Title: Multiple herbicide resistance in barnyardgrass (Echinochloa crus-galli) in direct-seeded rice in the Philippines

Abstract: Barnyardgrass (Echinochloa crus-galli [L.] Beauv.), a troublesome weed in rice production, has been confirmed for the first time to be resistant to both chloroacetamide (butachlor)- and acetanilide (propanil)-group herbicides commonly used in direct-seeded rice in the Philippines. Resistance screening showed that 17 of 18 sampled populations (94%) were resistant to butachlor + propanil. Dose-response assays using butachlor + propanil on the populations resulted in all but one not being controlled at twice the recommended rate for field application (1.4 kg ai or 2 l/ha) and seven populations not being controlled by 4 l/ha (2.8 kg ai). Dose-response assays using butachlor and propanil separately indicated that the latter populations were resistant to both of the herbicides. LD50 values for butachlor + propanil populations ranged from 0.6 l/ha (0.42 kg ai) to 2.9 l/ha (2.03 kg ai) indicating 1.9 to 9.1 times less sensitivity than a known susceptible population. Thus, what was perceived by farmers to be reduced herbicide efficacy is actually herbicide resistance. Hence, this new development in major herbicides has become a threat in rice production and will alter weed management in direct-seeded rice. Concerted efforts in raising awareness on herbicide resistance and implementing an effective integrated weed management program are needed. [Leylani M. Juliano, Madonna C. Casimero & Rick Llewellyn (2010). Multiple herbicide resistance in barnyardgrass (Echinochloa crus-galli) in direct-seeded rice in the Philippines. International Journal of Pest Management, Volume 56, Issue 4, pages 299 - 307. DOI: 10.1080/09670874.2010.495795] Keywords: barnyardgrass; Echinochloa crus-galli (ECHCG); multiple resistance; herbicide screening; dose-response

From http://www.informaworld.com, see original source.



Article: WeedsNews1027 (permalink)
Categories: :WeedsNews:research alert, :WeedsNews:agricultural weed, :WeedsNews:herbicide resistance, :WeedsNews:rice
Date: 21 September 2010; 9:59:12 am Australian Eastern Standard Time

Author Name: David Low
Author ID: adminDavid