Are wax beans yellow when they start growing or are they green and then when they get big turn yellow?
They turn yellow on the wine, they will have a slight greenish cast to the pod, which is normal.
I just purchased 40 pounds of yellow beans from our local organic farmer. My mistake: I should have looked at them before getting home. All of them have rust spots. What happens if you can them with rust spots?
The rust will not hurt you. It causes discoloration to the beans, but is not harmful to people. If you can them, the high heat will kill the rust fungus anyway, but they will still have spots.
Leaves on runner beans going yellow. Is this too much watering? If so, how often should they be watered?
It could be either but likely they are underwatered. They need 5-10cm of water a week. I recommend longer, less frequent periods of watering when watering. This will get the water in deeper into the ground. For additional causes of yellowing leaves, this article will help: https://www.gardeningknowhow.com/edible/vegetables/beans/yellow-leaves-on-beans.htm