This research was supported in part by the Horticultural Research Institute, 1000 Vermont Avenue, NW, Suite 300, Washington, DC 20005 and by Dip `N Grow, Inc., Clackamas, OR 97015. Mention of a trademark, proprietary product, or vendor does not
Eugene K. Blythe, Jeff L. Sibley, Ken M. Tilt, and John M. Ruter
Eugene K. Blythe and Jeff L. Sibley
powder (Dip-Gel; Dip 'N Grow, Inc., Clackamas, OR) to 20 °C deionized (DI) water or an alcohol-based auxin solution (Dip 'N Grow Liquid Rooting Concentrate; Dip 'N Grow, Inc.) diluted to 10% using DI water with manual stirring. Solutions were allowed to
Jeffrey G. Norcini, William G. Hudson, Melvin P. Garber, Ronald K. Jones, Ann R. Chase, and Kane Bondari
Growers in the American Association of Nurserymen and the Society of American Florists were queried as to their use of plant growth regulators (PGRs) and nonchemical alternative practices during 1993. Daminozide (B-Nine SP) and chlormequat chloride (Cycocel) accounted for 78% of the total pounds active ingredient and were used by 20% and 17% of the respondents, respectively. In contrast, the rooting compounds indolebutyric acid (Dip `N Grow, Rootone, and Hormoroot) and naphthaleneacetic acid (Dip `N Grow, and Hormodin I, II, and III) were used by 53% and 24% of the respondents, respectively, but combined accounted for less than 3% of total pounds active ingredient. Pruning/pinching was used by the greatest number of respondents (82%) and was the only alternative to PGRs rated as very effective by more than 60% of the respondents. Use of chemical PGRs and nonchemical alternative practices was influenced by region and firm size. In the northeastern United States, growers reported relatively low use of PGRs (frequency and total pounds) and the lowest use of mechanical brushing as an alternative practice. In contrast, mechanical brushing was used most in the western United States. Large firms (more than $2 million in annual sales) reported the greatest use of chemical and nonchemical means of regulating growth.
David Vandergriff and Willard T. Witte
Fifteen-cm terminal cuttings of llex × `Nellie R. Stevens' were harvested 28 Nov. 1993. Basal leaves were stripped with five to six terminal leaves remaining. Groups of 10 cuttings were treated with a 5-s quick-dip by inserting stem bases to a depth of 2.5 cm into the treatment solution. Treated cuttings were immediately inserted into 12-cm-deep nursery flats containing moist 40% Pro-Mix/60% perlite. Hormone treatments were dilutions of Dip'N Grow formulation (10,000 ppm IBA + 5000 ppm NAA). IBA/NAA levels were set at 3000, 6000, and 9000 ppm and combined in a factorial arrangement with penetrating agents of 20% dimethylformamide and 20% triethanolamine with water as a control for nine treatment combinations. Ten replications were placed on a propagation bench with bottom heat (25C) and intermittent mist. When most cuttings were well-rooted, each cutting was rated on a scale of 1 (no or little rooting) to 5 (heavy rooting). Analysis of variance showed each level of rooting hormone to be different from every other level, with best rooting at 9000 ppm (3.80). Penetrating agent treatments were different from each other, with best rooting in triethanolamine treatments (3.54), followed by dimethylformamide treatments (3.29), and controls (2.65).
Thomas Holt, Brian K. Maynard, and William A. Johnson
Subirrigation is a viable alternative to mist for the cutting propagation of many woody and herbaceous plants. However, poor success has been reported with rhododendron cuttings. This study evaluated the rooting of two Rhododendron cultivars in a subirrigation system maintained at two different levels of substrate pH. Stem cuttings of Rhododendron `PJM' and R. `Catawbiense album' were wounded, treated with Dip `n Grow (1:10 dilution), and rooted in subirrigated perlite subirrigated with tap water (pH 7.5), or tap water adjusted to pH 4.5 with weak sulfuric acid (1N H2SO4). Percent rooting and root ball displacement were recorded after 7 weeks. The pH of the subirrigation system dramatically affected root initiation and development. At pH 4.5 `PJM' cuttings rooted 100% with an average displacement of 7.6 ml; cuttings of `Catawbiense Album' rooted 88% with an average displacement of 12.1 ml. At pH 7.5, `PJM' cuttings rooted 52.5%, with an average displacement of 0.8 ml, while `Catawbiense album' rooted 73% with an average displacement of 2.5 ml. A root ball displacement of ≥3 ml was judged to be commercially acceptable for rooted cuttings of `PJM' rhododendron, ≥4.5 ml for `Catawbiense album'. At pH 7.5 only 15% of the `Catawbiense album' cuttings and none of the `PJM' cuttings produced commercially acceptable rooted cuttings. At pH 4.5, 83% of the `Catawbiense album' cuttings and 93% of the `PJM' cuttings were commercially acceptable. Subirrigation is a suitable method of irrigating rhododendron cuttings during rooting if a low substrate pH is maintained.
Asmita Paudel, Youping Sun, Larry A. Rupp, and Richard Anderson
1-napthaleneacetic acid (NAA) as Dip’N Grow (1% IBA, 0.5% NAA, Dip’N Grow, Clackamas, OR) in 25% ethanol following a quick-dip technique (5 s, 1 cm deep). The cuttings were stuck in a rooting substrate containing perlite (Hess perlite, Malad City, ID
Eugene K. Blythe
prepared 4.75 to 5.50 inches in length with four vegetative buds, trimming 0.5 inch above and below a vegetative bud. Caliper of the cuttings ranged from 0.35 to 0.40 inch. Auxin solutions were prepared by diluting Dip ’N Grow (10,000 ppm IBA + 5000 ppm NAA
John M. Ruter
Tifton Campus and planted in the field for further evaluation. Growing conditions were as previously described ( Ruter, 2004 ). Semi-hardwood cuttings were collected in May 2004 for propagation, treated in a 1:5 dilution of Dip N' Grow (Dip N' Grow Inc
Eugene K. Blythe and Jeff L. Sibley
each date using the previous season’s growth with stems being firm but green. No leaves were removed from the cuttings. Auxin solutions were prepared by diluting Dip ’N Grow (IBA + NAA; Dip ’N Grow, Clackamas, OR) with deionized water. In all
John M. Ruter
. Semihardwood cuttings were collected in June, treated with a 1:5 dilution of Dip ‘N Grow (IBA + NAA; Dip ‘N Grow Inc., Clackamas, OR) as a 5-s quick dip and were stuck in 7.9 × 7.9 cm plastic pots filled with a substrate consisting of milled pine bark and