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Postemergence Herbicides for Calendula
- Forcella, Frank, Papiernik, Sharon K., Gesch, Russ W.
- Weed technology 2012 v.26 no.3 pp. 566
- Calendula, developmental stages, herbicide resistance, imazamethabenz, phenmedipham, postemergent weed control, seed yield
- Calendula is an alternative oilseed crop whose seed oil is valued as a substitute for tung oil and a replacement for petroleum-based volatile organic compounds in paints and other coatings. Calendula tolerances to most POST-applied herbicides are unknown. Two POST-applied herbicides were tested for tolerance by calendula. Imazamethabenz at 0.44 kg ai ha⁻¹ plus surfactant and desmedipham plus phenmedipham at 0.36 + 0.36 kg ai ha⁻¹ were tolerated by calendula, but the latter herbicide must be applied after the four–leaf-pair stage of growth to avoid severe injury. Neither herbicide adversely affected calendula seed yield if applied at the four–leaf-pair stage. Because these herbicides can control several weed species, calendula tolerance to them may encourage more growers and crop advisors to test this new oilseed crop on commercial farms.Nomenclature: Desmedipham; imazamethabenz; phenmedipham; calendula, Calendula officinalis L.