This looks like a pretty good source, so maybe I can also find a reference of Muhammad refusing food to one of the other Jewish tribes he laid siege to - I believe it was the Banu Qaynuqa tribe if memory serves.
Bombardment of al Ta'if by Catapult
The Muslims encamped and waited for new orders. Some tribesmen spoke to the Prophet in favor of a prolonged siege, claiming that nothing the Muslims had would help them scale Ta'if's fortifications. Time alone, they argued, would eventually force Ta'if's people out of their safe foxholes. Muhammad, however, found it difficult to return without having achieved a victory over Ta'if. Banu Daws, one of the tribes living to the south of Makkah, were fully acquainted with the use of the catapult and had experience in tank-led assaults upon high fortifications. A1Tufayl, one of its leaders, who had accompanied Muhammad ever since the conquest of Khaybar, stood at the Prophet's side always on the ready to fulfill his wishes. At Muhammad's command, al Tufayl speeded to his tribe with a request for their assistance, and they responded by bringing with them their tools of war. Reaching al Ta'if four days after the Muslim siege began, they put their catapult to immediate use. They also brought their tanks into the battlefield, and sent a number of their men under their cover to the fortified walls. The soldiers of Ta'if, however, were clever enough to force the men of Banu Daws to flee. Having heated pieces of iron to red hot temperatures, they threw these missiles onto the tanks and put them to flame. The Muslim soldiers which the tanks were covering had to flee or be burnt alive. As they emerged from under their tanks, they were shot at with arrows and a number of them were killed. Having failed at this new effort, the Muslims became convinced that there was no way to storm the fortresses of Ta'if.
Destruction of al Ta'if's Orchards
What was left for them to do? Muhammad pondered this question for a long while. Suddenly, the thought occurred to him that he had achieved victory over Banu al Nadir and forced their evacuation simply by destroying their orchards. The vineyards of Ta'if were far more important than the orchards of Banu al Nadir and were known throughout Arabia for their produce. It was due to them that the city of al Ta'if acquired the reputation of being a little paradise in the desert. Without further ado, Muhammad gave the order, and the Muslims began systematically to cut down and burn the orchards. Upon discovering this destruction and realizing that Muhammad really meant to spare none of their vineyards, the Ta'if tribesmen sent to him pleading that they would rather give away their vineyards to Muhammad, or to those citizens of al Ta'if-and there were large numbers of them who were bound to Muhammad in blood relationships. Muhammad stopped his men temporarily and called out to the besieged city that he would set free any man who surrendered to him. Twenty people responded to his appeal. From them he learned that enough ammunition and provisions were available that the city could withstand the siege for a very long time. Considering that his own men were anxious to return home and enjoy the fruits of their victory over Hawazin-indeed, that their patience would be at an end if the siege were prolonged-Muhammad ordered the Muslims to withdraw. With the arrival of the new moon (the month of Dhu al Qi'dah) the siege had become one month old, and the holy season during which no war was permitted had begun. Muhammad returned to Makkah with his army, visiting the holy places and performing the lesser pilgrimage or `umrah. He announced that he would resume the war against al Ta'if at the expiration of the holy months.
http://www.witness-pioneer.org/vil/Book ... l_taif.htm
