Interactive Effects of Pruning and Cyclanilide Application on Growth of Woody Nursery Crops

Abstract

Abstract A study was conducted to determine the effects of pruning on plant response to cyclanilide (CYC), a bioregulator that promotes lateral branching of fruit trees and selected woody nursery crops. In April 2004, non-pruned ‘Elizabeth Ann’ Japanese camellia (Camellia japonica L.) and small anisetree (Illicium parviflorum Michx. ex Vent.) received a single foliar application of 0, 25, 50, 100 or 200 ppm CYC, while the same species received a foliar spray of 0, 50 or 100 ppm CYC following uniform pruning. In June 2006, a single foliar application of 0, 100 or 200 ppm CYC was made to plants of ternstroemia (Ternstroemia gymnanthera Thunb.), ‘Sky Pencil’ holly (Ilex crenata Thunb.) and ‘Jennifer’ azalea (Rhododendron L.) that were either not pruned or uniformly pruned before CYC treatment. At 30 and 60 days after treatment (DAT), non-pruned, CYC-treated plants formed more shoots than pruned CYC-treated plants, however quality ratings at 120 DAT were generally higher in plants pruned prior to CYC treatment. In a third experiment, the effects of 200 ppm CYC on branching of ternstroemia, ‘Sky Pencil’ holly, ‘Jennifer’ azalea and ‘Snow White’ Indian hawthorn were ascertained when applied at three stages of lateral shoot development following pruning: immediately after pruning [developmental stage 1 (DS 1)], when new shoots were 1.3 to 2.6 cm (0.5 to 1 in) in length (DS 2), or when new shoots were 2.6 to 5.1 cm (1.0 to 2.0 in) in length (DS 3). At 60 days after pruning (DAP), shoot counts in ternstroemia and ‘Sky Pencil’ holly treated at DS 3 and ‘Snow White’ Indian hawthorn treated at DS 2 were greater than those of pruned controls. Shoot counts in ‘Jennifer’ azalea were not affected by plant developmental stage at the time of CYC application. Relatively minor injury was evident at 60 and 120 DAP in all species except ‘Jennifer’ azalea, and was most pronounced in ternstroemia and ‘Sky Pencil’ holly treated at DS 3 and in ‘Snow White’ Indian hawthorn treated at DS 2. Quality ratings were similarly high for plants of all species and treatments, except in ‘Sky Pencil’ holly in which quality ratings of plants treated with CYC at DS 1 or DS 3 were higher than those of pruned controls.