Broomrape is a severe problem in the continuous cropping of bidi tobacco in India. Fifteen herbicides were evaluated for postemergence control, at different dates and rates, in field experiments in Nipani, Karnataka State. The effects of the herbicides on Orobanche control and growth and yield of tobacco were compared to the effects of handweeding and an untreated check. Following this screening experiment, four herbicides were selected for further testing. Glyphosate at 500 g ai/ha applied at 60 days after transplanting (DAT) and imazaquin at 10 g ai/ha applied at 30 DAT reduced the number of aboveground broomrape spikes by 75 to 80% and increased the tobacco yields by 80 to > 100% compared to the untreated plots. Imazethapyr and EPTC were found to be less effective for broomrape control, but they still led to substantially higher tobacco yield. None of the herbicide treatments resulted in yields higher than those in the hand-weeded plots. These plots probably did not yet reflect the potential yield of tobacco under broomrape-free conditions, due to nonemerged spikes. Toxicity to tobacco of all herbicides was higher for the higher rates tested. It was lowest with imazaquin.

Regional pine seedling tolerance experiments were conducted on five pine (Pinus spp.) species at ten forest nurseries in 1974. Similar studies in 1975 included four pine species at nine locations. From these studies, herbicides appearing safe for preemergence use are bifenox [methyl 5-(2,4-dichlorophenoxy)-2-nitrobenzoate] at 1.7, 3.4, and 6.7 kg/ha; butralin [4-(1,1-dimethylethyl)-N-(1-methylpropyl)-2,6-dinitrobenzenamine] at 2.2, 3.4, 4.5, and 6.7 kg/ha, napropamide [2-(α-naphthoxy)-N,N-diethylpropionamide] at 1.7 kg/ha; napropamide at 1.1 kg/ha plus bifenox at 3.4 kg/ha; dinitramine (N4,N4-diethyl-α,α,α-trifluoro-3,5-dinitrotoluene-2,4-diamine) at 0.37 and 0.74 kg/ha; diphenamid (N,N-dimethyl-2,2-diphenylacetamide) at 4.5 kg/ha, trifluralin (α,α,α-trifluoro-2,6-dinitro-N,N-dipropyl-p-toluidine) at 1.1 kg/ha; and profluralin [N-(cyclopropylmethyl)-α,α,α-trifluoro-2,6-dinitro-N-propyl-p-toluidine] at 1.1 and 2.2 kg/ha. Southern pine seedling tolerance to oryzalin (3,5-dinitro-N4,N4-dipropylsulfanilamide) was unacceptable at 1.1 and 2.2 kg/ha. Napropamide severely stunted seedlings at 6.7 kg/ha but affected seedlings only slightly at 3.4 kg/ha.