Nature, Occurrence, and Cost of Herbicide-Resistant Wild Oat (Avena fatua) in Small-Grain Production Areas

Abstract

Surveys were conducted across the northern Great Plains of Canada in 1996 and 1997 to determine the nature and occurrence of herbicide-resistant (HR) biotypes of wild oat (Avena fatua). The surveys indicated that resistance to acetyl-CoA carboxylase (ACCase) inhibitors (Group 1) occurred most frequently relative to other herbicide groups. Group 1-HR wild oat occurred in over one-half of fields surveyed in each of the three prairie provinces. Of particular concern was the relatively high incidence of multiple-group resistance in wild oat in Saskatchewan and Manitoba. In Saskatchewan, 18% of Group 1-HR populations were also resistant to acetolactate synthase inhibitors (imidazolinones), even though these herbicides were not frequently used. In Manitoba, 27% of fields surveyed had wild oat resistant to herbicides from more than one group. Four populations were resistant to all herbicides registered for use in wheat (Triticum aestivum). Depending on the nature of resistance in wild oat, alternative herbicides available for their control may substantially increase costs to the grower. The cost to growers of managing HR wild oat in Saskatchewan and Manitoba using alternative herbicides is estimated at over $4 million annually. For some HR biotypes, alternative herbicides either are not available or all have the same site of action, which restricts crop or herbicide rotation options and threatens the future sustainability of small-grain annual cropping systems where these infestations occur.

Herbicide-tolerant canola: weed control and yield comparisons in western Canada

“…Growing glyphosate-and glufosinatetolerant canola may help delay the threat of herbicide-resistant weeds by encouraging the use of new in-crop mode of action groups (Radosevich et al 1997). HTC are already providing flexibility on some western Canadian farms with wild oat populations resistant to four mode of action groups (Beckie et al 1999). On the other hand, the popularity of HTC may encourage the overuse of some herbicides and, with increased selection intensity, may increase resistant weed populations (Maxwell and Mortimer 1994;Derksen et al 1999).…”

A field survey of crop management practices and distribution of ALS resistant Euphorbia heterophylla in two states in southern Brazil

“…Heap (2003) reports the occurrence of resistant biotypes to be limited to less than 10 places, whereas Cerqueira et al (2002) reported the occurrence of resistant biotypes to be over 50 counties in southern Brazil. No surveys of weed resistance in Brazil are found in the literature; however several surveys document the status of weed resistance in other parts of the world (Bourgeois & Morrison, 1997;Bourgeois et al, 1997;Beckie et al., 1999;Légere et al, 2000;Llewellyn & Powles, 2001). …”

Wild oat (Avena fatua L.) biotypes resistant to acetolactate synthase and acetyl-CoA carboxylase inhibitors in Poland

“…Resistance index to pinoxaden for biotype R1 amounted to 8.4. Denotations: S -sensitive biotype; R1, R3 -biotypes resistant to sulfonylurea herbicides: 1 -untreated; 2 -iodosulfuron + mesosulfuron-methyl; 3 -sulfometuron Biotypes of wild oat are most often resistant to inhibitors of acetolactate synthase and acetyl-CoA carboxylase (Seefeldt et al 1996, Cavan et al 1998, Beckie et al 1999. The results of the present research and those obtained by Stokłosa and Kieć (2006) demonstrate that in Poland resistance of wild oat is related also to herbicides with that mechanism of action.…”

“…Therefore it is a clear signal that there is a problem of resistant biotypes of wild oat and one may assume it will become more significant in the following years. Wild oat belongs to the group of weeds that are the most susceptible to the development of resistance (Bourgeois et al 1997, Beckie et al 1999, De Prado and Franco 2004. Such traits are affected by: genetic diversity of the species, great fertility, common occurrence and very high competitiveness in comparison with cultivated plants.…”