How to deal with blast? Know the symptoms and causes

What kind of disease is blast?

The current state of the field died tragically due to the “blast”.

Blast disease along with “mongare disease” is a disease that occurs and causes serious damage on rice plants. It is said that blast is the most important rice disease in Japan because it is one of the causes of crop failure.
Blast disease occurs almost the entire growing season of the rice plant, from the seeding stage to the time of harvest, caused by the “blast fungus” infection. Then, individual parts such as leaves, nodes, spines and firs can be affected and the name changes to “leaf blast disease”, “button blast disease”, “blast disease”, etc.

Status “blast leaf”

When it becomes “leaf blast,” manifests white, gray or brown rhombohedral lesions on leaves and withers. And if the symptoms are severe, most leaves may die and the rice ears may not produce enough. Even when making the rice, if fungus infects the rice paddy, it can be “blast” and the rice can not grow. If that happens, you won’t be able to expect any harvest at all, and it will turn into a very dreadful disease. Since it happens regardless of season or department, it can be said that the rice farmer needs to monitor and prepare for an outbreak of blast.

The condition of the rice lines where the “blast disease” occurs. The neck is brown and all ears are white

There were many causes of the explosion

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So why is there an explosion? First of all, it is thought that the climate is prone to occur years with relatively high humidity and low temperature. Especially in the summer, when the temperature is low, with a lot of rain and not enough sunshine, this phenomenon easily occurs. Furthermore, the cold water overflow into the rice fields is also considered to be one of the causes.
Another factor is nitrogen fertilizer abuse. If too much nitrogen fertilizer is applied, the resistance of the rice plant will be weakened, if it is overgrown, the level in the paddy field will increase and it is easy to develop rice blast disease. Because there are many types of nitrogenous fertilizers, it is very important to choose a fertilizer that is suitable for the soil and crop conditions and to maintain a reasonable amount of fertilizer.

Basically stop the explosion

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Next, I want to look at how to deal with the explosion. Once blast develops, even with treatment, it can be completely cured, so it’s important to avoid it before it happens.

Do not let straw and firs spoil, and dispose of the seedlings provided.

First, make sure that rice straw and rice blast damaged by blast are not left unattended. When there is no rain and remains dry, the tree does not die and becomes a source of blast the following year. Take care not to allow damaged straw in or around the nursery.
In addition, it is important to dispose of stored trees for replenishment as soon as possible as they are a source of blast disease.

Use the right amount of nitrogenous fertilizer

By applying the right amount of nitrogenous fertilizers, it is possible to prevent the onset of blast caused by nitrogen fertilizer abuse. Dosage and timing of fertilizer application are so important that it is important to carefully define the area.

Thoroughly disinfect using healthy fir seeds

Blast can also occur due to the infection of the seeds. Use healthy seeds that are not contaminated with blast fungus and thoroughly disinfect the seeds to prevent bacteria from getting in.

Plant the seedlings at the right times

If sowing in the field is too thick, the plants will grow overgrown and the humidity between plants will increase. Plant the right density to avoid creating an environment that is easy for bacteria to grow.

Check daily carefully for problems with rice

Blast infection can spread quickly if the temperature is about 20 to 25 degrees Celsius and the humidity is high. The earlier it is to detect the disease, the easier it is to heal, so observe the plant every day and make sure you don’t miss any signs of the disease, such as brown spots on leaves.

The current state of the field “blast leaf disease” occurred.

If blast occurs, use appropriate microbicides to prevent the fungus from entering the rice plants. However, keep in mind that prevention is more important than anything else, as it only prevents the disease from getting worse than it’s cured.

Efforts are also underway to produce rice blast resistant rice varieties.

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So far, we’ve looked at the blast, but we realize that the most important thing is to stop it. And as one of the methods, efforts are being made to improve rice to create rice blast resistant varieties, and new varieties are actually coming. An example is “Tomohonami”.
“Tomohonami” was a rice variety that was researched and developed at the Aichi Prefectural Agricultural Experiment Station in 2009. Until then, earth rice (okabo) was one of the rice varieties that are resistant to blast, but The main problem is that it has a lower flavor than rice. Therefore, by detecting the blast resistance gene from the soil rice and knowing its exact location, we were able to accurately distinguish the part of the chromosome that needed to be introduced from the soil. And we have succeeded in producing a variety that is resistant to disease and has a good taste.
By planting these rice varieties, it is possible to reduce the amount of biocides used, which is expected to reduce the burden on the rice grower as much as possible. Why don’t you consider it one of the options?

For rice farmers, blast is a dreaded disease that can reduce yields that year. Be sure to prevent it and prevent infection.

Cooperation / Photos provided (images not included): Center for Agricultural Research Central, National Research and Development Corporation, Agricultural Technology Research Organization and Food Industry