Yellow nutsedge control with metham-sodium in transplanted cantaloupe

Authors: Johnson, Wiley - Carroll

Submitted to: International Conference on Methyl Bromide Alternatives and Emissions Reductions
Publication Type: Proceedings
Publication Acceptance Date: 10/21/2006
Publication Date: 11/6/2006
Citation: Johnson, W.C. 2006. Yellow nutsedge control with metham-sodium in transplanted cantaloupe. Proc. 2006 Methyl Bromide Alternatives Conferencer, November 6-9, 2006, Orlando, FL. pp. 115-1 - 115-7.

Interpretive Summary: Metham-sodium has been identified as a possible alternative to methyl bromide fumigation for weed control in transplanted vegetable crops. However, questions persist regarding the optimum combination of preplant fumigation interval, rate, and seedbed mulching with a polyethylene tarp. Trials were conducted in Tifton, GA from 2001 to 2003 to evaluate all possible combinations of preplant fumigation intervals (1-wk, 2-wk, or 3-wk before transplanting), three metham-sodium rates (nontreated, 40 gal./A, and 80 gal./A rate), and mulching (bareground or black polyethylene mulched seedbeds). Metham-sodium sprayed and incorporated 2-wk before transplanting effectively controlled yellow nutsedge, with minimal fumigant phytotoxicity to cantaloupe. In contrast, metham-sodium fumigation 3-wk before transplanting was not as effective in controlling yellow nutsedge as fumigation closer to transplanting. Black polyethylene mulch improved yellow nutsedge control and increased cantaloupe yield compared to bareground seedbeds. Plots fumigated with metham-sodium at 80 gal./A had greater yield than either non-fumigated plots or plots treated with metham-sodium at 40 gal./A. Cantaloupe yield response was attributed to superior yellow nutsedge control. These results show that metham-sodium at 80 gal./A, sprayed and incorporated 2- to 3-wk before transplanting, with seedbeds immediately covered with black polyethylene mulch, is a cost-effective alternative to methyl bromide fumigation for perennial nutsedge control.

Technical Abstract: Trials were conducted from 2001 through 2003 in Tifton, GA to determine the optimum combination of preplant fumigation interval, metham-sodium rate, and polyethylene mulching for yellow nutsedge control in transplanted cantaloupe. The trial evaluated all possible combinations of preplant fumigation intervals (1-wk, 2-wk, or 3-wk before transplanting), three metham-sodium rates (nontreated, 374 l/ha, and 748 l/ha), and seedbed mulching (bareground or black polyethylene mulched seedbeds). Metham-sodium sprayed and incorporated 2-wk before transplanting effectively controlled yellow nutsedge, with minimal fumigant phytotoxicity. Metham-sodium applied 1-wk before transplanting provided acceptable yellow nutsedge control, but stunted cantaloupe. In contrast, metham-sodium fumigation 3-wk before transplanting was not as effective in controlling yellow nutsedge as fumigation closer to transplanting. Black polyethylene mulch improved yellow nutsedge control and increased yield across all possible combinations of preplant fumigation intervals and metham-sodium rates. Plots fumigated with metham-sodium at the 749 l/ha had better yellow nutsedge control and greater yield than either non-fumigated or treated with metham-sodium at 374 l/ha. Cantaloupe yield response was attributed to superior yellow nutsedge control across all mulching treatments provided by the 748 l/ha. Black polyethylene mulch applied immediately prior to transplanting suppressed yellow nutsedge emergence without the need for metham-sodium fumigation, giving transplanted cantaloupe the opportunity to shade seedbeds before weed emergence. This suggests a useful cultural practice for yellow nutsedge management in organic cropping systems.