Winter Wheat Yield Reduction from Interference by Italian Ryegrass¹

Abstract

Italian ryegrass (Lolium multiflorum Lam.) is a serious and widespread weed problem in grain fields of western Oregon and Washington. Field studies were conducted to measure effects of Italian ryegrass interference on winter wheat (Triticum aestivum L.) yields. Wheat cultivars used were ‘Nugaines,’ ‘Druchamp,’ ‘Hyslop,’ and ‘Yamhill.’ Ryegrass densities ranging from 0 to approximately 100 plants/m2 were established by hand distribution on the soil surface, followed by harrowing. Urea fertilizer was applied in the spring at 56, 112, and 168 kg of N/ha. As ryegrass densities increased, wheat grain yields decreased. In one experiment, wheat grain yield was reduced by 4,100 kg/ha when the ryegrass density was increased from 0.7 to 93 plants/m2. Interference caused greater percentage reductions in wheat yields at 168 kg N/ha than at 56 kg N/ha when ryegrass densities were high. The percentage of yield reduction tended to be higher in short wheat cultivars, Nugaines and Hyslop, than in tall cultivars, Druchamp and Yamhill. When no weed control measures were used, ryegrass infestations in the 1970 crop caused wheat yield reductions in the 1971 crop. This was due to higher ryegrass densities in 1971 in plots where the heaviest ryegrass densities occurred in 1970. When ryegrass was controlled with diuron [3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea] in 1971, no carry‐over effects from previous ryegrass infestations could be measured. Results obtained in these studies illustrate the importance of good ryegrass control in winter wheat management systems.

Antagonismo das associações de clodinafop-propargyl com metsulfuron-methyl e 2,4-D no controle de azevém (Lolium multiflorum)

“…Dentre os fatores que influenciam a capacidade competitiva de azevém com trigo estão as condições de ambiente, o cultivar utilizado e a densidade das plantas competidoras. Densidades de azevém anual de 29 a 118 plantas m -2 reduziram o rendimento de trigo entre 7 e 50% (Appleby et al, 1976). A cada 10 plantas m -2 de azevém, Liebel & Worsham (1987) constataram redução na produtividade de trigo de 4,2%.…”

“…O azevém compete com plantas de trigo durante as fases de crescimento vegetativo e reprodutivo e causa problemas na colheita, por se manter vegetando neste período. Densidades de azevém anuais de 29 a 118 plantas m -2 podem reduzir o rendimento de trigo em 7 a 50% (Appleby et al, 1976). A competição causada por azevém reduziu a produtividade de trigo em 4,2% para cada 10 plantas m -2 de azevém (Liebel & Worsham, 1987).…”

Winter Wheat Response to Weed Control and Residual Herbicides

“…Liebl and Worsham [13] noted that wheat grain yields were reduced by 4% for every ten Italian ryegrass plants per m 2 and that declining yields could be primarily attributed to reductions in crop tillering. According to Appleby et al [14], Italian ryegrass infestations of 29-118 plants per m 2 reduced wheat yields between 7 and 50%. Italian ryegrass has similar growth stages to soft red winter wheat (Figure 3) and thus competes for resources in terms of space, sunlight, nutrients, and moisture.…”

An evaluation of the resistance of annual and perennial ryegrass to herbicides

“…Lolium multiflorum is indigenous to Europe, Asia and northern Africa (Edgar & Connor 2010). However, it has spread worldwide and has become a major weed in many different cropping systems (Stanger & Appleby 1989) as it can significantly reduce winter wheat yields (Appleby et al 1975). Internationally, L. multiflorum has developed multiple resistance to herbicides through repetitive exposure to herbicides with the same mode of action (Heap 2017).…”