A ProMED-mail post
http://www.promedmail.org
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International Society for Infectious Diseases
http://www.isid.org
Date: Fri 22 Mar 2024
Source: Punjab Newsline [summ. Mod.DHA, edited]
https://www.punjabnewsline.com/news/hu-scientists-discovered-new-pea-disease-for-the-first- time-76302
Scientists from Haryana Agricultural University have identified a new and potentially devastating disease affecting pea crops. Named "Witches' Broom," the disease is associated with the pathogen _Candidatus_ Phytoplasma asteris (16SrI).
Symptoms appeared in the pea crop in 2023. The new disease was first observed in the pea crop at the Central State Farm, where 10% of the pea plants became stunted and bushy. Early identification of the disease will help in developing a planned breeding program. Scientists should start working on disease control as soon as possible.
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Communicated by:
ProMED
[The source publication (see link below) states the 1st report of a 16SrI-B group phytoplasma associated with phyllody and witches' broom symptoms in pea in India. A survey at the farm of 15 ha (37 acres) found deformities in approximately 10% of pea plants, such as bushy appearance, phyllody, deformed leaves and short internodes (witches' broom symptoms). It is not made clear, however, if this is a new global host record for pea (_Pisum sativum_) or merely a 1st report of the disease for the country.
Aster yellows phytoplasma (_Candidatus_ Phytoplasma asteris, 16SrI-B taxonomic group) can infect a wide variety of broadleaf (dicotyledoneous) crops such as oilseed rape, potato ("purple top"), grapevine, lucerne and some vegetables. Cereals and other monocots are usually affected to a lesser extent. Depending on the host, symptoms may include stunting of plants, discolourations, as well as malformation of leaves and flowers (phyllody). Infected plants typically do not produce seed.
The 16SrI species group is one of the most diverse phytoplasma groups known. Members can infect over 300 host species and cause or are involved in a large number of serious crop diseases; coinfections with other phytoplasmas have been reported as causes of both Al-Wijam disease of date palm (ProMED posts 20070514.1536, 20110519.1512) and yellowing diseases of some palms (see ProMED post 20131115.2056292).
Ornamentals and weeds can serve as pathogen reservoirs. The pathogens can overwinter in the living crowns of perennials and are transmitted by grafting or contaminated tools, but not in soil or by seed. The main vectors appear to be the aster leafhopper (_Macrosteles quadrilineatus_) and related species. Insects remain infectious for life. The pathogens may be present in host species at very low levels; however, the level can increase under favourable conditions resulting in an outbreak with potential crop losses. Disease management in field crops may include vector control and removal of weeds serving as pathogen and/or vector reservoirs. For vegetatively propagated and woody hosts, clean planting and/or grafting material and good plant hygiene practices are most important.
Pictures
Aster yellows symptoms on oilseed rape:
https://www.canolacouncil.org/wp-content/uploads/2020/10/aster-yellows-pink-leaves-MAFRI.jpg and
https://assets.syngenta.ca/images/pest/125/aster_yellows_ccc_500.png
Aster yellows symptoms in barley:
https://www.plantdiseases.org/sites/default/files/plant_disease/images/0111.jpg
Aster leafhopper:
http://bugguide.net/images/raw/WKKKPKIKAKMKTKAQZS1QT0GQEK4QD0GQ2KKKUKHKT0HKUKHK9KZK6KKKPK6Q6K5QB0UQ30VQDK0K.jpg
Links
Additional news story:
https://www.tribuneindia.com/news/haryana/witches-broom-a-new-threat-to-pea-crop-603541
Source publication:
https://doi.org/10.1094/PDIS-10-23-2035-PDN
Information on _Ca._ P. asteris, diseases and vectors:
https://www.thespruce.com/how-to-identify-aster-yellows-4781045,
https://extension.umn.edu/plant-diseases/aster-yellows,
https://www.canolacouncil.org/download/157/canola-encyclopedia/18524/aster-yellows-final (disease cycle),
https://doi.org/10.1099/ijs.0.02843-0 and
https://doi.org/10.1603/0022-0493-100.5.1504
Aster yellows phytoplasma taxonomy:
https://www.uniprot.org/taxonomy/35779
16SrI phytoplasma group taxonomy and species list via:
http://www.uniprot.org/taxonomy/85620
Phytoplasma resource centre:
https://plantpathology.ba.ars.usda.gov/phytoplasma.html
Taxonomy and information for phytoplasma vectors (with pictures) via:
http://www.psyllids.org/index.htm and
http://www.psyllids.org/psyllidsMorphology.htm
- Mod.DHA]
See Also
2023
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Aster yellows, oilseed rape - Canada: (western) alert 20230614.8710588
2021
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Purple top, potato - Colombia: (NA) 20210929.8698774
2019
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Purple top, potato - Ecuador: emerging disease 20190812.6617432
Phytoplasmas, stone fruit - USA 20190224.6334529
2018
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Elephantiasis, banana - Colombia: phytoplasma 20180314.5687320
2013
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Lethal wilt, oil palm - Colombia: phytoplasma 20131115.2056292
2012
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Phytoplasmas, potato - Romania, Russia (Southern): surveys 20121101.1385861
Light leaf spot & aster yellows, oilseed rape - UK, Canada 20121022.1356899
Aster yellows, wheat & barley - Canada 20120806.1229839
2008
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Aster yellows phytoplasma, grapevine - South Africa: update 20080519.1666
2007
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Aster yellows phytoplasma, canola - Canada: (SK) 20071114.3692
2006
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Aster yellows phytoplasma, chili, pigeon pea - India 20060324.0910
2004
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Aster yellows phytoplasma, grapevine - Tunisia 20040512.1280
Potato purple top disease - USA (WA, OR) 20040415.1041
and additional items on 16SrI phytoplasmas in the archives
Topics
Species
