Plant diseases of angel wing begonias are normally rare; there are two that stand out. Both of these are caused by excessive moisture. Do not despair though; the prevention is simple while the treatment can be a challenge.
Angel wing begonias are noted to be sensitive to moisture. You either have too little or too much. A plant that receives too little moisture will be droopy, and the leaves will begin to dry up. The solution to this problem is simple-water the plant. On the other hand, if you have too much moisture you can develop a powdery mildew problem and/or rot.
Powdery mildew is a fungal problem caused by excessive moisture. How do you know if you have this plant disease? Well, take a look at the plant. If you see a white or gray powdery coating on the leaves, stems, and/or flowers then you have a powdery mildew problem. While there are chemical treatments for this plant disease, there is a very strong chance that it will do nothing. The best approach if this problem is discovered is to simply pull the plant up and throw it away. Do not compost. This will just spread the plant disease. But what is one to do? The answer is basic and starts off at the beginning.
When planting your angel wing begonia make sure that you space the plants out enough. This means that you need three to five inches between plants planted in a landscape. If you are growing the angel wing begonia as a container garden, make sure that you do not crowd the plant. Depending on the size of the container, you may only have room for the begonia or up to only three plants.
The second thing you can do to prevent this plant disease is to only water with the top inches of the soil is dry. While you can purchase a tool to read soil moisture, why would you when you have all you need and the end of your hand. Yes, it said at the end of your hand. What am I talking about? Well, your fingers. All you need to do to use this technique is to push your index finger into the soil and pull straight up. If it comes out clean then you need to water. On the other hand, if it comes out with damp soil then you can skip watering.
The second plant disease that angel wing begonias can suffer from is rot. Really the name says it all. The stems of the plant will look mushy and waterlogged. If you pulled the plant up, you would notice the same thing with the roots. The cause of the plant disease is overwatering and the solution again is to check the soil before you water. But, if you plant already shows signs, save time and pull it up. It is cheaper to go buy a new plant then spend money on a chemical treatment that chances are will not work.