Dave makes a good point. If the squash tastes good or if you just want to grow it for decorative purposes and you want to save the seeds from it, then you need to take special precautions to prevent more cross pollination from happening. And by that I mean you have to hand pollinate them. Take a male flower from the plant you want to save seeds from and pollinate a female flower from the same plant with it. You have to be sure that the female flower wasn't already pollinated and after you do the pollinating you need to tie the blossom closed to prevent it from being pollinated with other pollen. Be sure to mark the squash in some way (like loosely tying a piece of string around the stem so as not to girdle it) so that you know which ones are pure. Even after doing this, it could take years to stabilize the traits that you want. The pumpkins I mentioned in my previous comment are the only type of squash I grow which means I don't have to worry about cross pollination. So the thought of even more crosses happening didn't cross my mind (pun intended). And a melon and squash can't cross. Rodney

There are several different varieties of so-called "wild cucumbers" and they look different. But without it going to the blooming stage I don't know that you can tell for sure. Volunteers from previous crops, mulches, and compost are sure possibilities but I'd suspect "bird transport" from the patch behind the house and just pull it. Use the space for something that is a sure thing. Dave

Heliopsis are typically 30-60 inches tall, sometimes shorter. They are supposed to have 10-18 ray florets, but I've seen them with as few as 5. What I can see of the phyllaries and leaves looks more like Heliopsis than Helianthus. Also, Heliopsis ray flowers have a style and stigma, while Helianthus rays lack both. I'm pretty sure that your flower is a Heliopsis.

That link was great, thanks! That looks exactly like what I'm seeing. Any idea if you can scrape back to healthy wood using a sharp sterilized pruning knife with this form of canker to save trunks/large branches? I wonder if this is more of a younger tree issue. One thing about this region is that there are old, abandoned apple trees everywhere around here. I've gone up and inspected some of these over the years. They haven't had any human intervention in possibly decades, yet continue to produce abundantly and never seem to have any major physiological issues, if any. Makes you think.