The biggies I am always fighting are privet, elaeagnus (aka russian olive, and autumn olive), multiflora rose, wild cherry, and wild pear.

The rose and wild pear are the worst to deal with. Here's a pic of a typical wild pear thorn:

[Linked Image]

They go through gloves, boot soles, tractor tires, and steel belted truck tires.

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Boots were made for walking
Winds were blowing change
Boys fall in the jungle
As I Came of Age