Q: We harvested many sweet potatoes from our garden recently. A few were deformed and very large. What causes the deformity? Most of the potatoes were shaped nicely. Even though they were odd looking they still were good eating.
A: Looks like sweet potato wireworms have had a good meal in your garden. The wireworm is the larval form of the click beetle, which I used to turn upside down when I was kid, just to watch it vigorously “click” into an upright position.
No insecticides are labeled for use against wireworms in a garden. Trap wireworms in pieces of potato scattered around the garden, rotate crops and plow or cultivate infested soil in late summer or in autumn to kill or expose various insect stages to predators. Cultivation in the spring, well in advance of planting can help reduce wireworm populations.
Consider releasing insect-killing nematodes in your potato rows. Scroll to the bottom of the following publication for more information.
The sweet potato varieties ‘Jewel’, ‘Nugget’ and ‘All Gold’ possess some wireworm resistance, while ‘Resisto’ and ‘Regal’ have even more. ‘Beauregard’, ‘Pope’, ‘Hernandez’, and ‘Cordner’ have low resistance or none.