Why have some of my spinach leaves over the weekend turned yellow?

Question:I have about 40 spinach plants in my garden and over the weekend about 10 of them have turned from green leaves to yellow leaves. We have not had any adverse weather and the temps have been in the mid-60's. Are they lacking fertilizer or is the soil PH too high?

Answers:
They may have had too much water. Plants often turn yellow when that is the case.