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Response of Azalea (Rhododendron obtusum) Cultivars to Sethoxydim and Fluazifop-P

Published online by Cambridge University Press:  12 June 2017

Jeffrey F. Derr*
Affiliation:
Dep. Plant Path., Physiol. Weed Sci., Va. Polytech. Inst. State Univ., Blacksburg, VA 24061

Abstract

Experiments were conducted to evaluate varietal susceptibility of azalea [Rhododendron obtusum (Lindl.) Planch] to fluazifop-P {(R)-2-[4-[[5-(trifluoromethyl)-2-pyridinyl] oxy] phenoxy] propanoic acid } and sethoxydim {2-[l-(ethoxyimino)butyl]-5-[2-(ethylthio)propyl]-3-hydroxy-2-cyclohexen-1-one}. Injury observed on ‘Delaware Valley White’, ‘Hinocrimson’, and ‘Poukhanense’, following broadcast applications of fluazifop-P at 1.12 kg ai/ha, ranged from 5 to 53% foliar damage. Injury symptoms observed were leaf burn, spotting, and distortion, especially in younger leaves. Sethoxydim at 2.24 kg ai/ha caused either slight or no foliar injury to the cultivars tested. Both sethoxydim and fluazifop-P caused temporary growth reduction in ‘Hershey Red’. Foliar injury or growth reduction resulting from these herbicides was temporary, with no damage evident 6 weeks after application. Although adding either crop oil concentration or a nonionic surfactant increased phytotoxicity of fluazifop-P to Hinocrimson and Poukhanense, these adjuvants were not phytotoxic to azalea cultivars when applied alone.

Type
Research
Copyright
Copyright © 1987 by the Weed Science Society of America 

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References

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