudis Sauer) were mixed in the upper 5 cm of soil contained in 45 by 58 cm wooden frames. Seeds were buried in the fall of 1994 and 1995 within eight weeks of seed harvest. A randomized complete block design with five replications per species was used. Soil was tilled to a depth of 5 cm in early spring of the second and third years following burial. Corn or soybean was planted in 91 cm rows between frames to simulate field conditions. Weed emergence was monitored during the 1995, 1996, and 1997 growing seasons by counting and removing all seedlings at three to four day intervals. Averaged over 2 years, emergence for first year seed was 36% for giant foxtail, 52% for woolly cupgrass, 8% for velvetleaf, and 14% for common waterhemp. In the 3 years following burial of 1994 seed, emergence accounted for 42, 54, 17, and 13% of the seed from giant foxtail, woolly cupgrass, velvetleaf, and waterhemp, respectively. Less than 1% of the 1994 seed of all species emerged during the third year after burial. Emergence in 1996 and 1997 accounted for 45% of giant foxtail, 64% of woolly cupgrass, 23% of velvetleaf, and 22% of common waterhemp seed buried in 1995. Each species had a characteristic emergence pattern that was consistent in all years. Woolly cupgrass was the first weed to emerge and reached 90% emergence within three weeks of initial emergence. Waterhemp was the last of the four species to initiate emergence and had a prolonged emergence pattern; 90% emergence did not occur until six weeks after initial emergence.