Answer: Heat is not the problem at this time of the year. It sounds like a root or crown infecting fungus has attacked your plants. Dig up a plant in the early stages of decline and look for brown roots or lesions at the base of the stem. Other possible causes are bacterial diseases on the leaves.
Either way, it would be best not to water so often as it can aggravate the problem and promote spread of the disease. Your next planting will probably do better in the warmer soil conditions.
Pole beans like 'Kentucky Wonder' take a little too long to reach harvest to perform well for you in Austin. Look for pole or bush varieties closer to the 50 days-to-harvest range. While we think of the south as having a long growing season, for many veggies we have two short seasons (spring and fall) separated by the scorching heat of summer when some plants will not set fruit.
Q&A Library Searching Tips