Prospects for new cassava varieties resistant to mosaic disease

According to the Department of Agriculture and Rural Development (DARD), Tay Ninh is a province with favorable conditions for land, climate and abundant irrigation water, which is favorable for growing crops, including cassava. Currently, the province's annual cassava growing area is over 62,000 hectares, the second largest in the country after Gia Lai. The average yield is 33 - 35 tons/ha (1.7 times higher than the national average yield), ranking first in the country.

Not met the demand

However, according to experts, continuous intensive cultivation creates conditions for many diseases to develop and cause damage to cassava plants, affecting the yield and quality of cassava. These include collar rot (tuber rot), which was discovered in 2014, and mosaic disease, which was first discovered in mid-July 2017.

Mr. Nguyen Dinh Xuan - Director of the Department of Agriculture and Rural Development (second from right) surveyed the cassava harvesting work at the Tay Ninh Agricultural Experimental Center.

According to a survey by the Department of Agriculture, in the 2023-2024 Winter-Spring crop, more than 300 hectares of cassava were affected by collar rot disease in the province. The diseased area spread across major cassava growing districts such as Tan Chau, Tan Bien, Duong Minh Chau and continued to spread.

Typical symptoms of root collar rot are lesions that appear at the root collar (the part that touches the ground), then spread to cover the entire circumference of the root collar, causing the base of the stem to shrink, crack, ooze dark brown sap, become wet and rot. Cassava leaves turn yellow and wilt suddenly. The disease spreads down to the tubers, causing them to rot.

As for mosaic disease, this is a dangerous disease that causes great damage to yield and starch quality, and there is currently no specific treatment. From 2018 to present, the Department of Agriculture and Rural Development has coordinated with the Institute of Agricultural Genetics, the International Center for Tropical Agriculture (CIAT), and the Hung Loc Agricultural Research and Experimental Center (Hung Loc for short) to conduct research, testing, and evaluation of many potential cassava varieties with disease resistance suitable to the natural conditions of the province and the Southeast region. As a result, 6 cassava varieties resistant to mosaic disease have been selected and announced for circulation by the Ministry of Agriculture and Rural Development , including: HN1, HN3, HN5, HN36, HN80, HN97.

Although these varieties have shown positive signs when put into use, research units are still continuing to survey, crossbreed and select new cassava varieties that not only have genes resistant to mosaic disease but also have high yield and tuber quality, and are resistant to typical diseases on cassava plants such as root rot, witch's broom, etc.

There will be new varieties

On October 14 and 15, the Department of Agriculture and Rural Development coordinated with the International Center for Tropical Agriculture (CIAT) and the Hung Loc Agricultural Research and Experimental Center to harvest and evaluate varieties with the ability to resist mosaic disease that have been tested and continuously selected at the Tay Ninh Agricultural Experimental Center (Thai Binh commune, Chau Thanh district) from 2021 to present. Accordingly, after this harvest, it is expected that there will be about two new varieties with genes resistant to mosaic disease and some common diseases on cassava plants, while also giving higher yield and starch quality than or equal to previous varieties.

Mr. Ha Thanh Tung - Director of Tay Ninh Agricultural Extension Center introduces new cassava varieties.

Mr. Jonathan Newby - Director of the International Cassava Program, CIAT Center said that since the cassava mosaic disease began to appear in Vietnam, CIAT Center and specialized units of the Agriculture sector have conducted tests to find a number of varieties with genes resistant to this disease. In order to continue researching and improving the quality of cassava varieties that are both resistant to mosaic disease, have high quality yield, and are suitable for local soil conditions, from 2021, CIAT Center and specialized units of the Agriculture sector will carry out crossbreeding between varieties with mosaic disease resistance genes and potential varieties of Vietnam.

This process is carried out continuously, each year breeding and testing about 1,000 new lines to select good disease-resistant varieties. This is the fourth year of implementation, hopefully about 5-10 potential lines can be selected to be recognized and put into production.

Mr. Ha Thanh Tung - Director of Tay Ninh Agricultural Extension Center said that after this harvest, experts will have a specific assessment of some varieties that meet the requirements of mosaic disease resistance, powder quality and good yield to make a process to request the Ministry of Agriculture and Rural Development to recognize and grant a circulation license, from which the Agricultural Extension Center will quickly deploy the work of propagating new varieties to meet the needs of the people.

According to Mr. Tung, in order to diversify the new variety set, which is resistant to mosaic disease, has higher yield and starch quality, and can also withstand some common diseases, especially cassava root rot. In the coming time, the Provincial Agricultural Extension Center will advise the Department of Agriculture and Rural Development to coordinate with CIAT and Hung Loc to continue testing and evaluating more new cassava lines and varieties, searching for new promising varieties in Tay Ninh province.

It is expected that the new variety will overcome the shortcomings of previous varieties.

Mr. Nguyen Dinh Xuan - Director of the Department of Agriculture and Rural Development said that Tay Ninh is one of the provinces with the largest cassava area and productivity in the country. In recent years, cassava has been one of the crops with high economic value, helping farmers develop their economy and stabilize their lives.

However, the cassava mosaic disease outbreak in Tay Ninh since 2017 has infected thousands of hectares of cassava in the province, seriously affecting the productivity and quality of cassava products.

With the efforts of domestic and foreign scientists in researching, breeding, testing and selecting, there are now a number of varieties that have been recognized and licensed for circulation. However, when these varieties are grown in the field, they reveal many different shortcomings. For example, the HN5 variety has a large trunk, large tubers but the starch content is not high. The HN1 variety is very successful in terms of starch yield and quality but is affected by other diseases such as: root rot, stem rot or broom on the top...

According to Mr. Nguyen Dinh Xuan, the viewpoint of Tay Ninh Department of Agriculture is not to increase the area of cassava cultivation but to increase the yield and quality on the same area. Therefore, the Director of the Department of Agriculture and Rural Development hopes that after this harvest and evaluation, scientists will continue to find new varieties that can resist mosaic disease and many other diseases, at the same time, overcome the shortcomings of previous varieties, helping to improve the yield and quality of cassava in the province.

Minh Duong

Source: https://baotayninh.vn/trien-vong-them-giong-mi-moi-khang-duoc-benh-kham-la-a180420.html