The Royals were, for the most part, clinical in front of goal as Hal Robson-Kanu opened the scoring before Harte and Long stole the show to seal a deserved win, despite Leroy Lita netting a brace of his own in two rare Boro attacks.
Robson-Kanu opened the scoring from Jimmy Kebe's cross and although Lita pegged his former side back, Harte netted his first of the afternoon with a sublime free-kick shortly before half-time.
The full-back received a slice of luck for his second goal when another free-kick went across the face of goal and into the net.
Harte then set up Long with a pin-point cross to leave the striker with the simplest of finishes before the 24-year-old sealed victory after bursting through on goal and sliding home.
Lita pulled one back from the penalty spot after Matt Mills fouled the striker in the area but it proved mere consolation.
Source: PA
Source: PA