ARS | Publication request: EMERGENCE DATE AFFECTS GROWTH AND FECUNDITY OF REDROOT PIGWEED

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 28, 2004
Publication Date: July 28, 2004
Citation: Uscanga-Mortera, E., Forcella, F., Clay, S., Gunsolus, J. 2004. Emergence date affects growth and fecundity of redroot pigweed. [abstract]. Seventh International Conference on Precision Agriculture Conference Abstracts. p. 206.

Technical Abstract: New cropping systems such as minimum tillage coupled with the use of Roundup-Ready cultivars, have created a favorable environment for success of redroot pigweed (RRP), Amaranthus retroflexus. This species sometimes escapes control because of delayed seedling emergence. Our objectives were to determine: (1) the effect of simulated emergence date (transplanting date) on seed production of RRP that potentially could escape control under the Roundup-Ready system and (2) the effect of soybean and corn competition on the growth and seed production of RRP "emerging" at different times. Greenhouse grown seedlings with the first true leaf were planted in monoculture, or with soybean, or corn on 4th and 18th June and 2nd and 16th July in 2001 and 2002 in western Minnesota. Seedlings were placed between two crop rows (76 cm wide) and spaced 25 cm apart. RRP plants were monitored periodically for several morphological characteristics including height and diameter. RRP plant dry weight and seed production were determined at the end of the growing season. Biomass and seed production of RRP were not affected by emergence date for plants grown in monoculture. Plants emerging from 0 to 14 days after soybean emergence produced about twice as much seed as plants grown in corn. Late emerging RRP plants grown in association with crops produced less biomass and had less seed than plants emerging early. RRP plants grown in association with either soybean or corn produced almost no seed if they emerged greater than 28 days after crop emergence.