Alternaria Beet

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

Alternaria, or beet black spot, most often develops on damaged and weakened crops. And you can encounter it in almost any area of beet growing. Most of all, the disease covers old leaves, on which a plaque of fungal sporulation forms rather quickly. As a rule, the symptoms of alternaria are found closer to the end of summer, when the outer leaves turn brown and are affected by necrosis from the very tips. The establishment of prolonged rainy weather is especially favorable for its development

A few words about the disease

On beet leaves affected by black spot, rather large elongated or rounded specks of dark brown color begin to appear with concentric circles located between the veins. Sometimes these spots can start from the edges of the leaves. After some time, they turn black and merge, covering a significant part of the leaf blades. The leaves become dry and brittle, leading to a significant weakening of the growing crops. It is noteworthy that the inner beet leaves are rarely affected by Alternaria.

On the tissues of root crops attacked by Alternaria, a dark olive or black bloom of sporulation occurs. The mycelium developing on these tissues almost always leads to decay of root crops. Most often, as a result of damage by saprophytic fungi, damaged and undried beets rot.

Mushrooms-causative agents of this most unpleasant misfortune settle on oppressed and weakened plants. Especially often they inhabit crops that have received some mechanical damage or damaged by insects and slugs. The pathogen overwinters on plant remains in the form of conidia and mycelium, and the preservation of infection in most cases is noted on stored root crops and plant debris. Slightly less often, it can persist on the seed glomeruli and uterine roots. And the pathogen is spread exclusively by conidia.

The mycelium of the pathogen can be either colorless or brown or olive green, with numerous septa. Unbranched conidiophores separating in the form of segmented short hyphae are painted in the same color as the mycelium. As for the conidia, they are usually smooth, although sometimes there are also conidia covered with warts or thorns. Almost all of them are equipped with thin and long beaks with septa, the size of which often reaches one third of the total size of the formed conidia. There are also conidia without beaks - usually they have an ovoid or elliptical shape, and at the ends such conidia are almost always spherical or rounded. Much less often you can observe and pack-like conidia with central septa.

The germination of conidia and the subsequent infection of plants is favored by a temperature in the range from twenty-two to twenty-six degrees, as well as the presence of drip moisture on the plants for two hours or more.

How to fight

When growing beets, you should follow the rules of crop rotation. The seed used must be of high quality, and the acidic soils must be carefully calcareous. It is not recommended to place mother crops in the immediate vicinity of production crops. Active weed control will also help to curb the spread of the ill-fated misfortune. Also, in spring and autumn, it is recommended to treat the soil with various biofungicides.

It is extremely important to collect and destroy all plant residues in a timely manner. And for subsequent storage, only well-ripened, healthy and whole root crops are selected that do not have any mechanical damage.

Beet crops affected by Alternaria are often sprayed with "Raek".