...evidently an early work:
http://www.amazon.co.uk/Musikwissenschaftlicher-Verlag-Wolf-Violin-Concerto/dp/B00I2X12E0/ref=sr_1_12?ie=UTF8&qid=1393789135&sr=8-12&keywords=hugo+wolf (http://www.amazon.co.uk/Musikwissenschaftlicher-Verlag-Wolf-Violin-Concerto/dp/B00I2X12E0/ref=sr_1_12?ie=UTF8&qid=1393789135&sr=8-12&keywords=hugo+wolf)
After finally convincing his father that he had to become a composer, that it was his very reason for being, Wolf enrolled at the Vienna Conservatory in 1875. He lasted there almost two full years before being expelled for his insubordination (he considered all his teachers to be incompetent and freely said so), neglect of his studies, and radicalism. By this time he had become a social, political and musical radical and had also managed to contract the syphilis which would later wreck his health and mind, leading to his death. He had already composed a violin concerto and had begun writing piano pieces, songs, and choruses, all with only rudimentary musical training.(emphasis added)
http://www.teachmeaboutmusic.com/tonskald/166-hugo-wolf-1860-1903 (http://www.teachmeaboutmusic.com/tonskald/166-hugo-wolf-1860-1903)
Never orchestrated, maybe? Odd that the piano is listed first.
David
" Aus dem Jahre 1877: Konzert für Klavier und Violine (Unvollendet.) " (from Haberlandt, 1903, "Hugo Wolf: Erinnerungen und Gedanken".) (hugowolf.at dates it to 1875, giving (the completion?) Op.6 and placing it in their edition's volume 15 (kammermusik).)
Thanks, Eric. Very early, then.