Greenhouse and growth chamber experiments were conducted to investigate the sprouting potential of rootstock; the effect of temperature, burial depth, and length of rootstock on sprouting; and the effect of shoot removal on resprouting ability of rootstock in redvine and trumpetcreeper. Glyphosate translocation along the rootstock of redvine was also measured. Higher sprouting was observed at 20 to 40 C in trumpetcreeper (60 to 73%) and at 30 to 40 C in redvine (45 to 47%) compared with other temperatures. Redvine sprouting was totally inhibited at 15 C, whereas trumpetcreeper had a sprouting of 12%. Emergence of shoot from a 28-cm planting depth was completely inhibited in redvine, whereas trumpetcreeper had 23% sprout emergence. After shoot removal treatments applied every 3 wk, redvine rootstock segments ≤2 cm long were totally depleted after fifth shoot removal treatment (15 wk after planting [WAP]). In trumpetcreeper, total depletion was not reached by 15 WAP, regardless of rootstock length. ¹⁴C-glyphosate was translocated from the treated shoot attached to the apical end of a 35-cm rootstock to the untreated end with slightly less ¹⁴C-glyphosate recovered at the untreated end compared with 5 to 10 cm from the treated shoot. These results indicated that vegetative reproduction in redvine is more sensitive to cool temperatures, deep burial depth, and short rootstock segment than trumpetcreeper. Variable control of redvine with glyphosate could be due to inadequate herbicide translocation within the rootstock.

Nomenclature: Glyphosate; redvine, Brunnichia ovata (Walt.) Shinners #³ BRVCI; trumpetcreeper, Campsis radicans (L.) Seem. ex Bureau # CMIRA.

Additional index words: Absorption, regrowth, sprout regeneration, uptake.

Abbreviations: DAT, days after treatment; WAP, weeks after planting; WAT, weeks after treatment.