Can Tho (VNA) - The Mekong Deltashould use technology to create rice varieties resistant to bacterial leafblight, speakers told a two-day international conference which concluded in CanTho city on August 20.

Prof. Dr. Nguyen Hong Son, Director of the Vietnam Academy ofAgricultural Sciences, told the sixth International Conference on BacterialBlight of Rice and Bacterial Leaf Streak that the disease is one of the mostserious production constraints world-wide, causing losses of up to 74 percentof production.

For bacterial diseases that show no initial symptoms and aredifficult to detect, prevention by only using antibiotics is not veryeffective, he said, adding that the most effective solution in Vietnam and theworld is to create disease-resistant rice varieties.

Many countries have been successful in creating resistantrice varieties, but bacteria mutate into new strains quickly, requiring morethan one resistance gene in each rice variety, he added. 

Dr. Nguyen Thi Phong Lan, head of the plant protectiondepartment at the Mekong Delta Rice Institute, said rice blight disease hadworsened in the delta, and now affected 50,000-60,000ha each crop. Thereare no measures to control the disease completely, she said.

According to the International Rice ResearchInstitute, bacterial blight could reduce rice yields by 30-70 percentdepending on the stage of the infection, environmental conditions and whichrice season it is. 

Experts recommended that farmers should apply integratedmeasures to manage pests such as using rice varieties with good resistance,resilience and suitability to local conditions.

They should also apply appropriate rice cultivationtechniques such as moderate density of sowing with balanced fertilisation and gooddrainage.

The institute is currently cooperating with Germany’s BayerCompany to test two transgenic hybrid rice varieties resistant to leaf blight. Theyhave been tested for nearly two months and remain free of blight. 

Dr. Tran Ngoc Thach, Director of the Mekong Delta RiceInstitute, said Vietnam should “learn from Germany and the US” to research intothis disease.

The conference acted as a forum for exchanging informationand fostering collaboration between scientists from around the globe for theeffective control and management of the disease, he said.

It helped make significant progress in understanding thedisease through analyses of the interactions between the pathogen and rice atmany levels, including studies focused on the epidemiology, population biology,physiology, cell biology, bio-chemistry, molecular genetics, and effectorsinvolved in the interactions, he added.

According to experts, bacterial blight and bacterial leafstreak of rice are major diseases due to their high epidemic potential,especially when there is extreme climate variation, and its destructiveness onhigh-yielding but susceptible cultivars. 

Despite attempts to control the diseases by incorporatinggenetic resistance into high-yielding cultivars, both remain a major constrainton production in both favourable and unfavourable rice environments throughoutAsia. 

The pathogen causes yellowing and drying of leaves, wiltingof seedlings and blight lesions (in case of severe strains), which may alsoaffect panicles. Various saprophytic fungi could invade the lesions,contributing to the damage. 

The favourable factors for bacterial leaf blight are rain,high levels of fertiliser, high humidity, standing pools of water, and warmtemperatures.-VNA