Outdoor studies were conducted to determine the extent of leafy spurge biomass reduction resulting from broadcast application of 2,4-D (2,244 g ae ha−1) with and without wiper-applied glyphosate. Glyphosate (575 g ae L−1) was applied at 0%, 33%, 50%, and 75% diluted concentrate with a wiper 24 h after 2,4-D was broadcast-applied. Injury estimates and shoot biomass did not differ between plants treated with 2,4-D only or when glyphosate was wiper-applied 21 d after treatment. Shoot regrowth biomass of plants treated with 2,4-D only was approximately 560% greater than nontreated plants 3 mo after treatment. Plants treated with wiper-applied glyphosate exhibited shoot regrowth biomass of less than 10% compared with nontreated plants 3 mo after treatment. Root biomass of plants treated with 2,4-D only (160% of nontreated plants) exhibited a similar pattern of shoot regrowth biomass. Root biomass of plants treated with wiper-applied glyphosate exhibited approximately 50% reductions compared with nontreated plants. All vegetative metrics were equally reduced with all tested concentrations of glyphosate; therefore, all labeled concentrations should be effective. The results of the experiment indicate that broadcast-applied 2,4-D is more effective at reducing leafy spurge biomass with the addition of wiper-applied glyphosate.

Wells and streams in 10 North Dakota counties were surveyed for picloram (4-amino-3,5,6-trichloro-2-pyridinecarboxylic acid), the major herbicide used to control leafy spurge (Euphorbia esula L. # EPHES). Three rivers and 144 wells were sampled in 1985. Picloram concentration ranged from <0.1 to 12.4 ppb in the water from five wells in five counties and from <0.1 to 6 ppb in two rivers. An additional 44 wells were sampled in 1986; they were located within 2 km of the five wells where picloram was detected in 1985. Picloram concentrations in 1986 ranged from non-detectable to 6.7 ppb in the original contaminated wells and was 0.97 ppb in water from one of the additional 44 wells. Picloram concentration in the river water was lower in 1986 than in 1985 but was detected farther downstream. All contaminated wells were within 1.5 km of an area treated for leafy spurge, but picloram had been spilled accidentally or misapplied near all but one of the wells. The concentrations detected were at least 100 times below suggested tolerance levels for water.

In this review, we examine current techniques and recent advances directed toward understanding cellular mechanisms involved in controlling dormancy in vegetative propagules. Vegetative propagules (including stems, rhizomes, tubers, bulbs, stolons, creeping roots, etc.) contain axillary and adventitious buds capable of producing new stems/branches under permissive environments. Axillary and adventitious buds are distinct in that axillary buds are formed in the axil of leaves and are responsible for production of lateral shoots (branches). Adventitious buds refer to buds that arise on the plant at places (stems, roots, or leaves) other than leaf axils. Both axillary and adventitious buds generally undergo periods of dormancy. Dormancy has been described as a temporary suspension of visible growth of any plant structure containing a meristem (Lang et al. 1987). Dormancy can be subdivided into three categories: (1) ecodormancy-arrest is under the control of external environmental factors; (2) paradormancy-arrest is under the control of external physiological factors within the plant; and (3) endodormancy-arrest is under the control of internal physiological factors. One common feature in all of these processes is prevention of growth under conditions where growth should otherwise continue. There is growing evidence that lack of growth is due to blockage of cell division resulting from interactions between the signaling pathways controlling dormancy and those controlling the cell cycle.