What form of electricity killed the wheat and other crops in the dust bowl?

Answer: Static electricity.

The Dust Bowl was a period of severe drought and dust storms that damaged the ecology and economy of the American prairies during the 1930s. Because of insufficient knowledge of the ecology of the plans, farmers had conducted extensive plowing of the soil, and displaced the native grasses that normally trapped soil and moisture. The Dust Bowl forced tens of thousands of families to abandon their farms and relocate to other states, which were at the same time affected by the Great Depression.

Another effect of this dust was that it contributed to the creation of static electricity. So much built up between the ground and airborne dust that blue flames leapt from barbed wire fences. Static electricity could also short out engines and car radios.