Fumigant combinations for Cyperus esculentum L control

Abstract

The phase-out of methyl bromide as a soil fumigant has stimulated research into the use of other soil fumigants for weed control. Methyl bromide, methyl iodide, propargyl bromide, 1,3-dichloropropene (1,3-D) and metam-sodium were tested alone and in combination with chloropicrin in laboratory experiments to determine their efficacy against Cyperus esculentus L (yellow nutsedge) tubers. Propargyl bromide and metam-sodium were the most efficacious fumigants tested, with EC50 values of 3.7 and 6.5 microM, respectively. The relative potencies of methyl iodide and chloropicrin were not significantly different but were 2.6 and 2.9 times more potent than methyl bromide, respectively. The EC50 values for all fumigants other than 1,3-D were significantly lower than that of methyl bromide. Combining each fumigant with 17% chloropicrin resulted in a synergistic interaction. The greatest increase in potency between the expected result and the actual result was a relative potency of 3.8 with the methyl bromide/chloropicrin combination. The smallest increase in efficacy was with propargyl bromide and chloropicrin, with a relative potency of 1.5. There was no significant difference between the EC50 values of methyl bromide/chloropicrin and methyl iodide/chloropicrin combinations. Combining 1,3-D with 17% chloropicrin resulted in an EC50 value for C. esculentus control similar to that of methyl iodide applied alone.

Factors Influencing Metham Efficacy on Yellow Nutsedge (Cyperus esculentus) Tubers

“…The soil used in this research had not been treated with metham for 5 yr or longer. Another possible explanation for difference between this and previous work is that germination was recorded for up to 6 wk after treatment in this trial, whereas Hutchinson et al (2003) only evaluated germination 5 d after fumigation. In this trial, significant shoot emergence continued to occur up to 2 wk after fumigation.…”

“…In the field, where MITC is lost to the atmosphere, warmer soil temperatures, while increasing the conversion of metham to MITC, are also likely to increase MITC loss from the soil to the air (Saeed et al 2000). I 50 values in our trial were magnitudes greater than reported by Hutchinson et al (2003). Tuber treatment, temperature, soil moisture, and exposure duration for their research fell within parameters used in this trial.…”

Weed Community Composition in Tree Fruit Nurseries Treated with Methyl Bromide and Alternative Fumigants

“…Vill., Geranium carolinianum L., Gnaphalium purpureum L., Oenothera laciniata Hill. (Csinos et al 2000), Cyperus esculentus L. (Hutchinson et al, 2004), Polygonum aviculare L., and Portulaca oleracea L. (Haar et al, 2003). However, this fumigant provided poor control of Malva parviflora L. and Erodium cicutarium (L.) L'Hér.…”

Methyl Iodide

“…Similarly, Ohr et al (1996) and Zhang et al (1997) concluded that MeI appears to be a suitable replacement for MeBr because it can be used in similar situations and has a superior efficacy against a broad spectrum of weed pests. In the control of yellow nutsedge tubers, Hutchinson et al (2004) reported that MeI was around 2.6 times more potent that MeBr, and that combining MeI with 17% chloropicrin resulted in a synergistic interaction and an improved control of the pest. The same authors also noted that MeI produced similar control of the pest to a combination of 1,3-dichloropropene with 17% chloropicrin (essentially the commercial product, Telone C-17).…”