PHYTOTOXICITY SCREENING OF 4 POSTEMERGENCE APPLIED HERBICIDES ON 7 HERBS

A herbicide screening experiment determined the phytotoxicity of norfl urazon, simazine, bentazon, and dicamba on sage (Salvia officinalis L. ), pot marjoram (Origanum onites Benth.), wild marjoram (Origanum vulg are subsp. 'vulgare'), lavender (Lavandula angustifolia Mill.), winter savory (Satureja montana L.). rosemary (Rosmarinus officinalis L.), a nd sweet marjoram (Origanum mejorana L.). Plants were arranged in a st rip-split plot design with four replicates. In September 1991, four he rbicides at three rates were sprayed along the strip arrangement acros s replicates. Phytotoxicity ratings were determined 21d after treatmen t application. Differences between herbicides, rates, and herbs were s ignificant (P<0.05). Also, the interactions herbicide x rate, herbicid e x herbs, rate x herb, and herbicide x rate x herb were significant ( P<0.05). Norflurazon proved to be the least phytotoxic herbicide. Crop vigor of wild marjoram, lavender, winter savory, rosemary, and sweet marjoram were not affected by norflurazon applied at 0.56 kg a.i. ha-1 (.5x). No visual effects by norflurazon were observed on lavender and rosemary at 1.12 kg a.i. ha-1 (lx). Also bentazon at 0.84 kg a.i. ha- 1 (.5x) for sage, pot marjoram, winter savory, and rosemary, and also for rosemary at 1.68 kg a.i. ha-1 (1x); and dicamba at 0.02 kg a.i. ha -1 (.5x) for sage, rosemary, and sweet marjoram showed potential for l abeling. Simazine killed exposed plants at all rates.