Causal Agent: 

Potyvirus (Zucchini yellow mosaic virus) or ZYMV

Characteristic Symptoms:
 
Symptoms may resemble those caused by PRSV-W, depending on the strain involved.
   
Leaves of affected plants show yellow mosaic (dark green bubbles on the leaf contrast with the lighter green of the rest of the leaves), severe malformation, blisters, serration and extreme reduction in the size of leaf lamina.
   
Transmission and Spread:
 
The virus is spread in a non-persistent manner by a number of aphid species, including Myzus persicae.
   
The virus is also easily transmitted mechanically through contaminated tools/implements.
   
There is circumstantial evidence of seed transmission but it has been very difficult to prove.
   
The virus was found to infect wild cucurbits, which may be important reservoirs.
   
Management and Control:
 
Use resistant varieties, if available.
   
Use virus-free seedlings.
   
Remove infected plants as early as virus symptoms are observed to prevent/minimize spread of the virus by aphids.
   
Remove weeds that serve as alternate hosts/virus reservoirs.
   
Disinfect tools, farm implements with chlorine solution before moving from diseased areas to healthy areas.
   
Control/minimize aphid population by using plastic mulch, yellow sticky traps and/or use of insecticides such as azadirachtin (neem), cartap hydrochloride (e.g.  PadanⓇ, Barena 50 SP, Gemtrak®), acetamiprid (e.g. MospilanⓇ), acephate (e.g. AcetamⓇ, CompeteⓇ), chlorphenapyr (e.g. Kotetsu) or penthoate (e.g. PennantⓇ, VidexⓇ).
   
References:
Compendium of Cucurbit Diseases (1996) by the American Phytopathological Society
   

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