A ProMED-mail post <http://www.promedmail.org>
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Date: Tue 28 Apr 2015
Source: IPM in the South, Southeast Farm Press report [edited] <http://ipmsouth.com/2015/04/28/gummy-stem-blight-confirmed-in-watermelon-in-north-florida/>
Gummy stem blight in watermelon in North Florida
Gummy stem blight is currently confirmed in multiple locations in northwest and northeast Florida. Recent high humidity and high temperatures have been ideal for gummy stem blight throughout the northern part of the state. It is a highly destructive foliar fungal disease of watermelon and can cause yield losses of more than 50 percent.
For disease management, it is critical to use clean transplants, followed by use of protective and systemic fungicides in rotation, depending upon existing weather conditions, and stage of the crop.
Based on research trials conducted in Florida and other southeastern states, the 2015 UF [University of Florida] Watermelon Spray Guide [<http://nwdistrict.ifas.ufl.edu/phag/files/2015/04/UF-Watermelon-Spray-Guide-2014-15.pdf>] provides potential options.
[Byline: Mathews Paret, University of Florida]
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Communicated by: ProMED-mail <promed@promedmail.org>
[Gummy stem blight (GSB) of cucurbits is caused by the fungus _Didymella bryoniae_ and is the most common leaf disease of watermelon. Symptoms include lesions on leaves and stems of seedlings.
The seedling may be girdled by the lesions and collapse, or be so weakened by the infection that it is never productive. Gummy stem blight requires prolonged moisture to become established and consequently is a serious problem in regions of high rainfall and glasshouse crops. The fungus also causes black rot if it infects the fruits.
Spores may be seed borne or spread by air currents, water from rain or irrigation systems, or mechanical means (including insect and human activities). The fungus can survive between growing seasons in an over-wintering structure, and wild cucurbits or volunteer crop hosts may serve as pathogen reservoirs. Disease management includes fungicides and use of certified GSB-free seed or transplants.
Maps
USA:
<http://www.mapsofworld.com/usa/usa-state-and-capital-map.html> and <http://healthmap.org/promed/p/212>
Florida:
<http://www.mapsofworld.com/usa/states/florida/>
Pictures
GSB symptoms on cucurbit leaf:
<http://www.omafra.gov.on.ca/english/crops/facts/09-051wf6.jpg> and <http://www.agf.gov.bc.ca/cropprot/images/gummysb2.jpg>
GSB on cucurbit transplants:
<http://agdev.anr.udel.edu/weeklycropupdate/wp-content/uploads/2008/05/gummystem-300x253.jpg>
and
<http://www.forestryimages.org/images/192x128/1234191.jpg>
GSB on cucurbits, photo gallery:
<http://vegetablemdonline.ppath.cornell.edu/Images/Cucurbits/GummyStem/GummySB_Collage.jpg>
Links
Gummy stem blight information:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Cucurbit_GSBlight.htm>,
<http://ohioline.osu.edu/hyg-fact/3000/3126.html>, and <http://www.ces.purdue.edu/extmedia/BP/BP-142-W.pdf>
_D. bryoniae_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=224305>
- Mod.DHA]
[See Also:
2012
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Gummy stem blight, watermelon - Trinidad & Tobago: (MR)
20121008.1329578
2009
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Gummy stem blight, watermelon - USA: new strains 20090521.1899
2007
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Downy mildew, cucurbits - USA (02): clarification 20071109.3633 Downy mildew, cucurbits - USA: (SC), new strain 20071023.3448]
Topics
Species
