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Steven E. Newman, Karen L. Panter, Michael J. Roll, and Robert O. Miller

Two cultivars of zonal geraniums (Pelargonium ×hortorum Bailey), `Danielle' and `Kim', were grown in media containing three grind sizes of rubber (2.4, 6, or 10 mm) and fiber from the fabric belting processed from waste tires in three proportions: 1 rubber or fiber: 1 peat; 1 rubber or fiber: 1 vermiculite: 2 peat; and 2 rubber or fiber: 1 vermiculite: 1 peat (by volume). Two control media were also included: 1 vermiculite: 1 peat, and 1 rockwool: 1 peat (by volume). Geranium plants were grown in media containing up to 25% waste tire products along with traditional medium components without reducing plant quality. Plant growth was best and flower count was highest in the vermiculite and peat medium, plants were smallest and flower count was lowest in media containing the rubber grinds at 2.4 or 6 mm, making up 50% of the media. The medium 1 rubber: 1 vermiculite: 2 peat, regardless of grind or fiber, produced plants equal to the rockwool and peat moss medium. All plants grown in media containing rubber by-products had elevated Zn and Cu in the foliage; however, Zn and Cu were highest in media containing 50% rubber. Foliar P: Zn ratios were less for plants grown in media containing 50% rubber and also were lower in plants grown in media with smaller rubber grind sizes.

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Arlette S. Cuomo, Steven E. Newman, Hassan H. Nassar, and Ronald J. Harkrader

There are many naturally occurring substances that have the potential to be adapted to modern pest control chemistry. Azadirachtin, an insect growth regulator, is one such naturally occurring compound that has been widely accepted in insect pest management. Quartenary benzophenanthridine alkaloids (QBAs) are known to be effective in the control of crop-damaging fungal diseases. QBAs can be isolated from plants in the Papaveraceae. Extracts of Macleaya cordata, a species rich in QBAs, were formulated for drench application to Cucumis sativa `White Wonder' seedlings. The seedlings were grown in a peat-lite medium using 10-cm plastic pots and inoculated with Rhizoctonia solani. Test formulations were prepared with and without QBAs and applied at 75, 150, and 300 ppm QBAs as a 100 ml/pot drench. The QBA formulations that provided effective control of Rhizoctonia solani lost 20% or fewer seedlings compared to the formulation without QBA, which lost more than 60% of the seedlings. Treated plants were evaluated confirming Rhizoctonia solani infection.

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Karen L. Panter, Steven E. Newman, Amy M. Briggs, and Michael J. Roll

Three application rates of two new growing medium surfactants were tested under two different irrigation systems on Dianthus barbatus plants. The objectives of the study were to determine if either of the surfactants influenced plant growth and development and to determine if surfactant applications decreased irrigation frequencies. The three levels of surfactant tested were 0 mg·L–1 (control), 10 mg·L–1 applied at each watering, and 100 mg·L–1 applied once a week. Each surfactant and rate was tested on hand-watered and ebb-and-flood irrigated plants. D. barbatus plants were grown for 8 weeks in 875-ml (12.7 cm) pots. Plants were watered when at least one plant per treatment showed visible wilt. Results showed that phytotoxicity symptoms occurred with repeated applications of both surfactants tested, especially at the 10 mg·L–1 rate at each watering. Application of either surfactant at 10 mg·L–1 at each watering decreased plant heights, dry weights, and plant widths, and increased phytotoxicity symptoms over the controls and the 100 mg·L–1 weekly treatments. Fewer waterings were required in surfactant-treated containers.

Free access

April D. Edwards, Steven E. Newman, Frank B. Matta, and Adolph J. Laiche

During recent freezes in the mid-south, crape myrtles have suffered severe freeze damage. Some increased levels of cold hardiness have been observed in the National Arboretum crape myrtle releases, but the degree of tolerance has not been documented. The relative cold hardiness of five hybrid crape myrtle cultivars `Muskogee', `Natchez', `Osage', `Tuskegee' and `Yuma' was determined using differential thermal analysis. Stem samples were collected from established trees at two locations, Poplarville, Zone 8 and Starkville, Zone 7 once per month from October through April. Freezing point suppression was determined from five samples from each cultivar and location. Observed exotherms ranged from -7C to -13C.

Free access

Shannon M. Coleman, Bledar Bisha, Steven E. Newman, Marisa Bunning, and Lawrence D. Goodridge

Hydroponic greenhouse tomato production’s popularity has grown in the United States to meet the demands for year-round availability of fresh tomatoes. Although Salmonella has been the cause of several foodborne illness outbreaks linked to tomatoes, the potential for contamination in hydroponic production is not well understood. The objectives of this study were to determine whether biweekly inoculation of Salmonella in a hydroponic tomato nutrient solution would lead to Salmonella survival and contamination of the tomato fruit and plants, hydroponic nutrient film technique (NFT) troughs, and water receptacles. An avirulent strain of Salmonella Typhimurium was used to contaminate the nutrient solution at a concentration of 105 colony-forming units (CFU)/mL. Inoculation was conducted on day 0 and biweekly until the termination of project at 12 weeks; samples were filtered and plated on selective media. Leaves and biofilm coupons were collected on day 0 and every 2 weeks postinoculation. Leaf samples were analyzed using culture methods. The biofilm coupons were analyzed using tape fluorescence in situ hybridization (FISH) method. Fruit samples were collected 6 weeks postinoculation until termination of project and analyzed using culture methods. Typical Salmonella morphology of colonies on plates streaked from overnight cultures from plant samples were confirmed by automated ribotyping. A 2-log10 reduction of cells was observed in water samples 2 days post initial inoculation. Reduction continued over the 2-week period with few cells surviving until the next inoculation. S. Typhimurium was observed on the surface of the root systems. However, a splash incident resulted in low-level contamination of selected leaves and fruit samples. The results of the study indicate that although contaminated hydroponic nutrient solution led to surface contamination of roots, such an event may not pose a high risk of contamination of hydroponically grown fruit.

Open access

Steven E. Newman, Susan B. Tenney, and Melissa W. Follett

Abstract

Production of hibiscus commonly includes chloromequat chloride application to induce shortened plant internodes and to darken green leaves (Wilkins and Kotecki, 1985), but its application has been reported to reduce flower size and flower number of some cultivars (Ball, 1985). Therefore, we evaluated the effectiveness of (E)-(p-chlorophenyl)-4,4-dimethyl-2-(1,2,4-triazol-1-y1)-1-pentene-3-ol (uniconazole) for control of plant height, width, leaf distortion, and the number of breaks (vegetative shoots produced from lateral buds) per plant on hibiscus.