Answer: Rutabagas are subject to the same insect pests as plants in the cabbage family, which can include aphids and loopers. Without seeing the problem first hand, I can only suggest that a new colony of aphids and a new generation of caterpillars found the leaves of your rutabagas. If you find similar problems on your next crop of rutabagas, try hosing the pests off the leaves. If they return, wash them off again. Since you're really only interested in eating the roots, some insect damage on the leaves won't harm the crop.
Better luck with your next crop!
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