Peat-based Mix Research Articles

Substrate Comparison for Tomato Propagation under Different Fertigation Protocols

Greenhouse tomato production faces multiple challenges, including the excessive use of nonrenewable substrates that are difficult to dispose of after use. Currently, most growers propagate tomatoes in rockwool, but there is an increasing demand for sustainable media. The objective of this research was to evaluate sustainable and organic alternatives for greenhouse propagation of tomato seedlings intended for high-wire production. Different organic and inorganic substrates were evaluated in three experiments, using a nutrient solution composed of a complete water-soluble fertilizer. Germination and growth parameters, including height, stem diameter, number of leaves, leaf area, foliar chlorophyll levels (SPAD), and shoot fresh and dry weight, were measured. In the first experiment, which employed overhead irrigation, rockwool, coir, wood fiber–coir mix, medium-grade pine bark, pine bark < 0.64 cm, and pine bark < 0.32 cm were evaluated. Tomato germination was faster and achieved higher percentages with pine bark < 0.64 cm compared to other substrates. However, growth performance was similar or better in coir than in rockwool four weeks after transplantation. For the second experiment with sub-irrigation only, rockwool, coir, wood fiber–coir mix, pine bark < 0.32 cm bark, and peat were evaluated at different container heights. Peat resulted in greater growth across all parameters, followed by wood fiber–coir mix in all container heights, while pine bark had the least growth across all measured parameters. In the third experiment with overhead irrigation, rockwool, wood fiber–coir mix, pine bark < 0.32 cm, and a commercial peat-based mixture were evaluated under different fertilizer rates (electrical conductivity of 1.1 and 2.2 mS·cm−1). Wood fiber–coir mix, peat-based mix, and rockwool were the substrates with the highest values for all evaluated parameters. While all the organic substrates showed potential for use in tomato propagation, pine bark < 0.32 cm bark and wood fiber–coir mix provided the best media for germination. Peat and wood fiber–coir mix showed the best media for subsequent seedling growth and demonstrated potential to be used as substitutes for rockwool.

Effect of Fertilizer Rate, Substrate, and Container Type on Greenhouse Production of Sandhill Milkweed

Sandhill milkweed [Asclepias humistrata (Walter)] is important for monarch butterfly [Danaus plexippus (L.)] conservation efforts, yet precise cultivation practices are largely not available. We tested the effects of three fertilizer rates and four substrate types and four container types on the performance of sandhill milkweed during greenhouse production. Seedlings fertilized with a high (0.90 g per 48-cell container) controlled-release fertilizer rate of 15N–3.9P–10.0K (15–9–12 Osmocote® Plus) had reduced performance compared with low and medium fertilizer rates (0.34 and 0.56 g per 48-cell container, respectively). Seedlings grown in large containers (∼175 mL including standard 32-cell liners and tall tree-tubes) outperformed seedlings grown in small containers (∼100 mL including standard 48-cell liners and short tree tubes). A transplant ready plant can be produced for spring within 16 weeks when seeds are sown in early January. Although sandhill milkweed seedlings can be grown under various fertilizer rates and in various containers and substrates, seedlings grown in tall tree tubes in a peat-based mix (Sunshine Mix) outperformed a nursery standard substrate and two wood fiber substrates. We recommend growing plants in a peat-based substrate within tall tree tube containers and applying a medium fertilizer rate.

Comparison of Peat–Perlite-based and Peat–Biochar-based Substrates with Varying Rates of Calcium Silicate on Growth and Cannabinoid Production of Cannabis sativa ‘BaOx’

Growers have been searching for alternative horticultural growing media components because of their desire to use sustainable resources. Biochar is a carbon-based material that has been evaluated for use as an alternative aggregate in peat-based soilless substrates. Additionally, silicon (Si) has been examined as a beneficial element to promote plant growth and plant quality in a variety of crops. However, there has been limited research regarding the interaction of biochar as an aggregate and Si in soilless substrates. This study aimed to determine the impact of Si and biochar on plant growth and nutrient uptake for greenhouse-cultivated hemp (Cannabis sativa L.). Hemp plants were grown in one of 12 different substrate blends: with two rates of calcium silicate (CaSiO3), two aggregate types of biochar (medium or coarse) or perlite, and aggregate percentages of 85% peat + 15% aggregate and 70% peat + 30% aggregate. The cannabinoid concentration, plant height, diameter, or total plant biomass were similar across all substrate blends after 12 weeks of growth. Additionally, the use of CaSiO3 as a Si substrate amendment increased Si foliar concentrations, and the addition of biochar to peat-based mixes did not limit the Si availability for plant uptake. However, Si substrate amendments did not impact plant height, diameter, or total plant biomass. This suggests that the biochar tested during this study is suitable in peat-based substrates for C. sativa ‘BaOx’ production at rates up to 30% (by volume) in peat-based substrates with CaSiO3 amendments.

The Use of Wood Fiber for Reducing Risks of Hydrophobicity in Peat-Based Substrates

Peat substrates are well known to become hydrophobic during desiccation, thus degrading their water retention properties. Synthetic wetting agents are commonly incorporated to limit the risk of hydrophobicity, but substrates companies are searching for more sustainable alternatives. To that end, the effect of wood fiber addition in peat-based mixes was measured using contact angles and hydration curves. The study was carried out on two raw materials (white milled peat and wood fiber) and binary mixes. The results showed a shift from hydrophilic to more hydrophobic character with a decrease in the ability to rewet of peat-based substrates in relation to the intensity of drying, whereas wood fiber remained hydrophilic. Increasing wood fiber content in peat-based mixes improved the rehydration efficiency, but with a lower intensity of that measured with synthetic wetting agent addition. Our results highlighted the hydrophilic nature of wood fiber and demonstrated an additional benefit of wood fiber use in peat-based growing media.

Relevant hydraulic properties of peat-based mixes for explaining root development according to irrigation strategies

Relevant hydraulic properties of peat-based mixes for explaining root development according to irrigation strategies

Using Processed Corn Stover as an Alternative to Peat

Processed corn (Zea mays L.) stover (PCS), defined as finely ground stover with or without additions, could be a potential alternative to peat in greenhouse mixes. However, this option has not yet been examined. We performed two split-plot experiments (1 and 2) with tomatoes (Solanum lycopersicum L.) and marigolds (Tagetes patula L.) as main plots. Expt. 1 involved five stover rates (0%, 25%, 50%, 75%, and 100% by volume) mixed with peat as subplots. Expt. 2 involved 0% stover mixed with peat, 25% distillers grain, and 50% quick compost (mechanically processed to accelerate compost process) stover with and without CaO, and 75% quick compost stover without CaO, as subplots. We measured growth parameters (height, dry weight, and flower number) and properties of the mixes. During Expt. 1, across both species, the addition of stover at rates >50% reduced relative greenness by 40%, vegetative biomass yield by 74%, and reproductive biomass yield by 73% compared to mixes with 0% and 25% stover. As the stover rate increased, available water content in the mixes decreased (r = −0.34; P < 0.001). Mixes with 0% and 25% stover had 34% more available water than mixes with 100% stover, which probably reduced plant growth in the 100% stover treatment. As the stover rate increased, plant tissue N and P concentrations decreased. Mixes with 0% stover generally had greater N and P concentrations than mixes with stover. During Expt. 2, for marigolds, the addition of 50% quick compost stover+CaO and 75% quick compost stover-CaO reduced relative greenness by 19% and vegetative biomass by 66% compared to mixes with 25% distillers grain or 0% stover. For tomatoes, the addition of 50% quick compost stover+CaO and 75% quick compost stover-CaO reduced biomass yield by 64%, which may be due to the higher pH and electrical conductivity (EC) of both treatments. Plant tissue N and P concentrations were greater in the mix with 25% distillers grain compared to most treatments, but N and P concentrations in the other mixes varied. Overall, the 25% distillers grain (3 peat: 1 distiller grain: 4 perlite) and 25% stover (3 peat: 1 stover: 4 perlite) treatments showed the most promise as additives in a peat-based mix.

Physicochemical, agronomical and microbiological evaluation of alternative growing media for the production of rapini (Brassica rapa L.) microgreens.

Peat-based mixes and synthetic mats are the main substrates used for microgreens production. However, both are expensive and non-renewable. Recycled fibrous materials may represent low-cost and renewable alternative substrates. Recycled textile-fiber (TF; polyester, cotton and polyurethane traces) and jute-kenaf-fiber (JKF; 85% jute, 15% kenaf-fibers) mats were characterized and compared with peat and Sure to Grow® (Sure to Grow, Beachwood, OH, USA; http://suretogrow.com) (STG; 100% polyethylene-terephthalate) for the production of rapini (Brassica rapa L.; Broccoletto group) microgreens. All substrates had suitable physicochemical properties for the production of microgreens. On average, microgreens fresh yield was 1502 g m-2 in peat, TF and JKF, and was 13.1% lower with STG. Peat-grown microgreen shoots had a higher concentration of K+ and SO42- and a two-fold higher NO3- concentration [1959 versus 940 mg kg-1 fresh weight (FW)] than those grown on STG, TF and JKF. At harvest, substrates did not influence microgreens aerobic bacterial populations (log 6.48 CFU g-1 FW). Peat- and JKF-grown microgreens had higher yeast-mould counts than TF- and STG microgreens (log 2.64 versus 1.80 CFU g-1 FW). Peat-grown microgreens had the highest population of Enterobacteriaceae (log 5.46 ± 0.82 CFU g-1 ) and Escherichia coli (log 1.46 ± 0.15 CFU g-1 ). Escherichia coli was not detected in microgreens grown on other media. TF and JKF may be valid alternatives to peat and STG because both ensured a competitive yield, low nitrate content and a similar or higher microbiological quality. © 2016 Society of Chemical Industry.

Preliminary Species and Media Selection for the Veggie Space Hardware

ABSTRACT Plants will be an important component of off-Earth life support systems for food production and atmosphere recycling. “Veggie” is a small vegetable production unit designed for space flight, with a passive water delivery system. Plants can be grown in Veggie using small bags with a wicking surface containing media and fertilizer, i.e., pillows. Pillows planted with seeds can be placed on the wicking surface of the Veggie reservoir and water will wick throughout the media. Multiple small salad and herb species were grown in Veggie analog conditions using both commercial peat-based media and arcillite. Biometric measurements and microbial loads were assessed. Some species grew better in a particular media, but no general trends were apparent. Lettuce plants grew best in the blends of the peat-based and arcillite media. Microbial counts were lower on plants grown in arcillite. Four media types (peat-based mix, arcillite, and blends of the two) were tested in the rooting pillows; tests included Chinese cabbage, Swiss chard, lettuce, snow pea, and radish. Most species grew best in blends of the commercial mix and arcillite. Edible biomass production varied from 3.5-8 grams dry mass/m2/day with lettuce having the lowest biomass and Chinese cabbage highest. Radish plants showed an increasing percentage of partitioning to edible roots with increasing arcillite in the media. Pillows appear to offer a simple, effective strategy for containing rooting media and avoiding free water while growing plants in the Veggie hardware.

Effectiveness of AG3 phosphonate formulation in suppressing phytophthora blight in cucumber and bell pepper plants under growth room conditions

Phytophthora blight or crown or root rot (Phytophthora capsici Leonian) is an important disease of a wide range of plant species including peppers, tomatoes, cucumbers and other cucurbits in Canada and worldwide. We have previously demonstrated the effectiveness of a new liquid formulation of AG3 phosphonate (Calirus 150, Bromine Compounds Ltd., Beer Sheva, Israel) in suppressing pythium damping-off of cucumbers and clubroot of bok choy and cabbage. In this study, the effectiveness of AG3 phosphonate formulation to suppress phytophthora damping-off and root rot of cucumber (Cucumis sativus L.) seedlings or phytophthora blight of bell pepper (Capsicum annuum L.) plants was determined in a peat-based mix or sandy-loam soil artificially infested with soil inoculum of P. capsici under growth room conditions. In an infested peat-based mix, AG3 phosphonate preplanting amendment or postplanting drench treatments (0.05%, 0.1% and 0.2% a.i.) and a 10-min seed-soak treatment (10.45% a.i.) significantly increased the percentage of healthy cucumber seedlings and reduced damping-off and root rot severity. The seed-soak and 0.2% treatments were the most effective treatments that consistently suppressed damping-off and root rot of cucumber even in a peat-based mix infested with high inoculum levels of P. capsici. Disease severity on cucumber plants was also significantly less in the AG3 phosphonate treatments. The single drench applications of AG3 phosphonate (0.05%, 0.1% and 0.2% a.i.) significantly reduced the incidence and severity of phytophthora blight of bell pepper plants in an infested peat-based mix or a sandy-loam soil compared with the control plants receiving no treatment. The best control of phytophthora blight of bell pepper was achieved with the higher rate (0.2% a.i.) in both peat-based mix and soil with 90% of the plants remaining healthy compared with none in the control. The disease protection increased with increasing concentrations of AG3 phosphonate in both bell peppers and cucumbers without any phytotoxicity.

Detection of High Concentrations of Organic Acids in Fish Emulsion and Their Role in Pathogen or Disease Suppression

Fish emulsion (FE) added to a sandy-loam soil at 1 and 2% rates reduced the viability of Verticillium dahliae microsclerotia by 39 and 74% in 1 day, 87 and 98% in 3 days, and 95 and 99% in 6 days, respectively. The immediate kill of microsclerotia indicated that FE contains toxic substances. We found in FE high concentrations (400 mmol/liter) of organic acids, including some known toxicants. Glycolic, acetic, formic, n-butyric, and propionic acids were the major organic acids detected in FE at the proportions of 52.5, 26.9, 7.9, 7.2, and 4.7%, respectively. In solution assays, the viability of V. dahliae microsclerotia treated for 24 h in 1, 2, 5, and 10% FE (pH 3.6 to 3.0) or a mixture of organic acids (pH 4.1 to 3.9) equivalent to the proportions in FE was reduced by 74, 94, 97, and 99% or 81, 91, 98, and 99%, respectively. The viability of microsclerotia was increased when the treatment solutions were buffered to pH 6.0. The organic acids mixtures and formic (0.025%) and acetic (0.1%) acids were toxic to Pythium ultimum. A mixture of organic acids (1, 2, and 4%) provided immediate protection of cucumber seedlings from damping-off in P. ultimum-infested muck and sandy-loam soils but not in peat-based mix. FE (1 and 2%) provided immediate protection of cucumber seedlings from damping-off in an infested muck soil, and disease protection was consistent when planting was delayed for 7, 14, and 28 days after adding FE. FE (1, 2, and 4%) did not provide immediate protection of cucumber seedlings from damping-off in a P. ultimum-infested peat-based mix; however, disease suppression was evident when planting was delayed for 7, 14, and 21 days after adding FE. Real-time polymerase chain reaction analyses of the peat-based mix indicated that the P. ultimum populations in the FE-amended mix declined over time. This study suggests that these organic acids in FE played a major role in pathogen or disease suppression, depending on the soil and substrate.

PROPAGATION AND PRODUCTION OF ZAMIOCULCAS ZAMIIFOLIA

PROPAGATION AND PRODUCTION OF ZAMIOCULCAS ZAMIIFOLIA

Evaluation of Composted Green Waste In Ornamental Container-Grown Plants: Effects on Growth and Plant Water Relations

Ornamental nurseries extensively utilize peat in commercial soilless potting media, but its use as an organic amendment with a superior water holding capacity is challenged by economic and environmental pressures so potential alternatives to peat need to be investigated. In our experiment, commercially available peat-based soilless mixes were amended with increasing composted green waste (CGW) percentages. Results on Photinia X fraseri and Viburnum tinus suggest that CGW could partially substitute peat in containerized nursery production, with a different effectiveness related to species behavior. Viburnum seemed to be less affected by CGW addition (only CGW-based media, T100, showed a significant difference compared to peat-based media, used as control), which on the contrary hardly affected Photinia growth in terms of biomass production and quality. On the other hand, a higher CGW content (75% or 100%) also improved plant susceptibility to water shortage. Concluding, peat-based media partially amended with CGW may have positive agronomic and economic consequences for commercial ornamental nursery production.

Managing soilborne diseases of vegetable crops with a pre-plant soil or substrate amendment of a corn distillation product1

The efficacy of condensed distiller's solubles (CDS), a co-product of ethanol production from corn, rich in organic matter, and high in carbon to nitrogen ratio, was tested as a pre-plant amendment against Verticillium wilt of eggplant and potato scab in potato soils from commercial fields and against damping-off diseases of radish and cucumber seedlings in a peat-based mix and muck soil. Eggplants grown in a potato soil amended with CDS (1% mass/mass) showed less Verticillium wilt and increased fresh (37–54%) and dry (31–45%) plant biomass compared to the control in the greenhouse. In a potato soil with medium levels of disease, CDS (1 or 2%) increased the percentage of marketable tubers by 116% under greenhouse, 119% under micro-plot and 75% under field conditions. In the growth room, CDS (1, 2, and 4%) amendment to a peat-based mix infested with Rhizoctonia solani 1 week before planting seeds improved the percentage of healthy radish seedlings (22–72% healthy seedlings compared to 2% in the control). Levels of disease suppression increased with the incubation time prior to planting. Disease control effect of CDS was not consistent between different batches of peat-based mix. In a non-suppressive batch of peat-based mix, disease suppression by CDS was enhanced by a bio-control agent, Trichoderma hamatum 382. In muck soil from a commercial field naturally-infested with Pythium spp., CDS (0.25, 0.5, and 1%) provided protection of cucumber seedlings from damping-off immediately after incorporation, but the maximum protection was seen after 1 week with all three rates. The number of total bacteria was enhanced in the CDS-amended muck soil. In the micro-plots, CDS (0.5 and 1%) as an amendment to muck soil 2 weeks before planting improved the percentage of healthy cucumber seedlings and fresh plant weight compared to the control. CDS is not toxic to the pathogens and disease suppression is believed to be due to biological activity stimulated by CDS in the substrate.

Using Compost for Container Production of Ornamental Wetland and Flatwood Species Native to Florida

Seven ornamental species, coastal plain tickseed (Coreopsis gladiata Walt. [Asteraceae]), swamp sunflower (Helianthus angustifolius L. [Asteraceae]), climbing aster (Ampelaster carolinianus (Walt.) Nesom [Asteraceae] syn = Aster carolinianus Walt.), pineland lantana (Lantana depressa Small [Verbenaceae]), spotted beebalm (Monarda punctata L. [Lamiaceae]), blackeyed Susan (Rudbeckia hirta L. [Asteraceae]), and Carolina wild petunia (Ruellia caroliniensis (J.F. Gmel.) Steud. [Acanthaceae]) were transplanted in containers filled with a biosolid:yard waste compost, a commercial peat-based mix, or a formulated compost-based mix (4:5:1, compost:pine bark:sand, v:v:v). At 8 wk, plants grown in compost or the medium amended with compost had similar (coastal plain tickseed and swamp sunflower) or greater (climbing aster, pineland lantana, spotted beebalm, blackeyed Susan, and Carolina wild petunia) biomass than plants grown in the peatbased medium. This study suggests that compost may serve as a viable alternative substrate for peat in the production of ornamental wetland and flatwood species native to Florida. Wilson SB, Stoffella PJ. 2006. Using compost for container production of ornamental wetland and flatwood species native to Florida. Native Plants Journal 7(3):293‐300.

Suppressiveness of 18 composts against 7 pathosystems: Variability in pathogen response

Compost is often reported as a substrate that is able to suppress soilborne plant pathogens, but suppression varies according to the type of compost and pathosystem. Reports often deal with a single pathogen while in reality crops are attacked by multiple plant pathogens. The goal of the present study was to evaluate the disease suppression ability of a wide range of composts for a range of plant pathogens. This study was conducted by a consortium of researchers from several European countries. Composts originated from different countries and source materials including green and yard waste, straw, bark, biowaste and municipal sewage. Suppressiveness of compost-amended (20% vol./vol.) peat-based potting soil was determined against Verticillium dahliae on eggplant, Rhizoctonia solani on cauliflower, Phytophthora nicotianae on tomato, Phytophthora cinnamomi on lupin and Cylindrocladium spathiphylli on Spathiphyllum sp., and of compost-amended loamy soil (20% vol./vol.) against R. solani on Pinus sylvestris and Fusarium oxysporum f. sp. lini on flax. From the 120 bioassays involving 18 composts and 7 pathosystems, significant disease suppression was found in 54% of the cases while only 3% of the cases showed significant disease enhancement. Pathogens were affected differently by the composts. In general, prediction of disease suppression was better when parameters derived from the compost mixes were used rather than those derived from the pure composts. Regression analyses of disease suppression of the individual pathogens with parameters of compost-amended peat-based mixes revealed the following groupings: (1) competition-sensitive: F. oxysporum and R. solani/cauliflower; (2) rhizosphere-affected: V. dahliae; (3) pH-related: P. nicotianae; and (4) specific/unknown: R. solani/pine, P. cinnamomi and C. spathiphylli. It was concluded that application of compost has in general a positive or no effect on disease suppression, and only rarely a disease stimulating effect.

Seed Treatment with Phosphonate (AG3) Suppresses Pythium Damping-off of Cucumber Seedlings.

A formulation of phosphonate (AG3) was tested as a seed treatment for the control of Pythium damping-off of cucumber (Cucumis sativus L.) plants under controlled environment and field conditions. Cucumber seed were treated by soaking for 10 min in phosphonate solution. They were then planted into peat-based mix or sandy-loam soil mixed with Pythium aphanidermatum or P. ultimum inoculum or into muck soil naturally infested with P. irregulare, P. ultimum, and other Pythium spp. Under growth-room conditions, phosphonate seed treatment provided more than 80% control of damping-off in all infested substrates tested. Effective disease control was obtained even when treated seed were stored for 5 weeks and up to 18 months prior to planting. In microplots containing naturally infested muck soil, phosphonate seed treatment decreased the percentage of diseased cucumber plants and increased total fresh weights compared with untreated seed and phosphonate post-planting drench. In field-plot tests 6 weeks after planting treated seed in Pythium-infested muck soil, cucumber stands were 63% compared with 18% in the control, which had no phosphonate exposure, and 53% in the post-planting drench. Tests for potential phytotoxicity in the greenhouse showed that radish and bok choy germination was reduced by phosphonate treatment but corn, cucumber, soybean, sugar beet, tomato, and wheat were not affected. Phosphonate seed treatment is a cost-effective way of protecting cucumber plants from Pythium damping-off.

Using Compost for Container Production of Ornamental Wetland and Flatwood Species Native to Florida

Abstract Seven ornamental species, coastal plain tickseed (Coreopsis gladiata Walt. [Asteraceae]), swamp sunflower (Helianthus angustifolius L. [Asteraceae]), climbing aster (Ampelaster carolinianus (Walt.) Nesom [Asteraceae] syn = Aster carolinianus Walt.), pineland lantana (Lantana depressa Small [Verbenaceae]), spotted beebalm (Monarda punctata L. [Lamiaceae]), blackeyed Susan (Rudbeckia hirta L. [Asteraceae]), and Carolina wild petunia (Ruellia caroliniensis (J.F. Gmel.) Steud. [Acanthaceae]) were transplanted in containers filled with a biosolid:yard waste compost, a commercial peat-based mix, or a formulated compost-based mix (4:5:1, compost:pine bark:sand, v:v:v). At 8 wk, plants grown in compost or the medium amended with compost had similar (coastal plain tickseed and swamp sunflower) or greater (climbing aster, pineland lantana, spotted beebalm, blackeyed Susan, and Carolina wild petunia) biomass than plants grown in the peat-based medium. This study suggests that compost may serve as a viable alternative substrate for peat in the production of ornamental wetland and flatwood species native to Florida.

Effects of AG3 phosphonate formulations on incidence and severity of Pythium damping-off of cucumber seedlings under growth room, microplot, and field conditions

New formulations of phosphonates (AG3) were tested for their efficacy to control Pythium damping-off of cucumber seedlings in peat-based mix (P-mix), muck soil (Mu-soil), and sandy loam soil (SL-soil). Aqueous solutions of various phosphonate formulations (0.035%–0.280% active ingredient (a.i.), v/m) were added to pathogen-infested Pmix or SL- or Mu-soils as a preplanting amendment or postplanting drench treatments. In artificially infested P-mix, preplanting amendment with powder or liquid phosphonate formulation provided control of damping-off and disease suppression that increased with the concentration of phosphonate. Higher rates (0.140% or 0.280% a.i.) provided almost 100% disease control whereas lower rates (0.035% or 0.070% a.i.) had on average 34%–75% healthy plants compared with less than 5% in the control. AG3 liquid formulation as a preplanting treatment also provided effective control in naturally infested Mu-soil and artificially infested SL-soil. Postplanting drench with AG3 was equally effective in all three soil substrates. AG3 applied as an amendment 2 weeks prior to planting in Mu-soil was as effective as that added just prior to planting. Treatments made prior to 2 weeks were less effective. AG3 also provided effective control of Pythium damping-off of cucumber seedlings under microplot and field conditions. The amount and frequency of irrigation and rainfall can affect the disease suppression by AG3 phosphonate in the field.

Effect of neem cake soil amendment on reduction of damping-off severity and population densities of plant-parasitic nematodes and soilborne plant pathogens

The effects of neem cake, a nutrient-rich organic material derived from neem seed, on plant-parasitic nematodes, Verticillium dahliae, and seedling damping-off diseases caused by Rhizoctonia solani and Pythium aphanidermatum were investigated. In greenhouse trials, 1% neem cake (mass/mass soil) caused a 67%–90% reduction in the number of lesion (Pratylenchus penetrans) and root-knot (Meloidogyne hapla) nematodes in tomato roots grown in three different soils. In the field, 1% neem cake (mass/mass soil) reduced the number of lesion nematodes by 23% in corn roots and 70% in soil around roots. Population densities of free-living nematodes were either enhanced or not affected by neem cake treatment. In laboratory tests, addition of 3% neem cake (mass/mass soil) to soil killed V. dahliae microsclerotia and increased soil pH from 5.2 to 8.7. Killing of microsclerotia appeared to be caused by generation of ammonia during decomposition of neem cake. In growth room assays, addition of 2% neem cake (mass/mass peat-based mix) to R. solani -infested peat-based mix 28 days before planting radishes reduced damping-off severity. In a sandy loam soil artificially infested with R. solani and a muck soil naturally infested with damping-off pathogens, addition of 0.5% neem cake (mass/mass soil) had no immediate effect on damping-off, whereas incubation of the amended soil for 7 days before planting radish or cucumber reduced damping-off severity. This suggested that neem cake was not directly toxic to the damping-off pathogens but that during incubation neem cake may have created a biological climate that was suppressive to disease.

Using Compost for Container Production of Ornamental Hammock Species Native to Florida

Four hammock species native to Florida were larger with more flowers 8 wk after transplanting into containers filled with compost or media amended with compost when compared with a Florida peat-based control. Our study indicated that compost can serve as a viable alternative substrate to peat for container production of Florida butterfly sage (Cordia globosa (Jacq.) Kunth [Boraginaceae]), firebush (Hamelia patens Jacq. [Rubiaceae]), scorpions tail (Heliotropium angiospermum (Murray) Britton. [Boraginaceae]), and tropical sage (Salvia coccinea Buc'hoz ex Etl. [Lamiaceae]). Plants transplanted to containers filled with a biosolid:yard waste compost or a formulated compost-based mix (4:5:1, compost:pine bark:sand, v:v:v) grew better than plants transplanted to a commercial peat-based mix, although initial analyses of the medium indicated that compost alone had higher pH; electrical conductivity (EC); N, P, K, Ca, Zn, Cu, Mn, Al, Fe, and B contents; and similar air-filled porosity and C contents when compared with the peat- or compost-based media.