Herbicide Resistant Weeds

MULTIPLE RESISTANT COMMON PURSLANE (Portulaca oleracea)
Resistance to herbicides in groups C1/5, and C2/7
USA: Michigan

Saturday, July 31, 2010

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Common Purslane

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

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Introduction

Level of Infestation

Common Purslane (Portulaca oleracea) is a dicot weed in the Portulacaceae family. In Michigan this weed first evolved multiple resistance ( to 2 herbicide modes of action) in 1991 and infests carrot, and vegetables. Multiple resistance has evolved to herbicides in the Groups C1/5, and C2/7. These particular biotypes are known to have resistance to atrazine, and linuron and they may be cross-resistant to other herbicides in the Groups C1/5, and C2/7.

Local weed scientists estimate that multiple resistant Common Purslane in Michigan infests 2-5 sites and the number of sites are increasing. They also estimate that there are 101-500 acres infested with multiple resistant Common Purslane 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 Mar 05, 2007 )
Common Name	Common Purslane
Species	Portulaca oleracea
Group	Photosystem II inhibitors (C1/5) Ureas and amides (C2/7)
Herbicides	atrazine, and linuron
Location	USA, Michigan
Year	1991
Situation(s)	carrot, and vegetables
Sites	2-5
Acres Infested	101-500
Contributors	Steven Gower, Joseph G. Masabni, and Bernard Zandstra
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NOTES ABOUT THIS BIOTYPE

AREAS FOUND

Bernard Zandstra

Lapeer county, 1 mile north of Imlay City, Brandt Farms, SE of packingshed near pond.

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GENERAL

Bernard Zandstra

The resistant common purslane is concentrated at the end of the rows where linuron would be concentrated by boom overlap and final passes. This biotype is immune to atrazine with no reaction to over 200 kg/ha.

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ACADEMIC ASPECTS

Confirmation Tests

Field, and Greenhouse trials comparing a known susceptible Common Purslane biotype with this Common Purslane 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

Triazine resistant weeds often exhibit a lower relative fitness when compared to susceptible biotypes. The most common mutation conferring triazine resistance (Ser 264 to Gly mutation of the psbA gene) also causes a reduction in CO₂ fixation, quantum yield, and seed and biomass production. There is no record in this database referring specifically to fitness studies on multiple resistant Common Purslane from Michigan.

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HERBICIDE RESISTANT COMMON PURSLANE GLOBALLY
#	Country	Year	Sites	Acres	Mode of Action
1.	USA (Michigan) Multiple Resistance	1991	2-5	101-500	Photosystem II inhibitors (C1/5) Ureas and amides (C2/7)

FACT SHEETS AND OTHER LITERATURE	Format
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Scientific Abstracts on Herbicide Resistant Portulaca oleracea
Linuron resistance in Portulaca oleracea.
Masabni, J. G., B. H. Zandstra, C. N. Yerkes, S. C. Weller, H. Brown (ed.), G. W. Cussans (ed.), M. D. Devine (ed.), S. O. Duke (ed.), C. Fernandez Quintanilla (ed.), A. Helweg (ed.), R. E. Labrada (ed.), M. Landes (ed.), P. Kudsk (ed.), and Streibig. 1996. Linuron resistance in Portulaca oleracea. Proceedings of the second international weed control congress, Copenhagen, Denmark, 25-28 June 1996. 1-4: 571-575.
Control of atrazine-tolerant broad-leaved weeds in maize by fluroxypyr.
Yehia, Z. R., H. R. El Wekil, G. M. Mekhail, and M. S. Tewfik. 1992. Control of atrazine-tolerant broad-leaved weeds in maize by fluroxypyr. Assiut Journal of Agricultural Sciences. 23: 159-170.

CONTRIBUTING WEED SCIENTISTS

STEVEN GOWER	Edit
Weed Science Diagnostician Michigan State University Diagnostic Services 113 Center for Integrated Plant Systems East Lansing, 48824, Michigan USA Email Steven Gower

JOSEPH G. MASABNI	Edit
Michigan State University Department of Horticulture PSSB East Lansing, 48824-1325, Michigan USA Email Joseph G. Masabni

BERNARD ZANDSTRA	Edit
Michigan State University Dept. of Horticulture 440 Plant and Soil Science Bldg. East Lansing, Michigan USA Email Bernard Zandstra Web : Web Site Link

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 Michigan have been instrumental in providing you this information. Particular thanks is given to Steven Gower, Joseph G. Masabni, and Bernard Zandstra for providing detailed information.

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