Surmount, Tordon 22k, or MezaVue. Those are the chemicals to use if you are strictly targeting pear. Follow label and then wait. MezaVue has quickest kill time, but all three chemicals work great.
If you have cows, burn (carefully with water on standby!) the needles off and let the cows eat em. No grass left so it'd be a treat! Then spray em when we have grass again.
Get a grubbing hoe, dig them up by the roots, drag and stack them on top of each other so the ones on the bottom get no sun. They will die. Then the small ones will keep coming up, so you will need to repeat. Not fun, but it's free exercise. Avoid heat stroke and wear good leather gloves and boots. You can always hire someone certified to spray. Talk to your county extension agent.
Unfortunately, this is probably best option and definitely your cheapest.
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