Atrimmec Suppresses Shoot Length and Promotes Branching of Lonicera x heckrottii ‘Goldflame’ (Goldflame Honeysuckle)

Abstract

Abstract Studies were conducted in 1999 and 2000 to determine effects of Atrimmec (dikegulac-sodium) applied at 0, 2340 or 4680 ppm and pruning just prior to Atrimmec application (1999 only) on shoot length and shoot number of Lonicera × heckrottii ‘Goldflame’ (Goldflame honeysuckle). When Atrimmec was applied in June 1999, shoot lengths were suppressed in non-pruned plants 21–24% 2 weeks after treatment (WAT), 16–19% 4 WAT, 16–17% 8 WAT, and 15–16% 10 WAT compared to control plants. Shoot length was suppressed 933% in pruned plants from 2 through 10 WAT, with increased suppression from concurrent pruning evident in control plants 2 WAT, and for plants treated with the higher Atrimmec rate 2 through 10 WAT. Following 10 WAT, increasing Atrimmec rate suppressed shoot length linearly and independent of pruning, 15–21% 12 WAT and 14–21% 14 WAT. When Atrimmec was applied in April 2000, shoot length of non-pruned plants was suppressed quadratically by increasing Atrimmec rate with suppression at the highest rate (4680 ppm) of 17% 2 WAT, 24% 4 WAT, 21% 6 WAT, 22% 8 WAT, and 20% 10 WAT. In 1999, Atrimmec and pruning affected shoot number independently. There was a linear and later a quadratic increase in shoot number with increasing Atrimmec rate of 44–122% 6 WAT, 18–68% 8 WAT, and up to 24% 10 WAT. Shoot number of non-pruned plants was greater than pruned with mean increases of 8 shoots 6 and 8 WAT and 5 shoots 10 WAT. Increasing rates of Atrimmec increased shoot number in the 2000 study up to 62% 2 WAT, 47–106% 4 WAT, 57–67% 6 WAT, and 9-27% 8 WAT.