|Hartzler, Robert - IOWA STATE UNIVERSITY|
Submitted to: North Central Weed Science Society US Proceedings
Publication Type: Proceedings
Publication Acceptance Date: December 12, 1996
Publication Date: N/A
Technical Abstract: Two thousand seeds of giant foxtail, woolly cupgrass, velvetleaf and common waterhemp were buried 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 after harvest. A randomized complete block design with five frames per species were used. Frames established in 1994 were tilled to a depth of 5 cm on April 5, 1996. Weed emergence was monitored throughout the 1995 and 1996 growing seasons by counting and removing all seedlings at three to four day intervals. Averaged over two seasons, emergence for first year seed was 36% for giant foxtail, 52% for woolly cupgrass, 8% for velvetleaf, and 14% for common waterhemp. There was no difference in emergence percentage for the two broadleaf species during 1995 and 1996 for 1994 seed, whereas emergence during 1996 for the grass species was approximately 25% of that observed in 1995. In the two years following burial of 1994 seed, emergence accounted for 41, 53, 16, and 12% of the buried seed from giant foxtail, woolly cupgrass, velvetleaf, and waterhemp, respectively. Each species had a characteristic emergence pattern that was consistent in both 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.