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Bennett J. Sondeno and Karen L. Panter

Osha (Ligusticum porteri) is a Rocky Mountain native frequently used as a medicinal herb. It is currently harvested largely from the wild. Studies have been under way since 2001 to find ways to propagate and produce the plant. To potentially increase rooting success of crown cuttings of osha, two different rooting hormones were used, each at two concentrations. Treatments were controls, 2500 ppm, and 5000 ppm solutions each of indole-3-butyric acid (IBA) and α-naphthalene acetic acid (NAA). Cuttings were soaked in deionized water or treatment solutions for 2 min. After soaking cuttings were stuck in sterilized sand in 725-mL2 containers, one cutting per container. Containers were placed on a mist propagation bench at 21 °C in a completely randomized design under natural light and day lengths. Data taken were days to visible root and shoot, and presence or absence of root formation after 50 days. Results indicated only one of 70 cuttings (<1%) produced a shoot. Roots formed on 14% of control cuttings, 64% in 2500 ppm IBA, 86% in 5000 ppm IBA, 36% in 2500 ppm NAA, and 14% in 5000 ppm NAA. Days to rooting ranged from 14.9 (2500 ppm IBA) to 29.0 (5000 ppm NAA). Due to considerable variation in days to rooting, and the number of cuttings that did not root, analysis of variance showed no differences among treatments. Frequency analysis indicated differences among treatments in root presence or absence. The 2500 and 5000 ppm IBA treatments showed more root formation than the controls or either NAA treatment. This indicates IBA may enhance rooting of osha crown cuttings.

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Laura Pickett Pottorff and Karen L. Panter

Crops grown in high tunnels are just as susceptible to pests and diseases as those grown under greenhouse and field conditions. Crops that lend themselves economically to this type of production system are edible and/or minor crops. Therefore, labeled pesticides for these crops are limited and sometimes nonexistent. However, there is a wide range of integrated pest management (IPM) strategies available to high tunnel producers. These strategies include biological control, which is often left out of traditional IPM programs when labeled pesticides are available. High tunnel production is very conducive to the inclusion of biological controls and allows for a truly IPM system. This article provides a selective overview of common arthropod pests and diseases encountered in high tunnels, as well as strategies that have potential for becoming best management practices in high tunnels with additional research.

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Laura Pickett Pottorff and Karen L. Panter

The purpose of this study was to determine if irrigation water is a source of Pythium and Phytophthora spp. introduction into Colorado greenhouses. Nine greenhouses took part in the study; three each used municipal, well, or surface water as their irrigation supply. Water samples were collected from each greenhouse three times during Summer 1993. Samples were filtered, filter pads were incubated on selective media, and isolated pathogens were used to inoculate susceptible Cucumis sativus L. and Lupinus polyphyllus Findl. indicator plants. Pythium rostratum Butler and P. dissotocum Drechsler were isolated from surface water supplies. No Phytophthora was found in any water source. No differences were found in stem length or leaf number on inoculated versus control cucumbers or lupines. It was determined that both species of Pythium recovered are weak pathogens. Apparently, pathogenic Pythium and Phytophthora spp. are introduced into greenhouses in three counties in Colorado via means other than water supply.

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

Catharanthus roseus plants were grown in three media, each containing one of two by-products of shredded waste tires. The media were no. 1) 1 rubber*: 1 peat moss, no. 2) 1 rubber*: 1 vermiculite: 2 peat moss, and no. 3) 2 rubber*: 1 vermiculite: 1 peat moss (by volume) where rubber* indicates either 0.6 cm shredded rubber or a fibrous by-product. Control plants were grown in 1 peatmoss: 1 rockwool and 1 vermiculite: 1 peatmoss (by volume). Catharanthus roseus cv. Peppermint Cooler plants were grown for 7 weeks in 10-cm containers at a commercial Denver-area greenhouse. Data taken included plant heights, plant widths, flowers per stem, and dry weights. Visually, plants grown in the no. 2 mix, with either fiber or 0.6-cm rubber, were similar to the controls and superior to the other two mixes. Ending plant heights were similar among the two controls and no. 2 with fiber and were taller than all other combinations. Flower numbers were greater in the 1 rockwool: 1 peat moss control and no. 2 mix with fiber than any other treatment. The same was true for stem number and dry weight. Results indicate that the no. 2 mix of 1 fiber: 1 vermiculite: 2 peatmoss has potential for container crop production.

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

The objective of this study was to determine which combination of three types of irrigation systems, three fertilization method, and four growing media produced optimum growth of flowering vinca, Catharanthus roseus. Irrigation systems used included ebb-and-fl ood, drip, and pulse; fertilization methods included slow release, prepackaged, and custom mixed; and the four growing media were peatmoss:perlite:vermiculite (1:1:1, by volume), peatmoss:rockwool (1:1, by volume), and 0.6-cm diameter shredded rubber or fabric from waste tires: vermiculite:peatmoss (1:1:2, by volume). Four replications of five plants each were used in each of the 36 treatment combinations. Plants were potted 29 and 30 May 1996 in 10-cm containers, grown for 10 weeks, and harvested 6 Aug. 1996. The drip-irrigated benches were irrigated once per day for 15 s. Pulse-irrigated benches were watered twice per day for 6 s. This resulted in the drip- and pulse-irrigated plants receiving a similar volume of water daily. Ebb-and-fl ood benches were filled once per day with drainage occurring 15 min after filling. Ending plant heights and dry weights indicated that those plants in the prepackaged fertilizer/drip or ebb-and-fl ood irrigation/shredded tire fiber growing medium were comparable to plants grown in the peatmoss:rockwool medium with the same fertilizer and irrigation methods.

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Karen L. Panter, Rebecca E. Ashley, Karin M. Guernsey and Caroline M. Johnson

Osha (Ligusticum porteri) is a perennial plant native to the Rocky Mountain region of the United States and has been used as a medicinal herb to alleviate certain ailments caused by viruses, yeasts, and other microbes. It is generally harvested in the wild and is believed to be in danger of overharvest. The objectives of this study were to determine if osha could be grown successfully from seeds, seeds still attached to umbels, root cuttings, and/or vegetative crown cuttings. Seeds were harvested from the wild in Fall 2000. Roots were collected in May 2001. Seeds, either detached or attached to umbels, were given one of four treatments: 1) no stratification; 2) 6 weeks at 4.4 °C (40 °F); 3) 4 weeks each alternating 4.4 °C, then 12 hour 20.0 °C (68 °F) and 12 hours 30.0 °C (86 °F); or 4) 12 weeks at 4.4 °C. Roots were divided into crown cuttings, each containing a vegetative node, and were placed on a 21.1 °C (70 °F) mist propagation bench until rooted. Twelve weeks of stratification, whether seed was detached or attached to umbels, were beneficial for germination of osha seeds, but only gave about 11% emergence. Propagation from root cuttings was not successful. Propagation via vegetative crown cuttings was most successful, with 90% of cuttings rooting. Vegetative propagation of osha appears to be the most promising method, preferable over seed propagation.

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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.

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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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Karen L. Panter, Timmothy M. Gergeni, Casey P. Seals and Andrea R. Garfinkel

High tunnels are gaining popularity for their use in horticultural crop production. However, little is known about the effect of high tunnel orientation on plant growth and development. In this set of studies, we show tunnel orientation does not necessarily affect the production of cut sunflower (Helianthus annuus) and culinary herbs oregano (Origanum vulgare), marjoram (Origanum majorana), and garlic chive (Allium tuberosum). Two high tunnels, one with the long axis oriented north-south (NS) and the other east-west (EW), were used to test the effects of high tunnel orientation on several crops over a 5-year period: cut sunflower (2012 and 2016); marjoram, oregano, and garlic chive (2013 and 2014); and garlic chive (2015). The tunnels are 12 × 16 ft, smaller than those used in commercial production. The size would be appropriate for hobby and seasonal production of horticultural crops for local markets. Cut sunflower stems were similar lengths both years in both high tunnels. Sunflower times to harvest were different between cultivars but not between high tunnels. Oregano fresh weight yields were highest in the NS tunnel in 2013 but similar between tunnels in 2014. Marjoram fresh weights were highest in 2013 in the EW tunnel but highest in 2014 in the NS tunnel. Garlic chive fresh weights were similar between tunnels all 3 years. We show that differences are more a function of innate cultivar characteristics than which way small high tunnels are oriented.