Cucumbers and melons don't cross.......only Armenian cukes [really a melon] might.

The biggesr danger might be cucuber beetles congregating in one spot or diseases like mildew spreading to each other near naturity time.

Apparently it's rare that melons and cukes cross-pollinate though it occasionally happens, despite many claims that they don't.

One thing you could do to get pure seeds of an OP melon or cuke is hand-pollinate them and then bag them to prevent further pollination by busy bees or whatever else wants to roam in your garden. Don't worry about trying to figure out how far apart to separate them! Let the bagged ones mature and develop seeds and eat the rest! Even if the rest were cross-pollinated, it would affect only the seeds, not the fruit form or taste, and you wouldn't care about that since you'd have the pure seeds you wanted.

Here is a link that might be useful: Banana Melon-cross pollinate with cucumber?

I have always hear that the crossing of melons only shows up when planting the seeds from the crossed fruit. In the link below, in the "Troubleshooting" section, the Bonnie people say that a watermelon and a cucumber can not only cross, but the fruit produced by the original cross will taste bitter. From what I have read on this forum an from other sources, I find that difficult to believe. What's fact and what's fiction?

Here is a link that might be useful: Bonnie Watermelon Growing Tips

Sorry but I read the whole article and don't see your referenced statement. Here is a copy of the entire torubleshooting section. Is it perhaps located somewhere else or in another article you read?

Troubleshooting

Watermelons are in the same plant family as squash and cucumbers, but they do not cross-pollinate successfully. Your garden will depend on bees to pollinate the flowers, so cool cloudy weather in the spring will slow down thier development. Be patient until the weather warms.

Fungal diseases can multiple rapidly on melon leaves. Alternaria leaf spot, anthracnose, and gummy stem blight produce spots on leaves, while stem blight also forms bleached or tan sections on stems and rot on fruit. Downy mildew causes yellow or pale green leaf spots, while powdery mildew produces white spots on leaves. Treat fungal diseases with fungicides. Check with your local garden center or Extension service to learn which fungicides are approved in your state for the disease youÂre fighting.

Melon aphids can quickly colonize a vine, so inspect leaf undersides daily. If you spot aphids, treat them with insecticidal soap.

Spotted and striped cucumber beetles can attack vines, transmitting bacterial wilt disease, which causes vines to collapse. Infected vines donÂt recover. Treat adult beetles with rotenone or a pyrethrum-based insecticide; apply at dusk to avoid harming honey bees.

In fact it specifically says, "Watermelons are in the same plant family as squash and cucumbers, but they do not cross-pollinate successfully."

Dave

Bonnie must have corrected the article after I posted the question. I even clicked on the link after I posted it to make sure it worked and the sentence was there. So I guess that answers my question and they were indeed wrong. Thanks!

I grew up on farm and was always told that squash or watermelon or Cantaloupes would cross with cucumbers. Don't remember now if it was seed or fruit they talked about. I do remember my dad complaining about the seed he saved wasn't as good as original. He blamed it on Hybrid.
I have planted cucumbers and squash and watermelons close, 'within 10 foot' and they crossed, Fruit was uneatable. Squash and mellon tasted a little like cucumbers.
This was original seed NOT saved seed., James