Echinochloa species are among the most troblesome weeds in Italian rice fields. One of the major recent issues is the development of herbicides resistance in several populations. The objective of this study was to assess the sensitivity of 29 Echinochloa spp. populations (25 E. crus-galli and 4 E. phyllopogon) which were selected in 2010 in Italian rice fields where they repeatedly escaped herbicide treatments. The following herbicides were examined: penoxsulam (40 g/ha), cyhalofop butyl (300 g/ha), profoxidim (100 g/ha), byspiribac-sodium (30.6 g/ha), imazamox (35 g/ha). An untreated control was included for each population. The experiment was conducted twice in 2011 in the greenhouse. Plants grown in pots (4 plants/pot) were sprayed at BBCH stage 13-14. The treatments were arranged in a RCBD with tree replicates. Aboveground plant fresh weight was assessed at 20 days after treatment and efficacy was expressed as percent of weight reduction in comparison to untreated plants. The popoulations were classified in six classes: SS, highly sensitive (> 95% efficacy); S, sensitive (85-95%); MS, medium sensitive (70-85%); MR, medium resistant (50- 70%); R, resistant (25-50%); RR, higly resistant (< 25%). The percentages of populations classified as R or RR were: penoxsulam 62%, byspiribac-sodium 83%, imazamox 55%, cyhalofop butyl 10%, profoxidim 7%. The percentages of SS and S populations were: penoxsulam 20%, byspiribac-sodium 3%, imazamox 17%, cyhalofop butyl 55%, profoxidim 79%. The results showed a low level of sensitivity towards ALS-inhibitors (penoxsulam, bispyribac-sodium, imazamox) in several populations and suggest the need to apply adequate management practices to mitigate the phenomenon and to deepen the knowledge on the actual degree and type of resistance.
Sensitivity to rice herbicides in Echinochloa spp. populations from Italian rice fields
FERRERO, Aldo;VIDOTTO, Francesco;TESIO, FRANCO;
2012-01-01
Abstract
Echinochloa species are among the most troblesome weeds in Italian rice fields. One of the major recent issues is the development of herbicides resistance in several populations. The objective of this study was to assess the sensitivity of 29 Echinochloa spp. populations (25 E. crus-galli and 4 E. phyllopogon) which were selected in 2010 in Italian rice fields where they repeatedly escaped herbicide treatments. The following herbicides were examined: penoxsulam (40 g/ha), cyhalofop butyl (300 g/ha), profoxidim (100 g/ha), byspiribac-sodium (30.6 g/ha), imazamox (35 g/ha). An untreated control was included for each population. The experiment was conducted twice in 2011 in the greenhouse. Plants grown in pots (4 plants/pot) were sprayed at BBCH stage 13-14. The treatments were arranged in a RCBD with tree replicates. Aboveground plant fresh weight was assessed at 20 days after treatment and efficacy was expressed as percent of weight reduction in comparison to untreated plants. The popoulations were classified in six classes: SS, highly sensitive (> 95% efficacy); S, sensitive (85-95%); MS, medium sensitive (70-85%); MR, medium resistant (50- 70%); R, resistant (25-50%); RR, higly resistant (< 25%). The percentages of populations classified as R or RR were: penoxsulam 62%, byspiribac-sodium 83%, imazamox 55%, cyhalofop butyl 10%, profoxidim 7%. The percentages of SS and S populations were: penoxsulam 20%, byspiribac-sodium 3%, imazamox 17%, cyhalofop butyl 55%, profoxidim 79%. The results showed a low level of sensitivity towards ALS-inhibitors (penoxsulam, bispyribac-sodium, imazamox) in several populations and suggest the need to apply adequate management practices to mitigate the phenomenon and to deepen the knowledge on the actual degree and type of resistance.
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