A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases <http://www.isid.org>
Date: Wed 28 Sep 2011
Source: Australian Broadcasting Corporation (ABC) Rural [edited] <http://www.abc.net.au/rural/news/content/201109/s3327465.htm>
Fusarium wilt arrives in NT
Watermelon growers in the Northern Territory (NT) are battling a disease that can kill their crops. The Territory had been the only part of Australia without fusarium wilt, but it has recently been found near Katherine and Darwin.
Plant health manager Steven West says while the disease can be managed by changing plant varieties, it's something that growers will have to learn to adapt to.
"Once you've got the disease, it lives in the soil and carries over from crop to crop to crop," he said. "So you can never be free of the disease once your property has become infected."
[Byline: Steven Schubert]
[Fusarium wilt (FW) on watermelon (_Citrullus lanatus_) is caused by the fungus _Fusarium oxysporum_ f. sp. _niveum_ and can cause serious crop losses. Symptoms include discolouration of vascular bundles and wilting of the plant. Plants may be affected at any growth stage:
young seedlings are killed or severely stunted, while older plants wilt at midday for a few days, then permanently wilt and die. Disease development is favoured by high soil temperatures.
The fungus can persist in the soil for many years. Spread occurs mainly with soil, infected crop debris, irrigation water, and human activities (for example on contaminated farm machinery). Disease management requires an integrated approach including crop rotation and phytosanitary measures to avoid spread to new fields. The usefulness of resistant cultivars, if available, may also depend on fungal populations in the soil. Flooding of fields has been reported to reduce pathogen survival in the soil.
Different strains of the fungus affect other cucurbit crops, for example _F. o._ f. sp. _cucumerinum_ affects cucumber (_Cucumis sativus_), and f. sp. _melonis_ affects rockmelon and muskmelon (both _Cucumis melo_). Each pathogen is highly specialised attacking only a single crop species.
<http://www.ga.gov.au/image_cache/GA4073.jpg> and <http://healthmap.org/r/1i3t> Northern Territory:
Fusarium wilt on watermelon plants:
<http://www.ars.usda.gov/is/pr/2006/060814.fusarium-i.jpg>, and <http://ohioline.osu.edu/hyg-fact/3000/images/3113_2.jpg>
FW affected melon vines:
FW in rockmelon field:
Information on fusarium wilt of melons:
<http://www.avrdc.org/LC/cucurbits/fusarium.html>, and <http://vegetablemdonline.ppath.cornell.edu/factsheets/Cucurbits_Fusarium.htm>
_F. oxysporum_ f. sp. _niveum_ taxonomy:
Yellow vine decline & fusarium wilt, watermelon - USA 20100615.2003
Fusarium oxysporum, melon - Mexico (Colima) 20041220.3357
Fusarium wilt, cucumber - Spain (Almerma) 20021109.5759 2000
Melon root rot - USA (California): EPPO report 20001228.2290]