A ProMED-mail post
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International Society for Infectious Diseases
http://www.isid.org

Date: Wed 6 Sep 2023
Source: AGDAILY [summ. Mod.DHA, edited]
https://www.agdaily.com/crops/new-corn-bacterial-disease-identified-texas-panhandle/


_Pantoea_ bacteria are known to cause 2 corn diseases: Stewart's wilt and stalk rot. In 2020 and 2021, unusual symptoms appeared in corn stands at Texas A&M AgriLife Experiment Station. The overall yield loss in affected field plots averaged about 93%. Leaves had light green, long spots which were slightly opaque which turned brown and necrotic. The sick plants also didn't grow well, had unhealthy ears, and often developed stalk rot. In 2021, widespread lodging attributed to stalk rot was observed in a grower's irrigated corn field, causing widespread loss. _Pantoea_ sp. was recovered from the affected stands. In 2022, identical symptoms occurred in corn fields in 7 more areas.

Diagnosis of symptomatic tissues consistently recovered bacteria. BLAST searches of the partial 16S rRNA sequences of the isolates were identified as belonging to the genus _Pantoea_. Investigations of the pathogenicity of 2 isolates under greenhouse conditions relying on Koch's postulates resulted in the development of symptoms identical to those observed on symptomatic field plants. On healthy plants, they again caused the same symptoms. The 2 bacterial isolates were found to be closely related to _P. ananatis_ but were identified as distinctly different species.

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Communicated by:
ProMED

[Symptoms of Stewart's wilt of maize caused by the bacterium _Pantoea stewartii_ subsp. _stewartii_. (Pss; previously _Erwinia stewartii_) can vary on different host varieties but may include leaf stripes, wilting, necrosis of tassels and spots on husks of cobs. Plants may be killed at the seedling stage; infection later in the growth cycle can lead to serious yield losses. Many grassy hosts are susceptible and may serve as pathogen reservoirs. Pss also causes a leaf blight of rice and is considered an emerging pathogen of that crop (as is _P. ananatis_, ProMED post 20170504.5012251). Pss fruit bronzing is considered an emerging disease of jackfruit in southern Asia (ProMED posts 20170905.5294905, 20171123.5460703).

Species in the genus _Pantoea_ can cause diseases on a number of crops, such as leaf blights of cereals (_P. agglomerans_), pink disease of pineapple (_P. citrea_), brown stalk rot of maize (_P. ananatis_ and a novel _Pantoea_ species), and center rot of onion (_P. ananatis_). The effects of different bacterial strains on hosts can vary dramatically. The bacteria are generally transmitted by insect vectors, plant material and infected seed, making them a quarantine risk.

Pictures
Symptoms of Stewart's wilt on maize:
http://www.plantmanagementnetwork.org/pub/php/brief/2007/goss/image/corn1.jpg,
http://www.plantpath.cornell.edu/labs/nelson_r/images/photos/Stewart_wilt2.jpg,
https://assets.corteva.com/is/image/dpagco/stewarts_wilt_symptoms_1,
https://www.ent.iastate.edu/images/plantpath/corn/stewartsdis/0796.12sweetstew.jpg,
https://c1.staticflickr.com/5/4098/4926954251_0473d6a10e_b.jpg and
https://www.apsnet.org/edcenter/disandpath/prokaryote/Article%20Images/StewartWilt26.jpg

Links
Information on Stewart's wilt of maize:
https://gd.eppo.int/taxon/ERWIST (with distribution map),
https://www.apsnet.org/edcenter/disandpath/prokaryote/pdlessons/Pages/StewartWilt.aspx,
http://www.omafra.gov.on.ca/IPM/english/sweet-corn/diseases-and-disorders/stewerts-wilt.html and
https://pnwhandbooks.org/plantdisease/host-disease/corn-zea-mays-stewarts-disease-stewarts-bacterial-wilt
Information on _Pantoea_ species and subspecies:
http://www.bacterio.net/pantoea.html and
https://doi.org/10.1128/JCM.01916-08
Genus _Pantoea_ taxonomy and species list:
http://www.uniprot.org/taxonomy/53335
- Mod.DHA

ProMED map:
Texas, United States: https://promedmail.org/promed-post?place=8712310,245]

See Also

Multiple diseases, rice - India: (OR) 20230505.8709882
2022
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Stewart's wilt, maize - Italy: reoccurrence 20220729.8704745
Pantoea leaf blight, rice - India: (KL) 20220706.8704271
Pantoea leaf blight, rice - China: 1st rep 20220216.8701489
2019
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Pantoea leaf blight, rice - Malaysia: 1st rep 20190418.6428936
Stewart's wilt, maize - Slovenia: 1st rep (SP) 20190128.6282188
2017
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Pantoea bronzing, jackfruit - Americas: 1st rep (Mexico) 20171123.5460703
Pantoea bronzing, jackfruit - Malaysia: 1st rep (PH) 20170905.5294905
2016
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Pantoea, papaya - Australia: new subspecies (WA) 20160104.3911037

Website: http://www.isid.org

Published: September 26, 2023