EVALUATING PLANT GROWTH REGULATORS FOR GROWTH CONTROL OF HERBACEOUS PERENNIALS: AGASTACHE, HYPERICUM, PENSTEMON, AND PHYSTOSTEGIA

摘要

We evaluated the growth control of established, actively growing containerized perennials treated with spray or drench applications of uniconazole or paclobutrazol or spray applications of daminozide (applied twice) or a tank mix of daminozide and chlormequat chloride (all chemicals by Fine Americas, Inc.). Crops tested included Agastache 'Purple Haze,1 Hypericum cafycinum, Penstemon x mexicale Tike's Peak' and Physostegia virginiana 'Miss Manners'. Treatments were applied 2 weeks after plugs were planted in 3.4-liter containers filled with a peat-pine bark medium. Agastache was responsive to all of the uniconazole and daminozide treatments with reductions in vegetative plant height, but less responsive to paclobutrazol and the daminozide/chlormequat chloride tank mix. All treatments except daminozide reduced Hypericum plant width. None of the treatments reduced Penstemon or Physostegia height. Recommended PGR applications include: Agastache - uniconazole as a 1 to 2 ppm drench or a 30 ppm spray orpaclobutrazol as an 8 to 12 ppm drench; Hypericum -uniconazole as <1 ppm drench or 60 ppm spray or paclobutrazol as <4 ppm drench or a 160 ppm spray.