The Effect of Glyphosate on Suppressing Basal Suckers on Mediterranean Fan Palm

Clumping landscape palms such as Mediterranean fan palm (Chamaerops humilis L.) produce basal offshoots (suckers) that are typically pruned to manipulate clump density and future palm height, which is a time-consuming and costly procedure.  To investigate an alternative method, we pruned five suckers on each of 10 landscape clumps; the just-pruned surfaces on 5 clumps were treated with a 3% solution of glyphosate while the other 5 clumps were left untreated. Every 6 months, we re-cut the same suckers to the original pruning point and dried and weighed the clippings. We also counted new leaf growth from unpruned suckers and assessed overall palm quality. Glyphosate reduced cumulative sucker biomass by nearly 70% compared to untreated suckers during the 2 years of the study. Clumps with glyphosate-treated suckers tended to produce fewer leaves overall (7 treated vs. 9 untreated) but quality of the clump was unaffected. Thus, glyphosate or similar materials may hold promise for retarding or eliminating small, short, unwanted basal suckers of clumping palms. Further work is needed, though, to determine more accurate frequency and rates of application as well as long-term effect (5 years or more) on clumps.