Fumigation Temperature Research Articles

EFEKTIFITAS PEMANASAN KAMAR ASAP MELALUI DISTRIBUSI UDARA MASUK (FORCED DRIVE FAN/FDF) DAN UDARA KELUAR (INDUCED DRIVE FAN/IDF) PADA PENGOLAHAN KARET LEMBARAN (RIBBED SMOKE SHEET) : REVIEW

The smoke chamber used has a capacity of 3,420 kg with a rubber sheet smoking period of five days. Reducing the water content (moisture content) on the rubber sheet is used by heating it with a smoking system. For smoke chamber operations, the fumigation temperature used on the first day is 40 - 45°C, on the second day 45 - 50°C, on the third day 50 - 55°C, on the fourth day 55 - 60°C, and on the fifth day the smoking temperature was maintained at 60°C. FDF and IDF are two air distribution devices, where the FDF functions to blow the air into the smoke chamber and the IDF draws the air into the smoke chamber. The balance between exhaled air and that drawn out of the smoke chamber must be proportional. Too much airflow will collect in the smoke chamber and too much the air withdrawal will affect heat transfer. After installing the FDF and IDF tools, the smoking time is 4 (four) days, so the use of smoked wood (rubber stem wood) is reduced from 3.19 m3 (for 5 days of smoking) to 2.55 m3 (for 4 days of smoking). There is a saving of one operational day. Reducing the use of smoked wood has an impact on processing efficiency. Heat energy from smoking has also increased. Before the installation of the FDF and IDF devices, the amount of heat energy was 64,074 kcal/day (320,372 kcal in 5 days). After installing the FDF and IDF devices, they increase the amount of air / oxygen (O2) in the combustion process so that there is an additional heat energy of 9,461 kcal/day (47,305 kcal in 5 days). The total amount of heat energy produced is 367,677 kcal for 5 (five) days of smoking. FDF and IDF are two air blowers commonly known as blowers with their respective specifications: The FDF used has an electric power of 3 kilowatts (4 horsepower/hp) with a rotation of 1,420 rpm, while the IDF has an electric power of 7.5 kilowatts (10 horsepower/hp). hp) at 1,440 rpm.

Experimental Investigation on Performance and Emission Characteristics of Diesel Lean Burn HCCI Engines

The purpose of this study is to analyse the effect of premixed diesel fumigation on the performance and emission characteristics of Homogeneous Charge Combustion Ignition (HCCI) engine and to optimize the diesel fumigation temperature. An experimental investigation was carried out on a single cylinder, four stroke, water cooled, port injected Kirloskar SVI engine. An electric air heater is fixed at the suction pipe. During the experimental study, the diesel fuel was premixed by port injector and get vaporized or fumigated by heated suction air. After the process of heating and premixing, the diesel has changed its phase and mixed with the air in the form of partially homogenous mixture. During the test, the engine was operated at different diesel fumigation temperature of 100 C, 110 C, 120 C, 130 C, 140 C and 150 C to assess the performance and emissions characteristics of the engine. It is observed that the diesel fumigation has made the huge impact on NOx and smoke formation. The emission of NOx and smoke were decreased simultaneously about 10% and 16% compared to the compression ignition engine. Moreover, this engine has produced high amount of CO and HC emissions at low fumigation temperature and also reduced the high fumigation temperature. The suction air temperatures of 120ï‚°C and 130ï‚°C operated under HCCI engine were found to produce lesser NOx and smoke emissions. Moreover, the engine fuel consumption was increased due to the low volumetric efficiency and also slightly affected the brake thermal efficiency.

Temperature of the superglue fuming process under the scope of accreditation

The superglue fuming process is widely used to develop latent fingermarks in the forensic community. That is why we confidently submitted this method for accreditation both in our central and departmental forensic laboratories. A review by non-practitioner auditors raised a point for which we had no answer. “Why must you heat cyanoacrylate to 120 °C?”. While the influence of humidity on the quality of fingermark development has been abundantly studied and published, we found no publications about the optimal cyanoacrylate fumigation temperature. We wonder if the quality of a fingermark developed by the superglue fuming process could be better at a different temperature. The aim of this study is to estimate the influence of the fumigation temperature on the quality of developed fingermarks for a constant humidity rate. The results show that the quality of a fingermark is appreciably better at 150 °C but a temperature of 120 °C gives very satisfactory results.

Effect of Premixed Diesel Fumigation on Performance and Emissions Characteristics of Homogenous Charge Compression Ignition Engine

The effect of premixed diesel fumigation (PDF) on performance and emissions characteristics of Homogenous Charge Compression Ignition (HCCI) engine and optimisation of the diesel fumigation temperature are prime focus of this study. The experimental investigations were carried on single cylinder, four stroke, water cooled, port injected Kirloskar SV1 engine. For this research, the engine was modified as HCCI engine with electric air heater, fixed at suction pipe. During the experimental investigation the diesel fuel was premixed by the port injector and vaporised or fumigated the fuel by heated suction air. After heating process, the diesel has changed its phase and mixed with air and form partially homogenous mixture. During the test, the engine was operated with different diesel fumigation temperature from 100ï‚°C to 150ï‚°C in steps of 10ï‚°C and observed the performance and emissions characteristics of the engine. The effective diesel fumigation temperature for creating better homogeneous charge is identified. The diesel fumigation made huge impact on NOx and smoke formation. The level of NOx and smoke emissions were decreased simultaneously as 10% and 16% compared to compression ignition (CI) engine. At the same time, the HCCI engine has emitted high CO and HC emissions at low fumigation temperatures and they were reduced at high fumigation temperatures, because of improved combustion. The suction air temperatures of 120ï‚°C and 130ï‚°C for the HCCI engine registered low NOx and smoke emissions. From the performance point of view, the HCCI engine consumed much more fuel due to low volumetric efficiency and slightly affected the brake thermal efficiency.

Does Fumigation of Durum Wheat and Semolina with Sulfuryl Fluoride Affect Quality of the Grain, Semolina, and Derived Spaghetti and Bread?

There is no information on the effect of sulfuryl fluoride (SF) on durum wheat technological properties and products made from fumigated durum wheat. Durum wheat and semolina were exposed to a range of SF applications under conditions that might be typically encountered in bulk storage facilities used in many countries. SF greatly reduced the germination percentage of fumigated durum wheat, with increasing impact under higher SF concentration, grain moisture content, and fumigation temperature. SF greatly reduced seed germination percentage, impacting more the higher the SF concentration. SF had little to no effect on grain test weight, 1,000‐grain weight, hardness, protein content, semolina ash content, and mixograph properties. At the highest SF concentration (31.25 mg/L for 48 h) there was a tendency for pasta cooking loss to be increased but still acceptable, and other pasta properties were largely unaffected. Fumigation with SF did not have any impact on the baking properties of a wholemeal durum flour–commercial flour mix. Therefore, SF is not recommended if the grains are to be used as seeds for agricultural production, but for the production of semolina, pasta, and bread, SF used under typical fumigation conditions has little to no impact on technological properties of durum wheat.

Multiple quarantine treatment using bale compression and a three-day fumigation to control Hessian fly (Diptera: Cecidomyiidae) in exported hay.

A multiple quarantine treatment was developed to control Hessian fly puparia, Mayetiola destructor (Say), the stage of regulatory concern in exported hay. In a commercial test using 51.589 puparia, no insects survived to the adult stage after exposure to bale compression at 137 kg/cm2 and fumigation with 61 g/28.3 m3 hydrogen phosphide for 3d. The puparia were fumigated in infested wheat seedlings in cloth bags inside compressed timothy bales placed in different locations in three replicate freight containers in a heated building. Fumigant concentrations were 345-522 ppm on day 1; 580-824 ppm on day 2; and 680-861 ppm on day 3. Monitored temperatures were < 20 degrees C in all locations allowing the fumigation temperature to be established at > or = 20 degrees C. Copper detection plate corrosion values were severe inside the freight container doors, and moderate in the middle of bales in all locations, providing visual confirmation of exposure to hydrogen phosphide. Hydrogen phosphide residues in exposed hay bales were found in trace amounts, below the U.S. Environmental Protection Agency tolerance of 0.1 ppm for animal feeds. Timothy hay used in the commercial test is the representative species for all previously exported hay and straw species. The new multiple quarantine treatment is proposed for use with all previously tested bale sizes and wrapper styles for which 3-d fumigation data has been reported, and for bales and wrappers derived from those tested.

Approved Quarantine Treatment for Hessian Fly (Diptera: Cecidomyiidae) in Large-Size Hay Bales and Hessian Fly and Cereal Leaf Beetle (Coleoptera: Chrysomelidae) Control by Bale Compression

A quarantine treatment using bale compression (32 kg/cm2 pressure) and phosphine fumigation (61 g/28.3 m3 aluminum phosphide for 7 d at 20 degrees C) was approved to control Hessian fly, Mayetiola destructor (Say), in large-size, polypropylene fabric-wrapped bales exported from the western states to Japan. No Hessian fly puparia (45,366) survived to the adult stage in infested wheat, Triticum aestivum L., seedlings exposed to the treatment in a large-scale commercial test. Daily temperatures (mean +/- SEM) inside and among bales in three test freight containers were 17.8 +/- 0.2 front top, 17.0 +/- 0.2 front bottom, 17.3 +/- 0.2 middle bale, 15.7 +/- 0.3 middle air, 18.5 +/- 0.1 back top, and 18.1 +/- 0.1 degrees C back bottom, allowing the fumigation temperature to be established at > or = 20 degrees C. Mean fumigant concentrations ranged from 208 to 340 ppm during the first 3 d and ranged from 328 to 461 ppm after 7 d of fumigation. Copper plate corrosion values inside the doors, and in the middle of the large-size bales in all locations indicated moderate exposure to hydrogen phosphide (PH3). PH3 residues were below the U.S. Environmental Protection Agency tolerance of 0.1 ppm in animal feeds. The research was approved by Japan and U.S. regulatory agencies, and regulations were implemented on 20 May 2005. Compression in large-size bale compressors resulted in 3-3.6 and 0% survival of Hessian fly puparia and cereal leaf beetle, Oulema melanopus (L.), respectively. Bale compression can be used as a single treatment for cereal leaf beetle and as a component in a systems approach for quarantine control of Hessian fly.

Design of Fumigation Temperature Control System Based on Single-Chip Microcontroller

In order to mitigate problems such as temperature non-linearity, severe hysteresis, and large magnitude of fluctuation, we have designed a fumigation temperature control system based on AT89C52 single-chip microcontroller. The combination of improved PID algorithm and Pulse Width Modulation (PMW) technology results in whole-process fumigation temperature controlling with reduced overshoot and shortened lag time. Our test results show that the design leads to superior temperature control capability and dynamic performance. The fumigation temperature control system based on this design has very good stability and reliability, with friendly user-machine interface that allows easy operation. The circuits and programs used in the design have good versatility and portability.

Evaluation of the Factors Affecting the Phosphine Residue in the Fumigation–Aeration Process of Stored Wheat Using Orthogonal Array Design

Factors that affect the phosphine residue in the fumigation–aeration process were studied. Simulated experiments were carried out on the samples in nine different conditions (nine treatments using L9 orthogonal array on four factors: amount of aluminum phosphide, fumigation time, aeration time, and fumigation temperature). The extracted phosphine residue of grains was quantified by UV/visible spectrophotometry at 410 nm. The results revealed that the most important factors are the aeration and fumigation time. The fumigation temperature has negligible effect on the phosphine residue, and there is no significant effect from the amount of aluminum phosphide. Under optimum conditions, the phosphine residue content was 0.0067 mg/kg of wheat grain, which is very less than the reported amounts by related organizations.

Dose Response of Weed Seeds, Plant-Parasitic Nematodes, and Pathogens to Twelve Rates of Metam Sodium in a California Soil

Metam sodium (sodium N-methyl dithiocarbamate, metam-Na) is widely used in agricultural and floricultural production for controlling soilborne plant pathogens, parasitic nematodes, and weeds. It undergoes rapid decomposition to the biocide methyl isothiocyanate (MITC) in moist soils. In this study, the efficacy of 12 concentrations of metam-Na (10 to 2,650 μmol kg-1 soil) to control seeds or tubers of five major weed species, three soilborne pathogens, and one parasitic nematode was evaluated in a sandy loam soil under controlled conditions. Soils were exposed to the fumigant in microcosms for 24 h at 10 and 20°C. Generation and dissipation curves of MITC in soil under controlled conditions showed that MITC concentrations in soils were highest 2 h after metam-Na application and decreased steadily over the 24-h incubation period. After 24 h, remaining MITC concentrations in soil microcosms at 10 and 20°C were 53 and 38% of the original amount applied, respectively, indicating a 20% reduction in MITC dissipation at the lower soil temperature. Logistic dose-response models were used to estimate the effective concentration necessary to reduce soil pest viability by 50 (LC50) or 90 (LC90) percent under both temperatures. Seed of Portulaca oleracea, with LC90 values of ≤1,242 μmol kg-1 soil, was the most sensitive to soil fumigation with metam-Na, followed by Polygonum arenastrum with LC90 values of ≤1,922 μmol kg-1 soil. At 10°C fumigation temperature, metam-Na at the highest dose tested in this study, 2,650 μmol kg-1 soil, was not sufficient to achieve adequate control of Stellaria media and Malva parviflora seed and Cyperus esculentus tubers. Weed control efficacy (average reduction in LC90 values) of metam-Na was between 25 and 60% higher if soils were fumigated at 20°C compared with 10°C, with the exception of M. parviflora. Phytophthora cactorum and Pythium ultimum were more sensitive to soil fumigation with metam-Na (LC90 ≤ 165 μmol kg-1 soil) than Verticillium dahliae (LC90 ≤ 737 μmol kg-1 soil). The nematode Tylenchulus semipenetrans was highly sensitive to soil fumigation with metam-Na (LC90 ≤ 98 μmol kg-1 soil), and the efficacy of control increased by 30% if soil was fumigated at 20°C compared with 10°C. In this sandy loam soil, metam-Na at a concentration of 850 μmol kg-1 reduced the viability of Portulaca oleracea and Polygonum arenastrum seeds, C. esculentus tubers, and all soilborne pathogens and parasitic nematodes tested by 90% at 20°C after 24 h exposure. These results indicate that metam-Na can provide effective pest and disease control at maximum label rate for the commercial formulation, but there was a reduction in efficacy at low temperature.

Effects of Methyl Bromide Concentration, Fumigation Time, and Fumigation Temperature on Mediterranean and Oriental Fruit Fly (Diptera: Tephritidae) Egg and Larval Survival

The effects of methyl bromide (MB) concentration (16, 32,48, or 64 g/m3), fumigation temperature (15, 20, 25, or 30 degrees C), and fumigation time interactions on the survival of Mediterranean fruit fly, Ceratitis capitata (Wiedemann), and oriental fruit fly, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae), eggs and first and third instars were recorded. Increasing the fumigation temperature from 15 to 20 degrees C or from 20 to 25 degrees C resulted in a significant reduction in fumigation time required for equivalent egg and larval mortalities at all studied MB concentrations; no further reductions in fumigation time resulted from increasing the temperature from 25 to 30 degrees C. Conversely, increasing temperature and time allowed for a reduction in MB concentration to obtain equivalent mortality. Thus, the optimum fumigation temperature for Mediterranean and oriental fruit fly eggs and larvae was 25 degrees C. Reducing MB concentrations required for phytosanitary fumigations would save time and expense, and reduce the amount of MB released into the atmosphere during aeration. Mediterranean fruit fly was as or more tolerant to MB than oriental fruit fly in MB tolerance for eggs and first instars. The egg stage was generally more tolerant to MB regardless of concentration. However, Mediterranean fruit fly eggs showed similar tolerance to first instars at 25 degrees C for the three highest concentrations and to third instars at 25 and 30 degrees C for the highest concentration, with no significant difference between them. Therefore, eggs alone can be used to obtain MB fumigation efficacy and quarantine security data at fumigation temperatures between 15 and 30 degrees C for Mediterranean and oriental fruit fly.

Development of non-chemical disinfestation procedures in New Zealand using non-empirical, multi-disciplinary research

Abstract Non-chemical disinfestation procedures are urgently required for those horticultural exports currently fumigated in New Zealand and overseas with methyl bromide, and for South Pacific imports fumigated with ethylene dibromide (EDB). Restrictions on the use of EDB are imminent. Disinfestation research in New Zealand seeks to develop non-chemical procedures as substitutes for these chemical fumigants. Chemical postharvest disinfestation procedures were largely developed empirically by entomologists and plant physiologists, varying the parameters of fumigant dose, fumigation temperature, and treatment duration. In contrast, non-chemical procedures require a less empirical and more multi-disciplinary approach. This is discussed with reference to pre-shipment clearance and pest reclassification procedures, and non-chemical treatments induding high temperature, controlled atmospheres, and modified atmosphere packaging. A recent revision of the New Zealand quarantine regulations for imports results in r...

QUALITY CHARACTERISTICS OF ‘BING’ AND ‘RAINIER’ SWEET CHERRIES TREATED WITH GIBBERELLIC ACID, FOLLOWING FUMIGATION WITH METHYL BROMIDE

ABSTRACTMethyl bromide (MeBr) fumigation did not significantly influence weight loss, fruit color or soluble solids of either ‘Bing’ or ‘Rainier’ sweet cherries. MeBr increased pitting and reduced objective and subjective stem color of both cultivars. There was a slight advantage in quality (bruising, pitting and stem color) for the 48g/m3 at 12°C over the 64g/m3 at 6°C MeBr treatment. As fumigation temperature increased, bruising and pitting increased and stem color decreased. Use of gibberellic acid resulted in increased firmness for ‘Bing’ cherries and superior fruit and stem color with less pitting for both ‘Bing’ and ‘Rainier’ cherries.

Factors affecting the efficacy of methyl bromide fumigation to control Liriomyza trifolii in imported chrysanthemum cuttings

SUMMARYLaboratory investigations were made into the effect of cultivar type, prior cold storage, fumigation temperature and methyl bromide concentration, on the efficacy of a fumigation treatment to control Liriomyza trifolii in chrysanthemum cuttings. The tests related to the standard quarantine treatment used in the UK to control Spodoptera littoralis on imported chrysanthemum cuttings: cold storage for 2 days at 1 – 2°C followed by methyl bromide fumigation at 15°C with a concentration time product (CTP) of 54 g h/m3. L. trifolii larvae, within detached leaves, and 1 – 2 and 2 – 3 day old pupae, were treated. Methyl bromide concentrations of 6·75 or 13·5 g/m3 were used to achieve a range of CTPs and thus obtain accurate dose‐response lines and estimates of the LD99 and LD99·9 for each insect stage. Fumigation temperatures were 8, 11 or 15°C.Efficacy of the standard treatments differed between the three cultivars tested, but the LD99 for larvae remained below 54 g h/m3. Decreasing fumigation temperature to 11°C or less increased LD99 values for larvae and pupae and substantially increased variability. There is therefore little scope for using fumigation temperatures of less than 15°C for quarantine purposes. Omitting the cold storage treatment prior to fumigation did not significantly affect efficacy of fumigation. Reducing the methyl bromide concentration from 13·5 to 6·75 g/m3 did not significantly affect the LD99 for larvae but significantly reduced LD99s for pupae.

Response of SO2-fumigated Pinus resinosa seedlings to postfuniigation temperature

Effects of postfumigation temperature on SO2-fumigated seedlings of red pine (Pinus resinosa Ait.) were studied. Seedlings were fumigated with either 0.2 ppm SO2 for 91 h or with 0.5 ppm SO2 for 30 h. Seedling injury was much greater at the higher SO2 concentration. At the lower SO2 concentration, only root weight of fumigated seedlings was affected, and it was about 20% less than that of unfumigated controls after 6 weeks at 12, 22, or 32 °C; there was no interaction between SO2 treatment and postfumigation temperature on growth rate. Postfumigation growth was reduced more by the higher concentration of SO2. Significant interaction between SO2 and postfumigation temperature occurred, with growth of roots, primary needles, and secondary needles being reduced most at 12 °C. At higher postfumigation temperatures, SO2-fumigated seedlings recovered (partially) and initiated secondary needles, thereby providing a new source of photosynthate and further reducing growth inhibition. But at 12 °C, shoot growth was slow and injured needle tissue was not replaced; hence the dry weight of roots of plants fumigated at the higher SO2 concentration was &lt;30% of that of controls after 6 weeks. Interpretation of effects of fumigation temperature on SO2 toxicity should also consider influences of postfumigation temperature regimes.

Oriental Fruit Fly: Factors Affecting Ethylene Dibromide Fumigation of Infested Papayas12

The minimal dose of ethylene dibromide (EOB) needed to obtain 99.997% mortality of eggs and larvae of Dacus dorsalis Hendel in papayas, Carica papaya L., varied with the concentration of EDB in the fumigation chamber, the type and number of containers, and the fumigation temperature. The effect of container type on the EDB concentration after 0.5 h of fumigation was increased adsorption of EDB in the following order: perforated polyethylene tray < painted wooden field box < wooden field box ≤ fiberboard carton. Hot water treatments to control anthracnose of papaya improved the efficacy of EDB fumigation and reduced EDB residues more as a postfumigation treatment than prefumigation treatment. The quarantine treatment developed for oriental fruit fly-infested papayas in perforated polyethylene trays was fumigation with 7 g EDB/m3 for 2 h at 21.1°C and loading of 46% (by volume). The EDB residues in such fumigated papayas after 1-, 3-, and 5-day storage in cartons at 12.8°C were 2.1±0.12, 0.6±0.05, and 0.4±0.07 ppm, respectively. When similarly treated fruits were hot water-treated for 20 min at 46.1°C after the fumigation, the residues, at similar times and storage, were 1.8±0.2, 0.5±0.05, and 0.1 ±0.02 ppm. The quarantine treatment developed for fruits in wooden field boxes was fumigation with 8 g EDB/m3 for 2 h at 21.1°C plus postfumigation hot water treatment at 60.6°c for 20 sec. For such fruits stored 1 and 3 days in cartons at 20.0°-25.6°C (ambient temperature), the EDB residues were 0.4±0.04 and 0.05 ppm to trace, respectively; after 1, 3, and 5 days of storage at 7.2°C, the residues were 2.1±0.13, 0.7±0.06, and 0.3±0.02 ppm, respectively.

Ethylene dibromide and inorganic bromide residues in oranges after fumigation and storage

Levels of residues of ethylene dibromide (EDB) and inorganic bromide were measured in oranges that had been fumigated by a new EDB fumigation schedule, for the control of Queensland fruit fly. This schedule is based on 24 g EDB m-3 at 20�C for 2 hours. The fumigation was conducted in 0.28 m3 chambers with 40% loading. After fumigation the fruit was held at the fumigation temperature for 24 hours then stored at 6�C for a further 27 days to simulate export conditions. EDB residues in excess of the 0.5 �g g-1 Australian NHMRC limit were recorded during the first 14 days, but by 28 days no EDB residues were detected. Inorganic bromide residues were well below the 30 �g g-1 NHMRC and Codex limits but after 28 days they approached, and occasionally exceeded the 10�g g-1 USFDA limit. Fruit that is held at ambient temperatures for 24 hours and then exported at lowered temperatures should have acceptable EDB levels after two weeks although inorganic bromide levels could exceed some overseas tolerances.

Untersuchungen zur Wirkung von Methylbromid besonders bei niedrigen Temperaturen gegen Khaprakäfer-Larven (Trogoderma granarium Everts (Dermestidae, Coleoptera)

Tests on the efficiency of methyl bromide especially at lower temperatures in controlling Khapra Beetle Larvae (Trogoderma granarium Everts), Dermestidae, Coleoptera In the laboratory, experiments were carried out to investigate the efficiency of methyl bromide in controlling the Khapra Beetle (Trogoderma granarium Everts) in a specially developed fumigation apparatus at 30, 25, 20, 15, 10, 5, 0, −6, and −10 °C as well as 40 – 70% relative humidity. The lethal dosis as c. t. products in mg.h/l were estimated at different temperatures from the dosis-mortality regression lines. The treated larvae were divided after the fumigation into two series (1 and 2). The larvae of serie 1 were held immediately after the fumigation time at 28°C, while the larvae of serie 2 were kept for another 10 days at the same fumigation temperature, then removed to 28°C until final control. Experimental results of both series showed that, for a given mortality the c. t. product required at low temperatures considerably increased and accordingly the tolerance of the larvae decreased with a rise in temperature (in range 0–30°C). A maximum in the tolerance of the larvae to methyl bromide was found at 0°C. At lower trial temperatures −6 and −10°C the required c. t. product subsequently decreased. This result was caused through the combined harmful effect of the low temperatures and the methyl bromide. It is evident from the estimated values that the c. t. products of methyl bromide required for a given mortality in serie 2 especially at lower temperatures (from +10 to −10°C) are lower than that in serie 1. For example in serie 2 the c. t. product required to kill the larvae decreased at 5°C to less than 50%. This effect of the post-treatment temperature was also examined to obtain the shortest holding time for maximum mortality, which was observed after 3–4, 7–8, 7–8 and 8–9 days at 10, 5, 0, and −6°C respectively. From a practical aspect this result is of great importance, because it proves the influence of the factors prevailing after a quarantine fumigation.

Methyl Bromide: Effect of Multiple Fumigation on Residues in Flour2

Pallet-size plywood containers holding forty-eight 50-lb bags of flour were fumigated with methyl bromide. These fumigations at 15.6, 21.1, and 26.7°C were repeated until the 125-ppm tolerance for inorganic bromide on the flour was reached or exceeded. The inorganic bromide residues increased with an increase in fumigation temperature even though the methyl bromide dosage was decreased. About 3, 4, and 5 methyl bromide fumigations of flour can be made at 26.7, 21.1, and 15.6°C, respectively, without exceeding residue tolerances.

Effect of Temperature and Commodity on Distribution of CCl4-CS2 (80:20) and EDC-CCl4 (75:25) Applied by Gravity Penetration and Closed Recirculation

Gravity penetration and closed recirculation fumigations were conducted in wheat, corn, and sorghum at 45, 65, and 85°F to investigate the effect of temperature and commodity on the distribution of 2 liquid fumigant mixtures. carbon tetrachloride-carbon disulfide (CCI4-CS2, 80:20) and ethylene dichloride-carbon tetrachloride (EDC.CCI4°. 75:25). The fumigations were conducted in 5-ft metal towers each containing 2 bushels of grain. In the gravity fumigations the time required for the passage of a detectable concentration of fumigant through the commodity increased as grain temperatures decreased. Penetration time at each temperature tested was least in com and greatest in sorghum. Concentrations of each component were generally higher in the recirculation fumigations than in the gravity fumigations, particularly at 45°F fumigations. CS2 was less affected by decreased temperatures or changes in commodity than CCl4 or EDC. Comparison of the total component concentrations obtained in each commodity fumigation with the total obtained at each fumigation temperature indicates that the high sorption capacity of sorghum was a more limiting distribution factor than the slower rate of volatilization and penetration resulting from fumigation at 45°F in both gravity and recirculation fumigations.