Here is a photo of the watermelon - its definately got powdery mildew and I've started treating it with a milk solution, but it also looks obviously yellow and I'm not sure why.
The pumpkin has well and truly kicked and has two tendrils of about 2-3 metres long each.
Here is a good photo to show how out of control the zucchini plants have become- they've grown down the side of the mound, across the ditch and are taking over the lawn