Peas with yellow on the bottoms of the vines?

Question:Our peas have yellowed on the bottom of the vines including the leaves in those areas. Now the leaves are dying and getting crackled. The rest of the plant, the tops are nice and green and producing fat peapods. We thought it was from overwatering, so we laid off for a while, but my boyfriend swears the yellowing is moving up the plant. So now he thinks it means not enough water. Any ideas please to what is going on with it and how to help it?

Answers:
It could also be the natural cycle of the plant. Once the weather turns hot or the plant succeeds in producing some mature pods, the plant starts to yellow and die. Keep the pods picked as they mature, and don't expect the plants to live much longer since they're short-lived anyway. If you think that they didn't produce a full season's worth of peas, you might try planting earlier next year so that the plants have a chance to make pods before hot weather hits.

http://www.yardener.com/problemswithpeas...

It has a list of symptoms, probable cause and Control
-Yellowing is listed as caused by different things, there are better descriptions to help with which meets your needs-

Hope this helps.