Foxtail Barley Heading, Yield, and Quality as Influenced by Growth Regulators and a Desiccant¹

Abstract

Foxtail barley (Hordeum jubatum L.) mixed with other forages harvested after heading or accumulated material bears awns that mechanically injure livestock and game animals upon consumption. This study examines the use of several growth regulators and a desiccant on supression of heading of foxtail barley and subsequent changes in forage yield and quality. During 1979 and 1981, stands of foxtail barley on two subirrigated, lowland sites (Ustic Torriflu· vent and Typic Ustifluvent soils) were treated at different stages with growth regulators, at different rates, and with a desiccant. Effects of treatments were determined on number of heads, dry matter (DM) yield, estimated in vivo DM digestibility, and crude protein concentration of the foxtail barley forage. Treatments (kg a.i. ha-1 ) were as follows: metolachlor [2-chloro-N-{2-ethyl-6-methylphenyi)-N-{2methoxy-1-methylethyl) acetamide) at 2. 8, 5.6, and 8.4; mefluidide [N-(2,4-dimethyl-5-[((trifluoromethyl)-sulfonyl)amino)phenyl) acetamide) at 0.28, 0.56, and 0.84; maleic hydrazide (MH) [1,2-dihydro-3,6-pyridazinedione) alone at 4.5; MH at 3.36 with chlorflurenol [methyl-2-chloro-9-hydroxyfluorene-9-carboxylate) at 1.12; and paraquat [1,1'-dimethyl-4, 4'-bipyridinum dichloride) at 0.9 with 0.5% (v/v) X-77 (spreader-activator). Paraquat and MH plus chlorflurenol were the only chemicals that consistently reduced heading of foxtail barley (83 to 98%) both years. Maleic hydrazide plus chlorflurenol also consistently reduced heading when applied either 1 or 3 weeks after the first floral primordia developed. Reducing heading more than 90% reduced DM yield more than 50% the 1st year and 80% the 2nd year. Reducing heading more than 90% increased estimated in vivo DM digestibility and crude protein from 10 to 90 g kg-• units both years depending upon the chemical, and rate, and date of application. The 1st year's results indicated that metolachlor and mefluidide should be applied within a week of when the first floral primordia of foxtail barley develops for maximum control of heading but additional research should be done to confirm this. Moisture stress of foxtail barley during May of 1981 limited the effectiveness of the growth regulators in controlling heading the 2nd year.

Salinity Tolerance of Foxtail Barley (Hordeum jubatum) and Desirable Pasture Grasses

“…When foxtail barley matures, it produces stiff awns that can penetrate and become lodged in the mouth, eyes, ears, and skin of animals, commonly leading to infection, irritation, weight loss, and other debilitating injuries (Best et al 1978;Blouch 1953;Bowes 1984;Cords 1960). Forage quality and value of grasses grown for hay are also negatively affected by the presence of foxtail barley (White 1984). The adaptability and tolerance that foxtail barley exhibits in saline soils greatly exceeds that of many other pasture grasses and, therefore, explains its dominance in meadows, prairies, and pastures where salinity is a limiting factor (Badger and Ungar 1990;Dodd and Coupland 1966;Whitson et al 2000).…”

EFFECT OF MEFLUIDIDE APPLICATION DATE ON YIELD AND FORAGE QUALITY OF Bromus SPECIES

“…At the2-4 May application 90-95% of tillers had just initiated floral primordia. White (1984White ( , 1989 observed that, in foxtail barley and crested wheatgrass, reduction in seed head density was maximized when mefluidide was applied within 2 wk of floral differentiation.…”

“…Several authors have attributed this variability to the stage of plant morphological or floral development at application time (Gerrish and Dougherty 1983;Shaeffer and Marten 1986;White 1989). Reduction in seed head density was greatest in foxtail barley when mefluidide was applied within a week of floral primordia initiation (White 1984). In crested wheatgrass yield and seed head reductions, IVDOM and crude protein improvements were greatest when mefluidide applications (0.56 kg ha-') were made within 2 wk of the initiation of floral primordia (White 1989).…”