Is it permitted to irrigate the vineyard? It depends on where and when. Many believe that it is forbidden in e.g. France. However, that is not the case. Even in France it is allowed in some districts and under some conditions (at certain pre-defined periods during the year). Usually not for the better wines though. After the extremely dry 2003 there’s been a lot of discussion about a more liberal attitude towards irrigation in France.
In the New World the situation is sometimes the opposite. There are no restrictions on irrigation (as a matter of fact, some wine districts would not exist without it). But there are some arguments raised that perhaps it should be used less.
Read more about that debate, primarily on the US west coast, in SFGate.
