Sulfentrazone is a promising new herbicide now under evaluation for use in agronomic and ornamental cropping systems. Sulfentrazone selectively controls yellow nutsedge, morningglories, and other annual grasses and broadleaf weeds. Research was conducted to evaluate the efficacy of sulfentrazone in combination with other labeled products for preemergence weed control in nursery crops. Treatments included sulfentrazone at 0.56 and 1.12 kg a.i./ha and sulfentrazone at 0.37 kg a.i./ha in combination with the following; dithiopyr at 0.37 kg, oxyfluorfen at 0.56 kg, metolachlor at 3.36 kg, isoxaben at 0.56 kg, norfluorazon at 2.64 kg, and isoxaben plus oryzalin at 2.24 kg a.i./ha. Combinations of sulfentrazone with isoxaben or metolachlor provided superior control of morningglory spp., honeyvine milkweed, Carolina horsenettle, and yellow nutsedge. Sulfentrazone plus oxyfluorfen or isoxaben plus oryzalin also provided good control. Poorest overall control was obtained with sulfentrazone plus dithiopyr. Viburnum and deciduous holly were slightly injured 4 WAT with sulfentrazone plus metolachlor. Sulfentrazone plus dithiopyr treatments resulted in serious injury to burning bush 4 WAT and slight injury at 8 WAT.
Michael P. Crotser, Leslie A. Weston, and Robert McNiel
James Klett*, Dave Staats, and Matt Rogoyski
During the 2003 season, preemergence herbicide was applied to twelve container grown herbaceous perennials and woody plants and evaluated for weed control, phytotoxicity, and effect on plant growth. The herbicide and rates were: Flumioxazin (Broadstar) 113.5 g (label rate), 227 g and 454 g a.i./A. Herbicides were applied to Buxus microphylla `Winter Gem', Cytisus purgans `Spanish Gold', Festuca ovina glauca `Elijah Blue', Hakonechloa macra `Aureola', Lonicera tatarica `Arnold Red', Pachysandra terminalis `Green Sheen', Hydrangea arborescens `Annabelle', Mahonia aquifolium, Phalaris arundinacea `Picta', Carex buchananii, Cerastium tomentosum, and Achillea millefolium `Red Beauty'. Weed control was excellent at all rates and controlled at least 99% of all weeds. No phytotoxicity symptoms were apparent on Mahonia, Buxus, Cytisus, Festuca, Hakonechloa, Pachysandra or Phlaris. Phytotoxicity resulted on some of the other plants. Carex had smaller plants (dry weights) at all rates. Cerastium had severe phytotoxicty at the 227 g and 454 g rates and moderate stunting at the recommended label rate, 113.5 g. Hydrangea became chlorotic and stunted at the 113.5 g rate and some fatal toxicity ocurred at the 227 g and 454 g rates. Phytotoxicity resulted on Lonicera at all rates and ranged from mild chlorosis in leaf veins (113.5 g rate) to plant death (454 g rate). Achillea at the 113.5 g rate only resulted in stunted plant growth while the 227 g and 454 g rates resulted in severe phytotoxcity and plant death.
James E. Klett, David Staats, and Matt Rogoyski
During the 2004 season, preemergence herbicide was applied to 12 container-grown herbaceous perennials and woody plants and evaluated for weed control, phytotoxicity, and effect on plant growth. The herbicide and rates were: pendimethalin (Pendulum 2G) 908 g (label rate), 1816 g, and 3632 g/acre a.i. Herbicides were applied to lady's mantle (Alchemilla mollis), purple rock cress (Aubretia species), blue wild indigo (Baptisia australis), pink pussytoes (Antennaria dioica var. rosea), common sneezeweed (Helenium autumnale), redhot poker (Kniphofia uvaria), showy goldenrod (Solidago speciosa), heartleaf foamflower (Tiarella cordifolia), lavender (Lavendula angustifolia), blue flax (Linum perenne), catmint (Nepeta ×faassenii), and hen and chicks (Sempervivum tectorum). At 32 and 117 days after application, plants were evaluated for phytotoxicity. No phytotoxicity symptoms were apparent on any of the plants tested. Weed control was good in most cases with this herbicide but it did not control all weeds. Increasing the rates from 1× (label rate) did not significantly improve weed control.
David Staats, James Klett, Teri Howlett, and Matt Rogoyski
During the 2005 season, three preemergence herbicides were applied to four container-grown herbaceous perennials and evaluated for weed control, phytotoxicity, and effect on plant growth. The herbicides and application rates were: 1) Pendimethalin (Pendulum 2G) 2.24, 4.48, and 8.96 kg/ha; 2) Trifluralin and Isoxaben (Snapshot 2.5 TG) 2.8, 5.6, and 11.2 kg/ha; and 3) S-metolachlor (Pennant Magnum 7.6 EC) 2.8, 5.6, and 11.2 kg/ha. Herbicides were applied to Coral Bells (Heuchera sanguinea), Hopflower Oregano (Origanum libanoticum), CORONADO™ Hyssop (Agastache aurantiaca), and SPANISH PEAKS™ Foxglove (Digitalis thapsi). Treatments were applied twice with 30 days between applications. Plants were evaluated for phytotoxicity after 1, 2, and 4 weeks after applying herbicide treatments. No phytotoxicity symptoms were apparent on any of the plants treated with Pendulum, and plant size (dry mass) was not affected. Snapshot resulted in visual phytotoxicity with Digitalis and Heuchera at the higher rates and also resulted in smaller plants. Pennant Magnum caused phytotoxicity at all rates in all plants and resulted in significantly smaller plants than the control. Weed control was very good with all herbicides, but did not control every weed.
Dennis C. Odero, Jose V. Fernandez, and Nikol Havranek
L.) ( Legal Information Institute, 2010 ). Recently, S -metolachlor was registered for preemergence weed control in root and tuber vegetable crops Group 1B under Special Local Needs 24 (c) registration through the Third Party Registrations, Inc., a
Amber N. Bates, Gerald M. Henry, and Cynthia B. McKenney
, s-metolachlor, oryzalin, isoxaben, and oxadiazon may be used for preemergence weed control in hooker’s evening primrose without causing excessive phytotoxicity (>20%) and potential yield loss. Trifluralin + isoxaben treatments exhibited 60% hooker
Wayne C. Porter
Selected herbicides, alone or in combination with polyethylene bed covers, were evaluated for preemergence weed control in sweet potato plant beds. No injury to sweet potato transplants was found when the herbicide was applied to the soil surface of freshly bedded sweet potato roots before application of the polyethylene or was applied to newly emerged transplants immediately after the bed cover was removed. Some foliar chlorosis was observed in transplants from beds treated with clomazone, but after the first transplant pulling, no reappearance occurred. Clomazone, chloramben, and napropamide provided excellent control of all annual grasses. Herbicides, regardless of timing of application, did not adversely affect number or weight of sweet potato transplants. Beds covered with polyethylene film produced more transplants at the early and total harvests than the uncovered beds.
Wayne C. Porter
High annual rainfall and frequent torrential deluges have always made weed control a tenuous affair in Louisiana. Herbicide leaching and soil erosion often take preemergence herbicides to the nether regions. Before the time of postemergent grass herbicides, frequent cultivation was the only method to try to salvage the sweetpotato crop when preemergence weed control was lost. For many years, the most serious weed problems were prickly sida, cocklebur, and purple nutsedge with occasional hotspots of morning-glory. However, due to the change in herbicides used, the species of problem weeds have shifted to rice flatsedge, yellow and purple nutsedge, carpetweed, and various pigweeds. Before the registration of Command herbicide for use in sweetpotatoes, many sweetpotato growers used herbicides that effectively controlled or suppressed the current problem weeds. With the widespread use of Command, prior problem weed species are effectively controlled, but these other problem weeds are released.
Robert J. Richardson and Bernard H. Zandstra
Four studies were conducted from 2001 to 2004 in Michigan to determine Christmas tree tolerance and weed control with flumioxazin and other herbicide treatments. In Study 1, fraser fir (Abies fraseri) leader length was greater with fall-applied flumioxazin (0.38 lb/acre) than with halosulfuron (0.21 lb/acre), isoxaben (1 lb/acre), oxyfluorfen (1 lb/acre), simazine (2 lb/acre), or sulfentrazone (0.5 lb/acre). Flumioxazin applied in the fall provided preemergent control of common ragweed (Ambrosia artemisiifolia), field violet (Viola arvensis), and hoary alyssum (Berteroa incana) 79% to 98% the following summer. Preemergence weed control with the other herbicides was more variable. In Study 2, fraser fir treated in the spring with oxyfluorfen had the shortest leader length (terminal stem growth of the current growing season) at 4.3 inches. Trees treated in the spring with flumioxazin, isoxaben, simazine, and sulfentrazone had leader lengths of 6.7 to 8.7 inches. Flumioxazin applied preemergence in the spring controlled common ragweed 80%, but controlled field violet, hoary alyssum, and white campion (Silene alba) only 43% to 64%. In Study 3, fall-applied flumioxazin alone did not injure colorado blue spruce (Picea pungens). However, mixtures of flumioxazin plus pendimethalin (3 lb/acre) caused 5% and 6% tree injury at 6 months after treatment (MAT) and sulfentrazone plus pendimethalin caused 9% and 23% injury at 6 MAT in 2003 and 2004, and 52% injury at 9 MAT in 2004. There was no significant injury to the trees treated with isoxaben plus pendimethalin, oxyfluorfen plus pendimethalin, or simazine plus pendimethalin in 2003 and 2004. Leader length was reduced by sulfentrazone plus pendimethalin compared with flumioxazin plus pendimethalin and oxyfluorfen plus pendimethalin. Flumioxazin plus pendimethalin provided 84% to 88% preemergence control of annual grasses, common catsear (Hypochoeris radicata), horseweed (Conyza canadensis), and virginia pepperweed (Lepidium virginicum). In Study 4, spring-applied mixtures of flumioxazin plus pendimethalin resulted in minor (2%–10%) visual injury to colorado blue spruce, although leader length at the end of the season did not differ significantly from the control. In summary, flumioxazin controlled several weed species with acceptable selectivity in colorado blue spruce and fraser fir Christmas trees.
Charles L. Webber III, James W. Shrefler, and Merritt J. Taylor
research, it was not feasible to use CGM for preemergence weed control in direct-seed crops because broadcast applications of CGM reduced direct-seeded seedling survival of beans, muskmelon, and watermelons by 98% ( Webber and Shrefler, 2007b ). These