Consider having them take their pictures first. Get better photo-assignment forms. Assign one photographer per series. Reporters and photographers need to talk early on, and understand their respective needs on the story. Sometimes the best picture can be captured after the reporter has left.
Photographers have to be sensitive in difficult situations, such as a greiving subject.
They know that taking a picture will quickly end an interview, and they work hard not to do that. Reporters should fill out the photo forms as completely as possible, even when it is not clear what the story is all about.