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Fusarium solani is an emerging pathogen reported on Spanish strawberry crops both in nurseries and in fruit production fields, causing wilt and root rot. Pathogenicity, morphocultural characteristics, and sensitivity to biocides of 103 F. solani isolates recovered from symptomatic strawberry plants and soils from both Spanish strawberry areas were determined. The differences of isolates within and between nurseries and field crops in relation to these parameters were analyzed. Considerable variability in morphological and pathogenic characteristics was observed among the isolates in both areas. The majority of isolates were not pathogenic (62%), and only 38 F. solani isolates (37.62%) caused disease on strawberry plants under controlled conditions; 52.63% of pathogenic isolates induced low severity symptoms. Almost 70% of pathogenic isolates caused stunting on plants. The morphological characters that best explain the F. solani variability (86.85%) were colony color and the presence of macroconidia on culture medium. The sensitivity to the fumigants tested was similar between the isolates from nurseries and fruit production fields, showing greater sensitivity to the field doses of dazomet and chloropicrin. However, the isolates were less sensitive to metam sodium and poorly sensitive to 1,3-dichloropropene. This work can contribute to the advancement of sustainable production of strawberry.

Take-all disease is the most important root disease in wheat caused by the fungus Gaeumannomyces graminis var. tritici. Considering economic importance of wheat, the disease is a serious problem worldwide. The effective and economically feasible control of the disease is a major problem around the globe. Strategies based on chemical control of take-all have been inefficient due to that the control of soil-borne pathogen is depending on the use of soil fumigants of broad-spectrum gaseous as methyl bromide, chloropicrin, metam sodium which are unacceptable in agriculture. The discovery of suppressive soils involving major plant–microbe interactions resulted in some significant advances, particularly in elucidating the role of the enzymes. These microbes through several mechanisms including the biocontrol, antibiosis, systemic resistance in plants (ISR) have made advanced progress in identifying major factors involved host range and pathogenicity determining as well as recognizing the mechanism that explains disease suppression. Moreover, the high-throughput sequencing techniques open new avenues for microbial control of plant disease considering, for example, the engineering plant microbiome to improve the plant health and food security.

Plant parasitic nematodes are a significant constraint on carrot production in Ontario, Canada. Growers need new tools to control the primary nematodes impacting carrots in the muck soil growing regions of Ontario, Meloidogyne hapla and Heterodera carotae. Growth room, microplot and field trials were conducted to evaluate new nematicides (abamectin, oleoresin of capsicum + AITC, spirotetramat, mustard seed meal, fluensulfone) and currently registered fumigants (chloropicrin, metam sodium, dazomet) for their efficacy against plant parasitic nematodes. Abamectin and fluensulfone decreased nematode damage in growth room trials. Chloropicrin and metam sodium provided the most consistent control and increased yields in field conditions. Nematode extraction methods were also evaluated to determine their efficacy at extracting plant parasitic nematodes relevant to carrots. The SC method was found to be effective at extracting more Heterodera spp. but not Meloidogyne spp. This research provides strategies to better manage plant parasitic nematodes in carrots produced in Ontario. Fresh Vegetable Growers of Ontario, Bradford Co-op, Holland Marsh Growers' Association, Canadian Agricultural Adaptation Program and the University of Guelph/OMAFRA partnership.

Metam sodium (MS) is a widespread biocide with a broad-spectrum activity. Here, we addressed the behavioral impact of MS by exposing female mice to 50, 100 and 150 mg/kg of MS during both pregnancy and lactation, and evaluated the oxidative stress as a potential mechanism of MS-induced neurotoxicity. The results showed that MS affected fertility and reproduction parameters as well as some aspects of maternal behavior, especially at high doses. In offspring, MS caused a significant delay in the ontogeny of sensorimotor functions. In addition, treated mice exhibited during adulthood an increase of anxiety-like, depression-like behaviors as well as learning and memory impairment. These alterations were accompanied by an increase of the superoxide dismutase activity, and a significant decreased catalase and malondialdehyde activities in specific brain areas. The present work revealed that early exposure to MS induced sensorimotor and behavioral impairments in offspring likely associated with onset of oxidative stress.

Background Chloropicrin (PIC) mixtures of 1,3-dichloropropene and chloropicrin (DD:PIC), dazomet, and metam sodium (MS) have been applied as chemical alternatives to methyl bromide (MB) in Spanish strawberry nurseries since MB was banned as a soil fumigant in 2005. These chemical alternatives were applied to soil in two Spanish strawberry nurseries between 2003 and 2017 to test their efficacy against the main crown and root disease and soil fungal populations in comparison with the use of MB and PIC (MB:PIC). These chemicals were applied at several doses with different application methods under plastic films. Crown and root disease incidence was calculated as the percentage of plants with symptoms caused by soil-borne pathogens. Soil fungal populations were estimated as colony forming units per gram of dry soil. Results All chemicals significantly reduced soil-borne fungal disease incidence and fungal population in both nurseries over the years. Phytophthora cactorum and Fusarium spp. were the main pathogens causing soil-borne diseases, followed by Verticillium spp. MB:PIC remained the treatment that best controlled P. cactorum. MS and DD:PIC controlled Fusarium disease to a lesser extent than MB:PIC and dazomet in both nurseries. MB:PIC and PIC were the two treatments that most reduced Verticillium spp. The population of Verticillium spp. declined and the presence of other species such as Colletotrichum spp. and Rhizoctonia spp. was minimal during the study. Conclusion Chemicals are necessary to obtain healthy strawberry plants. The use of chemical alternatives to MB has resulted in changes in the incidence of soil-borne diseases and soil fungal populations in strawberry nurseries. Dazomet was an effective alternative to MB as a soil-borne disease control, except against Verticillium spp. MB alternatives in strawberry nursery soils have caused Fusarium spp. to displace Verticillium spp.

Internal decay is a common problem in poles or timbers of thin sapwood species. Several internal treatments have been developed to arrest this attack, and these systems are widely used in North America. Although these treatments have been evaluated in numerous independent field trials, there is no single test of all treatments. The objective of this study was to assess the chemical distribution and fungal colonization in Douglas-fir poles treated with each of 13 different internal remedial treatments over a 10-year period. Metam sodium treatments provided the shortest protective period, with little evidence of residual chemical 3 years after treatment. Methylisothiocyanate (MITC) in pure form provided a very high initial flush of active ingredient and a longer protective period extending from 5 to 8 years after treatment. Dazomet, which must decompose to produce MITC, took slightly longer to reach effective levels, but was still present at effective levels 10 years after treatment. Chloropicrin, which has strong interactions with wood, was associated with the highest chemical levels after 10 years. Borates took longer to reach effective levels in the poles and their protective zone was narrower than the fumigants, but boron was still present at effective levels 10 years after application. The results illustrate the different properties provided by each treatment, but also show that all tested remedial treatments were effective within certain limitations.

Dimethyl disulfide (DMDS) is a methyl bromide alternative with good to excellent nutsedge control when mixed with chloropicrin (Pic). Combining fumigants is a common practice to improve pest control spectrum, however, the use of Pic is restricted in some countries. In order to determine the legitimacy of replacing Pic in DMDS:Pic combinations, a low and high rate of metam sodium (MNa) was used alone and in combination with DMDS and were compared to a single rate of DMDS alone and in combination with Pic to determine their efficacy against nutsedge species and impact on muskmelon yield. All DMDS combinations resulted in lesser nutsedge populations than MNa alone and the non-treated control. MNa applied alone, even under totally impermeable film, was not enough to control nutsedge species. DMDS combinations also provided greater nutsedge control than DMDS applied alone at seasons end. Furthermore, MNa applied concurrently with DMDS may have the potential to replace DMDS:Pic combinations without losing efficacy on nutsedge species in geographies where the use of Pic is restricted.

On October 25, 2016, media reports alerted the Uganda Ministry of Health to an outbreak of >80 cases of vomiting, syncope, and acute diarrhea among workers at a flower farm in central Uganda; 27 workers were hospitalized. On November 1, an investigation was undertaken by the Uganda Public Health Fellowship Program.* A case-control study found that working inside greenhouse 7, which had been fumigated with the organosulfur compound metam sodium the night of October 13, was strongly associated with illness. Employees who worked in this greenhouse during October 14-21 reported a strong "suffocating" smell in the greenhouse. Investigation revealed that, in violation of safety protocols, workers did not properly cover the soil after fumigation, allowing vapors to become trapped inside the greenhouse. The farm management, unaware of the lapse, failed to inform workers to avoid the vicinity of the fumigation. Respiratory protective measures were not routinely available for workers, which likely contributed to the severity and extent of the outbreak. Although metam sodium is generally considered to be of low risk when used according to manufacturer's instructions (1), occupational exposure in the absence of recommended safety measures can have serious health consequences. The investigation highlighted the importance of identifying potential occupational hazards to workers, as well as establishing safety protocols in occupational settings, training workers at risk, such as pesticide sprayers and flower pickers,† and ensuring enforcement of safety protocols. After this outbreak, the farm management reviewed, revised, and trained the workers on safety protocols to prevent future outbreaks.

Chemical fumigation and biofumigation are used to reduce soil-borne diseases in agricultural production systems; however, other essential soil processes such as the soil nitrogen (N) cycle may also be affected. This study compared the effects of chemical fumigation and biofumigation on soil net N mineralization, nitrification, denitrification, and soil nitrifier and denitrifier abundance. Six treatments were compared using soil microcosms over a 160-day incubation period: fumigation with chloropicrin; fumigation with metam sodium used alone (MS) or combined with barley plant residues (MSBR); biofumigation with mustard residues; addition of non-biofumigant barley residues; and an untreated control. Biofumigation did not inhibit soil nitrification, whereas chemical fumigation with MS (with or without barley) and chloropicrin inhibited nitrification for 16 and 64 days, respectively. Biofumigation, barley residues, and MSBR increased soil respiration, N2O emission, and denitrification rates. However, biofumigation had lower denitrification and N2O cumulative emissions and rates compared to barley residues, suggesting that biofumigation may reduce N2O production pathways. All chemical fumigation treatments significantly decreased nitrifier gene abundance compared to biofumigation; however, only chloropicrin decreased the abundance of denitrifying genes. After 160 days, 22% of the added plant residue dry matter remained in the MSBR-treated soil, which was ∼2-fold greater than the barley-treated soil, indicating chemical fumigation may also affect the carbon cycle. Overall, these results suggest that chemical fumigation, especially with chloropicrin, has a greater impact on nitrification and nitrifier and denitrifier gene abundance than biofumigation with mustard residues.

Clubroot, caused by Plasmodiophora brassicae, has become a serious threat to canola (Brassica napus) production in western Canada. Experiments were conducted to evaluate the effect of rate of metam sodium fumigant (dithiocarbamate; sodium N-methyldithiocarbamate; trade name Vapam) and application methods including watering, soil surface covering, and soil incorporation on clubroot of canola. At higher rates (0.4–1.6 mL−1 L soil) metam sodium increased canola seedling emergence and plant health, and reduced root hair infection, gall weight and clubroot severity under greenhouse conditions. Metam sodium application improved subsequent plant growth and reduced clubroot severity, but land preparation and volume of water applied did not affect efficacy. The incorporation of metam sodium into the soil and plastic covering after application improved fumigant efficacy. The study showed that soil fumigation with metam sodium can reduce clubroot severity and improve plant health in the subsequent canola crop.

Field studies were conducted to determine the effect of metam sodium andS-metolachlor applied through drip irrigation on yellow nutsedge, common purslane, bell pepper, and tomato (injury and yield) in plasticulture. Treatments consisted of weed-free, weedy,S-metolachlor alone at 0.85 kg ha-1, methyl bromide, metam sodium (43, 86, 176, and 358 kg ai ha–1) alone, and metam sodium (43, 86, 176, and 358 kg ai ha–1) followed byS-metolachlor at 0.85 kg ha–1. Metam sodium andS-metolachlor was applied preplant 2 wk before and 2 wk after transplanting (WAT) through drip irrigation, respectively. No injury was observed to bell pepper and tomato from metam sodium alone, or metam sodium fbS-metolachlor treatments. With the exception of yellow nutsedge density 15 WAT in bell pepper, herbicide program did not influence yellow nutsedge and common purslane density at 4 and 6 WAT and bell pepper and tomato yield. At 15 WAT, yellow nutsedge density was lower in treatments that received metam sodium fbS-metolachlor compared to those treatments that only received metam sodium. Drip-applied metam sodium at 176 and 358 kg ha–1in both bell pepper and tomato provided similar control of common purslane, and yellow nutsedge, produced comparable yields, and failed to elicit any negative crop growth responses when compared to MeBr. In conclusion, metam sodium at 176 and 358 kg ha–1fbS-metolachlor 0.85 kg ha–1is an effective MeBr alternative for season long weed control in plasticulture bell pepper and tomato.

Research has shown that while fumigation and use of ammonium N can both reduce the severity of verticillium wilt (Verticillium dahliae Kleb.) of potatoes (Solanum tuberosum L.), the use of the two practices together raises concerns over feeding the crop only ammonium N under reduced nitrification conditions. To assess the validity of this concern, we conducted two 3-year field split-plot experiments with both using metam sodium fumigant (none, fall or spring applied) as the main plot. For the first experiment, N source (134 kg N ha−1 as ammonium sulfate, urea, or ammonium nitrate) was the split, whereas for the second trial in-season N rate (0, 67, 134, or 202 kg N ha−1 all as ammonium sulfate) was the split. For both trials, in 2 of the 3 years, fumigation significantly increased tuber yield by an average of 9.9 Mg ha−1 and decreased late-season verticillium severity ratings from 77 to 45%. In some years, fumigation also increased the proportion of U.S. No. 1 tubers and tubers >170 g. No differences in crop yield or quality were observed between the various N sources applied. This was true even on spring-fumigated areas with the highest rate of ammonium N applied. These experiments confirm that the choice between in-season potato N fertilizer should be based on factors such as potential for benefits or N losses, cost, and convenience of use rather than concern over an interaction between fumigation and ammonical N. While both fumigation and N rate reduced verticillium severity ratings in some years, the lack of interaction suggests these factors are functioning independently.

Summary Goal: An exploratory study evaluated best-management techniques for replanting a commercial vineyard suffering from both a high incidence of Grapevine leafroll associated virus-3 and high densities of northern root-knot nematode ( Meloidogyne hapla ). The grower had two goals: to reduce the density of plant-parasitic nematodes, which can delay establishment of young vines, using a pre-plant fumigant, and to reduce survival of virus-infected vine tissue by applying an herbicide to the foliage prior to vine removal. Key Findings: Fall-applied metam sodium reduced densities of M. hapla in the following growing season. Its herbicidal properties also resulted in high root mortality. In cases where vines survived, only a few shoots (and suckers) emerged, displaying typical morphology. Fall-applied foliar glyphosate significantly reduced shoot and sucker regrowth, but did not kill root tissue. In the few instances where shoots and suckers grew the following spring, that tissue expressed typical symptoms of glyphosate phytotoxicity. While low rates of abnormal growth would eliminate much of the aerial reservoir of virus, the presence of live roots indicates that rogue vines and living root debris could contribute to infection of new, virus-free planting stock. Combining fumigant and foliar glyphosate was additive: nematode control, root mortality, and a lack of healthy shoot/crown sucker regrowth. Impact and Significance: This preliminary work showed that the combination of fall fumigation and foliar glyphosate application reduced nematode populations and vine survival. In situations where plant-parasitic nematodes are the sole issue facing replanting, fumigation alone suffices. Where virus alone is the impetus for replanting, fall-applied foliar glyphosate may provide sufficient overall vine mortality, with a caveat of low root mortality and its attendant risk of root-feeding vectors spreading the virus to new planting stock.

Soil solarization is a non-chemical soil disinfestation method proven effective against soil-borne pathogens and weeds. However, it should be assessed under local cropping conditions before it can be implemented in commercial crops, since the process is highly dependent on climate conditions, among other factors. Soil biosolarization combines biofumigation with solarization to improve its effectiveness but knowledge about its use on tomato crops is still rather scarce and limited to nematode control. We have tested the effectiveness of soil solarization, biosolarization and fumigation with metam sodium over three tomato cropping seasons, to control corky root caused by Pyrenochaeta lycopersici and weeds under screen-house conditions in the Canary Islands (Spain). During the three seasons, maximum soil temperatures at 10 cm depth in solarized and biosolarized plots were about 10 °C higher than in controls, rising up to 41.4–43.3 °C in solarization and 43.0–44.7 °C in biosolarization, with an accumulated number of hours exceeding 40 °C of 48.8–138.2 and 92.3–204.7 h in solarized and biosolarized plots, respectively. The most effective treatment was biosolarization, which significantly increased tomato yield by 12.4% in 2001–02; 22.8% in 2002–03 and 22.2% in 2003–04, and reduced corky root severity in the last two seasons. Corky root was also significantly reduced by solarization in 2003–04, whereas there was no difference between metam sodium and control plots in any season. Weed infestation was evaluated in 2002–03 and 2003–04, in which weed density in biosolarized plots was significantly lower than in controls (88.8% and 50.6% reduction at 45 and 165 days after tomato transplanting in 2002–03; and 69.6% after 120 days in 2003–04). In contrast, weeds were not controlled by solarization, and inconsistent results were obtained with metam sodium. Here we show that soil biosolarization is clearly a way to improve the effectiveness of soil solarization under less favorable environmental conditions, like those prevailing in tomato screen-houses in the Canaries, and a feasible alternative to chemical fumigation for the control of corky root and weeds.

Powdery scab caused by Spongospora subterranea f. sp. subterranea (Sss) causes extensive losses in potato production systems globally. Two pot experiments were established in the greenhouse in summer 2013 and winter 2014 to evaluate the effectiveness of different soil chemicals, fumigant, amendments and biological control agents (BCAs) against Sss in the rhizospheric soil, potato roots and tubers. The study used visual assessment methods to assess the effect of treatments on root galling and zoosporangia production, and qPCR to measure Sss concentration in the soil and in the potato roots and tubers. All six soil treatments, namely metam sodium, fluazinam, ZincMax, calcium cyanamide, Biocult and a combination of Bacillus subtilis and Trichoderma asperellum recorded significantly (P

This study aimed to assess the non-target impacts of pesticides on soil biological processes, particularly N2O emissions and improve understanding of the contributions of nitrification and denitrification to N2O production in sugarcane soils. We conducted a laboratory incubation experiment, in which a herbicide Roundup®, an insecticide Confidor®, a fungicide Shirtan®, and a fumigant metam sodium were added to a Ferrosol and then incubated at 25°C for 38 days at 2 moisture regimes (55 % and 90% water holding capacity (WHC)). At day 28, soil water contents in the 55% WHC treatments were also increased to 90% WHC to create a condition to favour denitrification. The 55% and 90% WHC treatments received NH4SO4 at 40µg N g−1 dry soil and KNO3 at 40µg N g−1 dry soil, respectively, with K15NO3 added at 2 µg N g−1 of dry soil in all treatments. Compared with the control treatment, Confidor application significantly increased net nitrification rates and N2O emissions at 55% WHC. After increasing water content from 55% to 90% WHC at day 28, net denitrification occurred in the metam sodium treatment; N2O emissions increased in the order: metam sodium > Shirtan > Glyphosate treatment, with little changes in the Confidor and control treatments. During the 38-day incubation at 90% WHC, the metam sodium treatment emitted more N2O emissions than other treatments in the first 15 days of the incubation but no significant differences were observed among the other treatments at the end of the incubation.

© 2020 by the authors, In this field study, the fungicidal and nematicidal activity of two plant extracts (Larrea spp. (LR), Liquidambar spp. (LQ)), and an organosulfur soil fungicide metam sodium alone (MS), and a mix of LR and MS (LR + MS) was assayed under pepper cropping in southeastern Spain. Metam sodium treatments (MS and LR + MS) produced the highest crop yields and were more effective in controlling root-knot nematodes and fungal pathogens (Fusarium, Pythium, and Rhizoctonia solani) than the plant extracts treatments (LQ and LR). Furthermore, the effect of the metam sodium treatments applied negatively affected the soil microbial community, principally bacteria, but not fungi. These microbial community changes of the soil were principally observed after treatment application; the differences between the treatments were reduced at the end of the experiment, when recovery of the soil microbiota communities occurred., This study was supported by the Ministerio de Economía, Industria y Competitividad of Spain (RTC-2016-5489-2).

Trials were conducted in the 2017-2018 production season. Metam sodium 500 g / l (MS) (50, 75, 100 l / da) in 2 tomato greenhouses in Mersin-Adanalioglu, 3 doses, 4 replications were applied before planting. Tomato wilt and root rot (Fusarium oxysporum, Rhizoctonia solani) effect on the disease rate (%) S + MS 50, 75, 100 l / ha applications 66.65-73.69%, 84.91-90.00%, 89.98-92.26, respectively 47.58-56.79% in solarization alone application, 88.23-91.43% in comparison application (S + dazomet, 97%, 40 kg / da) (P

orld peanut production averages 23 million metric tons from harvest of approximately 20 million hectares on six continents (2). India, China, and the United States produced 70% of the world’s peanuts in 1990 and 1991. Production in the United States is concentrated in the southeast (Georgia, Florida, and Alabama), southwest (Texas and Oklahoma), and the mid-Atlantic region (Virginia, North Carolina, and South Carolina). Peanuts are grown in sandy-textured soils in warm, moist climates having a growing season of 140 or more days. Southeastern Virginia provides an excellent environment for commercial production, as evidenced by high yield and quality dating back to the Civil War (8). Today, the industries of producing, shelling, and processing peanuts are major pillars of the economy in southeastern Virginia. These industries are concentrated in an eight-county area, where the value of the crop to growers often ranges from $80 to $102 million, as in 1994 and 1990, respectively. Unfortunately, the warm and moist climate necessary for peanut production makes fungal diseases a chronic threat to profits. The rapid spread and the unforgiving nature of early leaf spot, caused by Cercospora arachidicola S. Hori, have earned the respect of growers in Virginia and around the world. Peanut growers are also keenly aware of soilborne diseases caused by fungi such as Sclerotinia minor Jagger (Sclerotinia blight), Sclerotium rolfsii Sacc. (southern stem rot), and Cylindrocladium parasiticum Crous, Wingfield & Alfenas (Cylindrocladium black rot). In 1990 and 1991, a systematic survey of peanut growers in southeastern Virginia was conducted to evaluate their perception of losses of yield to specific diseases and the use of pesticides (11; P. M. Phipps, unpublished). Sclerotinia blight and southern stem rot were named most frequently as responsible for yield losses exceeding 10% (Table 1). Sclerotinia blight was considered by the highest percentage of growers to be the most damaging disease. Clinical records, on-farm tests, and reports by extension agents and specialists supported these estimates, except for the claims of yield losses to southern stem rot. In this case, it was thought that the growers’ estimate of losses may have been excessive and possibly reflected some confusion with Sclerotinia blight. Peanuts require intensive management because of the crop’s vulnerability to yield losses caused by diseases, insects, and weeds. Chemicals play a major role in pest management strategies for peanut production due to the limited availability of acceptable alternatives. Based on the 1990 survey of peanut growers in Virginia, the input of pesticide active ingredients (a.i.) totaled 747 t and averaged 19 kg/ha (Table 2). The cost of these materials averaged $293 per ha. With the dramatic increase in the use of metam sodium for control of Cylindrocladium black rot (CBR) in 1991, the estimated input of pesticide a.i. totaled 970 t and averaged 25 kg/ha at a cost of $322 per ha. Metam sodium accounted for 36% of the total a.i. and 9% of cost. Chemicals for disease management alone accounted for 37 and 42% of the total cost of pesticides for production in 1990 and 1991, respectively. Recent changes in government programs (1) that control production quotas and prices growers receive for U.S. peanuts were expected to cause up to a 10% reduction in acreage and a 10% reduction in

Experiments were conducted during 1992 to 1995 to evaluate the effectiveness of application methods of metam sodium (MS; sodium N-methyldithio-carbamate) for the management of Fusarium crown and root rot (FCRR) caused by Fusarium oxysporum f. sp. radicis-lycopersici in mulched and staked tomatoes (Lycopersicon esculentum Mill.) grown on raised beds in commercial fields in southwest Florida. Efficacy of MS was compared with soil-injection of methyl bromide-chloropicrin (MBC), the current industry practice for production of tomatoes in Flor-ida. The incidence of FCRR was consistently high in nontreated plots (80 to 100%), but disease severity varied by site, and yields were reduced by 10 to 57% at sites with high disease severity when compared to sites treated with MBC at 336 to 448 kg/ha. Application of MBC reduced FCRR incidence in all experiments. Chemigation with MS at 701 or 935 liters/ha into mulched beds using either one or two drip irrigation tubes placed on the soil surface, and soil injection of MS at 935 liters/ha, failed to reduce the disease. The application of MS at 935 liters/ha to the soil surface prior to bed formation produced variable results. Rotovation of MS at the same rate into preformed beds consistently produced reductions in the incidence of FCRR equivalent to those achieved by MBC.

The fate of methyl isothiocyanate (MITC) was studied in agricultural soils following metam sodium (MS) application in a controlled system and under field conditions as it was related to disease control. Soil samples were collected from 34 field sites in Israel with no history of MS application. The generation and dissipation curves of MITC in these soils, under controlled conditions, varied significantly among the soils, as reflected by the concentration by time (C × T) product. This value was significantly related with the mortality level of Fusarium oxysporum f. sp. radicis-lycopersici as a test organism and sand content of the soils. Seven field experiments were conducted in potato fields from 2001 to 2004. The MS treatments significantly reduced Verticillium wilt incidence and severity in five and four experiments, respectively, out of seven. Combining MS with formalin was more effective for controlling disease than MS alone in most cases. A significant relationship was found between mortality of F. oxysporum f. sp. radicis-lycopersici in soil samples to which MS was applied under controlled conditions and the incidence of Verticillium wilt disease in the field, and between CMITC × T products and the incidence of Verticillium wilt disease in the field. These tests can be used for preplant assessment of potential MS efficacy.

Zveibil, A., Mor, N., Gnayem, N., and Freeman, S. 2012. Survival, host–pathogen interaction, and management of Macrophomina phaseolina on strawberry in Israel. Plant Dis. 96:265-272. Crown and root rot of strawberry, caused by Macrophomina phaseolina, have become predominant soilborne diseases of strawberry in Israel over the past 5 years. In total, 151 isolates of the pathogen were isolated from infected strawberry plants of commercially grown cultivars in Israel onto a modified agar medium for the genus Macrophomina. Sclerotia viability declined more rapidly in soil maintained at 25°C or at soil temperatures fluctuating from 18 to 32°C under greenhouse conditions, compared with sclerotia viability in soil kept at 30°C. After 30 to 40 weeks of exposure in soil, inocula maintained at 25 or 30°C or at fluctuating temperatures in a greenhouse declined to negligible levels. A significant increase in plant mortality was observed in infested soils maintained at 30 versus 25°C, whereas water stress at 25 or 30°C did not affect plant mortality in M. phaseolina-infested soils. This demonstrated the importance of elevated soil temperature, not moisture stress, on plant mortality caused by M. phaseolina. Host specificity was not evident when strawberry plants were inoculated with each of seven Israeli isolates of M. phaseolina obtained from six other plant species, suggesting the importance of keeping strawberry crops out of rotation with other host crops of the pathogen. The soil fumigants methyl bromide (applied at 500 kg/ha) and metam sodium (730 liter/ha) caused 90 and 95% pathogen mortality in field experiments, respectively, indicating that fumigation may be an effective method of managing this pathogen in infested soils. The increase in prevalence of crown and root rot caused by M. phaseolina in strawberry crops in Israel may be related to the phase-out of methyl bromide.

Elmer, W. H., and McGovern, R. J. 2013. Epidemiology and management of Fusarium wilt of China asters. Plant Dis. 97:530-536. The epidemiology and strategies for management of Fusarium wilt of China aster (Callistephus chinensis) were studied in Connecticut and Florida, USA, by examining seed contamination, on-farm disease incidence, sanitation, host resistance, and various soil treatments. Five out of 25 commercial seed packages from three separate distribution companies assayed in Connecticut had seeds contaminated with the pathogen Fusarium oxysporum f. sp. callistephi. Farm surveys of two cutflower farms in Connecticut had disease incidences of 32 and 58%, while in Florida, the incidence of the disease ranged from 0.002 to 71.2% in two cut-flower operations. All pathogenic isolates from seed and symptomatic plants in Connecticut were vegetatively compatible, suggesting a common origin. Pathogenic isolates from Florida and nonpathogenic isolates fell into different vegetative compatibility groups and may have had another origin. Sodium hypochlorite solutions (1%) eliminated the fungus from seeds and Styrofoam when applied as a soak or spray, respectively. Soil fumigation with methyl bromide + chloropicrin, 1,3-dichloropropene + chloropicrin, or metam sodium maintained Fusarium wilt at low levels at a Florida cut-flower production facility. Evaluations of disease resistance of 44 cultivars in the greenhouse identified eight cultivars with moderate resistance. Four cultivars were identified with moderate resistance in field trials and thus could serve as a source of resistant germplasm for future breeding programs. These findings should encourage growers to use sanitation protocols to prevent entry of the pathogen into their fields and to choose commercially available cultivars that have moderate resistance. The China aster (Callistephus chinensis (L.) Nees.) has long been valued for its brilliant flowers and diverse variety of sizes and shapes. Its preferred use in many ceremonies and festivals has assured its cultivation by many cultures. In India, China asters have become so valuable in festivals that over 6,000 tons of China asters

Fusarium wilt, caused by Fusarium oxysporum f. sp. spinaciae, is a significant constraint to the summer production of bunching spinach in Ontario, Canada. Trials were conducted to assess soil amendments (limestone) and fumigants (metam sodium, chloropicrin and dazomet) for the suppression of Fusarium oxysporum f. sp. spinaciae. Dolomitic limestone applied at a rate of 10 and 20 t ha−1 reduced the incidence of fusarium wilt by 10 and 47%, respectively, even though there was little change in soil pH (7.4–7.5) or soil calcium concentration (1598 vs 1483 in 20 t lime vs control, respectively. Fusarium wilt severity was lower in the 2013 than in the 2014 growing season. In 2014, the fumigants metam sodium, chloropicrin and dazomet reduced the population of Fusarium spp. propagules in the soil by 84, 93 and 100%, respectively. Chloropicrin provided the best control of the spinach fusarium wilt pathogen compared to the other fumigants but was only assessed one year. Chloropicrin was the only treatment to truly reduced spinach Fusarium wilt by preventing vascular discolouration. Brassica juncea and calcium cyanamide were not effective at suppressing the disease. A high rate of nitrogen, consisting of polymer coated sulphur coated urea, was applied to provide the same rate of nitrogen as the Brassica juncea and calcium cyanamide treatments. Applying nitrogen in this formulation was as effective as metam sodium in reducing the incidence and severity of Fusarium wilt and should be evaluated further to determine the economics and environmental impact of this approach.

The onion basal rot disease is a worldwide threat caused by species of the genus Fusarium. Today, Israel’s control of this disease is limited to a four-year growth cycle and Metam sodium soil disinfection. Here, commercial chemical fungicides were evaluated as control treatments against two of the primary pathogens involved, F. oxysporum f. sp. cepae and F. Acutatum. Out of 10 fungicides tested on culture plates, 3, Prochloraz, Azoxystrobin + Tebuconazole, and Fludioxonil + Sedaxen, had strong inhibitory effects on mycelial growth and were selected and tested in seeds in vitro. The preparations were applied as a seed coating and tested in two commercial cultivars, Riverside (Orlando, white cv.) and Noam (red cv.). Prochloraz (0.3% w/w concentration), the most promising compound, was efficient in reducing the Noam cv. sprouts’ disease symptoms. This preparation had no harmful in situ-toxicity effect and did not influence the plants’ seed germination and early development. In Noam cv. potted 30-day-old sprouts, the Prochloraz treatment was able to reduce the harmful impact of F. oxysporum f. sp. cepae. on the seedlings’ wet biomass, but was not effective in the Riverside cv. or against the F. acutatum pathogen. This suggests that future protective strategies must include an effective protective suit tailored to each of the pathogen species involved and the onion cultivar. The methods presented in this work can be applied for rapidly scanning multiple compounds while gradually ruling out ineffective ones. Eventually, this screening will enable field testing of the highest potential fungicides that successfully pass the pot experiments.

The availability and use of crop protectants including azoxystrobin in combination with fumigation has extended the Central Wisconsin effective growing season by 2 to 4 weeks. This study, evaluating the influence of these crop protection practices on the optimum nitrogen rate and time of application for Russet Burbank potato (Solanum tuberosum L.), was established as two 3-year field trials designed as split-split plot experiments. Both experiments used metam sodium as the main plots and fungicide treatment (chlorothalonil Zn alone or chlorothalonil Zn alternated with azoxystrobin for the first six sprays) as the first split. In-season fertilizer N rate (179, 224, 269, or 313 kg N ha−1) or in-season N timing (N split into two, three, or four applications at 269 kg N ha−1) was the second split. Not fumigating resulted in significantly higher verticillium ratings and severely repressed crop yield and tuber quality responses to both fungicide treatment and N rate. On average, fumigation increased total yield 13.6 Mg ha−1yr−1, U.S. No. 1 tubers by 9 % and U.S. No. 1 tubers >170 g by 5 % over where fumigation was not used. In 2 of the 3 years when azoxystrobin was included in the fungicide program early blight severity was reduced by about 50 %, and on fumigated areas yields were increased 4.8 Mg ha−1, whereas no yield increase was seen from this fungicide treatment on the non-fumigated plots. In these same years, fumigation increased optimum N rate by about 50 kg ha−1; however, there was no apparent interaction with fungicide treatment. Although fumigation, fungicide treatment, and time of N application each influenced tuber yield or tuber quality in some years, in the two more responsive years some interactions between these factors were statistically significant, with benefits generally only seen where plots were fumigated.

Preplant soil fumigation is commonly used to control soilborne pathogens and weeds in forest seedling nurseries of Oregon and Washington. However, lower chemical inputs are desired to meet state and federal application regulations, to minimize buffer zone size requirements, and to help protect the environment. Therefore, the objectives of this research were to evaluate the efficacy of three reduced rate soil fumigants under totally impermeable film (TIF) in managing soilborne diseases and weeds, and to determine if combined applications of up to four biocontrol agents improved soilborne disease control. Reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene, all applied in combination with chloropicrin, were effective in decreasing soil populations of Pythium and Fusarium as well as the presence of Pythium in root debris from the previous crop. The roots of Douglas-fir (Pseudotsuga menziesii) seedlings transplanted into each fumigant treatment were also colonized less by Pythium and Fusarium than those transplanted into nonfumigated control plots. However, biocontrol treatments were not effective against either pathogen. Weed biomass and weeding times were also significantly reduced by fumigation. Application costs were similar for all three fumigant treatments, but seedling size was largest from the methyl bromide and metam sodium treatments followed by the 1,3-dichloropropene treatment. Based on the results of this study, reduced rates of methyl bromide, metam sodium, and 1,3-dichloropropene show promise in managing soilborne diseases and weeds in forest nurseries.

Soil fumigants constitute a major tool for the control of soil borne fungal plant pathogens in protected crops. Dimethyl disulfide (DMDS) is a novel soil fumigant used either alone or in combination with other fumigants for the control of soil borne pests and diseases. In a commercial greenhouse for tomato production, we evaluated the impact of DMDS, comparatively to the alternative fumigant metam sodium, on the population of the dominant fungal plant pathogens in the study soil via q-PCR. Prior to soil fumigation, estimation of the fungal diversity in the studied soil via clone libraries identified Fusarium oxysporum and Rhizoctonia solani as the most abundant soil borne plant pathogens, while Cladosporium spp., known as opportunistic airborne tomato pathogens, were the most dominant fungi and based on this their dynamics upon fumigation was also studied. DMDS, at two dose rates, induced a drastic reduction in the population of F. oxysporum and R. solani, which lasted for the whole cultivation season. On the contrary, metam sodium exhibited an inhibitory effect on F. oxysporum that was alleviated at 120 d post fumigation. Both DMDS and metam sodium induced only a temporal reduction in the soil population of Cladosporium sp. which recovered by 60 days post fumigation. Our data suggest that DMDS even at the low dose rate (56.4 g m−2) could drastically reduce the population of the major soil borne tomato pathogens F. oxysporum and R. solani. Establishment of population thresholds as determined by q-PCR could represent a valuable tool for the estimation of the risk for disease severity and crop yield losses.

Twelve field trials were completed in North Carolina from 2005 to 2007 to determine the impact of planting pattern on peanut yield, market grade characteristics, and pest reaction for the Virginia market type cultivars Perry and VA 98R. The first set of experiments was designed to evaluate incidence of Cylindrocladium black rot (caused by Cylindrocladium parasiticum) using a factorial treatment arrangement of two cultivars, two levels of fumigation (none or metam sodium at 112 L/ha), and two levels of planting pattern (single rows spaced 91-cm apart or twin rows spaced 18 cm apart on 91-cm centers). Visible symptoms associated with Cylindrocladium black rot were not affected by planting pattern. However, in 1 of 3 trials pod scarring as a result of feeding by southern corn rootworm (Diabrotica undecimpunctata Howardi) was greater in twin rows compared with single rows. Damage from tobacco thrips (Frankliniella fusca) was also higher in the cultivar VA 98R planted in twin rows than in single rows or for the cultivar Perry. In the second set of experiments designed to evaluate incidence of Sclerotinia blight (caused by Sclerotinia minor), a factorial treatment arrangement consisting of two cultivars, two levels of boscalid (none or boscalid at 0.44 kg ai/ha), and two levels of planting pattern was implemented. Boscalid decreased Sclerotinia blight incidence at one of 4 locations, and increased pod yield. Yield of Perry was lower when grown in twin rows versus single rows, but yield of VA 98R was higher in twin rows. Peanut planted in twin rows yielded more than peanut planted in single rows regardless of cultivar, fumigation, or disease history in most trials. Results from these experiments suggest that planting pattern can have a minor impact on response to pests and that yield and market grades are often improved when peanut is planted in twin-row planting patterns compared with single rows.