Experiment 1


Products were applied on June 6, 2003 to #1 containers of actively growing ‘PJM’ rhododendron (Rhododendron ‘PJM’), ‘Rose Glow’ barberry (Berberis thunbergii var. atropurpurea), and ‘Goldsturm’ rudbeckia (Rudbeckia fulgida). Herbicide treatments included:

Herbicide Rate
Quinoclamine (Mogeton) 1 oz./gal
Quinoclamine (Mogeton) 2 oz./gal
Quinoclamine (Mogeton) 4 oz./gal
Broadstar 150 lb/acre
TerraCyte 650 lb/acre
Non-treated control  

Irrigation was withheld for 24 hours after herbicide application. Data collected included injury ratings for each species at 7, 14, 30, 60, and 90 days after treatment (DAT), growth index on ‘PJM’ rhododendron and ‘Rose Glow’ barberry 90 DAT, and shoot dry weight (SDW) on ‘Goldsturm’ rudbeckia 90 DAT.


Quinoclamine caused no visual injury to ‘Goldsturm’ rudbeckia, ‘PJM’ rhododendron, or ‘Rose Glow’ barberry (data not presented). TerraCyte caused slight injury to ‘Goldsturm’ rudbeckia.

These results are similar to that reported by others, in that the quinoclamine is very safe for spraying directly over the top of a wide variety of ornamentals. More research has to be done in order verify safety when sprayed over more tender plants such as: tissue cultured plants, recently rooted plants, recently germinated seedlings, etc. There is anecdotal evidence from growers who have trialed this product that it is safe in most of the situations I just listed. It would also be valuable to test safety of this product on other primitive non seed-bearing plants (ferns, for example).

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