Sydney NSW, Australia
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2023-01-09T23:49:00.0000000Z
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BLACKLEG AND LEAF BLIGHT, POTATO - AUSTRALIA

ProMED
http://www.promedmail.org

Source: FreshPlaza [summ. Mod.DHA, edited]
https://www.freshplaza.com/north-america/article/9488668/cold-wet-weather-and-disease-greatly-impacted-australia-potato-supply/

The 2022 season was a trying one for Australian potato growers. Big issues with blackleg and blight were running through the whole year, which impacted greatly on quality and storage. Produce supplies started to go downhill mid-year for the whole eastern seaboard. Crops could not be harvested due to extreme wet weather. This brought storage issues and even a breakdown in market availability of fresh potatoes. Growers of both ware and seed potatoes had the same problems.

The extended wet and cold weather has pushed plantings back for harvest in 2023. Australia is set to become a counter-season provider of high-quality seed tubers for Asia. 2023 has seen a substantial lift in orders, and it remains to be seen if the national growers can deliver.

[Byline: Nichola McGregor]

--
Communicated by:
ProMED

[Blackleg
---------
Blackleg of potato can be caused by several species and subspecies of bacteria in the genera _Pectobacterium_ and _Dickeya_. Symptoms may include stem rot leading to leaf yellowing, wilting and stunting of plants, as well as tuber rot, which usually starts at the stem end of the tuber. The bacteria are spread with contaminated plant or other material (including seed tubers, farm machinery), by mechanical means, and with water. Disease management may include seed tuber handling and cultural techniques, use of clean planting material, and phytosanitation to prevent introduction of the pathogen from external sources. Low levels of seed tuber infection pose a major risk of pathogen spread. Certification schemes are a vital part of disease management for these pathogens.

Population shifts of the blackleg pathogens are being observed in many areas. Possible reasons for these population shifts are thought to be climate changes and selection pressure due to intensified agriculture. In Australia, dickeya blackleg was reported for the first time in 2017 from Western Australia (ProMED post 20170710.5162819).

_Pectobacterium_ and _Dickeya_ species or subspecies also cause bacterial soft rot of potato. The pathogens can also affect other crops, causing, for example, a foot rot disease in rice as well as stem and root rot of sweet potato.

Leaf blight
------------
Two major leaf blights of potato are known. Early blight (_Alternaria solani_) causes spotting and early senescence of leaflets, as well as lesions on tubers; yield is reduced. Late blight (_Phytophthora infestans_) affects both leaves and tubers and may cause yield losses of up to 75%. The pathogens are spread with infected plant material (including seed tubers) and by mechanical means, wind, and rain. Management strategies include fungicide treatments of seed tubers and crops, as well as use of cultivars with reduced susceptibility. For more information see ProMED posts in the archives and links below.

For either disease, it is not specified which of the pathogens has been diagnosed above.

Maps
Australia (with states):
https://www.nationsonline.org/maps/australia-political-map.jpg

Pictures
Symptoms of blackleg on potato shoots:
http://vegetablemdonline.ppath.cornell.edu/Images/Impt_Diseases/85B_Pot_BlLg.jpg (stem)
Blackleg, tuber symptoms:
http://www.agroatlas.ru/content/diseases/Solani/Solani_Erwinia_carotovora_subsp_atroseptica/Solani_Erwinia_carotovora_subsp_atroseptica.jpg
Late blight on potato:
https://onvegetables.com/wp-content/uploads/2018/08/Potato-late-blight-No-halo.jpg,
https://www.thompson-morgan.com/static-images/tandm/static-articles/how-to-stop-potato-blight/what-is-potato-blight.jpg,
http://farm1.static.flickr.com/81/281344513_74bbffe5fe.jpg and
http://cdn.phys.org/newman/gfx/news/2013/keepingpacew.jpg (resistant vs. susceptible cultivars)
Early blight on potato:
http://www.potatogrower.com/Images/0513/EB%20lesions1_opt.jpeg,
http://www.suttonelms.org.uk/early-blight-1.jpg and
http://www.suttonelms.org.uk/early-blight-2.jpg

Links
Information on potato blackleg (and soft rot):
http://www.ipm.ucdavis.edu/PMG/r607100111.html and
http://www.agroatlas.ru/en/content/diseases/Solani/Solani_Erwinia_carotovora_subsp_atroseptica/
Taxonomy of blackleg bacteria via:
http://www.uniprot.org/taxonomy/2
Information on late blight:
https://gd.eppo.int/taxon/PHYTIN (with photo gallery),
https://doi.org/10.1079/cabicompendium.40970,
https://cipotato.org/press_room/blogs/combating-late-blight/,
https://www.gov.mb.ca/agriculture/crops/plant-diseases/print,mgmt-late-blight-potatoes.html and
https://www.hutton.ac.uk/research/departments/cell-and-molecular-sciences/epidemiology
Early blight fact sheet (with pictures):
http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_EarlyBlt.htm
Fungal taxonomy via:
http://www.indexfungorum.org/Names/Names.asp
- Mod.DHA]

Potato
Pectobacterium
Blackleg
Dickeya

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