Controlling curly top - how far?

Curly top virus took my 15 tomato plants. There are weeds in the neighborhood that look like mustard weed, which provides winter home for the leaf cutter insects that spread the virus to tomatoes in the spring. How far from the tomatoes do I have to control the weeds in order to prevent contagion next year? Should I keep the weeds killed all year? Roundup? I'm in Southern New Mexico.
Thanks.... Sarah

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