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[1] Indiana
[2] Nebraska, Iowa


[1] Indiana
Date: Tue 19 Aug 2008
Source: Wisconsin Ag Connection, USAgNet report [edited]
<http://www.wisconsinagconnection.com/story-national.php?Id=1935&yr=2008>

Goss's bacterial wilt confirmed in Indiana

There is a new disease of corn on the scene in Indiana: Goss's wilt [GW]. The disease was confirmed at the Purdue Plant and Pest Diagnostic Laboratory this week on field corn and popcorn samples submitted from northern Indiana. GW infects susceptible varieties of sweet corn, popcorn, and hybrid corn. This is Purdue's 1st confirmation in Indiana since the disease was discovered in Nebraska in 1969. GW is found sporadically throughout the Midwest.

Early hailstorms and recent heavy rains and windstorms likely contributed to the infection and dispersal of GW in Indiana.
Currently, the susceptibility level of most corn varieties to GW in Indiana is unknown. Partially resistant hybrids are available in other areas of the Midwest, such as Nebraska, but hybrid performance in Indiana is unknown at this time. It is important to note that fungicides will NOT control Goss's wilt, since the disease is caused by bacteria and not a fungus.

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[2] Nebraska, Iowa
Date: Mon 11 Aug 2008
Source: Iowa State University News [edited] <http://www.extension.iastate.edu/CropNews/2008/0811robertsonjesse.htm>

Goss's wilt prevalent in western Iowa

This past week [4-10 Aug 2008] several corn samples infected with Goss's wilt were submitted to the Iowa State University Plant and Insect Diagnostic Clinic. Tamra Jackson at University of Nebraska, Lincoln has also reported an increase in the prevalence of GW in Nebraska this growing season [2008].

GW was first reported on corn in Nebraska nearly 40 years ago; since then it has been reported across the entire Corn Belt. Symptoms of GW being reported in Iowa are leaf blight of the leaves at the top of corn plants causing growers to worry about anthracnose top dieback.
The disease may also be misdiagnosed as Northern leaf blight or Stewart's disease. There is nothing that can be done this growing season [2008] to manage GW. Partially resistant hybrids remain the most effective management tool for this disease.

[Byline: Alison Robertson, Laura Jesse]

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[Goss's wilt and blight of maize is caused by the Gram-positive bacterium _Clavibacter michiganensis_ subsp. _nebraskensis_. It is a persistent and economically serious disease of susceptible maize hybrids in the USA. The bacterium can also affect some grasses, which may serve as pathogen reservoirs. Symptoms include systemic wilting and/or leaf lesions and blighting. Infection of leaves, stems, and roots occurs primarily through wounds (mechanical, hail, or insect damage), and plants are susceptible at all growth stages. The pathogen is seed transmitted and overwinters on crop debris and maize kernels. Disease management includes cultural practices to minimise inoculum, crop rotation, and use of resistant crop varieties.

Subsp. _nebraskensis_ has so far not been reported outside the USA, however other subspecies affecting different hosts are found elsewhere. For example, potato ring rot with a reported yield loss of up to 50 percent is caused by subsp. _sepedonicus_, and subsp. _michiganensis_ causes bacterial canker of tomatoes resulting in up to 70 percent yield loss.

The other diseases mentioned above are: Stewart's wilt caused by the bacterium _Erwinia stewartii_; northern leaf blight caused by the fungus _Setosphaeria turcica_; and anthracnose caused by the fungi _Colletotrichum graminicola_ or _Glomerella tucumanensis_.

Maps
USA:
<http://www.mapsofworld.com/usa/usa-road-map-enlarge-view.html>  and
<http://healthmap.org/promed?v=40,-97.6,4>
US states:
<http://www.census.gov/geo/www/us_regdiv.pdf>

Pictures of Goss's wilt symptoms:
<http://cropwatch.unl.edu/photos/cwphoto/crop06-19gosswilt.jpg>,
<http://elkhorn.unl.edu/epublic/live/g1675/build/graphics/g1675-3.jpg>,
<http://elkhorn.unl.edu/epublic/live/g1675/build/graphics/g1675-5.jpg> and via <http://www.ipmimages.org/browse/subimages.cfm?area=72&sub=20561>

Links
Information on Goss's wilt:
<http://www.ianrpubs.unl.edu/epublic/pages/publicationD.jsp?publicationId=679>,
<http://www.ianrpubs.unl.edu/epublic/live/g1675/build/g1675.pdf>,
<http://www.lgseeds.com/LG_Tech2/Goss%20Wilt.asp>,  and <http://cropwatch.unl.edu/archives/2006/Crop19/gosswilt.htm>
_Clavibacter_ taxonomy and species list:
<http://www.bacterio.cict.fr/c/clavibacter.html>
List of diseases and pathogens of maize:
<http://www.apsnet.org/online/common/names/corn.asp>.  - Mod.DHA]