It isn't uncommon to see growths, lesions or discolorations on plant leaves. These unhealthy areas are often a result of disease caused by fungal infection. While some of these conditions are relatively harmless, others may eventually weaken or spread to other parts of the plant. There are several common types of leaf fungus disease that can be a source of concern. Does this Spark an idea?
Leaf Spot
Numerous types of leaf spot disease affect plant leaves, including oak leaf blister and black leaf spot. They are called leaf spot diseases because of the spotted appearance of the leaves. These diseases, when severe enough, may cause defoliation and eventual weakening of the plant. Various fungi cause the leaf spot disease; for example, the fungus Alternaria causes brown spots that may leave holes in the leaves, while the fungus Coniothyrium results in grayish-brown spots with dark borders. These types of fungi survive through the winter season on infected leaves only to spread to new leaves via wind and rain.
Powdery Mildew
Leaves that develop a white or gray, powdery appearance are often infected by fungi, such as Uncinula necator and Microsphaea alni, which causes powdery mildew. While it can appear on stems and flowers of a plant, it is most commonly noticed on the leaves, appearing on both the lower and upper sides. The fungus resides on the surface of the infected leaves and feeds by sending roots into the uppermost layer of cells. It does well in dry, warm areas with infection increasing the higher the humidity. However, although it requires humid conditions to germinate, leaf wetness is not required for infection. To control infection, dispose of infected leaves and all nearby debris, prune leaves among densely crowded plants to increase the flow of air and cut down on the potential for humidity, and avoid watering the leaves from above. In some cases, prevention techniques may not be enough, in which case fungicides may be necessary.
Rust
Rust is another series of fungal diseases. It can appear on the leaves of many plants, such as blueberry, roses and rhododendron. Different fungi can cause infection on different plants. Blueberry rust is caused by the fungus Naohidemyces vaccinii, also known as Pucciniastrum vaccinii, while the fungus that causes rose rust is of the Phragmidium species. The most effective way to prevent a rust fungi infection is to bring in plants that are disease-free. Since fungicides are largely ineffective against this type of infection, the primary method of treatment is to cut off the affected leaves and dispose of them.
Peach Leaf Curl
The fungus known as Taphrina deformans is the sole cause of the peach leaf curl disease. It primarily affects peach trees, but it also attacks nectarines and can damage the crops associated with these trees. It is identified by the presence of curled leaves that have reddish-purple distortions that show up early in spring, and then gray in the later months as a result of spores being produced. It may occasionally infect the fruit of the tree, where it can be identified by raised, reddish lesions. Prevention techniques involve the use of chlorothalonil or lime sulfur-based fungicides.
Tags: leaf spot, infected leaves, fungi cause, leaf spot disease, leaves These
