How To Recognize Sunflower Diseases? Part 1

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

Bright sunflowers delight our eyes and give us beautiful and healthy seeds. However, throughout the growing season, these magnificent plants are affected by a great variety of harmful diseases. They are especially often attacked by white and gray rot, as well as downy mildew. So that dangerous ailments do not catch summer residents by surprise, it is important to know how their main symptoms appear on sunflower

White rot

This ailment is also called sclerotinosis, and it manifests itself in the wilting of plants, the death of sunflower seedlings, damage to seeds and decay of baskets with stalks. The first manifestations of the unfortunate misfortune can be seen at the very beginning of flowering or a little later. A whitish felt bloom appears on the cotyledons and on the leaves of a young sunflower. If sunflowers are affected by the basal form of sclerotinosis, then plaque appears at the bases of the stems. The tops of the stems quickly droop, the leaves of the sunflower wither, and the whole plant eventually dries up. In some cases, unpleasant plaque can also be found between soil particles or on the surface of the roots. Damaged roots become wet and noticeably soften.

After some time, the stalks in the places where plaque appears become brownish-brownish and are characterized by rather rotten tissues. In addition, fungal sclerotia can be found in the affected tissues. The diseased stems are crushed and gradually broken, and the leaves located just above the infected areas wither and dry out. And when a sufficiently dry weather is established, discolored spots located in concentric zones appear on the stalks attacked by sclerotinosis.

Downy mildew

This disease can manifest itself on sunflower in several forms. In the first form, the planted crops begin to noticeably lag behind in growth, their stems become very thinner, and the root system is characterized by very weak development. The leaves on such plants are chlorotic and very small; moreover, sometimes they curl downward along the middle veins. And on the undersides of the leaves, an unpleasant whitish bloom forms.

In the second form of the disease, the sunflower also lags behind in growth and is characterized by underdeveloped internodes and thickened shortened stems. The seeds in this case are formed puny and underdeveloped, and the leaves become corrugated and are covered on top with a chlorotic angular spot, and below - with a whitish and gradually gray bloom.

The third form can be seen on a well-developed sunflower. In this case, it does not become dwarf, however, the symptoms of downy mildew are very clearly visible on the leaves: their lower sides are covered with the same whitish bloom, and their upper parts are covered with oily and spreading specks of light green color, which are characterized by some angularity.

As for the fourth form, outwardly, its symptoms do not appear at all - the disease is hidden. Localization of the pathogen in this case occurs in the underground parts of the sunflower, and it is far from always capable of spreading to the organs located above. If the disease still gets to the stems, then they acquire a light green color.

And the fifth form affects plants that have already suspended their growth. True, sunflower heads continue to develop in any case, however, a pathogen penetrating into the ovary provokes the death of the embryos, as a result of which the achenes remain empty.

Gray rot

On young crops, gray rot is manifested mainly near the bases of the stems and leaves. Sore areas turn brown and gradually tighten with a characteristic grayish bloom, and a little later, the formation of black tiny sclerotia begins on them. After a spring outbreak, the development of a harmful disease is temporarily suspended - most often this can be observed in the absence of rain. And then, when precipitation begins to fall, gray rot will attack the sunflower plantings with renewed vigor: streak will appear on the stems, and they will gradually begin to turn yellow.