The Beans that Killed my Summer Garden

The pretty color of the Rattlesnake Pole Bean

For years I have been looking for a Phaseolus vulgaris pole bean variety that does well in our summer environment. Many other bean varieties do incredibly well in the Tucson Heat, such as the Chinese Long Bean (Vigna unguiculata subsp. sesquipedalis) the Tepary bean (Phaseolus acutifolius) and the Purple Hyacinth Bean (Dolichos lablab L.). Unfortunately, the Chinese Long Bean and Purple Hyacinth bean take a lot of effort to prepare while the Tepary bean is a natural carrier of bean mosaic virus - a disease I do not need to expose my garden to. The Phaseolus vulgaris or common bean tastes good for my family no matter how we prepare it (baking, boiling, stir-frying, steaming, eating raw).

Rattlesnake Bean Flowers

Having heard that Rattlesnake pole bean grows quite well in Tucson and knowing it to be a a Phaseolus vulgaris variety I obtained this variety from a local seed source this last winter.

Rattlesnake Pole Beans are quite productive

Top left leaves showing the first Signs of Diseased Bean Leaves

Without considering the potential consequences of planting a “native grown” variety in my garden, I planted out all the seeds in the packet. The purpose of a pole bean variety in my garden is to provide west-side shade for my tomato plants. This requires that the beans that I plant be completely disease-free, as any disease such as mosaic or leaf curl can spread like wildfire among some of the most virulent tomato plants. Out of the 50 plants Rattlesnake bean plants that popped up about 5-8 had leaves that looked wrinkled and deformed. These were immediately pulled from the garden and discarded. As the remainder of the plants grew, I noticed that many of the lower leaves died off. Though the premature leaf death of lower leaves is very similar to the Tepary bean the yellow leaves with brownish-gray spots was not.

Rattlesnake Beans Spreading Blight to Tomato leaves

Rattlesnake Beans (dead leaves) next to dying tomato leaves

Another look at the Rattlesnake Pole Beans next to Tomatoes

By the time I noticed the yellowing leaves and brownish-gray spots on my tomato plants it was too late. A bacterial blight spread like wildfire directly from the Rattlesnake beans to my Tomatoes and Purple Burgandy Bush Beans (also Phaseolus vulgaris) then to my cucumber-melons. Normally, it can be difficult to trace the direct cause of a garden disease. However, in this case there was a direct correlation between where these beans were growing and where the disease spread to other plants. Every day I went outside to pull branches, leaves, and plants from my garden. 

The characteristic circles and yellowing associated with Tomato Blight

Leaves of Tomato Plant experiencing Blight

Tomato Blight leaf remains exhibit wilted yellow/grayish leaves

When the disease finally began to spread to my sweet potatoes I knew that this was truly a bacterial blight and that the only plants I had a chance of saving were my sweet potatoes and Sunchokes. 

Blight effecting Sweet Potato Leaves

Once I was certain I had ascertained the problem I spent the entire next week measuring my progress not by how fast my garden plants grew, but by how fast I could tear my garden out.

After pulling Blighted Leaves

Ripening Tomatoes Under Shade cloth before pulling out the stems.