Smeared Bands in PCR

[Reid, Thomas M.]

I am having problems with smeared bands when analyzing PCR products on 
agarose gels.  I am amplifying a 600 bp segment of a 25 Mbp fungal genome. 
 The smearing does not always occur although it seems to be somewhat 
polymerase-specific.  The smearing is above the major band so I don't think 
it's an exonuclease problem.

I would appreciate any advice, thoughts, etc.

Tom Reid