How To Recognize Rowan Diseases?

2024 Author: Gavin MacAdam | [email protected]. Last modified: 2023-12-16 13:38

Rowan, just like all other berry and fruit crops, is susceptible to various ailments. It is noteworthy that almost all diseases begin to appear on these beautiful trees closer to the second half of summer. Most often, rowan is attacked by rust, scab, cytosporosis, powdery mildew and gray or brown spot. To know the enemy by sight and take appropriate measures in a timely manner, you need to familiarize yourself with the main symptoms of the manifestation of these harmful ailments

Rust

In the first half of summer, numerous specks appear on rowan leaves. On the upper sides, they are, as a rule, rounded, reaching a diameter of 2 to 5 mm, colored in orange-yellowish shades and abundantly covered with dotted dark brown tubercles of spermogonia. And on the whitish specks on the lower sides of the leaves, a characteristic aecidial fungal sporulation is formed, which looks like a star-shaped cracking bizarre cone-shaped outgrowths, the length of which reaches about 1 - 2 mm. If the disease develops especially strongly, then the spots are easily able to cover the leaf blades almost completely, as a result of which the leaves will begin to gradually deform.

Scab

On both sides of the rowan leaves, you can see tiny brownish specks with fancy radiant edges. Such spots can differ in both round and irregular shape. After some time, the development of an olive and rather velvety mycelium coating begins on them, abundantly covered with conidial sporulation. During the summer, several generations of conidia infecting young leaves have time to form. At a fairly high level of infection, unpleasant specks can cover the entire leaf surface. Abundant rainfall throughout the summer season is especially favorable for the development of scab.

Cytosporosis

This ailment is also known as cytosporous necrosis. First, on mountain ash trunks and twigs, local oval-elongated unpleasant necrosis are formed, covered with a slightly yellowish bark. All necrotic areas grow at lightning speed, as a result of which they almost always merge and ring thin branches and trunks completely. In the thickness of the infected bark, the formation of pycnidia of the fungus, the causative agent of cytosporosis, begins. They look like tiny rounded or conical tubercles that protrude from the peridermal ruptures with dark or light tops. And with the onset of spring or, in extreme cases, at the beginning of summer, a slimy mass of spores begins to stand out from them, which freeze in the form of spirals, as well as in the form of tiny flagella or droplets colored yellow, dark or orange-red, or completely red Colour.

Powdery mildew

Approximately in the second half of July, on mountain ash leaves, you can notice an incredibly delicate cobweb white bloom of mycelium, densely covered with conidial sporulation. Despite the fact that the harmful mycelium develops on the leaves on both sides, it is the lower parts of the leaves that are especially affected by it. And towards the end of July, on the surface of the fungal mycelium, the formation of cleistothecia, small spherical fruiting bodies, begins. Initially, they look like tiny yellow dots, which can be located both in groups and chaotically. And as they mature, destructive clestothecia begin to darken, turning brownish or almost black. As a result, they can be easily seen against the background of a whitish bloom.

Gray spot

On both sides of the rowan leaves, the formation of characteristic gray spots of an irregular or round shape, framed by dark brown wide rims, begins. Then, on the upper sides of the leaves, the formation of fungal pycnidia begins. Often, all the specks merge with each other and cover most of the leaf surface.

Brown spot

The upper sides of the rowan leaves are covered with reddish-purple edges with reddish-brown spots. Most often, such spots are characterized by an irregular shape, and in their center there are almost always crowded black dots - mushroom pycnidia. And individual spots, as the disease develops, begin to merge, covering certain areas like a blanket.