Whether ye cut down (O ye Muslim!) The tender palm-trees, or ye left them standing on their roots, it was by leave of Allah, and in order that He might cover with shame the rebellious transgresses.
The unnecessary cutting down of fruit trees or
destruction of crops, or any wanton destruction whatever
in war, is forbidden by the law and practice of Islam. But
some destruction may be necessary for putting pressure
on the enemy, and to that extent it is allowed. But as far
as possible, consistently with that objective of military
operations, such trees should not be cut down.
Both these principles are in accordance with the Divine
Will, and were followed by the Muslims in their
Yusuf Ali, Abdullah. Translation and Commentary of the Quran. (surah 59 verse 5 Quran Arabic with English Translation & Commentary (Tafsir) by Abdullah Yusuf Ali, Free Download (quran4u.com)