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Diseases of wheat- Symptoms and Management

Diseases of wheat:

In this article you will learn about various diseases of wheat while cultivation of wheat in your field and for optimum yield performence you have know all the symptomes and recommended  management practices.

List of diseases of wheat:

1)Black or stem rust:

casual organism: Puccinia graminis tritici

Symptoms:

The first symptom of rust infection is flecking of leaves, leaf sheaths, culms and floral structures. These flecks soon develop as oblong, reddish brown uredo-pustules, frequently merging into one another, finally bursting to expose a mass of brown uredospores. When large number of uredosori burst and release their spores, the entire leaf blade and other affected parts will have a brownish appearance even from a distance. Later in the season, teleutosori are produced. They are conspicuous, linear or oblong, dark brown to black, and often merging with one another, to cause linear patches of black lesions, which account for the name black rust. On maturity the teleutosori burst open, exposing masses of dark brown teleutospores. In the transitional stage, there is a mosaic of brown and black masses of spores on the affected tissues, which dry up prematurely. Moreover, in the case of severe infections the diseased plants are stunted and produce small spikes and shrivelled grains, or no grain at all.

Management:

2)Leaf-brown or orange rust

casual organism: Puccinia recondita

Symptoms:

The first symptom of the disease is the appearance of minute, round, orange sori, irregularly distributed on the leaves, rarely on the leaf sheath and stem. The sori turn brown with maturity. As the disease advances, the telial stage may be found in the same pustule. The telia are small, oval to linear, black and covered by the epidermis. The telia are also found on the leaf sheath. Severe rusting of leaves causes reduction in yield.

Management:

2)Yellow or stripe rust:

casual organism: Puccinia striformis

Symptoms:

The uredosori appear as bright yellow pustules chiefly on the leaves. But in severe infections they may be seen on leaf sheaths also. The sori are elongated and are arranged in linear rows between the veins of the leaf and hence it is referred as stripe rust. The sori are mostly sub-epidermal and are remained covered by the epidermal layer and break only at the time of crop maturity. The teleutosori appear late in the season and are also arranged in linear rows. They are compact, elongated, and black which remain subepidermal. They do not break through epidermis for a long time remaining as black crust.

Management:

3)Loose smut:

causal organism: Ustilago nuda tritici 

Symptoms:

The symptoms are evident only at the time of emergence of the panicle from boot leaf. All the spikelets in a panicle transform into a mass of black powdery spores. The infected panicle emerges two days earlier than healthy and the spores are covered with the silvery membrane. This thin membrane gets ruptured exposing the mass of black spores. The spores are easily blown by wind leaving the bare rachis.

Management:

4) Karnal bunt:

causal organism: Neovossia indica

Symptoms:

The infection is usually confined to a few grains in the spike with irregular arrangement. In some cases the infection may spread to only a part of the grains. In severe cases, the grain is reduced to black shiny sac of teliospores. As the grains mature the outer glumes spread and the inner glumes expand, exposing the bunted grains. The bunt balls are first enclosed by the pericarp but when it bursts the masses of bunt spores are exposed. The bunt affected plants emits a foul smell which is mainly due to the presence of Trimethyl amine.

Management:

5) Leaf blight:

casual organism: Alternaria triticina

Symptoms:

Reddish brown oval spots appear on young seedlings with bright yellow margin. In severe cases, several spots coalesce to cause drying of leaves. The young leaves are not usually infected. Heavily infected fields display a burnt appearance even from a distance. In some varieties reduction in grain yield is as high as 90% if the infection takes place at or before the boot leaf stage.

Management:

6)Tundu disease or yellow slime disease of wheat:

casual organism: Anguina tritici (Nematode) + Corynebacterium tritici or Clavibacter tritici

Symptoms:

The tundu disease is characterized by the twisting of the stem, distortion of the ear head and rotting of the spikelets with a profuse oozing of yellow liquid from the affected tissues. The ooze contains masses of bacterial cells. The nematode alone causes winkling, twisting and various other distortion of the leaves, stem and produce small round galls on the leaves. The infected plants are shorter and thicker than healthy plants. In the distorted earheads dark galls are found in place of kernels. When the bacterium is associated with the nematode, the disease symptoms are intensified at the flowering stage and yellow ear rot sets in due to combined action of the nematode and bacterium. The earhead becomes chaffy and the kernels are replaced by dark nematode galls which also contain the bacterium. The infected plants produce more tillers than the healthy ones. Another interesting feature is the early emergence of ears in the nematode infected plants which is about 30 to 40 days earlier than the healthy ones.

Management:

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