Apparemment, non, le visa touristique suffit :
voir site :
http://www.wwoofusa.org/Dans les FAQ :
Q10: Will WWOOF help me get a visa or work permit?
A: NO. We CANNOT help you get a Visa, as we have neither the time or the staff, nor the recognition as an institution to do this. You are responsible to make your own visa arrangements. WWOOF is NOT about paid working, and WWOOF organizations CANNOT help you obtain work permits. You should not join WWOOF-USA as a means to getting a visa or work permit. Most people outside the United States come WWOOFing using a holiday or tourist visa. WWOOF-USA cannot assist with visas in any way, including answering questions about visas or providing papers or letters of introduction for visas. Please direct all your questions about visas to the United States Embassy. You can WWOOF here on a holiday or TOURIST VISA.