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Viruses
Host plants:
Zucchini/Courgette 
Cucurbits
Cucurbitaceae is a plant family commonly known as melons, gourds or cucurbits and includes crops like cucumbers, squashes (including pumpkins), luffas, melons and watermelons. The family is predominantly distributed around the tropics, where those with edible fruits were amongst the earliest cultivated plants in both the Old and New Worlds.
Necrosis
Necrosis is the death of some or all of the cells in an organ or tissue, caused by disease, physical or chemical injury.