Alternative methods of auxin application in cutting propagation

Trials were conducted to evaluate two alternative methods of applying auxin to stem cuttings of selected ornamental crops: (1) cuttings were sprayed to the drip point with an auxin solution after inserting cuttings into the rooting substrate; and (2) auxin was applied to the base of cuttings by inserting cuttings into a stabilized organic substrate (plugs) that had been pretreated with auxin.; In trials with landscape ornamentals, cuttings of Chrysanthemum pacificum sprayed with 50 + 25 ppm IBA + NAA or 0 to 50 ppm K-IBA showed similar root development compared with a basal quick-dip. Sprayed and quick-dipped cuttings of Forsythia × intermedia ‘Lynwood Gold’ were similar in root development, but cuttings sprayed with water or low auxin rates exhibited greater shoot growth. Root and shoot development were similar or lower with cuttings of other species sprayed with auxin compared to a basal quick-dip.; In trials with tropical ornamentals, number of roots and root length on cuttings of Aglaonema modestum sprayed with auxin were similar or less than with a basal quick-dip. Cuttings of Gardenia augusta ‘Radicans’ exhibited the greatest rooting responses with the basal quick-dip and with IBA + NAA spray treatments at higher rates compared with untreated cuttings. Rooting responses with Ficus benjamina and Hedera helix ‘Ivalace’ receiving spray treatments were similar or less than cuttings receiving no treatment or a basal quick-dip.; In five trials using single-node cuttings of Rosa ‘Red Cascade’, cuttings sprayed with IBA + NAA, K-IBA, or K-NAA exhibited rooting and shoot growth responses similar to or less than control cuttings. Addition of surfactant to spray treatments increased root and shoot development. Repeated sprays had no or negative effects.; Initial trials with single-node cuttings of Hedera helix and Rosa ‘Red Cascade’ inserted into auxin-treated plugs suggested that a low rate of auxin could be suitable, while higher rates were detrimental. In subsequent trials, rooting responses with cuttings of 11 woody species inserted in auxin-treated plugs were mostly similar to or greater than with a basal quick-dip. Initial shoot development on cuttings in K-IBA-treated plugs was similar to a basal quick-dip in K-IBA.