Causal Agent: 

Polerovirus (Cucurbit aphid-borne yellows virus or CABYV)

Characteristic Symptoms:
Initial symptoms include leaf wrinkling, downward cupping and mild yellow patches in older leaves.
Eventually, affected leaves become thick and dark green in color with shiny appearance.
Young leaves show interveinal chlorosis and extreme reduction in size.
In severe cases, plants become stunted and may not bear fruit due to the reduction of the number of female flowers produced.
Transmission and Spread:
The virus is spread in a persistent manner by 2 aphid species, Aphis gossypii and Myzus persicae and by grafting.
The virus infects other cucurbits (cucumber, watermelon, pumpkin) and weed species that serve as alternate hosts/virus reservoirs.
The virus is not transmitted by seeds or by mechanical means.
Management and Control:
Use resistant/moderately resistant varieties (e.g. hybrid bittergourd Galactica).
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.
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Ⓡ).
and acephate (e.g. Compete®)

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