Increase your propagation success by inoculating your medium appropriately. Broad-spectrum inoculants that include mycorrhizae and Trichoderma such as Great White Shark are outstanding for soaking Rockwool or peat-based plugs prior to sticking your cuttings. These "good guy microbes" protect the plant from root/stem rot diseases such as Pythium, Fusarium, and Rhizoctonia. In aeroponic or DWC cloning machines, use Botanicare's Hydroguard to keep the water clean and pathogen-free. Proper inoculation is crucial for successful cloning.