A thermal weed control device is fed with solid fuel and comprises a reactor means (3) provided with an inner cavity and with an outlet mouth means (5) connecting said inner cavity to outside. The reactor means (3) is provided with a closure means (7) assigned to close the end of the inner cavity opposed to the outlet mouth means (5). At least in a first operative condition of the device (1), said outlet mouth means (5) is positioned lower than said closure means (7). The reactor means (3) is further provided with a pierced grid means (9) dividing the inner cavity in a first chamber means (11) limited between the closure means (7) and the grid means (9) and a second chamber means (13) limited between the grid means (9) and the outlet mouth means (5). The device (1) is provided with first air blower means (15) flowing into the portion of the first chamber means (11) adjacent or close to the closure means (7) and with second air blower means (17) flowing into the second chamber means (13). In said first operative condition the first chamber means (11) contains at least some unburned solid fuel (P), the air blower means first (15) and second (17) adduct respectively primary and secondary air flows having corresponding deliveries, where the primary flow keeps a partial combustion of at least a portion (B) of the solid fuel (P) into the first chamber means (11) and the secondary flow supports the combustion into the second chamber means (13) of the gases produced by said partial combustion of a portion of the solid fuel (P). Said primary and secondary flows adducted by the air blower means first (15) and second (17) keep the pressure inside the inner cavity of the reactor means (3) at a value higher than the value of the external environmental atmospheric pressure and the flow of the gases exiting the outlet mouth means (5) at least in the first operative condition is at least partially downward oriented.
