Leaf disks may be difficult to wet. Seven surfactants tested in whole seedling immersion (WSI) inoculations all permitted good infection and sporulation; all but Tween 20 and 80 induced stunting. All treatments improved wetting of disks in LDI; sporulation was best with Tween 20. Sometimes in LDI inoculations sporulation is less than expected in incompatible cultivar-race combinations, or more than expected in incompatible combinations. Decreased sporulation is often associated with profuse bacterial growth. Of eleven readily available antibiotics tested rifampicin appeared best at reducing bacterial contamination without ad verse effects on downy mildew. Mold growth was often profuse on disks when bacterial competition was reduced by rifampicin treatment. In spite of these difficulties, the LDI method is proving useful in various studies, and efforts are being made to resolve the problems.