Soil Fumigation Research Articles

Effect of deep injection on field-scale emissions of 1,3-dichloropropene and chloropicrin from bare soil

Fumigating soil is important for the production of many high-value vegetable, fruit, and tree crops, but fumigants are toxic pesticides with relatively high volatility, which can lead to significant atmospheric emissions. A field experiment was conducted to measure emissions and subsurface diffusion of a mixture of 1,3-dichloropropene (1,3-D) and chloropicrin after shank injection to bare soil at 61 cm depth (i.e., deep injection). Three on-field methods, the aerodynamic (ADM), integrated horizontal flux (IHF), and theoretical profile shape (TPS) methods, were used to obtain fumigant flux density and cumulative emission values. Two air dispersion models (CALPUFF and ISCST3) were also used to back-calculate the flux density using air concentration measurements surrounding the fumigated field. Emissions were continuously measured for 16 days and the daily peak emission rates for the five methods ranged from 13 to 33 μg m−2 s−1 for 1,3-D and 0.22–3.2 μg m−2 s−1 for chloropicrin. Total 1,3-D mass lost to the atmosphere was approximately 23–41 kg ha−1, or 15–27% of the applied active ingredient and total mass loss of chloropicrin was <2%. Based on the five methods, deep injection reduced total emissions by approximately 2–24% compared to standard fumigation practices where fumigant injection is at 46 cm depth. Given the relatively wide range in emission-reduction percentages, a fumigant diffusion model was used to predict the percentage reduction in emissions by injecting at 61 cm, which yielded a 21% reduction in emissions. Significant reductions in emissions of 1,3-D and chloropicrin are possible by injecting soil fumigants deeper in soil.

The Effects of Fungicide, Soil Fumigant, Bio-Organic Fertilizer and Their Combined Application on Chrysanthemum Fusarium Wilt Controlling, Soil Enzyme Activities and Microbial Properties.

Sustained monoculture often leads to a decline in soil quality, in particular to the build-up of pathogen populations, a problem that is conventionally addressed by the use of either fungicide and/or soil fumigation. This practice is no longer considered to be either environmentally sustainable or safe. While the application of organic fertilizer is seen as a means of combating declining soil fertility, it has also been suggested as providing some control over certain soil-borne plant pathogens. Here, a greenhouse comparison was made of the Fusarium wilt control efficacy of various treatments given to a soil in which chrysanthemum had been produced continuously for many years. The treatments comprised the fungicide carbendazim (MBC), the soil fumigant dazomet (DAZ), the incorporation of a Paenibacillus polymyxa SQR21 (P. polymyxa SQR21, fungal antagonist) enhanced bio-organic fertilizer (BOF), and applications of BOF combined with either MBC or DAZ. Data suggest that all the treatments evaluated show good control over Fusarium wilt. The MBC and DAZ treatments were effective in suppressing the disease, but led to significant decrease in urease activity and no enhancement of catalase activity in the rhizosphere soils. BOF including treatments showed significant enhancement in soil enzyme activities and microbial communities compared to the MBC and DAZ, evidenced by differences in bacterial/fungi (B/F) ratios, Shannon–Wiener indexes and urease, catalase and sucrase activities in the rhizosphere soil of chrysanthemum. Of all the treatments evaluated, DAZ/BOF application not only greatly suppressed Fusarium wilt and enhanced soil enzyme activities and microbial communities but also promoted the quality of chrysanthemum obviously. Our findings suggest that combined BOF with DAZ could more effectively control Fusarium wilt disease of chrysanthemum.

Influence of brassicaceous soil amendments on potentially beneficial and pathogenic soil microorganisms and seedling growth in Douglas-fir nurseries

Fusarium, Cylindrocarpon and Pythium spp. are the major soil-borne pathogens of conifer seedlings. Soil fumigation with methyl bromide and chloropicrin has been the most effective method for reducing the population density and disease pressure of these organisms. Due to safety and environmental concerns, use of methyl bromide as a pre-plant soil fumigant has been abolished in the majority of cropping systems. However, the conifer seedling industry continues to use methyl bromide under a quarantine pre-shipment exemption due to a lack of effective alternatives. Toward identifying alternatives to methyl bromide for management of soil microbial populations, a three-year field study was conducted in northwest USA. The objective of this study was to examine the effects of brassica seed meals and green manures on potentially pathogenic and beneficial microorganisms, soil health, and seedling growth in conifer nursery fields. The study treatments were Brassica juncea seed meal, B. carinata seed meal, Sinapis alba seed meal, B. juncea green manure, methyl bromide/chloropicrin fumigation, and a non-treated control, with four replications in a randomized complete block design. The treatments were incorporated into soil in autumn or early spring, and Douglas-fir (Pseudotsuga menziesii) seedlings were transplanted into plots in late spring. Population densities of Fusarium, Cylindrocarpon, Pythium, actinomycetes, and Trichoderma; mineralizable nitrogen; and dehydrogenase enzyme activity in soil were assessed at pre-transplant, post-transplant, and seedling harvest. The pre-treatment soil pathogen count was similar among study plots. At transplant time, Fusarium spp. densities in soil were generally similar among most brassica treatments but fumigated plots generally had less Fusarium. Treatment with S. alba, however, increased soil densities of Fusarium spp. In 2012, Fusarium spp. density was significantly lower after B. juncea green manure incorporation [1.8 log CFU (colony forming units)] than after chemical fumigation (2.4 log CFU) or in the untreated control (2.6 log CFU); whereas the soil density of potentially antagonist Trichoderma spp. was significantly greater in fumigated plots (3.7 log CFU) followed by B. juncea green manure (3.4 log CFU) and lowest in control (3.2 log CFU). Fumigation produced the largest seedlings but B. juncea green manure also produced significantly larger seedlings than control. Dehydrogenase activity, an indicator of soil microbial activity, was greatest with B. juncea green manure and lowest in fumigated soil. Mineralizable nitrogen in soil followed the same trend. These results suggest that B. juncea green manure may have a suppressive effect on soil-borne pathogens, and maintain or improve soil and seedling health.

Assessment of the impact of the fumigant dimethyl disulfide on the dynamics of major fungal plant pathogens in greenhouse soils

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.

Efficacy of reduced rate fumigant alternatives and methyl bromide against soilborne pathogens and weeds in western forest nurseries

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.

Amplicon-based metabarcoding reveals temporal response of soil microbial community to fumigation-derived products

The use of soil fumigation products to manage soilborne pathogens raises the question of whether it has undesirable effects on the soil ecosystem. Therefore, the aim of this study was to investigate the impacts of alternative fumigation products on soil microbial population structure. We characterised soil bacterial and fungal communities in response to the soil treatment with microencapsulated terpene, Brassica seedmeal (BioFence™) and chloropicrin in a field trial. The effect of soil treatments on the overall microbial population structure and relative abundance of individual microbial OTUs (operational taxonomic units) was assessed using an amplicon-based metabarcoding approach at three time points. Classifying representative OTU sequences into taxonomic groups was more uncertain for bacteria than for fungi. Chloropicrin dramatically altered both bacterial and fungal populations within four weeks of application. The effect on bacterial population structure is short-lived and became non-significant 16 weeks after treatment; however, fungal population structure was more persistently affected by chloropicrin. Neither terpene nor BioFence™ significantly affected soil microbiota. This study highlights the need for reliable algorithms in classifying sequences into taxonomic units and also the importance of identifying microbes into finer taxonomic groups for understanding soil microbiota and their effects on crop production.

Effects of different methods to control the parasitic weed Phelipanche ramosa (L.) Pomel in processing tomato crops

The root-parasitic weed Phelipanche ramosa (L.) Pomel represents a major problem for processing tomato crops. The control of this holoparasitic plant is difficult, and better understanding of treatment methods is needed to develop new and specific control strategies. This study investigated 12 agronomic, chemical, biological and biotechnological strategies for the control of this parasitic weed, in comparison with the untreated situation. The trial was carried out in 2014 at the Department of Agriculture, Food and the Environment of the University of Foggia (southern Italy), using processing tomato plants grown in pots filled with soil from a field that was heavily infested with P. ramosa. After transplantation, top dressing was performed with 70 kg ha–1 nitrogen. A randomised block design with 3 replicates (pots) was adopted. During the growing cycle of the tomato, at 70, 75, 81 and 88 days after transplantation, the number of parasitic shoots (branched plants) that had emerged in each pot was determined, and the leaf chlorophyll of the plants was measured using a soil-plantanalysis- development meter. At harvesting on 8 August 2014, the major quanti-qualitative yield parameters were determined, including marketable yield, mean weight, dry matter, soluble solids, and fruit colour. The results show lower chlorophyll levels in the parasitised tomato plants, compared to healthy plants. None of the treatments provided complete control against P. ramosa. However, among the methods tested, Radicon® biostimulant (Radicon, Inc., Elk Grove Village, IL, USA), compost activated with Fusarium oxysporum, nitrogen and sulphur mineral fertilisers, EnzoneTM soil fumigant (Elliott Chemicals Ltd., Auckland, New Zealand), and a resistant tomato genotype mitigated the virulence of the attacks of this parasite. These effects should be improved by combining some of these treatments, especially for gradual and continued reduction in the seed bank of the parasite in the soil. For the tomato yields across the different treatments, there were no significant differences seen; however, the yields showed an improving trend for treatments with lower presence of the P. ramosa weed.

Chemical soil fumigation for raspberry nursery in Jalisco (Mexico)

Chemical soil fumigation for raspberry nursery in Jalisco (Mexico)

The Effects of Biochar Amendment on Dimethyl Disulfide Emission and Efficacy Against Soil-Borne Pests

Biochar can potentially reduce fumigant emissions in agriculture. Dimethyl disulfide (DMDS) is an effective soil fumigant for controlling soil-borne pests. However, it is important to reduce DMDS emissions because the compound has an unpleasant and easily perceived sulfur odor. This study therefore aimed to determine the effects of two types of biochar amendments on DMDS bioactivity and emission, using bioassay methods and soil columns. The efficacy of DMDS for controlling root-knot nematode and Fusarium spp. was not reduced when the biochar used in this study was applied at a rate less than 2 and 0.5 % (on a weight basis), respectively. The biochar with high specific surface area (SSA 113 m−2 g−1) reduced the efficacy of DMDS against soil-borne pests more than the low SSA biochar (14 m−2 g−1). Increased doses of DMDS were able to offset decreases in the efficacy of DMDS in soils amended with biochars, except for high SSA biochar applied at a rate of 2 %. Biochar amendments applied to the soil surface at shallow depth can significantly reduce DMDS emission to the atmosphere. The results of this study will support decision-making about the practical use of biochar to reduce DMDS emissions.

Evaluation of five pre-emergence herbicides for volunteer potato (Solanum tuberosum L.) control

Volunteer potatoes can cause significant weed problems in crops following potatoes as large numbers of potato tubers remain behind in the field after mechanical harvesting. These volunteer plants can create havoc with rotation programs and serve as a source of pests and diseases. The aim of this project was to identify a suitable product to control volunteer potato plants. A glasshouse trial was conducted in polyethylene pots filled with a sandy soil (9% clay). Two potato cultivars (Mondial and Sifra) and five pre-emergence herbicides (atrazine, clomazone, imazethapyr, mesotrione and picloram), together with a soil fumigant (metham potassium) and an untreated control were used in a randomised complete block experimental design. Only metham potassium provided 100% control, although both mesotrione and picloram provided significant reduction in plant growth. Tuber numbers were significantly reduced by mesotrione, picloram and clomazone. Similar results were noted for tuber mass, although Mondial appeared to be more sensitive than Sifra for this parameter. The herbicide results were similar to those obtained by other researchers. Although metham potassium was the only truly effective treatment, mesotrione showed great promise for volunteer control. Picloram is not registered for use in cropping systems and cannot be recommended.

Novel soil fumigation method for suppressing cucumber Fusarium wilt disease associated with soil microflora alterations

Fusarium wilt in cucumber results from continuous cropping and is a serious soil-borne fungal disease that threatens cucumber production around the world. The application of a novel fumigation agent based on ammonium bicarbonate to the soil as a strategy for controlling Fusarium wilt and its effects on soil microflora was investigated in a field with serious disease incidence in this study. Overall, the results showed that fumigation effectively controlled cucumber Fusarium wilt disease and significantly increased the total and mean cucumber fruit weight. Real-Time PCR results showed that the total bacterial and fungal numbers in the treatment (LAB) significantly decreased after fumigation and that significantly fewer fungi were observed after harvest (LABOF). The next-generation sequencing of the 16S rRNA and internal transcribed spacer (ITS) genes using MiSeq platform showed that the soil bacterial and fungal community structures in the fumigation treatment were significantly different from the control without fumigation regardless after fumigation or harvest. Compared to the control, higher abundances of Gemmatimonadetes, Verrucomicrobia and Zygomycota, and lower abundance of Ascomycota were observed in the fumigated soils after fumigation and harvest. Furthermore, the abundances of Mortierella and Gp1 were significantly higher. Most importantly, the abundance of Fusarium, which includes the pathogen potentially responsible for cucumber Fusarium wilt disease, was significantly lower in the fumigated soils after harvest. Redundancy analysis showed that the fumigated soils were dominated by Ohtaekwangia, Gp6, and Gp4, which were related to the soil total nitrogen (TN), ammonium nitrogen (NH4–N) and nitrate nitrogen (NO3–N) contents. In addition, Penicillium and Pseudaleuria fungi were dominant in the treatment and control, and the control was dominated by Fusarium. In conclusion, the observed disease suppression due to the novel ecological soil fumigation strategy may be attributed to general suppression resulting from altered soil properties, such as higher soil NH4–N, NO3–N and TON contents, and the alteration of the disturbed soil microflora in a cucumber monoculture system.

Distribution and Longevity of Pratylenchus penetrans in the Red Raspberry Production System.

One of the major constraints on the production of red raspberries in the Pacific Northwest is the presence of the root-lesion nematode Pratylenchus penetrans. Current management of this nematode relies heavily on preplant soil fumigation; however, regulations have made the practice more difficult and expensive. Additional issues with soil fumigation include lack of efficacy at deeper soil depths and potential inability to penetrate raspberry root material that remains in the field during fumigation which may harbor P. penetrans. To address these issues, two field experiments were conducted in northwestern Washington. In the first experiment, the residency time of P. penetrans in root material from the previous raspberry crop, which was terminated with or without the use of herbicides, was monitored over time. Pratylenchus penetrans was found in root material from 6 to 8 mon after the crop was terminated, and herbicide application did not reduce P. penetrans residency time compared to untreated root material. In a second experiment, the vertical distribution of P. penetrans at three different times during the field establishment process (pre- and postfumigation, and at planting) was determined at two locations. Both locations had detectable prefumigation P. penetrans populations at all depths. However, postfumigation populations showed a different distribution pattern between locations. The location with coarser soil had populations located mainly at shallower depths with a maximum of 44 P. penetrans/100 g soil at 16 to 30 cm deep, whereas the location with finer soil had populations located mainly at deeper depths with a maximum of 8 P. penetrans/100 g soil at 76 to 90 cm deep. At planting, distribution tended to equilibrate among depths at both locations, but the overall population pattern across depth at each location was similar to that observed at postfumigation. Understanding more about the residency time and distribution of this nematode may provide growers with information that can be used to more effectively target P. penetrans.

INFLUENCING FACTORS, EFFECTS AND DEVELOPMENT PROSPECT OF SOIL SOLARIZATION

Soil-borne diseases are one of the major constraints in the production of many economically important crops, especially vegetables and ornamentals. In the past decades, soil fumigants (such as methyl bromide) were the most common approach to control soil-borne diseases. However, such chemical treatments caused environmental hazards; thus, nonchemical soil disinfection methods are being widely pursued in recent years. Among these, soil solarization is one of the most promising methods to control soil-borne diseases. Soil temperature, mulching materials, soil moisture, and climatic conditions are the critical factors that affect the disinfection efficiency. In addition, other factors, for example, soil type; soil color; airtight state of glasshouse; etc. also influence the efficiency. Soil solarization controls soil-borne pests and diseases, nematodes, and weeds, and also influences soil properties and plant growth and yield. Although there are many merits for soil solarization, it also has significant limitations, for example, the relatively long duration of the process, the dependency on climatic conditions, inconsistencies in controlling high-tolerant pests, and problems related to used plastic film disposal. In order to increase treatment efficacy and predictability, integration of solarization with other disinfestation methods is recommended.

Optimized synthesis of CuInS2/ZnS:Al–TiO2 nanocomposites for 1,3-dichloropropene photodegradation

CuInS2/ZnS:Al–TiO2 nanocomposites were optimally prepared by response surface methodology and could be highly efficient for soil fumigant photodegradation.

Application of the combination of 1,3-dichloropropene and dimethyl disulfide by soil injection or chemigation: effects against soilborne pests in cucumber in China

The combination of 1,3-dichloropropene+dimethyl disulfide (1,3-D+DMDS), which forms a pre-plant soil fumigant, can provide a substitute for the environmentally unfriendly methyl bromide (MB). Three greenhouse trials were performed to evaluate the root-knot nematode and soilborne fungi control efficacy in the suburbs of Beijing in China in 2010–2014. Randomized blocks with three replicates were designed in each trial. The combination of 1,3-D+DMDS (10+30 g m−2) significantly controlled Meloidogyne incognita, effectively suppressed the infestation of Fusarium oxysporum and Phytophthora spp., and successfully provided high commercial fruit yields (equal to MB but higher than 1,3-D or DMDS). The fumigant soil treatments were significantly better than the untreated controls. These results indicate that 1,3-D+DMDS soil treatments can be applied by soil injection or chemigation as a promising MB alternative against soilborne pests in cucumber in China.

An Improved Method for Determination of Fumigant Degradation Half‐Life in Soil

Core Ideas Degradation of fumigants is an important component of their fate and transport. Traditional measurement of half‐life is limited by the large headspace in an incubation vial. A novel approach is presented that eliminates the incubation vial headspace. This novel approach yields shorter fumigant half‐lives due to greater contact with soil. Using the current approach, measurement of fumigant degradation half‐lives under realistic soil conditions is problematic due to the large headspace that is necessary above the soil during incubation. This results in a poor degree of contact between the fumigant and the soil's degrading surfaces, which differs markedly from field conditions. We report a simple, novel approach for determining fumigant degradation half‐lives in which the fumigant is in complete contact with the soil during incubation (no headspace) and which uses gastight, nonsorbing equipment commonly found in pesticide research laboratories. The approach was tested on a sandy loam soil. At both 23 and 50°C, the novel approach yielded much lower degradation half‐lives for cis‐ and trans‐1,3‐dichloropropene (1,3‐D) isomers and chloropicrin (CP) than the traditional approach. Percentage reductions ranged from 22 to 64% and were greater at the higher temperature. The results suggest that literature‐reported half‐lives of soil fumigants, and consequently their modeled soil–air emission rates, may be overestimated. The novel approach could potentially be applied to determining the degradation kinetics of other classes of volatile chemicals in soil.

Characteristics of growing media mixes and application for open-field production of strawberry (Fragaria ananassa)

Growing media are widely used for strawberry production in protected environments. Due to increasing restrictions on the use of soil fumigants, there is a need to investigate production of strawberry fruits in open fields using substrate media. The objectives of the study were to characterize chemical and hydraulic properties of a number of selected growing media mixes and to evaluate them in a two-year field study for strawberry production in open fields. The growing media mixes were 100% coconut coir, a peat–perlite (PP) mix, a peat-rice hull (PR) mix, and a peat–coir–rice hull (PCR) mix. Results indicated that major macro- and micro nutrient element concentrations, pH, and salinity found in these growing media, after supplemental fertilization, were in recommended ranges for strawberry production. Compared to field soil, higher water content values were found for these growing media mixes at saturation and after free drainage. Among these media mixes, 100% Coir showed the highest water content values at saturation (0.95cm3cm−3) and after free drainage (0.51cm3cm−3). The field study also demonstrated the most vigorous vegetative growth in Coir by showing higher values in plant canopy size and biomass dry weight. In year 1 field experiment, marketable strawberry fruit yields from Coir, PP, and PR averaged 41,640kgha−1 which was not significantly different from the soil beds. Marketable strawberry yields from the year 2 Coir and PP treatments averaged 48,520kgha−1, which was also not significantly different from the grower standard practice in field soils. The year 2 yield was higher than year 1 because of longer harvesting season and more favorable weather conditions for strawberry growth. The study demonstrated that certain growing media mixes such as PP or the 100% Coir possess the needed chemical and hydraulic properties for plant growth and the 100% Coir could be used as a promising substrate material for open-field production of strawberries. Additional work is needed to optimize the irrigation and fertilization regimes to reduce the volume of growing media needed per plant and to evaluate the reuse of the substrate media to reduce production cost.

Ethnographic movement methods: anthropology takes on the pesticide industry

In this article, I describe how the methods of anthropology proved productive and fruitful for research and environmental justice (EJ) activism against methyl iodide, a highly toxic soil fumigant pesticide used to sterilize soil before food crops like strawberries are transplanted. I continue a thread of discussion around what roles anthropology, and especially, public and applied anthropology, should play in addressing the serious problems traditionally encountered, documented, analyzed, and theorized through ethnographic research. Anthropological engagement and action on methyl iodide and other soil fumigants produced unique research opportunities and networks up and down the agricultural hierarchy, as well as spaces to contribute ethnographic labor and critical analysis and reflection to the EJ movement. While this activist approach— what I refer to as 'ethnographic movement methods'—presented some challenges, the victorious end-result of having methyl iodide's manufacturer pull their product from the U.S. market in 2012 also demonstrated how anthropologists, in cooperation with communities confronted by environmental suffering, can work cooperatively towards alternative agricultural and ecological futures.Keywords: activism; applied anthropology; environmental justice; farmworkers; ethnographic movement methods; pesticides

Suppression on plant-parasitic nematodes using a soil fumigation strategy based on ammonium bicarbonate and its effects on the nematode community.

Banana production is severely hindered by plant-parasitic nematodes in acidic, sandy soil. This study investigated the possibility of applying a novel fumigation agent based on ammonium bicarbonate as a strategy for controlling plant-parasitic nematodes under sealed conditions. Moreover, its effects on the nematode community in pot and field experiments were also measured using morphology and feeding-habit based classification and the PCR-DGGE method. Results showed that a mixture (LAB) of lime (L) and ammonium bicarbonate (AB) in suitable additive amounts (0.857 g kg−1 of L and 0.428 g kg−1 of AB) showed stronger nematicidal ability than did the use of AB alone or the use of ammonium hydroxide (AH) and calcium cyanamide (CC) with an equal nitrogen amount. The nematode community was altered by the different fumigants, and LAB showed an excellent plant-parasitic nematicidal ability, especially for Meloidogyne and Rotylenchulus, as revealed by morphology and feeding-habit based classification, and for Meloidogyne, as revealed by the PCR-DGGE method. Fungivores and omnivore-predators were more sensitive to the direct effects of the chemicals than bacterivores. This study explored a novel fumigation agent for controlling plant-parasitic nematodes based on LAB and provides a potential strategy to ensure the worldwide development of the banana industry.

The Eggplants Crop Technology Optimization by Grafting

Soil fumigation has been an essential component of greenhouses crops since the 1960’s. Growing vegetables without soil fumigants has remained a challenge, partially because of the lack resistance to many soil borne plant pathogens of the commercially acceptable eggplant cultivars produced through conventional breeding. In field production, crop rotation is important to prevent infestation with diseases and pests. However, crop rotation is rarely practiced in greenhouse production, which allows soil-borne pathogens and pests to accumulate, progressively reducing crop yields. Grafting cultivars with high quality and productivity on rootstocks that are resistant to the soil pests and diseases is a method known from years ago, which was improved and quickly spread in the last years. Therefore, the aim of this research was to evaluate the performance of the eggplant grafting on the some rootstocks, in greenhouse conditions. There have been determined and calculated the marketable yield, fruits quality, frequency and root galling index of soil-borne diseases and nematodes, in the experimental variants. Grafting was found to resulted in an increased marketable yield and significantly reduced the incidence of Verticillium dahliae and Fusarium oxysporum f. sp. melongenae.      Â