With the current weather : warm, sun and humidity, it is the perfect time for fungus to be out and spread. So be careful with your trees, if you find a fungus you can cut the disease branch and let it ventilate. It is the same for humans, with many diseases in the air in this period, it is also important to properly ventilate our home : cut the heat and open every day your windows for 5 min.
Ventilation is key !