Herbicide Resistant Weeds

MULTIPLE RESISTANT EARLY WATERGRASS (Echinochloa oryzicola)
Resistance to herbicides in groups A/1, and N/8
USA: California

Saturday, July 31, 2010

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Early Watergrass

1.	Introduction
2.	Level of Infestation
3.	Quick Statistics
4.	Notes about this biotype
5.	Academic Aspects
6.	R Early Watergrass Globally
7.	Fact Sheets and Literature
8.	Contributing Weed Scientists
9.	Acknowledgements
10.	Where to now?

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Introduction

Level of Infestation

Early Watergrass (Echinochloa oryzicola) is a monocot weed in the Poaceae family. In California this weed first evolved multiple resistance ( to 2 herbicide modes of action) in 2000 and infests rice. Multiple resistance has evolved to herbicides in the Groups A/1, and N/8. These particular biotypes are known to have resistance to cyhalofop-butyl, fenoxaprop-P-ethyl, molinate, and thiobencarb = benthiocarb and they may be cross-resistant to other herbicides in the Groups A/1, and N/8.

Local weed scientists estimate that multiple resistant Early Watergrass in California infests 11-50 sites and the number of sites are increasing. They also estimate that there are 101-500 acres infested with multiple resistant Early Watergrass and the area infested is increasing.

The 'Group' letters/numbers that you see throughout this web site refer to the classification of herbicides by their mode of action. To see a full list of herbicides and HRAC herbicide classifications click here.

QUIK STATS ( last updated Jan 14, 2003 )
Common Name	Early Watergrass
Species	Echinochloa oryzicola
Group	ACCase inhibitors (A/1) Thiocarbamates and others (N/8)
Herbicides	cyhalofop-butyl, fenoxaprop-P-ethyl, molinate, and thiobencarb = benthiocarb
Location	USA, California
Year	2000
Situation(s)	rice
Sites	11-50
Acres Infested	101-500
Contributors	Albert Fischer
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ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Early Watergrass biotype with this Early Watergrass biotype have been used to confirm resistance. For further information on the tests conducted please contact the local weed scientists that provided this information.

Genetics

The genetic basis of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the genetic inheritance of this biotype please update the database.

Mechanism of Resistance

The mechanism of resistance for this biotype is either unknown or has not been entered in the database. If you know anything about the mechanism of resistance for this biotype then please update the database.

Relative Fitness

There is no record of differences in fitness or competitiveness of these resistant biotypes when compared to that of normal susceptible biotypes. If you have any information pertaining to the fitness of multiple resistant Early Watergrass from California please update the database.

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HERBICIDE RESISTANT EARLY WATERGRASS GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	South Korea Multiple Resistance	2006	51-100	51-100	ACCase inhibitors (A/1) ALS inhibitors (B/2) Thiocarbamates and others (N/8)
2.	USA (California) Multiple Resistance	2000	11-50	101-500	ACCase inhibitors (A/1) Thiocarbamates and others (N/8)

FACT SHEETS AND OTHER LITERATURE	Format
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Scientific Abstracts on Herbicide Resistant Echinochloa oryzicola
Botanical identification of Spanish Echinochloa biotypes with differential responses to quinclorac.
Schmidt, O., O. Aurich, N. Lopez, R. DePrado, and H. Walter. 1998. Botanical identification of Spanish Echinochloa biotypes with differential responses to quinclorac. Comptes-rendus 6eme symposium mediterraneen EWRS, Montpellier, France, 13-15 mai 1998. : 232-233.
Difference in early growth of Echinochloa species and the differential susceptibility to herbicides.
Chun, J. C., S. E. Kim, and N. I. Park. 1996. Difference in early growth of Echinochloa species and the differential susceptibility to herbicides. Korean Journal of Weed Science. 16: 194-199.
A molecular assessment of genetic diversity in Echinochloa spp.
Lopez Martinez, N., R. Prado de, R. P. Finch, G. Marshall, and R. De Prado. 1995. A molecular assessment of genetic diversity in Echinochloa spp. Brighton crop protection conference: weeds. Proceedings of an international conference, Brighton, UK, 20-23 November 1995. 2: 445-450.

CONTRIBUTING WEED SCIENTISTS

ALBERT FISCHER	Edit
Associate Professor University of California Weed Science Program Vegetable Crops Department Davis, 95616, California USA Email Albert Fischer

Acknowledgements

Where to now?

The Herbicide Resistance Action Committee, The North American Herbicide Resistance Action Committee, the Weed Science Society of America, and weed scientists in California have been instrumental in providing you this information. Particular thanks is given to Albert Fischer for providing detailed information.

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