Methyl Iodide Fumigation Research Articles

Impact of sporicidal fumigation with methyl bromide or methyl iodide on electronic equipment

The effect of sporicidal fumigation with methyl bromide or methyl iodide on the functionality of valuable electronic equipment was evaluated using desktop computers as surrogates under target conditions of 200–250 mg/L fumigant for 48 h at 24–30 °C and 75–85% RH. Methyl iodide fumigation damaged light-emitting diodes and optical films in computer displays that were powered-on during fumigation. After five months of post-fumigation operation, five out of six methyl-bromide-fumigated and all six methyl-iodide-fumigated DVD ± RW optical drives failed. Deterioration of rubber spacers critical to maintaining correct disc geometry caused the failure. Metal coupons, included to measure corrosion, showed no significant differences in weight gain between control and fumigation conditions. Relative humidity sensors exhibited a substantial and sometimes irreversible reduction in sensitivity during and after methyl iodide fumigation. Methyl bromide and methyl iodide can cause damage to electronic equipment, but damage seems to be limited to organic materials rather than corrosion of metal surfaces.

Transport and Fate of Methyl Iodide and Its Pest Control in Soils

For fumigants, information on transport and fate as well as pest control is needed to develop management practices with the fewest negative environmental effects while offering sufficient pest control efficacy. For this purpose, a 2-D soil chamber with a surface-mounted flux chamber was designed to determine volatilization, real-time soil gas-phase concentration, degradation, and organism survivability after methyl iodide (MeI) fumigation. Three types of pests were used to give a broad spectrum of pest control information. An infected sandy loam soil with a volumetric water content of 10.6% was packed carefully into the 2-D chamber to a bulk density of 1.34 g cm(-3). After MeI fumigation at a rate of 56.4 kg ha(-1) for 24 h, about 28.9% of MeI was emitted into air, 6.8% remained in the soil, and 43.6% degraded in the soil (based on the residual iodide concentration). The uncertainty in the measured MeI degradation using iodide concentration was thought to mainly contribute to the unrecovered MeI (about 20%). The citrus nematodes [Tylenchulus semipenetrans] were effectively eliminated even at low concentration-time (CT) values (<30 microg h mL(-1)), but all Fusarium oxysporum survived. The response of barnyardgrass seeds [Echinochloa crus-galli] spatially varied with the CT values in the chamber. To fully control barnyardgrass seeds, CT of greater than 300 microg h mL(-1) was required. Using this experimental approach, different fumigant emission reduction strategies can be tested, and mathematical models can be verified to determine which strategies produce the least emission to the atmosphere while maintaining sufficient pest control efficacy.

Effect of methyl iodide fumigation on soil urease activity

Effect of methyl iodide fumigation on soil urease activity

Effects of methyl iodide fumigation on biological specimen DNA

Effects of methyl iodide fumigation on biological specimen DNA

Effects of Selected Marigold Varieties on Root-knot Nematodes and Tomato and Melon Yields.

Field experiments were conducted at two sites in California to evaluate the effects of marigold genotypes Tagetes patula var. Single Gold and Tagetes hybrid var. Polynema on Meloidogyne incognita infestation, root-galling, and yields of tomato grown immediately after marigold. Marigold cultivars were compared with a fallow control and with methyl iodide fumigation of soil prior to cultivation of M. incognita-susceptible and M. incognita-resistant tomato. Tomato yields after marigold were ca. 50% higher than after fallow. Marigold Single Gold consistently reduced nematode infestation and galling of tomato roots. Results were not significantly different between methyl iodide fumigation or marigold Single Gold at one site, but methyl iodide outperformed both marigold varieties at the other site. At one site, where melon var. Durango was grown during spring and summer of the year following cultivation of marigolds Single Gold and Polynema, melon yield increases of 95 and 45%, respectively, were still obtained.

Effects of carbonyl sulfide, methyl iodide, and sulfuryl fluoride on fruit phytotoxicity and insect mortality

SummaryThree potential chemical fumigants: carbonyl sulfide (COS), methyl iodide (MI) and sulfuryl fluoride (SF) were tested at selected dosages on lemons against California red scale (Aonidiella aurantii) and MI and COS were tested on nectarines against codling moth (Cydia pomonella). In nectarines, COS was tested at 0, 20, 40, 60 and 80 mg litre−1, MI at 0, 10, 15, 20 and 25 mg litre−1. Both fumigants intensified nectarine peel color, delayed fruit softening, but did not alter overall fruit quality. COS at 80 mg litre−1 resulted in 87% codling moth mortality, but the fumigant dosage was insufficient to reach the desired probits 9 level (99.9968%). MI gave 100% codling moth mortality at 25 mg litre−1. Lemons were treated with MI at 0,10,20,40,60 mg litre−1, SF at 0,10,20,40, 80 mg litre−1 and COS at 0,20,40, 60 and 80 mg litre−1. MI gave 100% red scale mortality at ≥40 mg litre−1 but caused significant fruit injury. Conditioning lemons at 15°C for 3 days before MI fumigation lessened lemon phytotoxicity. Forced aeration at 3.5 standard litres per minute of lemons for 24 h following MI fumigation at 20 mg litre−1 significantly reduced phytotoxicity compared to 2 h postfumigation aeration after MI treatment. SF at ≥40 mg litre−1 gave 100% red scale mortality but resulted in commodity phytotoxicity. Lemons treated with the highest selected dose of 80 mg litre−1 COS gave only 87% kill of red scale, but failed to reach the desired probit 9 level.

Effect of soil physical factors on methyl iodide and methyl bromide

Production and importation of methyl bromide is scheduled to be banned by 2001. Methyl iodide was evaluated as a possible replacement soil fumigant. The effects of soil moisture, temperature, soil texture and fumigation time on the efficacy of methyl iodide for the control of two common weeds, Abutilon theophrasti and Lolium multiflorum, were characterized and compared with those of methyl bromide. The optimal soil moisture for methyl iodide to kill both weed species in sandy soils was 14% water content (w/w). Greater efficacy was obtained when the temperature during fumigation was above 20°C. Compared to methyl bromide, the efficacy of methyl iodide was more consistent in different soils. Time to 100% mortality of weeds was 24 h for methyl iodide fumigation and 36 h for methyl bromide when 200 μM of fumigant was used. On a molar basis methyl iodide was consistently more effective than methyl bromide across the range of environmental factors tested. In terms of application technology and spectrum of activity, methyl bromide can be directly replaced by methyl iodide. © 1998 SCI

Evaluation of methyl iodide as a soil fumigant in container and small field plot studies

Methyl iodide was evaluated as a soil fumigant as a potential replacement for the widely used soil fumigant methyl bromide. In container trials, methyl iodide was significantly more effective than methyl bromide against the plant parasitic nematodes Meloidogyne incognita, Heterodera schachtii and Tylenchulus semipenetrans and the plant pathogenic fungus Rhizoctonia solani. In small field plots, soil populations of root-knot nematodes were no longer detected after methyl iodide fumigation at an application rate of 112 kg ha-1. However, after growing a susceptible lima bean host for two months, substantial root-knot galling occurred, while Rhizobium nodulation was absent. At 168 kg ha-1 of methyl iodide, root-knot galling was reduced to less than 1%, and no Pythium propagules were recovered on selective detection media. These efficacy data support the conclusion that methyl iodide is a likely candidate for replacing methyl bromide as a soil fumigant. © 1998 SCI.

Dose response of weeds to methyl iodide and methyl bromide

SummaryLabonuory bioassay and field experiments were conducted to characterize the dose response of weeds to methyl iodide and methyl bromide as soil fumigants. The patterns in potency of both fumigants and in sensitivity of diffcretit weed species to the fumigants were distinguished with the use of logistic dose‐response models. Similar to its response to methyl hromide fumigation. Amaranthus retrofleus L. was the most sensitive to methyl iodide fumigation. Cyperus rotundtis L. was the least sensitive to methyl iodide fumigation, whereas Portuloca oleracea L. was the least sensitive to methyl hromide. Lolium multiflorum Lam. Abutilon theophrasti Medik.Chenopodium album L. P. ateracea. Brassica kaber (D.C.) L.C. Wheeler and Cyperus escuden‐tus L. were similar in sensitivity to methyl iodide. Methyl iodide was as potent as methyl bromide for A. retroflexus but more potent than methyl bromide for L. multiflorum, A. theophrasti. C. album. P. oleracea. B. kaber, C. esculentus and C. rotundus. The dose response for weeds in the field was similar to that obtained in laboratory bioassays. Under fieid conditions. 280 kg ha‐1 methyl iodide killed all species tested except Solanum nigrum L Methyl iodide appears to be a suitable replacement for meihyl bromide because it can be used in situations simitar to methyl bromide fumigation, has superior efficacy against a broad spectrum of pests and has a low potential for degrading the earth's ozone lavers.