Beginner Gardening: my squash plants are all turning yellow and dieing , 1 by rubyw

rubyw wrote:
Last week I finally pulled up a zucchini plant that a few days before had begun turning a pretty uniform yellow all over the leaves. These plants have produced a bit already and this being our first go at vegetable gardening we are wondering what might be going on with them. Earlier my husband went to check the garden and has come back in saying that whatever happened to the plant last week has now started happening to some of the other plants. He is going to try and take a picture for me to post here and we are hoping that someone will have some ideas as to what might be occurring and how we will go about correcting it.

I should add that we are having a hotter summer in Central Virginia than anyone can remember at this time of year. The plants are being hand watered and we don't believe that they are either over or under watered. They are receiving a half gallon of water every other day and at least one good drink from a water hose recently. They also have cardboard and straw at their base.

Thanks in advance for any and all advice.

Ruby