Too much rain, too hot and then too cold, allow the fungi to develop and sicken the tree. Leaves get brown and dry, then the fruits rot and fall down. Would you like such a disease on your tree? I know I would not!
Weather changes favor fungi growth
Until a few years ago, I knew exactly when winter would end and spring would start. And then, when the warm summer weather would come and when the fall rains would begin. Each season lasted for about three months, so the weather was predictable even to weather novices. But then at some point, everything started to change and the summers started to be hotter, while autumn started to last even through December and sometimes through January. Christmas has often been without snow the last few years. Rains have started to be heavy and violent, even during winter. Long boring fall rains have started to happen in the spring too and even during summer. When spring arrives, the weather starts to warm up and nature comes to life. However, in an hour, everything changes and winter comes back again, on the back of a powerful blizzard. Later in the spring, when the weather really warms up, it warms up so hot, it feels like summer, so I start getting the summer clothes out of the closet. I put the blankets away and store winter things in the closet. But then, the temperature drops down so fast, that I need to take out the blankets again, together with the warm clothes. This is very confusing to us humans, but also for the plants and trees. The poor trees often bloom again during the fall, like they would have in the spring. Those weather changes affect the trees and plants very much, because the long, heavy rains allow the fungi to reanimate and grow.
What are fungi and how they affect trees
Fungi are members of the Eukaryotic family, which includes microorganisms such as yeasts and molds, but also the well-known mushrooms. Some fungi have an important role in nature by decomposing the dead organic matter and some are used as biological pesticides to control weeds, plant disease and insect pests. Mold is a type of fungus, which can be either bad or good, such as Aspergillus - bad for human health, when growing on wet walls or carpets - or Penicillium - good for human's health, as an antibiotic.
Fungi may damage to human food, when it isn't kept in proper conditions, such as a cold environment (like the refrigerator). Fungus spores lay on all surfaces and everywhere in nature. They start growing in proper conditions, meaning warmth and humidity. It is the same with the trees and plants, if the environmental conditions are correct they will grow. Insect pests help the fungi establish in a tree or plant, through the wound they make by biting or stinging the fruit, leaves or the tree's bark. Some of the best known fungal diseases are apple or pear scab, perennial canker, powdery mildew, speck rot, verticillium rot, sphaeropsis rot, monilinia rot.
My sad experience with fungal diseases
I learned about fungal disease on my trees in the most painful way, when my apricot died of apricot's apoplexy. It happened after a long period with heavy rains, that caused a severe disease to my apricots. One is called monilinia, caused by the monilinia fungi. The apricots in my tree molded and looked like "mummies", while part of the branches dried and turned brittle, because of this bad fungus. Some specialists say that even a very severe freeze during a hard winter can cause the apricot's apoplexy and I remember we had very severe winters, with deep freeze in 2012, 2013 and even in 2014, before my apricot died back. But the monilinia fungus' role was probably the most important.
Once the fungus' spores are spread throughout the garden, is very hard to keep them under control. That's why, after a year or two, my cherry tree was infected as well, with monilinia disease. Then followed the sour cherry tree, that got sick last summer. Pruning the trees without cleaning your tools with alcohol can also spread the disease, meaning the fungus spores.
Treatment and prevention is the key
Spraying with fungicide and insecticide is important for the trees' health, but it has to be done properly and scientifically, so that the environment can be preserved as healthy as possible. The bees need to be especially protected, that's why many modern fungicides and insecticides aren't poisonous for the bees. Read your labels and make sure what you are using is safe for the pollinators. Often, gardeners contact local bee keepers and work with them to keep the bees safe during the process. Spraying a copper fungicide during winter prevents many diseases on the trees, especially on the fruit trees. It is organic and safe. Once a disease has established, it's hard to keep the tree healthy. The alternatives are cutting back the tree or regular spraying with fungicide. Since I have learned my lesson, I've started to spray the trees on a special seasonal schedule. I know that now it's trendy to talk about organic fruits and vegetables, but, with these climate changes we just cannot do that in my region of Romania. I am very careful when spraying, especially with insecticide, which I always spray after sunset, when the bees are gone from the garden. Be careful when spraying your trees and ask for a horticultural engineer's advice before using any product you are not familiar with.