Benzyladenine (6-BA) Promotes Branching of Herbaceous Perennials

Benzyladenine, 6-BA (Configure, Fine Americas, Inc.), was applied as a foliar spray to Gaillardia aristata ‘Gallo Yellow,’ Gaura lindheimeri 'Siskiyou Pink,’ Geranium ‘Rozanne,’ Penstemon digitalis ‘Husker Red,’ Phlox paniculata ‘Laura,’ Veronica longifolia ‘Icicle,’ and four Echinacea cultivars, Fragrant Angel, Merlot, Sombrero Hot Pink, and Tiki Torch.  Plants were treated with 600 mg/L of 6-BA and compared to a control (using only water).  The effects of these spray applications on height, number of branches, and phytotoxicity, were assessed at 0, 2, 4, 6, 8 and 10 weeks after treatment (WAT).  The number of basal branches on treated E. 'Fragrant Angel,' 'Merlot,' and 'Tiki Torch' increased more than 69% at 4 WAT and beyond.  Height was suppressed in treated E. 'Fragrant Angel' and E. 'Merlot' by more than 10% at 4 WAT.  Treated G. aristata ‘Gallo Yellow’ plants had a 164% increase in the number of branches at 8 WAT.  Treated G. ‘Rozanne’ plants had a 24% increase in the number of branches at 2 WAT.  Treated G. lindheimeri 'Siskiyou Pink’ plants had a 32% increase in the number of branches at 4 WAT.   Treated P. digitalis ‘Husker Red’ plants had a 24% increase in the number of branches at 4 WAT and height was suppressed by 25% at 2 WAT.  Treated V. longifolia ‘Icicle’ plants had a 118% increase in the number of branches at 2 WAT, after which this difference diminished.  Plants that showed no response to 6-BA in terms of branching or height suppression were E. ‘Sombrero Hot Pink,’ and P. paniculata ‘Laura.’  Minor phytotoxicity was observed on all of the Echinacea cultivars and P. digitalis ‘Husker Red’ at 2 WAT but damage was insignificant at 3 WAT.