Watermelon, pumpkin & Zuchini

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

Watermelon-paused

The watermelon seems to have paused- this is the biggest fruit but its been this size for at least three weeks and just not growing- its about 20cm long x 4 cm wide. I've watered heavily for a week as its been very dry here but to no avail.

There are also many smaller fruits on the vines but nothing is growing.

Hints?