I’m in Toronto, good soil, sunny spot. A melon seed from composter soil sprouted and I have a long vine with many flowers and one pale green/dark green stripes, oval fruit, which is about 6″ long. The vine has now wilted and I suspect there are many causes. I just want to know if that one melon will still be edible and how long I should leave it attached to the vine.
It’s always interesting to find a surprise plant growing in the garden that will provide something edible. Free food, how good is that? Unfortunately, these plants can be the victims of disease, pests and fungus just like those that we intentionally plant. In the case of your melon, it is most likely that the vine has been attacked by squash vine borer (Melitta curcurbitae). It is a common clearwing moth found in home gardens and will attack melons, cucumbers, squash and pumpkins.
The wasp-like moth lays eggs at ground level and the larvae find their way into the chosen vine plant. The larvae eat their way through the vine which causes wilt as the stem is unable to pass water from the roots towards the new growth. If your melon fruit is closer to the beginning of the plant, and the wilt has occurred beyond it on the newer growth, then it still can receive water. If the fruit is is past the wilted section, then water won’t reach it and it will be stunted. Picking before ripeness will not enhance the fruit. It, like all melons, needs water and sun to enhance the sugar content of the fruit.
For further information: https://www.extension.umn.edu/garden/insects/find/squash-vine-borers/