[Cynthia, Prescott, AZ]

This really isn't the right way to pose a question. Fungal spores are everywhere. It is not just simply if the spore reaches a plant, it gets infected. Healthy plants do not get fungal problems. It is an indication that your culture is not good enough for the plant. Is the plant getting enough light. Are you keeping it warm enough. Are the leaves dry by the time the temperature starts to dip for the night. Using a fungicide spray to prophylactically prevent fungal problems is probably called for if you really can't get the culture up to par for a plant. Such sprays will reduce the presence of spores, and systemics may give protection to a plant for a while.