Yellow dwarf virus, stunted wilt on rice: New disease ...

Rice stunt disease in rice is a new disease, due to the mixing of 3 types of virus such as Dwarf rice grass, Dendrocalamus stunt disease caused by brown planthopper and Tungro disease. Dr. Pham Van Du, Ministry of Crop Disease - Rice Institute of Mekong Delta (Mekong Delta) explain more about the causes of dwarfism in rice .

Since 1989, there is a symptom of rice with yellow and dwarf rice, this rate can be 5-10% or 50% on some varieties and some fields, some like OM CS 96, OM 997-6, OM 1248 are reported to be infected. However, the concern here is that the above symptoms have the same peak of appearance of populations of brown backed rice plant hoppers .

Prime Minister Nguyen Tan Dung: It is imperative to extinguish rice disease

On November 4, in Ho Chi Minh City, Prime Minister Nguyen Tan Dung chaired a meeting to discuss measures to control brown plant hoppers, yellow dwarf diseases and rice leaf stunts in southern provinces and cities.Attending the meeting were representatives of the leaders of the Ministries: Finance;Agriculture and Rural Development, Government Office, Plant Protection Institutes and southern provinces and cities from Khanh Hoa onwards.According to information from the conference, the disease has spread to 21 provinces and cities, causing damage to over 500,000 hectares and reducing the output of 825 thousand tons of damage about 2 trillion VND for farmers, concentrating 500 thousand households with 2.5 million people.

In order to prevent this epidemic, the Prime Minister proposed to implement resolute solutions to prevent epidemics in this winter-spring crop, which must be eliminated by brown backed rice plant hopper and implementation of support measures. People are facing difficulties due to epidemics.

(VNA)

Thus, it is possible that this is a new disease, there should be studies to conclude to avoid widespread spread of disease. The disease usually occurs at a very low rate, but there are quite large years of damage.

As of late December 1999, there were 13,120 ha of rice infected in Ben Tre, Ho Chi Minh City, Bac Lieu and Long An provinces. Particularly, Ho Chi Minh City has 242 ha of yellow stunted and unremarkable diseases.

In 1999, the Southern Plant Protection Department conference called the disease ' Dwarf Gold ', unknown to the agent.

Recently, since the beginning of the Summer-Autumn crop in 2006, the disease has developed and spread in most of the Mekong Delta provinces, with a high density of brown backed rice plant hoppers and yellow infected areas in Dong Thap with losses of less than 30%. is 613 ha, and over 30% is 2,636 ha (of which, about 500 ha must be burned) .

Dwarf disease is caused by the mixing of 3 viruses

In the Mekong Delta Rice Institute, in those years there was a lack of facilities, especially ELISA reading machines and serum resistance of some rice virus strains such as Tungro (RTSV, RTBV), leaf curl (RRSV) grass rice dwarf ( RGGSV), Yellowish (RDV, rice dwarf virus) so only collected samples and sent to IRRI International Rice Research Institute, Philippines.

From April 1996 to January 1997, out of 163 samples sent out, there was a positive reaction for 3 RTBV, RTSV (Tungro) and RRSV dwarf virus with a very low rate of 4 samples / 140 .

In January 2005, we invited Dr. RC Cabunagan and IR Choi, two virologists from the International Rice Research Institute (IRRI), to analyze the results of the 52 samples of diseased rice, only 1 sample has a positive reaction for RTSV (tungro) and 7 samples with grass rice dwarf disease (RGSV)

Diagram of transmission of yellow dwarf disease in rice (Photo: Southern Plant Protection Center)

In March 2006, we invited Dr. Hong Soo Choi, specializing in viruses, plant diseases, National Institute of Agricultural Science and Technology, Suwon, Korea with Dr. IR Choi of IRRI, to take samples and continue to perform disease assessments using specialized techniques.

The results of antiserum showed a lot of potential for initial conclusions.

Rice infected with dwarf gold (Photo: Southern Plant Protection Center)

Sample results of dwarf gold samples collected in Tien Giang were guided and sampled by the Southern Plant Protection Center, An Giang Plant Protection Department instructed and collected samples: 2/30 samples reacted with Tungro RTSV, 27/30 samples reacting with grass rice dwarfs, 19/30 samples reacted with the upper leaf curly rice on the same rice plant.

Thus, after nearly 17 years of appearance and 10 years of research, until now, we can conclude initially: Dwarf yellow disease is a new disease due to the mixing of 3 types of virus, Grass Rice, The leafy stunt is spread by brown plant hopper and Tungro, which are transmitted by green plant hoppers.

The reinfection experiment was carried out by Dr. IR Choi at the IRRI greenhouse with the combination of the three viruses for the same symptoms seen in the Mekong Delta.

Treating yellow dwarf disease for rice

A sample of rice yellow dwarf disease (Photo: CLRRI)

The disease caused by a virus is a very difficult disease to treat and there are no specific chemotherapy drugs like other forms of disease.

New stunted gold is now more complicated because it involves many components in the ecosystem such as: (1) Very high population of brown planthopper (green plant hopper) (2) Combination of 3 viruses (curly leaves, grass and Tungro) (3) Intensive production environment, many continuous crops, high nitrogen fertilizer and (4) Rice varieties infected with hoppers and virus infection. Therefore, the following measures need to be taken:

First of all, to cultivate rice in the spirit of " 3 G, 3 T " (3 reductions, 3 increases)

In particular, reducing excess nitrogen, reducing the density of transplanting, reducing the use of chemical drugs to create a biological balance on a large scale. At the same time, it is necessary to apply a balanced fertilizer to create resistance for rice and sparse seedlings to create conditions for light to pass through the canopy, the fog will dissolve quickly on the leaves, due to the increase in temperature and humidity of the canopy in the canopy. Benefits for pests and diseases.

Expert of Rice Institute of Mekong Delta and foreign experts collected
Rice samples for research. (Photo: CLRRI)

Plowing away the number of infected rice fields because brown planthopper can continue to suck the sick rice plants and bring the virus to spread elsewhere, the diseased rice plants that remain in the field will be the germs containing micro- Withdrawing and plowing soil will kill virus germs in stubble.

Do not plant varieties with aphids, virus infection on a large scale. Sowing seedlings in a large area to limit the movement of psyllids. It is not advisable to plant scattered crops related to season 3, only 2 crops should be concentrated. The spread of dwarf gold disease is closely related to the continuous sowing season in the field, both space and time.

Enhancing the resistance of rice to viruses, using a number of stimulants can limit the development of viruses in rice plants such as K ₂ HPO ₄ , CuCl ₂ for seed treatment, Humid acid ( Risopla V) 1-1.5 kg / ha fertilizing is better.

The use of chemical drugs may reduce the hoppers' density but still cannot solve dwarfism, since the transmission of disease can occur between aphids and rice in a very short period of time.

Dr. Pham Van Du (Cuu Long Delta Rice Institute)