Fungal diseases are a very common problem. The most common types we see at Delaney's are powdery mildew and black spot.
Powdery mildew and black spot can destroy vegetable crops and rose bushes. It is important to prevent these fungal diseases or identify them quickly before they become untreatable.
How do you identify powdery mildew? It is a white fungus that appears on leaves and looks like a fuzzy powder. Powdery mildew has a blurred border, is hard to wipe off, and often reveals damaged leaf underneath the fungus. People may often see water spotting on their leaves and believe it is powdery mildew. The difference is that water spotting can be wiped off easily with a finger, has a smooth border and does not look as fuzzy. Below is a leave with powdery mildew.
Black spot is also a very common fungal disease that affects many plants. It is frequently seen on roses, so keep a close eye on roses. Black spot fungus is relatively easy to spot with its black spots.
For both fungi, the best treatment is prevention. A copper fungicide works the best to prevent and treat powdery mildew and black spot and is generally considered organic. We have several different types of copper soaps and sprays that come in a variety of application methods. If the copper sulfate is not working, your next step would be a systemic, broad-spectrum fungicide. Some people have had good luck with bicarb powder, which is similar to baking soda, on powdery mildew that has developed resistance to other fungicides.
If you have black spot or powdery mildew on your plants now, it is important to control it before winter comes. The disease can remain dormant and live in the soil until next spring, so it is vital to clean up the plant now and to spray for the fungus. If you spray with a dormant spray in the fall and in the spring, there is less of a chance that there will be a fungus problem in the spring.
Stop into Delaney's to pick up a spray or to speak with one of our many plant professionals!