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Victoria E. Anjichi and Edmund J. Holcomb

The flowering of Dwarf Bearded Iris as a potted plant requires knowledge of the effect of chilling time and photoperiod on the plant. An experiment was conducted to determine what combination of these two factors would lead to flowering. The treatments were chilling time (0,4, and 8 weeks) and irradiance treatment (short day, long day, and HID lighting). Iris rhizomes were potted into 6 inch pots, kept moist and placed in a 4°C cooler for the various lengths of time. These were then transferred to the different irradiance levels and allowed to flower in the greenhouse.

The plants that received 8 weeks of chilling flowered earliest, followed by those that received 4 weeks of chilling. The plants that were placed under HID lighting flowered earlier than those that were placed under long day light treatment. The plants that received short day light treatment did not flower except for those that received-8 weeks of chilling.

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Jay Young, Charles Heuser, and E.J. Holcomb

The use of spent mushroom compost (SMC) as a media amendment for containerized greenhouse and nursery crop production is a promising alternative to disposal of this by-product of mushroom production. Fresh SMC is the compost that is removed from the mushroom house and used without further weathering. The objectives of this study include first, identification of key factors involved its successful use and second demonstration of the effective use of SMC by nurserymen. The plant material used includes both bedding plants and woody perennial species. Results demonstrate that the key factor in the use of SMC for plant production is high soluble salts. Leaching can reduce the high soluble salts. In addition, special consideration should be given to the reduction in potted media volume over time due to composting that continues after the material is removed from mushroom production. SMC as the sole growing media was not as effective as when SMC was amended with a commercial nursery growing mix. Several species were grown in 0%, 25%, 50%, 75%, and 100% mixtures of SMC and a commercial nursery mix. All species grew well in 50% SMC/50% nursery mix.

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Wendy Britton, E.J. Holcomb, and David J. Beattie

Four rates of two slow-release fertilizers were tested for optimum growth of five hosta cultivars: Hosta sieboldiana `Elegans', Hosta plantaginea `Aphrodite', Hosta `Jade Scepter', Hosta `Hadspen Blue', and Hosta `Francee'. Tissue-cultured hostas from 2.5-cm plugs were planted in 6-inch (15-cm) pots filled with a commercial soilless medium, and the slow-release fertilizer was dibbled into the medium at 0, 3, 6, or 12 g/pot. The plants were maintained for 4 months. Root and shoot fresh and dry weights were recorded at the end of the experiment. In addition, foliar nutrient analysis was conducted on `Aphrodite', `Francee', and `Jade Sceptor'. Overall, hostas grew best when the medium was amended with 3 g of either Osmocote 14N-6P-11.5K or Sierrablen 17N-6P-12K slow-release fertilizer.

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Troy M. Buechel, David J. Beattie, and E. Jay Holcomb

A characteristic problem with peat moss is its difficulty in initial wetting and rewetting, especially in a subirrigation system. Wetting agents improve wetting characteristics primarily by reducing the surface tension of water. This results in a rapid, uniform movement of water by capillary rise through the growing medium.

Two methods were used to compare the effectiveness of different wetting agents: gravimetric and electrical. Ten cm pots containing peat moss were placed in a subirrigation system. The gravimetric method used a laboratory scale where pots were periodically weighed to determine the amount of water absorbed. The electrical method utilized thin beam load cells, which have strain gages bound to the surface, to determine the weight of a suspended object. Load cells were coupled with a Campbell Scientific datalogger to collect data every minute without removing the pot from subirrigation. Because the effect of buoyancy altered the true weights, equations were generated to adjust the water uptake values. Corrected weights were used to create absorption curves for comparison of the slopes to determine which wetting agent has the fastest rate of absorption. The load cell reliably and accurately described the wetting characteristics of Peat moss and we found good agreement with the gravimetric method.

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R.D. Berghage, E.J. Holcomb, and A.H. Michael

The New Guinea Impatiens (I. hawkeri Bull.) has become one of the most important spring crops for many growers. Rapid and continuous development of new and improved cultivars have lead to tremendous diversity in flower color, leaf color, plant size, and growth rate. Penn State has conducted large-scale garden evaluations of New Guinea Impatiens since the mid-1990s. Each cultivar is evaluated in both the sun and shade for uniformity, flowering, foliage, and overall growth and form. Ratings use a 1 to 5 scale with 1 being unacceptable, 2 = poor, 3 = fair, 4 = good, and 5 = excellent. Height, width, and flower size are measured in August. One hundred fourteen cultivars in 15 commercial series have been in the trials for two or more seasons. There are significant differences in the performance of cultivars and series in the trials. `Celebrette', `Paradise', `Pure Beauty', `Celebration', and `Riviera' were the top-performing series. Within each series there were outstanding cultivars and others that did not perform as well. Plants performed better in the shade than in the sun. The average rating for plants grown in the sun was 3.3 while the rating for shade grown plants was 3.8. New Guinea impatiens were shorter (11 vs. 12.3 cm), spread less (18.9 vs. 22.1 cm), and had smaller flowers (4.8 vs. 5.3 cm wide) in the sun than in the shade, respectively. There were no significant interactions between sun vs. shade, and cultivar or series.

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Robert D. Berghage, Dennis J. Wolnick, E. Jay Holcomb, and John E. Erwin

The Internet offers many new and unique opportunities to disseminate information. The development of the World Wide Web (WWW) and information browsers like Netscap, Mosaic, and simple-to-use server software like MacHTTP provides means to allow low-cost access to information, including pictures and graphics previously unavailable to most people. The Pennsylvania State Univ. variety trial garden annually tests >1000 plants. Information is gathered on garden and pack performance, and photos of superior plants and varieties are taken. To provide wider access to this information, we have begun development of a Cyberspace trial garden on the internet. This server contains a wide variety of garden trial information developed from trials conducted in State College and Dauphin, Pa.. This server and a similar effort at Univ. of Minnesota are being constructed cooperatively. Hot links are provided between the server in Pennsylvania and the one in Minnesota, providing users with seamless access to information from both servers.

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N.S. Khoury, E.J. Holcomb, J.W. White, and M. Rand

Recycled subirrigation systems are a possible solution to grower concerns over water use, ground water pollution, and regulations concerning these. The objectives of this experiment were to examine the differences between top- and subirrigated plants, with different fertilizer regimes and with mulches.

Six treatments of `Crimson Fire' and `Victoria' CVI geraniums were grown in 11 cm. pots. Treatments were: top irrigation, 100% N supplied with 20-10-20 soluble fertilizer; subirrigation, 100% N supplied with 20-10-20 soluble fertilizer; subirrigation, N supplied in equal portions of 20-10-20 soluble fertilizer and CRF, gel mulch; subirrigation, N supplied with CRF, gel mulch; subirrigation, N supplied in equal portions of 20-10-20 soluble fertilizer and CRF, wool mulch; subirrigation, all N supplied with CRF, wool mulch.

`Crimson Fire': fresh weight was not significantly different between top- and subirrigation; fresh weight at the same fertilizer level was not significantly different with either a gel or a rockwool mulch; all CRF resulted in the lowest fresh weights. `Victoria': top irrigated fresh weight was significantly higher compared to subirrigated. Gel mulched plants resulted in significantly lower fresh weights than wool mulched plants. All CRF resulted in the lowest fresh weights.

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N.S. Khoury, E.J. Holcomb, J.W. White, and M. Rand

Excessive electroconductivity measurements have been observed in the surface layer of subirrigated substrates. A hydrophilic gel and rockwool were used as pot mulches in order to reduce the surface layer salt buildup by absorbing the salts and/or reducing evaporation.

Six treatments of `Crimson Fire' and `Victoria' CVI geraniums were grown in 11 cm. pots. Treatments were: Trt 1 - top irrigation, N source 20-10-20; trt 2 - subirrigation, N source 20-10-20; trt 3 - subirrigation, N source in equal portions of 20-10-20 and CRF, gel mulch; trt 4 - subirrigation, N source CRF, gel mulch; trt 5 - subirrigation, N source in equal portions of 20-10-20 and CRF, wool mulch; trt 6 - subirrigation, all N source CRF, wool mulch.

Pots were divided into 3 equal volume portions. Electroconductivity, as a measure of soluble salt (SS) level, was taken. All treatments had increasing SS levels with increasing pot height. Trt 2 had surface layer salt levels significantly higher than trt 1. `Victoria' trts 3,4,5 and 6 surface layers had significantly lower SS levels than trt 1 surface layers. `Crimson Fire' trt 4's surface layer had significantly lower SS levels than the surface layer of trt 1. Trts 4 and 6 bottom layers of both cultivars had significantly lower SS levels than all other treatments.

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E. Jay Holcomb, Tracey L. Harpster, Robert D. Berghage, and Larry J. Kuhns

A set of studies was established in Summer 1998 to determine the tolerance of field-grown cut flower species to specific preemergence herbicides, the effectiveness of weed control by those materials, and to determine if productivity of cut flowers is affected either by the herbicides or by colored mulches. Pendimethalin provided excellent early season weed control, but poor late-season control. It consistently caused injury at 4 lb a.i./A and sometimes at the 2 lb a.i./A rate. Oryzalin provided good to excellent weed control, but slightly injured celosia and zinnia when applied at 4 lb a.i./A. Napropamide provided excellent early season weed control, but marginally acceptable weed control later in the season. Though napropamide caused some injury to celosia early in the season when applied at the high rate, no injury to any of the plants was observed later in the season. Prodiamine and trifluralin were the overall safest of the herbicides, but they provided the weakest weed control. OH-2 was very effective when placed on the soil surface, but was less effective when placed on an organic mulch. The organic mulch was designed to keep the OH-2 particles from splashing on to the crop plant and injuring the plants. OH-2 tended to be safer placed on a mulch than on the soil surface, but statice was slightly injured even when a mulch was used.

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William J. Lamont Jr., Michael D. Orzolek, E. Jay Holcomb, Kathy Demchak, Eric Burkhart, Lisa White, and Bruce Dye

At the Pennsylvania State University (Penn State) High Tunnel Research and Education Facility, a system of production of high-value horticultural crops in high tunnels has been developed that uses plastic mulch and drip irrigation. The Penn State system involves small-scale, plastic-application equipment that prepares and applies plastic mulch and drip-irrigation tape to individual raised beds. It differs from the production system developed by researchers at the University of New Hampshire in which drip-irrigation tape is manually applied to the soil surface and then the entire soil surface in the high tunnel is covered with a black plastic sheet. An overview of the production system used in the Penn State high tunnels is presented in this report.