Submitted to: American Peanut Research and Education Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 7/14/2006
Publication Date: 7/15/2006
Citation: Faircloth, W.H., Webster, T.M., Grey, T.L., Flanders, J.T., Prostko, E.P. 2006. Critical Period of Tropical Spederwort (Commelina benghalenisis) in Peanut. American Society of Agri Engineers Special Meetings and Conferences Papers. 38:82. Interpretive Summary: None required.
Technical Abstract: Tropical spiderwort (also known as Benghal dayflower) is one of the most troublesome weeds in Georgia peanut. There are several effective tropical spiderwort control options in peanut, but there is no information concerning the critical time of tropical spiderwort interference with peanut. Field studies were conducted in 2004 and 2005 to evaluate the relationship between the duration of tropical spiderwort interference and peanut yield in an effort to optimize the timing of weed control efforts. Critical period of weed control (CPWC) studies are composed of two similar sets of treatments. The first set of treatments allowed tropical spiderwort to interfere with peanut for intervals of 2 to 10 and 2 to 7 weeks after crop emergence in 2004 and 2005, respectively. Weeds were removed following these intervals. In the second set of treatments, plots were kept free of tropical spiderwort for the same intervals, after which tropical spiderwort emerged and competed with peanut. These two companion studies were used to estimate CPWC. Standard, small plot research procedures were followed using the peanut cultivar ‘Georgia Green’. In 2004, the tropical spiderwort CPWC necessary to avoid greater than 10% peanut yield loss was between 326 and 559 growing degree days (GDD), which corresponded to an interval between June 8 and June 28. The base temperature for the calculation of GDD was 15.5C. In 2005, the CPWC ranged from 250 to 480 GDD, an interval between June 5 and June 27. Maximum yield loss in 2005 from season-long interference of tropical spiderwort was 51%. In 2004, production of peanut pods was completely eliminated by interference with tropical spiderwort for the initial six weeks (495 GDD) of the growing season. Robust tropical spiderwort growth in 2004 shaded the peanut crop, likely intercepting fungicide applications and causing a reduction in peanut yield. Therefore, the competitive effects of tropical spiderwort are likely confounded with the activity of plant pathogens. However, this is a realistic scenario that a producer would encounter and the season-long presence of tropical spiderwort was associated with complete crop failure. In spite of higher tropical spiderwort population densities, greater tropical spiderwort growth, and greater peanut yield losses in 2004 than in 2005, the CPWC was a relatively similar three-week period beginning in early June.