Poultry litter-based organic fertilizers are usually incorporated into soil to improve its structure and fertility to increase crop production, however, poultry litter may also contain a variety of microorganisms which can compromise the safety of fresh produce when applied on agriculture lands. Composting can be a strategy to inactivate these microorganisms while creating a soil amendment beneficial for application to arable agricultural land. The objective of this study was to design and test the effect of moisture and temperature in a mechanically aerated in-vessel composting system for the purpose of reducing bacteria concentration in poultry litter while producing bio fertilizer. The actual composting occurred in four digesters which measured 1.2m x 1.2m x 1.2m. Four treatments were utilized with four different levels of moisture content in each vessel (treatment 1=65%, treatment 2=55% treatment 3=60% treatment 4=50%).Moisture gradually decreased and reached 55%, 44% and 48%, and 38.9% for treatment 1,2,3 and 4, respectively in the final compost product. The maximum average temperatures recorded for test 1, 2, 3 and, 4 were 50.54°C, 50.9 °C, 60.7 and 71.5°C respectively compared to outside temperature (15.4°C), and these temperatures were able to significantly reduce the concentration of total aerobic bacteria, fecal coliform and enterococcus listeria. The initial concentration of the compost piles was approximately 6.57, 6.04 and 3.72 log10 CFU/g of total aerobic bacteria, fecal coliform and enterococcus respectively. After analyzes, all target microorganisms were significantly eliminated. The significant levels of total aerobic bacteria, fecal coliform and enterococcus were p=0.0303, P=0.0258, p=0.0233 respectively. The presence of Salmonella spp. and Listeria spp. were not detected in all sampling period. Results of in-vessel compost analyses revealed a 16.9% N reduction; 10.1% P increase and 33.7% K increase. Moisture content decreased by 52.2% and elevated C/N ratio and pH by 27.7 % and 3.30% respectively. The leachates generated from the in-vessel composting for the first 21 days were analyzed, and the average results for week 1, 2, and 3, were observed to be 1043.7 mg/L, 1335.23mg/L, and 1029.9mg/L.Â

Aims The aim was to determine the survival and persistence of Escherichia coli in soil amended with compost from different manure sources. Method and Results Complex interactions of abiotic and biotic factors on E. coli survival were characterized in field experiment plots receiving randomly assigned compost treatments: dairy windrow, dairy vermicompost, poultry windrow or no compost. Biomass, activity and function of indigenous microbial communities in the composts and soils were measured concurrently to determine whether mechanisms of compost were driven by biotic or abiotic properties. E. coli persisted in compost containing poultry amendments but not in composts containing dairy or no amendments. Poultry compost contained more NH4-N and a distinct microbial community compared to dairy and no compost treatments. A laboratory experiment performed on compost extracts suggested that E. coli survived better in extracts devoid of indigenous microbes as long as bioavailable nutrients were plentiful. Conclusions Dairy-based composts are less likely to support E. coli survival than poultry-based composts. Significance and Impact of the Study Results aid in risk assessment of the use of different types of manure-based compost and soil amendments in fruit and vegetable production by elucidating the roles of nutrient and microbial community composition on survival of E. coli in amended field soils.

This report focuses on the efficacy of thermophilic and multi-stage treatment technologies in disinfecting generic E. coli, E. coli O157:H7, Salmonella spp., Listeria monocytogenes, parasites, and viruses in recycled organic residuals. Some recyclable organics can contain public health pathogens when delivered to a composting facility. Producing marketable soil amendments that meet high quality food safety standards for fresh produce commodities like leafy greens, tomatoes, onions, and cantaloupes requires diligent process management and record-keeping. Recent advances in composting and digestion technologies along with advances in knowledge of pathogen prevalence, survival, and susceptibility to treatments and natural attenuation provide a substantive foundation for improved sanitary quality of recycled organics for horticultural production. Establishment and use of Hazard Analysis Critical Control Point (HACCP) plans for facilities producing high quality soil amendments can aid process management for conventional and organic production systems. Use of HACCP approaches supports pathogen risk reduction metrics (e.g., E. coli O157:H7, Salmonella spp.) developed for targeted fresh and fresh-cut horticultural produce.

Aims: Zero‐valent iron (ZVI) filters may provide an efficient method to mitigate the contamination of produce crops through irrigation water.

The phytotoxic and antimicrobial properties of olive mill wastes have been widely investigated and demonstrated over the past decade. However, their potential utilization as biodegradable pesticides against plant pathogens is still poorly understood. In this study, a series of laboratory bioassays was designed to test the inhibitory effects of sterile water extracts of two-phase olive mill waste (TPOMW) and TPOMW composts with different degrees of stabilization on several different plant pathogens. Fungicidal properties of TPOMW extracts, assayed in a microwell assay format, showed that the growth of Phytophthora capsici was consistently and strongly inhibited by all TPOMW extracts diluted 1:10 (w:v). In contrast, suppression of Pythium ultimum and Botrytis cinerea by the extracts was not as strong and depended on the specific TPOMW sample. Mature compost inhibited P. capsici and B. cinerea at dilutions as great as 1:50, w:v. Neither TPOMW nor TPOMW compost extracts were able to inhibit the growth of the basidiomycete root rot agent Rhizoctonia solani. In addition, studies were conducted on the allelopathic effects of TPOMW extracts on seed germination of four highly invasive and globally distributed weeds (Amaranthus retroflexus, Solanum nigrum, Chenopodium album and Sorghum halepense). Both the TPOMW and immature TPOMW compost extracts substantially inhibited germination of A. retroflexus and S. nigrum, whereas mature composts extracts only partially reduced the germination of S. nigrum. Finally, TPOMW extracts strongly inhibited egg hatch and second-stage juvenile (J2) motility of the root-knot nematode Meloidogyne incognita. However, only higher concentrations of stage-one and stage-two TPOMW compost extracts exerted a suppressive effect on both J2 motility and on egg hatch. The study shows the high potential of naturally occurring chemicals present in TPOMW and TPOMW composts that should be further investigated as bio-pesticides for their use in sustainable agricultural systems.

Compost tea (CT) is an unheated on-farm infusion of compost used as a spray or soil drench to promote plant growth and control foliar and root diseases. Because food safety involves all aspects from farm to fork, CT should meet basic microbiological criteria for water quality. This report describes the effects of two CT production processes, aerated and nonaerated, on growth and survival of foodborne pathogens and fecal coliforms. Seven commercially available nutrients used to supplement CT were tested individually and in combination for their effects on the growth of Escherichia coli and Salmonella. Compost containing 10(1) to 10(3) CFU/g initial concentrations of E. coli O157:H7 and Salmonella Enteritidis were used to assess growth and survival responses to aerated CT (36-h preparations) and nonaerated CT (8.5-day preparations). Pathogen and fecal coliform populations were undetectable by 8.5 days in nonaerated CT without nutrient supplements. E. coli O157:H7 decreased to below detection levels in aerated CT at 36 h without the use of supplements. In contrast, the addition of commercially formulated mixtures or combinations of nutrient supplements resulted in growth of E. coli O157: H7, Salmonella, and fecal coliforms by 1 to 4 log CFU/g in both aerated and nonaerated CT. When nutrient supplements were added, aerated CT sustained higher concentrations of E. coli O157:H7, Salmonella, and fecal coliforms than did nonaerated CT. Thus, addition of supplements supports growth of human pathogens from very low initial concentrations in both aerated and nonaerated CT and should be avoided when CT is used on fresh produce.

Black root rot (BRR) can severely limit productivity in perennial, matted-row strawberry systems. In annual production systems, fumigation temporarily controls soilborne diseases. This report describes for the first time a novel, raised-bed growing method that uses 100% mature compost as an alternative to fumigation. Compost is pneumatically blown into flexible mesh tubes (“compost socks”) that lie directly on top of nonfumigated BRR-infested soil. Root health, plant growth, and yield of two cultivars, Chandler and Allstar, were evaluated after growth in compost socks, matted rows, and black plastic mulch at three locations in Maryland. Effects of a pre-plant soil drench with 20% vinegar were also examined. Results show that BRR symptoms were significantly reduced in all compost sock treatments, with or without vinegar, and that yields increased 16 to 32-times those observed in black plastic mulch or matted rows. In general, growth and yield of ‘Chandler’ surpassed that of ‘Allstar’ regardless of pre-plant vinegar and compost treatments. Vinegar alone was ineffective in preventing significant plant disease. Cotton-mesh compost socks readily decompose in soil eliminating the need for plastic removal. The compost sock system requires minimal equipment/supplies for startup, no fumigants, and is compatible with standard methods of weed management used in strawberry fields. Accepted for publication 2 June 2006. Published 16 October 2006.

Soil microbial properties are known to exhibit high spatial and temporal variability, which can hinder our understanding of the effects of agricultural management on soil microbial activities, populations and communities. However, if this variability is explicitly considered in soil sampling schemes, experimental results can help us better understand soil microbial properties. In this initial assessment of soil resources and microbial properties in a 16-ha landscape planted to corn, we hypothesized that soil microbial properties will vary by soil type. We defined soil type based on drainage class (4 levels), series (7 levels), map unit (11 levels), and texture of the Ap horizon (3 levels). We took soil samples from 16 map units in April, June, August, and October and measured 12 physical and chemical properties, and 27 microbial properties on at least one of these dates. Soil physical and chemical properties generally varied with soil type and canonical discriminant analyses showed that soil drainage classes, series, and map units were delineated by a similar set of soil properties (total C, total N, moisture, pH, equivalent CEC (CECe), and available P). Ap texture classes were delineated by a different set of soil properties (available K, Mg, and Ca and CECe). A number of soil microbial properties varied by soil type, but, in general, a smaller proportion of measured soil microbial properties showed soil type effects compared to the proportion of soil physical and chemical properties that showed soil type effects. Method of soil classification strongly influenced which soil microbial properties varied by soil type. However, soil microbial activities, population sizes, and community structures were generally greater or most unique in mid-range soils regardless of how soils were classified, possibly because soil moisture was optimal for microbiological activity and growth in these soils. Except at the level of drainage class, there was little consistency between patterns of variation in soil physical and chemical properties and patterns of variation in soil microbial properties among soil types. Thus, different soil sampling strategies may be required when accounting for variation in soil physical and chemical properties than when accounting for soil microbial properties at the landscape level. While sampling soils according to soil survey-defined map units indicated that some soil microbial properties vary by soil type, a number of limitations to this approach are discussed. To improve upon results presented here, future efforts to quantify landscape level variation of soil microbial properties should probably be sampled at a finer scale that explicitly accounts for soil properties that vary at the sub-map unit level, including terrain attributes, microtopography, soil texture, soil bulk density, and other factors that impact soil temperature and moisture dynamics.

Compost has been suggested as a nonchemical alternative to methyl bromide (MeBr) for control of root diseases. Its widespread availability and soil improvement properties are appealing to growers, but they need information on its use and effectiveness relative to the control of economically important root diseases in specific crops. Here, we report results from controlled-environment pot studies on the effects of manure composts on two major soilborne diseases of strawberry: red stele (RS) caused by Phythophthora fragariae, and black root rot (BRR), caused by a complex of fungi. Commercially available, on-farm-produced composts, based on either poultry/steer or dairy manure, were incorporated into two different, naturally infested soils at 5, 10, and 20% rates (v/v). Results show that significant control (36-79%) of RS in susceptible cultivar 'Chandler' occurred at all rates and with both types of compost in comparison with the unamended soil. Low rates (5%) of poultry/steer manure compost produced more disease control than equivalent or greater rates (10% and 20%) of dairy manure compost. However, the 20% rate had significantly greater soluble salts content than all other rates. At this 20% rate, root/shoot biomass accumulation and shoot health ratings were relatively low and equivalent to those from unamended soil, despite the improved content of soil organic matter, cation exchange capacity, and soil micronutrient content. The 5% amendment rate of poultry/steer manure compost provided more control than the 10% or 20% rates and more than the 5-20% rates of dairy manure compost. Soluble salts content in amended soils was significantly greater than in unamended soils, especially at 20% rates of poultry/steer compost. Leaf N from all treatments was deficient despite additional weekly supplemental fertilization. This deficiency coupled with increased soluble salt content at 20% poultry/steer compost amendments likely contributed to reduced root/shoot biomass accumulation and overall reduced plant vigor, thus increasing plant susceptibility to disease. In contrast to RS, BRR in all compost treatments was moderate in intensity and equivalent to the unamended soil, with slight but insignificant control at 5 and 10% rates of poultry/steer compost. Overall effects of the two manure compost amendments on BRR were inconclusive because no treatments, including the soil only, exhibited roots with extensive disease symptoms, despite cultural evidence of BRR pathogen colonization, especially by Rhizoctonia fragariae, during the course of this pot study. Effects of compost on appearance of BRR in strawberry should be pursued over a significantly longer time period than used here, possibly in field plots located on naturally infested soils subject to environmental stressors and seasonally realistic fertilization rates, because major BRR symptoms do not appear in the short-term even when fungal pathogens are present in the root.

The bacterial content of specially treated cottons used by other investigators to test human pulmonary responses to cotton dust was examined. Cotton from Lubbock, Tex. and Stoneville, Miss. were either (i) harvested by machine and handled as commercial bale cotton, (ii) harvested as closed bolls with bracts intact and opened under special conditions, (iii) harvested as closed bolls, with bracts being removed and opened under special conditions, or (iv) harvested by machine, handled as commercial bale cotton, washed in water, and dried (Stoneville only). Bacillus spp. were isolated from all samples and predominated in cotton from Stoneville. Enterobacter agglomerans was isolated from all but one sample, the Stoneville closed-boll bract-removed cotton, and predominated in Lubbock samples. Aerogenic and anaerogenic biogroups of E. agglomerans were isolated; only aerogenic strain b of E. agglomerans was present in samples from both locations. Klebsiella ozaenae and K. pneumoniae were isolated only from Lubbock samples. Cotton from Lubbock yielded 100 to 1,000 times more bacteria, both total and gram negative, than did comparably treated cotton from Stoneville. Thus, differences in growing and processing conditions at the two locations were associated with large differences in the bacterial content of the cotton, but harvesting green bolls and removing bracts had little effect. The bacterial content of Stoneville unwashed cotton was 10 to 100 times greater than that of the Stoneville washed cotton, and it paralleled the differences reported (Boehlecke et al., Am. Rev. Respir. Dis. 123:152, 1981) in pulmonary function responses when subjects were exposed to dust (0.6 mg/m3) from these two cottons. Levels of gram-negative and total bacteria on all samples were comparable to those previously reported for field-weathered cottons from various locations throughout the world.

Multistate and international foodborne illness outbreaks, particularly involving cantaloupe and often involving rare Salmonella spp., have increased dramatically over the past 13 years. This study assessed the sources and extent of melon rind contamination in production fields and at processing and packing facilities. In the spring of 1999, cantaloupe (Cucumis melo L. [reticulatus group] cv. Cruiser) sampled from two sites in the Rio Grande River Valley showed that postharvest-processed melon rinds often had greater plate counts of bacterial contaminants than field-fresh melons. Cantaloupe in the field had 2.5 to 3.5 log CFU g(-1) rind total coliforms by aerobic plate counts, whereas washed melons had 4.0 to 5.0 log CFU g(-1). In the fall of 1999, coliforms on honeydew melons (C. melo [inodorous group] cv. Honey Brew) ranged from 2.6 to 3.7 log CFU g(-1) after processing, and total and fecal coliforms and enterococci never fell below 2.5 log CFU g(-1). A hydrocooler at another site contaminated cantaloupe rinds with up to 3.4 log CFU g(-1) total and fecal enterococci; a secondary rinse with chlorinated water incompletely removed these bacteria. Sources of coliforms and enterococci were at high levels in melon production soils, especially in furrows that were flood irrigated, in standing water at one field, and in irrigation water at both sites. At one processing facility, wash water pumped from the Rio Grande River may not have been sufficiently disinfected prior to use. Because soil, irrigation water, and process water were potential sources of bacterial contamination, monitoring and management on-farm and at processing and packing facilities should focus on water quality as an important control point for growers and packers to reduce bacterial contamination on melon rinds.

A simple method for characterization of fungal communities in environmental samples was developed. Dilute suspensions of samples in 0.2% agar containing three different antibiotics were pipetted into 96-well plates (Biolog SF-N) containing a diverse collection of 95 different carbon sources. The plates were incubated for 4-12 days at 22 degrees C and the absorbance measured at 650 nm. Canonical variates analysis was then used to analyze the multivariate data. This method allowed fungal communities in rhizosphere soil of corn and soybean to be distinguished according to soil and plant type. Data taken at a single time-point, which varied greatly in total absorbance of the plate, separated rhizosphere samples primarily by soil type. When multiple time-points were combined to keep the total absorbance constant, differences in substrate utilization patterns due to different plant types could be distinguished. The method was also applicable to analysis of phylloplane and compost fungal communities. This method is readily applied to large numbers of samples and should be useful for community analysis in a variety of agricultural and ecological studies.

The 5.8S subunit and flanking internal transcribed spacer (ITS) regions in nuclear ribosomal DNA (rDNA) from spores of Glomus etunicatum MD107, MD127, TN101, and FL329 were amplified by polymerase chain reaction (PCR) using ITS1 Kpn and ITS4 Pst as primers. The amplification products (597, 599, 598, and 613 bp, respectively) were cloned and sequenced. The similarity among ITS region sequences from MD107, MD127, and TN101 was 99%, whereas the sequence similarity between the ITS regions of these three DNAs and that from FL329 was 91%. The 5.8S rDNA sequences of all four G. etunicatum isolates were identical. In contrast, major dissimilarities in the corresponding rDNA sequence regions of other glomalean taxa were observed. Oligonucleotide sequences unique to G. etunicatum were tested for their specificity in PCR amplification of genomic DNA from spores of 55 isolates comprising 29 glomalean fungi: 18 isolates of G. etunicatum , five G. intraradices , three G. claroideum , 16 other Glomus isolates, and 11 other glomalean taxa from each of four other genera. The G. etunicatum isolates were from a broad range of geographic regions and soils. The oligonucleotide pair GETU1:GETU2 primed specific amplification of an oligonucleotide sequence (approximately 400 bp) present in all G. etunicatum . This primer pair did not prime PCR when template consisted of DNA from any of the other glomalean fungi or any of the non-mycorrhizal controls, including roots of corn ( Zea mays ). In addition, the pair successfully detected G. etunicatum in nested PCR using a primary PCR product amplified from highly diluted extracts of colonized corn roots using modified ITS1:ITS4 primers. In the phylogenetic analysis of Glomus 5.8S and ITS2 rDNA region sequences, which included 500 bootstrap data sets, confidence in the G. etunicatum branch was very strong (90%) and clearly independent of G. claroideum and G. intraradices , to which it is very closely related.

Arbuscular mycorrhizal fungi [AMF] are soil fungi which form a mutualistic symbiosis with the roots of plants. A variety of benefits to the host have been ascribed to mycorrhizae, most often enhanced uptake of immobile nutrients from the soil, notably P. An understanding of the impacts of agronomic practices upon communities of these fungi would help to ensure an opportunity for the utilization of the symbiosis and contribute to the success of sustainable agriculture. Measurement of the diversity of AMF communities in field soils presents a variety of challenges, among them the difficulty of identifying field collected spores, the detection of non-sporulating members of the community, and the lack of relation between functional diversity and the morphological diversity of spores used to delineate species. These challenges, as well as current efforts to overcome them, are discussed and recent research elaborating the effects of agromonic practices upon AMF communities and the effectiveness of mycorrhizae is presented. (C)Elsevier Science B.V.

Particulate organic matter (POM) is more sensitive than total SOM to changes in management practices and, accordingly, may indicate changes in soil quality. A soil incubation study was conducted to determine the effects of added POM (75 to 250μm size fraction), or macroorganic matter (MOM, 250 to 2000μm size fraction) on C and N mineralization and microbial C and N content. A 1kg composite made from 16 predominantly silt loam soils was amended with 10g of POM, MOM or MOM ground to a reduced size of 75 to 250μm (GMOM). The MOM amendment equaled 4.55-fold and POM equaled 1.60-fold of total MOM and POM found in the composite soil. Carbon mineralization of MOM and POM after 8weeks was approximately 9 and 4%, respectively of the total MOM and POM-C added. Reducing the size of MOM to 75 to 250μm did not affect mineralization. Nitrogen mineralization was slightly greater in the amended soils after 8weeks and equaled 5 to 6% of the MOM or POM-total N added. Contribution of POM to total mineralized N from soil organic matter (SOM) in the composite soil was proportional to the POM content in SOM or approximately 12%. Amended soils had 25 to 42% more biomass-C than the control soil 2weeks after amendment application. After 8weeks, the amended soils contained about 32% more biomass-C. This increase in biomass-C at 8weeks accounted for approximately 2% of the added C. At 8weeks, microbial biomass-N in GMOM-, MOM- and POM-amended soils was about 56, 46 and 14% higher, respectively, than in the control soil. These increases were approximately 8% of the MOM-N added and 2% of the POM-N added. Increases in POM resulted in increases in soil respiration and microbial biomass-C and N, which also are suggested indicators of soil quality. Therefore, POM may be a suitable soil quality indicator that provides similar information as soil respiration or microbial biomass determinations.

The 5.8 S subunit and flanking internal transcribed spacer (ITS) regions in nuclear ribosomal DNA (rDNA) from spores of Glomus mosseae FL156 and UK118 were amplified by polymerase chain reaction (PCR) using ITS1 and ITS4 as primers. The amplification product from template DNA of UK118 was cloned and sequenced (569 bp); the amplified DNA from FL156 was sequenced directly (582 bp). There was a 95% sequence similarity between DNAs amplified from the two isolates; in contrast, major dissimilarities with partial sequences of seven other glomalean taxa were observed. Four oligonucleotide sequences unique to Glomus mosseae were identified as potential primers. Their specificity to Glomus mosseae was assessed by PCR amplification of genomic DNA from spores from 36 glomalean fungi: 13 isolates of Glomus mosseae , two Glomus monosporum , 10 other Glomus isolates, and 11 other glomalean taxa from each of four other genera. The Glomus mosseae isolates were from a broad range of temperate zone agricultural soils. Oligonucleotide pair GMOS1 : GMOS2 primed specific amplification of an oligonucleotide sequence (approximately 400 bp) present in all Glomus mosseae isolates and two isolates of the closely related Glomus monosporum . This primer pair did not prime PCR when the template consisted of DNA from any of the other glomalean fungi or any of the nonmycorrhizal controls. In addition, a 24- mer oligonucleotide, designated GMOS5, hybridized with Glomus mosseae and Glomus monosporum DNA amplified by PCR using primer pairs ITS1 : ITS4 and GMOS1 : GMOS2. Colony-blot assays showed that GMOS5 hybridized to 100% and 97% of E. coli pUC19 clones of amplification products from Glomus mosseae FL156 and UK118 DNA templates, respectively, indicating that nearly all clones contained an homologous sequence. GMOS5 was used successfully to detect specifically Glomus mosseae in DNA extracted from colonized sudan grass ( Sorghum sudanense L.) roots and amplified by PCR using the primer pair GMOS1 : GMOS2. The results confirm several previous indications that Glomus mosseae and Glomus monosporum are indistinguishable taxonomic entities.

In the United States, the traditional management practices used for biosolids (also known as sewage sludge) and municipal solid residues (MSW) were driven by the “disposal” concept rather than the resource recovery concept. These traditional practices are now recognized as environmentally, ecologically, and economically inadequate. As a nation we are generating more organic, recyclable municipal residues than ever before, and many areas are rapidly exhausting their standard options for the safe, effective management of these materials. Handling capacity of landfills and some older incinerators continues to decrease. Regulatory guidelines and limits to traditional biosolids and residue management practices also are being implemented at national, state, and local levels. Federal Sub-title D regulations imposing strict liner and management requirements were fully effective in 1994. Thus, it is increasingly difficult to keep existing landfills open or to establish new facilities. In 1995, a total of 3,197 landfills were in operation, but this total was 361 fewer than in 1994 and 4,803 fewer than in 1988 (Steuteville 1996). By 1997, 20 percent of states could exceed their landfill capacity (Repa and Sheets 1992).

Broiler litter, dairy manure, and steer/horse manure were separately cocomposted with other organic residues, and the resulting composts incorporated into potting mixes. All the compost-amended potting mixes were suppressive to damping-off caused by Pythium and Rhizoctonia relative to disease conducive controls. The type of manure in the compost had a greater influence on damping-off of Pythium than of Rhizoctonia. Composts differed in the relative amounts of suppression of Pythium damping-off as follows: dairy manure greater than or equal to steer manure 2 poultry litter. However, dairy manure compost contained phytotoxins generated in anaerobic zones of the windrow. There was no statistically significant association between disease suppression and compost age. Comparisons between disease losses in nonautoclaved and autoclaved potting mixes provided evidence that disease suppression was microbially mediated. There was also some evidence that low levels of NO2- - or NO3- - nitrogen were associated with suppression of Pythium damping-off.

A low-cost, low-maintenance system for soilless production of vesicular-arbuscular mycorrhizal (VAM) fungus spores and inoculum was developed and adapted for production of acidophilic and basophilic isolates. Corn (Zea mays) plants were grown with Glomus etunicatum, G. mosseae or Gigaspora margarita in sand automatically irrigated with modified Hoagland's solution. Sand particle size, irrigation frequency, P concentration, and buffer constituents were adjusted to maximize spore production. Modified half-strength Hoagland's solution buffered with 4-morpholine ethane-sulfonic acid (MES) automatically applied 5 times/day resulted in production of 235 G. etunicatum spores/g dry wt. of medium (341000 spores/pot) and 44 G. margarita spores/g dry wt. of medium (64800 spores/pot). For six basophilic isolates of G. mosseae, CaCO3 was incorporated into the sand and pots were supplied with the same nutrient solution as for acidophilic isolates. The increased pH from 6.1±0.2 to 7.2±0.2 resulted in spore production ranging from 70 to 145 spores/g dry wt. (102000–210000 spores/pot). Spore production by all isolates grown in the soilless sand system at Beltsville has exceeded that of traditional soil mixtures by 32–362% in 8–12 weeks.