The seasonal increase in temperature causes all sorts of pathogens to thrive....bugs, algae, and fungus commonly find a mother plant(s)that is too wet and warm to settle into. The immune system is tested and warmer climates require adjustments to maintain stasis in mothers. The common denominator making cloning harder is the mother, and the way we fortify, sterilize, and regulate their environment. In an ideal space, the plants are immune to temperature swings and all airborne pathogens but, this is harder than many can accomplish with the brutal summer heat. So, the angle I find helpful is to prepare the mothers by feeding them silica, fulvic acid, beneficials and then I use a sterilizing agent as well as a systemic insecticide. It might seem awkward to run bennies and then kill them but it will innoculate them and bolster their root systems. The heat will damage roots and encourage rot so I go sterile, the silica protects them from stress caused by temp, drought, and environmental fluctuation....it makes a tougher plant. A tougher mother is then prepped for cuttings to be taken by a light peroxide spray followed by a heavy rinsing of tap water. This cleans and opens up the leaves to breathe better in the dome, the rot potential is lessened, and the cuttings will be plump with stored water. Rot is too much heat and humidity in the dome...use as little water as possible and spray the dome and not the leaves. The best results come from clones that harden off early and stay as dry as possible. Clean the dome and switching out the tray is a good habit...but ideally they should be left alone, uncrowded, and free fom contact with the perpetually moist surfaces.