Volunteer Barley Interference in Spring Wheat Grown in a Zero-Tillage System

Abstract

There is no published information on the impact of volunteer barley on wheat yield loss or on the economics of controlling barley with a herbicide. With the registration of imazamox-resistant wheat, it is now possible to control volunteer barley in wheat. Thus, the likelihood of growing wheat in rotation with barley may increase. Field experiments were conducted in 2003 and 2004 at Beaverlodge, Lacombe, and Edmonton, AB, Canada, and Saskatoon, SK, Canada, to determine the impact of volunteer barley on yield of imazamox-resistant spring wheat seeded at relatively low (100 kg ha−1) and high (175 kg ha−1) rates. Barley was seeded at different densities to simulate volunteer barley infestations. Regression analysis indicated that wheat-plant density influenced the effects of volunteer barley interference on wheat yield loss, economic threshold values, and volunteer barley fecundity among locations and years. Economic thresholds varied from as few volunteer barley plants as 3 m−2at Beaverlodge in 2003 and 2004 to 48 m−2at Lacombe in 2003. In most cases, wheat yield loss and volunteer barley fecundity were lower and economic thresholds were higher when wheat was seeded at the higher rate. For example, averaged over both years at Beaverlodge initial slope values (percentage of wheat yield loss at low barley density) were 4.5 and 1.7%, and economic threshold values of volunteer barley plants were 3 m−2and 8 m−2at low and high wheat seeding rates, respectively. Results indicate that volunteer barley can be highly competitive in wheat, but yield losses and wheat seed contamination due to volunteer barley can be alleviated by seeding wheat at a relatively high rate.

Interference and management of herbicide-resistant crop volunteers

“…Barley is one of the most weed-competitive crops grown globally. Therefore, interference of barley volunteers can be significant in rotational crops (O'Donovan et al 2007;Shinn et al 1999). In studies conducted across western Canada, increasing density of barley volunteers up to 120 plants m −2 reduced spring wheat grain yield by 50% or more (O'Donovan et al 2007).…”

“…Therefore, interference of barley volunteers can be significant in rotational crops (O'Donovan et al 2007;Shinn et al 1999). In studies conducted across western Canada, increasing density of barley volunteers up to 120 plants m −2 reduced spring wheat grain yield by 50% or more (O'Donovan et al 2007). In a study in the Pacific Northwest region of the United States, barley volunteers at a density of 65 to 69 plants m −2 reduced winter wheat grain yield up to 10% (Shinn et al 1999).…”

Is volunteer wheat an economic weed in annual winter wheat production?

“…Research on volunteer wheat as a weed usually focuses on yield effects or contamination of a following crop that is a different species (e.g., Komatsuzaki et al., 1994; O'Donovan et al., 2007). This research generally concludes that a vigorous crop reduces the impact of volunteer wheat.…”

Adventitious Presence: Volunteer Flax (Linum usitatissimum) in Herbicide-Resistant Canola (Brassica napus)

“…Genetically engineered crop volunteers that emerge in subsequent crops can also be a significant agronomic concern (Beckie 2001;Beckie and Owen 2007). They are considered weeds because they compete with crops for nutrients, moisture, space, and light (Blackshaw et al 2005;O'Donovan et al 2007), thereby reducing crop yield and quality, and could also interfere in harvest operations (O'Donovan et al 2005(O'Donovan et al , 2007Williams and Boydston 2006). Herbicideresistant volunteers could become more problematic and difficult to control if a crop with the same trait is planted in rotation.…”