Make sure your wind players hear someone OTHER THAN THEMSELVES every time they play. Students should imagine that they are forming a TRIO with the players on either side of them and do their best to MATCH sound quality, pitch and volume with the members of their TRIO. A TRIO of like instruments within the wind ensemble should attempt to sound like ONE PERSON.
If you can hear ONE INDIVIDUAL PLAYER more than others inside a particular section within the wind ensemble, that INDIVIDUAL may not be attempting to BLEND with his or her section.
Another way to get an individual player to work on blend is to ask them to get their sound “inside” the sound of the player (or players) seated next to them.
I have found that when students understand and apply the concept of blend when playing in an ensemble, there tends to be a huge improvement in the intonation of those students.