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Date: 10 November 2008
Source: Plant Management Network [edited] <http://www.plantmanagementnetwork.org/pub/php/news/2008/YellowVine/>

Producers can add yellow vine to the long list of pumpkin diseases

This year [2008], amid a drought and more common disease issues, some pumpkin producers experienced the impact of a relatively new foe.
Celeste Welty, an Ohio State University Extension entomologist, said that some of Ohio's pumpkin crop fell victim to yellow vine, a disease of cucurbits thought to be spread by the squash bug.

Yellow vine disease has been in Ohio since 2003, but only sporadically. This year [2008], however, was more severe. "Ohio State specialists believe this may be the worst year yet for yellow vine,"
said Welty. "Because of the nature of how it's spread and the damage it does to the crops, there's concern that this has the potential to be a serious disease."

Welty collected samples of pumpkin and squash plants at Waterman Farm that exhibited symptoms of yellow vine. Half of the samples turned up positive for the disease. "Diagnosing the disease is tricky because the yellowing is similar to other diseases and symptoms don't show up until about 28 days after infection," said Welty. "The key to managing the disease is controlling the squash bug."

Ohio is one of the nation's top pumpkin-producing states, accounting for 18 percent of the country's supply in 2007 valued at over USD 33 million.

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[Cucurbit yellow vine decline (CYVD) is caused by the phloem-limited bacterium _Serratia marcescens_. It has been reported to severely reduce yield in a range of cucurbits such as pumpkin, melons, and squash, but it does not appear to affect cucumber. Symptoms include yellowing and wilting of leaves and vines, discolouration of phloem in lower crown and primary roots, failure to produce fruit, and plants may collapse and die. The disease is transmitted by squash bugs (insects of family _Coreidae_ with _Anasa tristis_ a common species in North America). Squash bugs overwinter as adults. The bacterium survives within the vector, which spreads it to the new season's crop. Disease management relies on vector control by crop rotation, biological, and chemical means. Some genetic resistance in triploid seedless watermelon has been identified.

_S. marcescens_ is a cosmopolitan microbe with different strains living in a range of environments including water and soil. Some strains are non-pathogenic saprophytes while others may affect vertebrates (including humans) or insects. In plants, some strains are growth promoting rhizobacteria or potential agricultural biocontrol agents with anti-fungal properties. The strains involved in CYVD have been shown to differ significantly from strains isolated from other ecological niches.

Maps
USA:
<http://www.mapsofworld.com/usa/usa-road-map-enlarge-view.html>  and
<http://healthmap.org/promed?v=40,-97.6,4>
US states:
<http://www.census.gov/geo/www/us_regdiv.pdf>

Pictures
CYVD symptoms on cucurbits:
<http://www.apsnet.org/education/introplantpath/pathogengroups/fastidious/images/fig13_sm.jpg>,
<http://plantpathology.tamu.edu/texlabn/vegetables/Watermelon/images/wmd79s.jpg>,
<http://www.hort.uconn.edu/ipm/veg/pics/cyvd1lg.jpg>  (leaf), <http://vegetablemdonline.ppath.cornell.edu/Images/Pumpkin_Insect_News/Fig10.jpg>
(vine),
<http://plantpathology.tamu.edu/texlabn/vegetables/Watermelon/p05.htm>  (phloem) Squash bugs:
<http://mdvegetables.umd.edu/images/Squash%20bug.JPG>,
<http://www.vegedge.umn.edu/mnvegnew/IMG/Lsbleaf.jpg>  (adults and nymphs)

Links:
Ohio State University news release:
<http://extension.osu.edu/~news/story.php?id=4886>
CYVD information:
<http://www.hort.uconn.edu/ipm/veg/htms/cucrbinct.htm>,
<http://cat.inist.fr/?aModele=afficheN&cpsidt=15006513>,
<http://www.lane-ag.org/mpm/current%20updates/archive/SBcontrol/s%20bug%20web%208%2003.htm>
and
<http://plantpathology.tamu.edu/texlabn/vegetables/Watermelon/wmelon.htm>
Information on _S. marcescens_ CYVD strains:
<http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1317323>
_S. marcescens_ taxonomy:
<http://www.bacterio.cict.fr/s/serratia.html>
Information on squash bugs:
<http://www.urbanext.uiuc.edu/bugreview/squashbug.html>,
<http://www.vegedge.umn.edu/vegpest/cucs/squabug.htm>  and <http://creatures.ifas.ufl.edu/veg/leaf/squash_bug.htm>.  - Mod.DHA]