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Apple replant disease (ARD) has been reported in all major fruit-growing regions of the world and is often caused by biotic factors (pathogen fungi) and abiotic factors (phenolic compounds). Soil chemical fumigation can kill soil pathogenic fungi; however, the traditionally used fumigant methyl bromide has been banned because of its ozone-depleting effects. There is thus a need to identify greener fumigant candidates. We characterized the effects of different fumigants on the replanted soil environment and the growth characteristics of Malus hupehensis Rehd. seedlings. All five experimental treatments [treatment 1 (T1), metham-sodium; treatment 2 (T2), dazomet; treatment 3 (T3), calcium cyanamide; treatment 4 (T4), 1,3-dichloropropene; and treatment 5 (T5), methyl bromide] promoted significantly the biomass, root growth, and root respiration rate of M. hupehensis seedlings and the ammonium nitrogen (NH4+-N) and nitrate nitrogen (NO3–-N) contents of replanted soil. Metham sodium (T1) and dazomet (T2) had stronger effects compared with 1,3-dichloropropene (T4) and calcium cyanamide (T3). At 172 days after T1, the height, root length, and root respiration rate of Malus hupehensis Rehd. seedlings, and the NH4+-N and NO3–-N contents of replanted soil increased by 91.64%, 97.67%, 69.78%, 81.98%, and 27.44%, respectively, compared with the control. Thus, dazomet and metham sodium were determined to be the optimal fumigants for use in practical applications. more...

Lateritic gravel is used for road building in Western Australia, with about 8 million m3 required annually. The introduced, soil-borne pathogen Phytophthora cinnamomi, which is associated with mortality of native plants, has been widely spread by using gravel from infested pits. Uninfested gravel is in demand, and in short supply. The biocide metham sodium is registered by the Australian Pesticides and Veterinary Medicine Authority (APVMA) as a soil fumigant, but the registered application method is unsuitable for treating gravel. In moist soil metham sodium decomposes into the fumigant-like pesticide, methyl isothiocyanate (MITC). Field experiments in which metham sodium was applied during the construction of 4 m3 gravel stockpiles, showed Phytophthora spp. are killed within 2 weeks of treatment with 80 mL m3–1 metham sodium. MITC is sealed within the stockpile by surface crusting; it was only detected 5 m downwind within the first 24 h of treatment. It was not detected in gravel 28 days after treatment. This application method that can safely eliminate Phytophthora spp. from infested gravel has been registered by the APVMA, allowing scaling-up trials to be considered. more...

Isothiocyanates (ITCs) were evaluated as an alternative to methyl bromide (MeBr) for control of Palmer amaranth, large crabgrass, and yellow nutsedge; reduction of tuber density; and increase in marketable tomato yield in low density polyethylene (LDPE)-mulched tomato production. Allyl ITC was applied at 450, 600, and 750 kg ai ha−1; metham sodium (methyl ITC generator) was applied at 180, 270, and 360 kg ai ha−1; and MeBr plus chloropicrin (mixture of MeBr and chloropicrin at 67 : 33%, respectively) was applied at 390 kg ai ha−1. A nontreated weedy check was included for comparison. There was no injury to tomato plants following allyl ITC, metham sodium, or MeBr application. Allyl ITC at 750 kg ha−1or metham sodium at 360 kg ha−1controlled Palmer amaranth ≥ 79%, large crabgrass ≥ 76%, and yellow nutsedge ≥ 80% and was comparable to the weed control with MeBr. Highest rates of allyl ITC and metham sodium reduced yellow nutsedge tuber density (≤ 76 tubers m−2) comparable to the MeBr application. Total marketable tomato yield was ≥ 31.6 t ha−1in plots treated with allyl ITC at 750 kg ha−1or metham sodium at 360 kg ha−1. Marketable tomato yield from the highest rate of allyl ITC or metham sodium were similar to the yield (38.2 t ha−1) with MeBr treatment. Therefore, allyl ITC at 750 kg ha−1and metham sodium at 360 kg ha−1are effective alternatives to MeBr for Palmer amaranth, large crabgrass, and yellow nutsedge control in LDPE-mulched tomato. more...

Field studies were conducted to evaluate potential methyl bromide alternatives against nematods in tobacco (Nicotiana tabacum L.). Metham-sodium and dazomet were evaluated respectively under a polyethylene cover as alternatives for methyl bromide in tobacco transplant production over a two-year period (2009-2010). One genera or species of nematodes, tobacco root-knot nematod (Meloidogyne spp.), was evaluated in Qingzhou, Shandong province of China. All of the fumigant candidates were successful in controlling the pest. Another Parameter, plant vigor, was measured too. Metham-sodium 60g/m2, dazomet 80g/m2 and methyl bromide were not significantly different (P=0.05) from each other in the parameters evaluated. Results of this study indicate that Metham-sodium and dazomet are potential methyl bromide alternatives available to growers for use in tobacco parasite nematods control. more...

The efficacy of dimethyl disulfide (DMDS) applied in pre-planting treatment by shank injection was investigated on the lettuce Fusarium oxysporum f.sp. lactucae (FOL) pathosystem in Northern Italy (Piedmont), in three experimental trials. DMDS was tested alone or in combination with metham sodium at 35.9 g/m2, on lettuce cultivars showing different levels of susceptibility to the pathogen. DMDS, at 60 g/m2, reduced FOL symptoms on the highly susceptible butterhead type of 70, 97 and 99%, and of 87, 97 and 100% on the moderately susceptible cultivar, respectively. DMDS at 30 and 40 g/m2 showed a only partial efficacy on both lettuce types used in naturally infested soil, with a disease reduction from 30.3 to 64.5%, significantly comparable with dazomet. The results provided by DMDS at 40 g/m2 plus metham sodium at 35.9 g/m2 were statistically similar to those obtained with DMDS alone at 60 g/m2, and better than those provided by dazomet alone. A positive effect on lettuce yield and weed control by DMDS, at the highest dosage tested and by DMDS plus metham sodium, was also observed. more...

Türkiye’nin Doğu Akdeniz Bölgesi örtü altı domates yetiştiriciliğinde Fusarium oxysporum f.sp. radicis-lycopersici (FORL)’nin neden olduğu domates kök ve kök boğazı çürüklüğü ekonomik kayıp oluşturan en önemli hastalıktır. Bu çalışmada FORL ile entegre mücadele için Solarizasyon (S), Metham sodium (MS), kompost (KOM), Bacillus subtilis QST-713 (BS) ve Trichoderma harzianum (TH-T ve TH-G) uygulamalarının yalnız başına veya değişik kombinasyonları araştırılmıştır. S+MS uygulamasının 5, 15, 25 ve 35 cm toprak derinliğinde patojen inokulumunun canlılığı üzerine etkisi azaltıcı yönde olurken, yalnız başına S uygulamasında 35 cm’de bu etki patojeni öldürücü sıcaklığa ulaşamamıştır. Her iki yıl sera denemelerinde hastalık oluşumu S+MS uygulanmamış toprakta birinci yıl en az % 21.3 ile BS uygulamasında, ikinci yıl ise % 20 ile TH-T uygulamasında saptanmıştır. Biyolojik ajanlar içerisinde her iki uygulamada FORL ile mücadelede en ümit var sonuçlar BS ve TH-T uygulamalarından elde edilmiştir. Fusarium crown and root rot of tomato caused by Fusarium oxysporum f.sp. radicis-lycopersici (FORL) is the most important disease that causes economically important losses on greenhouse-grown tomato in the Eastern Mediterranean region of Turkey. In the present study, we investigated the effects of Solarization (S), Metham Sodium (MS), compost (KOM), Bacillus subtilis QST-713 (BS) and Trichoderma harzianum (TH-T and TH-G) applications on integrated disease management of FORL, alone and in their combinations. S+MS application reduced the viability of the pathogen inoculum at 5, 15, 25, and 35 cm soil depth while application of solarization, alone did not reach the lethal temperature for the pathogen at 35 cm soil depth. The least disease incidence (21.3%) was observed in BS application in the first year of two-year greenhouse experiment in soil without S+MS application while it was determined in TH-T application with the disease incidence of 20% in the second year. Among biological agents, the best results in disease control of FORL were obtained with applications of BS and TH-T in both experiments more...

In an attempt to find effective control measures againstColletotrichum coccodes, an emerging pathogen causing root rot on tomato in northern Italy, four experimental trials were carried out during the years 2005 and 2006 in Piedmont and Liguria in order to evaluate the effectiveness of the combination of different rootstocks (Beaufort F1, He Man F1, Maxifort) with various fumigants. In the presence of medium to high disease incidence, the best results were obtained by combining the use of a resistant tomato rootstock with soil fumigation with dimethyl disulfide at 40 or 80 gm−2 or metham sodium at 192 g m−2. Chloropicrin, applied at 20 g m−2, and the tested rootstocks alone, did not enable effective control of the pathogen. The need to monitor the appearance of new diseases and the resurgence of old ones is stressed. more...

If methyl bromide is phased out for greenhouse use by 1 January 2005 it will cause many difficulties in agricultural industries that are now heavily reliant on its use. Three field experiments were conducted to compare management tactics on tomato and cucumber in commercial greenhouses naturally infested with root-knot nematodes (Meloidogyne spp.). Methyl bromide was used as a reference treatment and was consistently superior to all the other treatments and combinations of other fumigants with contact nematicides. A significant reduction of nematode juveniles and root-galling index was observed in plots treated with either metham sodium and cadusafos or 1,3-dichloropropene and cadusafos. Nematode decrease was greater when these three chemicals were applied in the same plots. Good nematode control based on the use of different chemicals combinations can be achieved only for one cropping season and therefore nematode management measures must be employed for the next cropping season more...

Field trials were conducted to test fumigants as alternatives to methyl bromide (MB) for production of hybrid freesia (Freesia × hybrida). One trial compared rates of 1,3-dichloropropene (DP) combined with chloropicrin (CP); the second trial compared iodomethane (IM) together with CP, DP:CP, and furfural with and without metham sodium; and the third trial compared rates and formulations of IM:CP to the standard MB:CP treatments. Most treatments reduced populations of Pythium spp. and controlled weeds compared to the untreated controls. Formulations of IM:CP reduced the incidence of disease caused by Fusarium oxysporum. Treatments of IM:CP performed as well as MB:CP, and treatments of DP:CP performed as well as IM:CP. Presently only the DP, CP and metham sodium formulations are registered for use on ornamental crops. Registration of the IM formulations will improve the options available to cut flower growers for management of plant pathogens and weeds. more...

Management of volunteer potato is difficult and requires an integrated approach. Soil fumigation is one tactic known to reduce population densities of certain weeds and may be a method to improve the management of volunteer potato. The effect of 1,3-dichloropropene (1,3-D) and metham sodium on potato tuber viability was tested in sealed glass jars at various doses, incubation temperatures, and times of exposure. Tuber viability data were fitted to a logistic model, and I90 doses (90% suppression) were calculated for each combination of temperature and time of exposure. I90 doses for 1,3-D ranged from 41 to 151 kg/ha and from 96 to over 480 kg/ha metham sodium. Both nondormant and dormant tubers were injured by exposure to metham sodium. Soil fumigation with 1,3-D and metham sodium has the potential to greatly reduce the number of viable potato tubers. Nomenclature: 1,3-dichloropropene; metham sodium; potato, Solanum tuberosum L. ‘Russet Burbank’. Additional index word: Groundkeeper. Abbreviations: 1,3-D, ... more...

SummaryStrawberries have been the target of research to find alternatives to methyl bromide (MB) as this crop is the largest single consumer of the chemical in Spain using 800 tonnes for fruit production and 237 tonnes in mother plant production. Electromagnetic waves (EW), Solarization (Sol), Biofumigation (Bio), Metham Sodium (MNa), Dazomet (Daz), 1,3-Dichloropropene (1,3-D) and Chloropicrin (Pic) were evaluated alone or in combination as alternatives for Methyl Bromide (MB) in strawberry production over a three-year period at two locations. The GGE biplot method was employed to study the MB alternative by environment two-way data. This method graphically displays MB alternative by environment data and hence facilitates the pattern of MB alternative performance across environments. 1,3-D plus 35% Pic (Telone C35), Pic alone, MB shank-applied to preformed beds under black polyethylene films and under black virtually impermeable films performed as well as the standard methyl bromide treatment and resulted... more...

Biofumigation is an important crop protection practice that uses a plant’s natural defence mechanisms to control agricultural crop pathogens and diseases. Glucosinolates are volatile compounds found in most Brassica species and when hydrolysed, it forms a range of natural toxins including isothiocyanates that act as biofumigants. Research suggests that biofumigation is a good alternative to chemical fumigants as it is effective in controlling plant pests but with lower health and environmental risks. Several studies have confirmed the effectiveness of the breakdown products, especially isothiocyanates, as fungicidal, bactericidal and nematicidal products against a series of plant pests. However, very little information is available on the effects of glucosinolates and its breakdown products on non-target and beneficial soil organisms. Negative effects on beneficial soil organisms can have serious negative impacts on soil quality especially when essential ecosystem functions such as nutrient cycling and soil bioturbation are affected. Three biofumigants, broccoli, mustard and oilseed radish, and two chemical fumigants, metham sodium and cadusafos, were investigated for possible effects on non-target and essential soil organisms such as earthworms and the soil microbial community. Sublethal endpoints, including growth and reproductive success of the earthworms, were monitored. The genotoxicity of the biologically active compounds found in the fumigants, towards earthworms, was evaluated by means of the comet assay. The DNA damage was quantified by tail intensity parameters. Furthermore, the changes in the soil microbial community function and structure were evaluated by means of community level physiological profiling (CLPP) and phospholipid fatty acid (PLFA) analyses respectively. All exposures were done in artificial soil prepared according to the OECD standard guidelines. In the biofumigant treated soils, results varied and different effects were observed on the non-target soil organisms. Broccoli reduced cocoon production and the number of hatchlings while mustard induced more DNA strand breaks in earthworm cells compared to the control. All the biofumigants stimulated microbial growth but broccoli and oilseed radish changed the microbial functional diversity. Mustard had no lasting effect on the functional diversity but altered the microbial community structure. The chemical fumigants had a marked negative impact on the survival, growth, reproduction and the genotoxicity of the earthworms with metham sodium causing greater harm than cadusafos. The effects on the microbial community varied. Both chemicals had an inhibitory effect on the microbial growth in terms of the viable biomass determined by PLFA and the average well colour development in the Biolog™ Ecoplates. No lasting effects were observed in the community structure. Overall, cadusafos had a more pronounced effect on the microbial community functional diversity than metham sodium. Results indicated that each bioindicator species illustrates effects at their own level of organisation MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015 more...

MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015 Biofumigation is an important crop protection practice that uses a plant’s natural defence mechanisms to control agricultural crop pathogens and diseases. Glucosinolates are volatile compounds found in most Brassica species and when hydrolysed, it forms a range of natural toxins including isothiocyanates that act as biofumigants. Research suggests that biofumigation is a good alternative to chemical fumigants as it is effective in controlling plant pests but with lower health and environmental risks. Several studies have confirmed the effectiveness of the breakdown products, especially isothiocyanates, as fungicidal, bactericidal and nematicidal products against a series of plant pests. However, very little information is available on the effects of glucosinolates and its breakdown products on non-target and beneficial soil organisms. Negative effects on beneficial soil organisms can have serious negative impacts on soil quality especially when essential ecosystem functions such as nutrient cycling and soil bioturbation are affected. Three biofumigants, broccoli, mustard and oilseed radish, and two chemical fumigants, metham sodium and cadusafos, were investigated for possible effects on non-target and essential soil organisms such as earthworms and the soil microbial community. Sublethal endpoints, including growth and reproductive success of the earthworms, were monitored. The genotoxicity of the biologically active compounds found in the fumigants, towards earthworms, was evaluated by means of the comet assay. The DNA damage was quantified by tail intensity parameters. Furthermore, the changes in the soil microbial community function and structure were evaluated by means of community level physiological profiling (CLPP) and phospholipid fatty acid (PLFA) analyses respectively. All exposures were done in artificial soil prepared according to the OECD standard guidelines. In the biofumigant treated soils, results varied and different effects were observed on the non-target soil organisms. Broccoli reduced cocoon production and the number of hatchlings while mustard induced more DNA strand breaks in earthworm cells compared to the control. All the biofumigants stimulated microbial growth but broccoli and oilseed radish changed the microbial functional diversity. Mustard had no lasting effect on the functional diversity but altered the microbial community structure. The chemical fumigants had a marked negative impact on the survival, growth, reproduction and the genotoxicity of the earthworms with metham sodium causing greater harm than cadusafos. The effects on the microbial community varied. Both chemicals had an inhibitory effect on the microbial growth in terms of the viable biomass determined by PLFA and the average well colour development in the Biolog™ Ecoplates. No lasting effects were observed in the community structure. Overall, cadusafos had a more pronounced effect on the microbial community functional diversity than metham sodium. Results indicated that each bioindicator species illustrates effects at their own level of organisation. Masters more...

Summary The use of metham-sodium as a possible control agent for armillaria root disease was studied on 13-year-old karri (Eucalyptus diversicolor) regrowth stumps. As a consequence its effect on colonisation by wood decay organisms was also examined. Armillaria luteobubalina-infccted stumps, with volumes of about 2000 cm3 (11–12 cm diam.) and 8000 cm3 (21.5–23.5 cm diam), were treated with 500 ml of metham-sodium and examined after 3½ years. Control stumps with volumes of about 4000 cm3 (16–17 cm diam.) were not treated. Compared to untreated stumps, the volume of uncolonised wood and advanced decay was significantly greater in metham-sodium treated stumps. The volume of stump colonised by A. luteobubalina was lower in metham-sodium treated stumps than in untreated stumps. In stumps with a volume of 2000 cm3, treatment with metham-sodium eliminated A. luteobubalina from 40% of the stumps and enhanced colonisation by white rot organisms, including an unknown species which colonised 45%-60% of the volume o... more...

The effects of soil fumigation with chloropicrin alone or in combination with metham sodium and or with EPTC on the growth of loblolly pine (Pinus taeda L.) seedlings and on nutsedge (Cyperus spp.) control were investigated at three forest tree nurseries. Fumigation with chloropicrin plus metham sodium (CMS) significantly increased seedling numbers and growth compared to controls. Averaged among nurseries, mean root-collar-diameter increased from 0.14 to 0.17 in., and biomass from 0.14 to 0.20 lb/ft2. This produced seven more plantable seedlings and 6.5 more grade 1 seedlings/ft2 in CMS compared to not fumigated plots. Fumigation increased average potential sales $7,100/ac and increased present values, projected for the growth increases for additional grade 1 seedlings, by $25,900/ac. Fumigation increased biomass per unit area similarly at tested bed densities (10 to 29/ft2), but at low bed densities (≤20/ft2) the present values associated with grade 1 seedlings increased more than at higher densities. South. J. Appl. For. 24(3):135-139. more...

'Sunny' tomato plants were grown, using four fumigant treatments and three mulch treatments. Fumigants were metham sodium at the rate of 935 l/ha and dazomet at rates of 336 kg/ha, 420 kg/ha and 504 kg/ha. Mulches were 1.25 mil black polyethylene (plastic), a spray-on styrene-butadiene polymer dispersion (Styrofan) sprayed over beds at a rate of 959 l/ha, or none. Plants in all mulch treatments produced similar marketable yields. Neither fumigant had an advantage over the other in yield. more...

The ability of mixtures of Basamid and metham sodium to produce methylisothiocyanate (MITC) in small blocks and sawdust of Douglas-fir (Pseudotsuga menziesii and southern pine (Pious spp.) was studied under varying moisture and temperature regimes. Mixtures of the two fumigants appeared to produce higher levels of MITC in small blocks than did the fumigants alone. Subsequent sawdust trials produced more variable results. MITC levels were similar for both wood species, and increased dramatically with increases in wood moisture content. Slight improvements in MITC levels were also noted with temperature increases. Addition of copper sulfate to the Basamid/metham sodium mixture resulted in increased MITC production early in the tests, but this effect diminished with time. The results suggest that mixtures of Basamid, metham sodium and copper sulfate could be used to provide a safer remedial treatment with the potential for both rapid initial and longterm control of fungal infestations. more...

Two methods were used to expose microsclerotia of V. dahliae to various rates of metham sodium ranging up to 935 l ha −1 . When microsclerotia were entrapped in a single layer of nylon mesh, buried in nonsterile soil and exposed to metham sodium, radial growth from the microsclerotia was reduced by rates as low as 93.5 l ha −1 of metham sodium. When microsclerotia were enclosed inside a nylon mesh envelope, buried in soil and exposed to metham sodium, growth rate was not affected by 1871 l ha −1 . The biocontrol fungi Gliocladium roseum and Talaromyces flavus were incorporated into alginate prill, buried in soil and exposed to metham sodium. Growth rate of G. roseum from prill was reduced by 187 and 935 l ha −1 metham sodium while growth rate of T. flavus was not affected by either rate of the fumigant. In a greenhouse test in field soil, infection of eggplant by V. dahliae was not reduced by 187 l ha −1 of metham sodium, but was reduced with 187 l ha −1 plus either biocontrol fungus. The combined effect of the sublethal rate of the fumigant with either biocontrol fungus was additive for reduction of disease incidence as was the sublethal rate of the fumigant with both biocontrol fungi together. more...

A survey of the potential side effects of volatilized pesticides on fungi and vascular plants in The Netherlands has been made for two herbicides (atrazine and MCPA), a fungicide (captan) and a soil fumigant (metham sodium). By applying existing models, a prediction is presented of post-treatment dispersal and deposition due to volatilization, both at short and long ranges, and of the potential side effects on fungi and vascular plants. The general conclusion is that side effects (stunting and growth anomalies) are to be expected outside the target area, especially close (500 m) to treated plots with atrazine and metham sodium. In view of agricultural acreage in The Netherlands, these short-range effects may impinge on a relatively large scale. There may also be an impact at greater distances from treated plots, especially in the case of compounds that are slow to degrade such as MITC (methyl isothiocyanate), the active toxic moiety generated in soil from metham sodium. more...

A Clovelly soil in Tala Valley (Natal) was fumigated with different concentrations of dazomet (300, 400, 500 kg ha−1) (granular formulation), and metham sodium (500, 750, 1000 L ha−1) (liquid formulation). Half the treatments were covered with plastic sheets during fumigation. After fumigation weed germination was rated and soil analysed for parasitic nematodes. The trial site was planted with ‘Robinvale’ lettuce seedlings. Dazomet was more effective than metham sodium in decreasing weed germination and efficacy of both chemicals was improved by covering the sites with plastic. Meloidogyne (root-knot nematode) and Trichodorus (stubby root nematode) were present prior to fumigation but their levels were reduced by dazomet. Nematode control by metham sodium was inconsistent and not improved by higher concentrations of fumigant. Nematode populations were counted again at harvest from both soil and root samples. These results were variable and could not be directly related to treatments. Dazomet significantly... more...

The mandated elimination of methyl bromide as a soil fumigant because of its ozone-depleting chemistry is scheduled to be complete by 2005. Chemicals in current use as soil fumigants and some promising new chemicals are reviewed. The compounds are listed with their important chemical and physical properties. Keywords: soil fumigant; drip irrigation; ozone depletion; methyl bromide; methyl bromide alternatives; control of plant pathogens; ozone hole; impermeable tarps; atmospheric emissions; methyl iodide; telone; chloropicrin; metham sodium; basamid; propargyl bromide more...

Greenhouse soils are regularly treated with metham-sodium, which in soil is quickly transformed to the fumigant methyl isothiocyanate. An experimental fumigation was carried out in a greenhouse with sandy soil. Data were collected on the behavior of methyl isothiocyanate in soil and its permeation through a film of low-density polyethene (LDPE) covering the soil. This cover was found to be highly permeable to methyl isothiocyanate. When the fumigation of greenhouse soil was simulated with a computation model, the use of LDPE film only appreciably reduced the rate of emission into the air in the first two days. The cumulative emission corresponded to about half of the dosage for some practical situations. It is concluded that dosages should be lower and applied more effectively, and less permeable soil covers should be used. more...

The Southern Pacific Railroad derailment near Dunsmuir, Calif., on July 14 that sent into the Sacramento River roughly 13,000 gal of a liquid metham-sodium formulation used as a soil sterilant migh... more...

Drip-irrigated tomato (`Sunny') plants were treated with five levels of fumigant in combination with three levels of mulch. Fumigants were metham sodium at two rates, 475 and 950 L/ha, a 67% methyl bromide + 33% chloropicrin formulation (164.5 kg/ha, and a 98% methyl bromide + 2% chloropicrin formulation (329 kg/ha). Mulching levels were 1.25 mil silver on black polyethylene (plastic), blue-black latex mulch sprayed over the plant beds, and no mulch. Plants treated with metham sodium (950 L/ha) had a significantly higher number of marketable fruit than plants treated with no fumigant or the 98% methyl bromide + 2% chloropicrin formulation. Marketable fruit weight was not significantly affected by the five fumigation levels. Plants grown with black plastic mulch had a significantly higher marketable yield than plants grown with no mulch, 58,100 kg/ha vs. 50,800 kg/ha, respectively. The level of mulching did not significantly affect the marketable number of fruit. more...

The interaction of Pratylenchus penetrans and Verticillium dahliae for symptom expression of potato early dying and yield and quality of tubers of Russet Burbank potato was evaluated in microplots and field plots. Soil was fumigated with metham sodium before being infested with varying population levels of the nematode and/or fungus. In the microplot study, low and high initial populations of P. penetrans (about 25 and 75/100 cm 3 of soil) or V. dahliae (about 3 and 9 colony-forming units/g of dry soil) had no effect on number and fresh weight of tubers compared to the control (...) more...

In field trials, loamy soils were fumigated by injecting dichloropropene and metham-sodium with a horizontal-blade injector. Concentrations of cis- and trans-1,3-dichloropropene, and of methyl isothiocyanate were measured. The influence of different methods of tillage on fumigation effectiveness was compared by computing concentration-time products at the various depths in the soil. With a fine-structured top layer, there was no clear beneficial effect of shallow or deep rotary tillage before injection. If a dense top layer was not rotary-tilled beforehand, deep and wide cracks were formed during injection. Shallow or deep rotary tillage both left loose cereal stubble mixed in the surface layer, which was difficult to finish off. Concentration-time products could be substantially increased by finishing off the soil surface better after injection. more...