ProMED-mail

ProMED-mail



BLUEBERRY RUST - NEW ZEALAND
****************************
A ProMED-mail post
http://www.promedmail.org
ProMED-mail is a program of the
International Society for Infectious Diseases
http://www.isid.org

Date: November 2019
Source: European Plant Protection Organisation (EPPO) Reporting Service 11/2019/223 [edited]
https://gd.eppo.int/reporting/article-6653


In New Zealand, the causal agent of rust on blueberries was determined by molecular and morphological analyses as _Pucciniastrum minimum_ (_Thekopsora minima_ - EPPO A2 List) rather than _Naohidemyces vacciniorum_ as 1st reported in 2004.

[Original publication: https://link.springer.com/article/10.1007%2Fs13314-019-0358-1]

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[Blueberry (leaf) rust can be caused by the fungus _Thekopsora minima_ or _Naohidemyces vaccinii_, depending on the region; a 3rd species _N. fujisanensis_ is restricted to Japan. The disease affects a range of plants in the _Ericaceae_ family, including _Vaccinium_ species with crops like blueberry, bilberry and cranberry, as well as ornamentals such as rhododendrons and heathers. Symptoms may include yellow leaf spots on the upper surfaces of young leaves, followed by orange pustules developing on leaf undersides that release the spores. In severe cases or on highly susceptible cultivars, leaves turn brown and drop prematurely, resulting in serious defoliation and potentially death of the plant.

Rust spores are spread by wind over long distances and by splashing rain and mechanical means locally. Infected plant material, including fruit and budwood, poses a high risk of spreading the disease. The rusts can overwinter on evergreen blueberry leaves or alternative hosts in milder climates. Commercial highbush varieties are most susceptible. Disease management for rusts is extremely difficult and relies mainly on timely fungicide applications, choice of crop cultivars, phytosanitation and control of pathogen reservoirs. Crop monitoring for early discovery of infection is important so action can be taken to limit the spread of the pathogens as well as build-up of inoculum.

_T. minima_ is also the cause of blueberry rust in Australia (ProMED-mail posts 20150105.3072963 & 20160817.4421210). Movement of fungal spores across the Tasman Sea between NZ and Australia is known to occur, but the incursions in both countries may also be due to separate introductions from outside the region.

Maps
New Zealand:
https://www.fotolip.com/wp-content/uploads/2016/05/New-Zealand-Map-1.jpg

Pictures
Rust symptoms on blueberry:
http://dpipwe.tas.gov.au/ContentImages/BlueberryRust_lg.jpg,
http://agriculture.vic.gov.au/__data/assets/image/0010/277543/Brust-lower69_web.jpg,
https://ohioline.osu.edu/sites/ohioline/files/imce/Plant_Pathology/PLPATH-FRU-43-blueberry-leaf-rust-symptoms.jpg,
https://www.agric.wa.gov.au/sites/gateway/files/styles/page_featured_image/public/DSC05751_0.JPG?itok=CGP4Dw6f&c=88adb430f8f7178c5bda0df7785d1461 (on fruit) and
https://nnimgt-a.akamaihd.net/transform/v1/crop/frm/silverstone-agfeed/2098012.jpg/r0_76_1500_924_w1200_h678_fmax.jpg (affected plant)

Links
Information on blueberry leaf rusts:
https://gd.eppo.int/taxon/THEKMI (with pictures),
https://pflanzengesundheit.julius-kuehn.de/dokumente/upload/1cc99_thekopsora-minima_expra_en.pdf,
http://dpipwe.tas.gov.au/Documents/BT_BlueberryRust_factsheet092014.pdf,
https://www.agric.wa.gov.au/plant-biosecurity/blueberry-rust-declared-pest,
http://msue.anr.msu.edu/news/be_on_the_lookout_for_leaf_rust_in_michigan_blueberry_fields and
http://www.ctahr.hawaii.edu/oc/freepubs/pdf/PD-51.pdf
_T. minima_ life cycle:
https://ohioline.osu.edu/sites/ohioline/files/imce/Plant_Pathology/PLPATH-FRU-43-blueberry-leaf-rust-disease-cycle.jpg
_T. minima_ taxonomy and synonyms:
http://www.indexfungorum.org/names/NamesRecord.asp?RecordID=546834 and
http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=546834
Other fungal taxonomy via:
http://www.indexfungorum.org/names/Names.asp
EPPO A2 quarantine list:
http://www.eppo.org/QUARANTINE/listA2.htm
- Mod.DHA]

See Also

Blueberry rust - Brazil: 1st rep (RS) 20190720.6578737
2017
----
Blueberry rust - China: 1st rep. (SC) 20170706.5154494
2016
---
Blueberry rust - Australia: (TS) 20160817.4421210
2015
---
Blueberry rust - Australia: (TS) 20150105.3072963
.................................................dha/msp/dk