Influence of wild radish on yield and quality of canola

Abstract

Wild radish is a prevalent annual weed throughout the cropping regions of southern Australia. Field experiments were conducted at Wagga Wagga, New South Wales, in 1998 and 1999 to determine the effect of various densities and emergence times of wild radish on yield and quality of canola and on wild radish seed production. As few as 4 wild radish m−2 emerging with canola reduced canola yield 9 to 11%, whereas 64 wild radish m−2 reduced canola yield 77 to 91%. Wild radish interference in canola was greatly affected by its time of emergence relative to canola. At 64 wild radish m−2, canola yield was reduced 77, 54, 33, and 19% in 1998 and 91, 65, 56, and 19% in 1999 when wild radish emerged 0, 2, 4, and 7 wk after canola, respectively. Wild radish that emerged 10 wk after canola did not reduce canola yield. Maximum wild radish seed production ranged from 24,183 to 32,167 seed m−2 when they emerged with canola at high densities. Wild radish that emerged later than canola produced much less seed, but some seed production still occurred in one of the 2 yr when it emerged as late as 10 wk after canola. Wild radish did not directly reduce canola quality in either year, but if wild radish seed were not separated from canola seed, the amount of erucic acid and glucosinolates was increased above marketable levels in some cases. The results of this study will be used to advise growers on wild radish control in canola and will aid the development of a multiyear management strategy for this troublesome weed in annual cropping systems.

The biology of Canadian weeds. 132. Raphanus raphanistrum L.

“…Several studies in Australia (Panetta et al 1988;Cousens et al 2001;Blackshaw et al 2002) have reported similar effects of wild radish density and time of emergence on wild radish biomass and seed yield. Even a short delay in R. raphanistrum emergence relative to narrow-leafed lupin (Panetta et al 1988), canola (Blackshaw et al 2002) or wheat (Cousens et al 2001) decreased the growth of wild radish considerably.…”

“…In Australia, yield losses of 20 to 91%, depending on wild radish densities and time of emergence, have been reported, along with potential contamination of seed lots and lower quality canola oil and meal (Blackshaw et al 2002). As few as 4 wild radish plants m -2 emerging with canola reduced canola yield 9 to 11%, whereas 64 wild radish m -2 reduced canola yield 77 to 91%.…”

“…R. raphanistrum seed production increased from 5 to 22 seeds per plant in unsprayed narrow-leafed lupin to 40 to 190 seeds per plant in simazine-treated lupin, as a result of reduced weed competition Walsh 1987, cited in Cheam andCode 1995). In a 2-yr study, Blackshaw et al (2002) reported that in Australia as few as 4 wild radish plants m -2 emerging with canola produced more than 5000 seeds per m -2 , whereas 64 wild radish plants m -2 produced 24 183 to 32 167 seeds m -2 , depending on the year.…”

“…Even a short delay in R. raphanistrum emergence relative to narrow-leafed lupin (Panetta et al 1988), canola (Blackshaw et al 2002) or wheat (Cousens et al 2001) decreased the growth of wild radish considerably. For example, a 2-wk delay in the emer- gence of wild radish relative to that of canola reduced wild radish biomass and seed yield by 40-60% (Blackshaw et al 2002). Nevertheless, wild radish plants emerging as much as 10 wk after the crop still produced some seeds (Cousens et al 2001;Blackshaw et al 2002).…”

“…For example, a 2-wk delay in the emer- gence of wild radish relative to that of canola reduced wild radish biomass and seed yield by 40-60% (Blackshaw et al 2002). Nevertheless, wild radish plants emerging as much as 10 wk after the crop still produced some seeds (Cousens et al 2001;Blackshaw et al 2002).…”