560 likes | 816 Views
Downy Brome Management in Montana Agriculture. Cropland Weed Research Montana State University Edward Davis, Fabian Menalled. Presentation Outline. Biology and identification of brome species. Weedy characteristics Management considerations. Herbicide options.
E N D
Downy Brome Management in Montana Agriculture Cropland Weed Research Montana State University Edward Davis, Fabian Menalled
Presentation Outline • Biology and identification of brome species. • Weedy characteristics • Management considerations. • Herbicide options. • Herbicide label rates and application timing. • MSU field trial results.
Weed Science Terminology For Brome Species “Cheatgrass” • Downy brome Bromus tectorum • Japanese brome Bromus japonicus • Cheat Bromus secalinus Not found in MT
Cheat Cheat is in Oklahoma, not MT! (Bromus secalinus) Weed scientists refer to Bromus secalinus as Cheat. However, they refer to Bromus tectorum as Downy brome or Cheatgrass. Not found in MT!!! Pictures from Interactive Encyclopedia of North American Weeds
Cheat Bromus secalinus Not found in MT Slide courtesy of Dr. Phil Stahlman, KSU
Downy brome (Bromus tectorum) Pictures from Interactive Encyclopedia of North American Weeds
Japanese brome (Bromus japonicus) Pictures from Interactive Encyclopedia of North American Weeds
Pictures from Interactive Encyclopedia of North American Weeds Japanese brome Downy brome Downy brome (Bromus tectorum) Taller ligule than Japanese, more serrated ligule than Japanese Japanese brome (Bromus japonicus) Shorter ligule than Downy, less serrated ligule than Downy More hairy, longer hairs than Downy, especially on underside of leaf
Downy brome Bromus tectorum Slide courtesy of Dr. Phil Stahlman, KSU
Japanese bromeBromus japonicus Slide courtesy of Dr. Phil Stahlman, KSU
Japanese brome Slide courtesy of Dr. Phil Stahlman, KSU
Downy brome Bromus tectorum Cheat (Chess) Bromus secalinus Japanese brome Bromus japonicus
Downy Brome (cheatgrass) • Bromus tectorum • Winter annual grass weed • Reduces crop yield • Reduces soil moisture
Downy brome • Found mostly in 6 to 22 inch precipitation zones • Grows at elevations up to 8850 ft • Prefers coarse textured soils, but grows well on all but extremely heavy or highly saline soils
Downy Brome • Up to 400 seed/plant • 500# seed/a • 125 million/a • 2,870/sq.ft. • Matures 4 wk earlier than wheat • Initial dormant period • Short soil seed life • 2-3 yrs.
Reasons Why Annual Bromes Are Increasing • Conservation tillage • Increased fertilization • Shorter, less competitive varieties • Highly effective broadleaf herbicides • Drought years ,CRP
Cultural Control PracticesManagement • Crop rotation • Delayed seeding • Winter wheat row spacing • Winter wheat seeding rates • Competitive wheat cultivars • Fertilizer timing and placement
Weed Response to Crop RotationSidney, NE Lyon and Baltensperger 1995
Delayed Seeding • Effective for downy brome control in only 1 of 6 years in Colorado. • Lower yield potential and higher risks of winter kill and wind erosion. • In Oklahoma, a 4-wk delay for cheat control resulted in economic loss. Anderson 1996 Ferreira et al. 1990
Row Spacing and Seeding Rate20 site-years in Oklahoma ---- 60 lb/A ---- ---- 120 lb/A ---- Epplin et al. 1996
Wheat Seeding Rate Affects Cheat20 site-years in Oklahoma • Epplin et al. 1996
Downy Brome Response to NPendleton, Oregon Rasmussen 1995
N Timing Affects Downy BromeAkron, CO Anderson 1991
N Placement on Downy BromeWyoming Miller 1990
Fertilizer PlacementPendleton, OR Rasmussen 1995
Weed-Crop Competition Winter annual grass interference is a function of several factors including: • resource availability • plant and tiller density • environmental conditions • winter wheat competitiveness • time of emergence relative to wheat
Weed-Crop Competition • Moderate weedy brome infestations reduce winter wheat yields by 20 to 40%; dense infestations up to 90%. • Yield losses are most severe when resources are limited and weeds and wheat emerge simultaneously.
Weed-Crop Competition • Research in Kansas and Alberta • With normal wheat stands and adequate resources, low to moderate infestations of downy brome that emerge 3 weeks or later than winter wheat usually do not reduce wheat yield. Blackshaw 1996 Stahlman and Miller 1990
Cultivar Competitiveness • Winter wheat cultivars vary widely in their competitiveness with weeds. • Plant height is the characteristic most associated with increased competitiveness. • Early plant growth, tillering ability, and leaf area also are important.
Less susceptible More susceptible Grass weed response to herbicides Downy brome Japanese brome
Maverick • Sulfosulfuron • ALS Enzyme Inhibitor (blocks protein synthesis) • The first selective herbicide developed for control of winter annual brome species in wheat. • Controls several common winter annual broadleaf weeds • Restrictive crop rotation intervals
Olympus • Propoxycarbazone-sodium • ALS Enzyme Inhibitor (blocks protein synthesis) • Main target weeds are cheat, downy brome and Japanese brome as well as a number of key broadleaves. • Olympus may control wild oat and suppress jointed goatgrass. • Olympus FLEX is a mixture of propoxycarbazone-sodium and mesosulfuron-methyl.
Osprey • mesosulfuron-methyl • ALS enzyme inhibitor (blocks protein synthesis) • Main target weeds are wild oat, Persian darnel and Italian ryegrass as well as a number of key broadleaves. • Osprey will suppress downy brome.
Environmental Stresses • Stress reduces postemergent herbicide effectiveness. • Effectiveness generally affected more by moisture than temperature stress. • Cold temperatures after application increases risk of crop injury. • Low density weed populations generally are more easily controlled than high density populations.
October 21, 2004 Amsterdam, MT
Maximum Single Application use Rates for Downy Brome Control in Rampart Winter Wheat. Fall Applied, Amsterdam 2005
April 7, 2005 Amsterdam, MT
Maximum Single Application use Rates for Downy Brome Control in Rampart Winter Wheat. Spring Applied, Amsterdam 2005
Maximum Single Application use Rates for Downy Brome Control in Rampart Winter Wheat. Fall Applied, Amsterdam 2005
Maximum Single Application use Rates for Downy Brome Control in Rampart Winter Wheat. Spring Applied, Amsterdam 2005
Possible Sequential Applications with Olympus Followed by Olympus
Possible Sequential Applications with Olympus followed by Osprey
Possible Sequential Applications with Olympus followed by Osprey
January 13, 2006 Moccasin, MT