(Sorghum bicolor)

ALS inhibitors (B/2)

United States, Iowa
Shattercane (Sorghum bicolor) is a monocot weed in the Poaceae family.  In Iowa this weed first evolved resistance to Group B/2 herbicides in 1998 and infests Corn (maize).   Group B/2 herbicides are known as ALS inhibitors (Inhibition of Acetolactate Synthase ).  Research has shown that these particular biotypes are resistant to imazethapyr and they may be cross-resistant to other Group B/2 herbicides.

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

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QUIK STATS (last updated Dec 28, 2004 )

Common NameShattercane
SpeciesSorghum bicolor
GroupALS inhibitors (B/2)
LocationUnited States, Iowa
Situation(s)Corn (maize)
Contributors - (Alphabetically)Ian Zelaya 
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Ian Zelaya
The resistant shattercane biotype was collected in Malvern, IA. Greenhouse and laboratory studies confirmed that the Malvern, IA biotype was susceptible to nicosulfuron but was resistant to imazethapyr (GR50 R:S ratio = 29). The susceptible shattercane biotype was collected at Curtiss Farm in Ames, IA. Source: Zelaya, I. A., and M. D. K. Owen. 2004. Evolved resistance to acetolactate synthase-inhibiting herbicides in common sunflower (Helianthus annuus), giant ragweed (Ambrosia trifida), and shattercane (Sorghum bicolor) in Iowa. Weed Science 52:538-548.

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Confirmation Tests

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

Genetic studies on Group B/2 resistant Shattercane have not been reported to the site.  There may be a note below or an article discussing the genetics of this biotype in the Fact Sheets and Other Literature
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 Group B/2 resistant Shattercane from Iowa please update the database.
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The Herbicide Resistance Action Committee, The Weed Science Society of America, and weed scientists in Iowa have been instrumental in providing you this information. Particular thanks is given to Ian Zelaya for providing detailed information.
Herbicide Resistant Shattercane Globally
(Sorghum bicolor)
Herbicide Resistant Shattercane Globally
(Sorghum bicolor)
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Herbicide Resistant Shattercane Globally
(Sorghum bicolor)
#CountryFirstYearSituationActive IngredientsSite of Action
1 United States (Nebraska) United StatesNebraska1994 Corn (maize) primisulfuron-methyl 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane474
2 United States (Kansas) United StatesKansas1996 Corn (maize) nicosulfuron, and primisulfuron-methyl 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane500
3 United States (Iowa) United StatesIowa1998 Corn (maize) imazethapyr 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane5229
4 United States (Ohio) United StatesOhio2000 Corn (maize) imazethapyr, nicosulfuron, and primisulfuron-methyl 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane5235
5 United States (Illinois) United StatesIllinois2000 Corn (maize) nicosulfuron 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane7861
6 United States (Pennsylvania) United StatesPennsylvania2001 Corn (maize), and Soybean imazamox, imazethapyr, nicosulfuron, oxasulfuron, and primisulfuron-methyl 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane5121
7 United States (Virginia) United StatesVirginia2003 Corn (maize) imazapyr, imazethapyr, and nicosulfuron 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane5204
8 United States (Indiana) United StatesIndiana2006 Corn (maize), and Soybean foramsulfuron, and nicosulfuron 45 ALS inhibitors (B/2)
165Sorghum bicolorShattercane5281
Literature about Similar Cases

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PERMISSION MUST BE OBTAINED FIRST if you intend to base a significant portion of a scientific paper on data derived from this site. Citation:
Heap, I.  The International Herbicide-Resistant Weed Database.  Online.  Monday, April 12, 2021 .  Available Copyright © 1993- 2021 All rights reserved. Fair use of this material is encouraged. Proper citation is requested.