How To Recognize Sunflower Diseases? Part 2

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

In the first part of the article, we figured out how gray and white rot, as well as downy mildew, appear on sunflowers. However, these are not all diseases that can affect growing sunflower. Not less often, bright sunflower is also affected by such ailments as ash rot, phomosis, verticillary wilting and powdery mildew. How do you recognize their symptoms?

Fomoz

The development of phomosis on sunflower can be both early and late. With early development (as soon as three or four pairs of true leaves are formed on the growing crops), the tops of the leaves are covered with dark brownish specks framed with yellow edges. The defeat usually starts from the lower tier of the leaves. After some time, all the spots increase noticeably and begin to cover the leaf blades with petioles almost completely. Infected leaves quickly wither and dry out, but at the same time they all continue to remain on the stems. And a little later, small dark brown spots can be seen on the green stalks - as a rule, they are concentrated near the root necks and in the places where the petioles are attached.

Growing, the spots encircle the lower parts of the stems, and by the time the sunflowers start blooming, all spots are painted in bluish-black tones and are combined into a common solid mass. And as soon as sunflower baskets begin to form, vague brownish specks will appear on their backs. At the same time, the tissues of the infected baskets noticeably soften, but rot still does not form on them.

As for the late development of the disease, it is observed after the sunflowers have faded. The infection begins to cover plants from the fourth internode and above, and along the stems you can notice small specks in the form of strokes, which, after some time, form stripes, clearly visible to the eye, from one to one and a half centimeters long. The specks formed closer to the periphery are usually light brown, and in the center they are always quite dark. Often such formations are surrounded by dark green edges. And on the backs of the sunflower baskets, brownish ulcers gradually begin to appear. With both forms of damage, the formation of harmful pycnidia occurs on the specks.

Powdery mildew

Approximately in the middle of summer, a characteristic whitish bloom forms on sunflower leaves (mainly from the upper sides), gradually acquiring a mealy structure and a light brownish or pinkish tint. The diseased leaves become very fragile and begin to crumble at the slightest touch. The yield as a result of damage by powdery mildew is reduced by an average of 5%.

Verticillary wilting

This ailment affects sunflower plantings, starting from the moment the baskets are formed and until their very ripening. First, individual sections of the leaves (mainly the middle) begin to fade, which after some time noticeably turn pale, dry out and turn yellow or brown. And after a while, the specks cover the leaf blades entirely. Sometimes they are surrounded by yellow edges consisting of withered tissues, which die off a little later.

Ash rot

In semi-arid and arid zones, ash rot is most common. And this attack manifests itself in separate foci, causing a general wilting of plants. The leaves of the affected sunflower turn brownish, and the stems are painted in characteristic ashy shades. And on the lower parts of the stems (especially near the root necks), the formation of tiny ovoid or spherical sclerotia occurs.