Often the fungus itself is only visible under a microscope. Chemical control is difficult as many Powdery Mildew fungicides are phytotoxic on Kalanchoe. Botrytis can cause leaf and stem rot in Kalanchoe during dark winter months. To avoid problems keep the foliage dry and allow for good air circulation within the crop. Keep in mind that many Botrytis fungicides leave very visible residue spots on the leaves.
Rhizopus can develop in warm, humid conditions.
The fungus is an opportunistic pathogen that infects weak, soft tissue. This disease can also occur during shipping if the environment is kept too warm and humid. Problems are also possible in dense crops with little lateral air movement and warm-humid micro climates between the plants. A variety of stem rots can affect Kalanchoe. Usually one of these fungi can be found on affected plants, but the damage is most often caused in combination with Fungus Gnats tunneling in the stem.