Nine species of field-grown flowering bulbs and perennials were screened for tolerance to the preemergence herbicide products Dacthal (DCPA), Gallery (isoxaben), Pennant (metolachlor), PRE-M (pendimethalin), Stakeout (dithiopyr), Derby (metolachlor + simazine) and Snapshot (isoxaben + oryzalin). Herbicides were applied at recommended rates three to five times over two to three years. No detrimental effects on growth, development or flowering were observed. Most products controlled large crabgrass, horseweed and prostrate spurge. However, control of crabgrass and spurge was poor with Gallery at 0.84 kg ai/ha, and control of horseweed and spurge was poor with Dacthal.

herbicide tolerance, ornamental plants, weed control, weed management
Dacthal (DCPA), dimethyl 2,3,5,6-tetrachloro-1,4-benzenedicarboxylate, Gallery (isoxaben), N-[3-(1-ethyl-1-methylpropyl)-5-isoxazolyl]-2,6-dimethoxybenzamide, Pennant (metolachlor), 2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide, PRE-M (pendimethalin), N-(1-ethylpropyl)-3,4-dimethyl-2,6-dinitrobenzenamine, Stakeout (dithiopyr), S,S-dimethyl 2-(difluoromethyl)-4-(2-methylpropyl)-6-(trifluoromethyl)-3,5-pyridinedicarbothioate, Derby (metolachlor) + (simazine), 6-chloro-N,N'-diethyl-1,3,5-triazine-2,4-diamine, Snapshot (isoxaben) + (oryzalin), 4-(dipropylamino)-3,5-dinitrobenzenesulfonamide.
Spring flowering: Drumsticks (Allium sphaerocephalon L.), Daffodil (Narcissus L. x ‘Ice Follies’), Star of Bethlehem (Ornithogalum umbellatum L.), Summer flowering: Indian Shot (Canna L. x ‘Firebird’), Falling Stars (Crocosmia x crocosmiiflora (Lemoine ex Burbidge & Dean) N. E. Brown3 ‘Lucifer’), Daylily (Hemerocallis L. x ‘Pink Charm’), German Iris (Iris x germanica L. ‘Matinata’), Sterling Star Asiatic Hybrid Lily (Lilium L. x ‘Sterling Star’), Sarah Bernhardt Peony (Paeonia L. x ‘Sarah Bernhardt’)
horseweed (Conyza canadensis (L.) Cronq.), large crabgrass (Digitaria sanguinalis (L.) Scop.), prostrate spurge (Euphorbia humistrata Engelm. ex Gray)
This content is only available as a PDF.

Author notes

2Professor, Research Assistant, Professor and Research Assistant, Department of Horticultural Science.

3Hortus Third (1976) cited the authority as (V. Lemoine ex E. Morr.) N.E. Brown. P.J. Kostelijk (1984) corrected it in Crocosmia in gardens. The Plantsman 5:246–253.

Copyright, All Rights Reserved
1994