Wheat blast disease was first seen in Brazil in 1985 and later spread to Brazil, Bolivia, Paraguay, and Argentina in South America. At various times about 3 million hectares of wheat land are affected by blasts and the yield is reduced at a significant rate. Variations in disease severity and output are observed depending on the wheat variety and sowing time. Due to this disease, the yield of affected wheat is reduced by 25 to 30 %, and the crops of some fields are almost entirely destroyed.
What Are Causes of The Disease?
Wheat blast is a harmful fungal disease. The scientific name of the fungus is Magnaporthe oryzae pathotype Triticum (Pyricularia oryzae). Transmission of this disease can occur if there is relatively warm and humid weather at the time of wheat seed emergence and flowering.
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- In the early stages of wheat fields affected by blasts, the grain turns white in some places, and in favorable weather, it spreads quickly throughout the field.
- Some grains of wheat have a whitish surface that is easily distinguishable from the green and healthy portion below; Almost the entire part of some seeds dries up and turns white. This is a typical symptom of the disease.
- Mainly wheat grain is attacked by the fungus. Black spots appear on the affected area of the seed and the upper part of the affected area turns white. However, if the base of the seed is attacked, the entire seed dries up and turns white.
- Infected pods are malnourished and shriveled and the pods turn gray. The leaves can also be attacked by blast disease and in this case, small gray necrotic spots like eyes appear on the leaves.
The disease is spread through infected seeds and wind. Infection occurs when wheat grains are wet for 12 to 24 hours due to rain and the temperature is 18°C or higher, and the disease germs spread rapidly through the air.
The pathogen of blast disease can live in some grasses such as alternative host weeds; But there the clear symptoms of the disease are not easily visible. Under favorable conditions, alternate host weeds can cause epidemics of blast disease.
- Seeds should be collected from blast-free wheat fields.
- Relatively less sensitive varieties should be cultivated.
- The seeds should be sown at the right time to avoid rain and high temperature at the time of germination.
- Before sowing, seeds should be treated with Provax 200 FF at the rate of 3 g per kg of seed or Vitaflo 200 FF at the rate of 3 ml. Seed treatment will also suppress other seed-borne diseases of wheat and increase yield.
- Wheat fields and aisles should be weeded.
- As a preventive measure, a fungicide should be sprayed once at the time of emergence and again after 12 to 15 days. 6 grams of Nativo 75WG -Novita 75 WG in 10 liters of water should be sprayed well for every 5 % of the land. Spraying will control wheat leaf blight, seed black spots,s and rust.
- Gloves and face masks should be used when using fungicides so that chemicals do not come into contact with the body and can be inhaled.