Stott W. Howard, Carl R. Libbey, Eric R. Hall
Several herbicides, including cinmethylin, DPX-L5300, DPX-M6316, fenoxan, imazethapyr, isoxaben, and lactofen, were evaluated for phytotoxicity and weed control efficacy on bulbous iris, narcissus, and tulip over a three-year period. Compared to the industry standards of oryzalin and a combination of chlorpropham plus dinoseb, only cinmethylin applied preemergence to the bulbs was consistent each year in controlling a broad spectrum of weeds without reducing bulbous iris, narcissus, and tulip yield. Lactofen, applied preemergence to the bulbs, was selective on bulbous iris and narcissus, however, it had a limited weed control spectrum and would need to be combined with other herbicides to be effective.

Postemergence applications of cinmethylin or lactofen were ineffective in controlling weeds and, in the case of lactofen, caused significant yield reductions in bulbous iris, narcissus, and tulip. DPX-L5300, DPX-M6316, fenoxan, imazethapyr, and isoxaben caused excessive bulb injury.

Howard, Stott W., Libbey, Carl R. and Hall, Eric R. (1990). HERBICIDE EVALUATION IN BULBOUS IRIS, NARCISSUS, AND TULIP. Acta Hortic. 266, 561-568
DOI: 10.17660/ActaHortic.1990.266.75

Acta Horticulturae