Almost 90 per cent of the 130 million hectares,in which wheat is grown across the globe faces the threat of the deadly UG99 stem rust, which can destroy acres of fields in just a few days. Ronnie Coffman, international professor of plant breeding and director of international programmes of the College of Agriculture and Life Sciences at Cornell University, tells Sanjeeb Mukherjee that the rust has reached Yemen and it could hit India, depending on the wind direction. Coffman is among the few plant scientists who did his doctorate under the legendary Nobel Laureate Norman Borlaug and is now associated with the Borlaug Global Rust Initiative (BGRI). Edited excerpts:
We have been hearing about UG 99 for a long time. How big is the threat to India’s wheat production?
No country where wheat is grown is outside the threat of UG 99, including India. But when it will come to India will depend on the wind direction. At present, it is in Africa, and scientists and experts at BGRI are trying to contain it there itself. Closest to India, it has been sighted in Yemen, but there are difficulties in stopping it there as Yemen has socio-political problems. But, we don’t know when it will become an epidemic. Most of the wind currents suggest that the rust has the potential to come to India.
We would like to clearly state that there is no need to panic. If it comes to India and scientists are better prepared, then there is no threat. And, I must mention that the Indian government has done an excellent job in expanding the coverage of wheat seeds, which are resistant to stem rust. The Indian Council of Agricultural Research (ICAR) has taken a lead in this field.
Which part of the country is more prone to getting affected with the rust?
In north India, the country’s main wheat growing belt, the risk is low, because of the hot climate in these parts during the crop-growing stage. But, across the country, the way wheat is grown has changed since the 1960s. Of 26 million hectares of land in which wheat is cultivated in India, peninsular India is most vulnerable as the rust germinates fast in moist climate.
What are the wheat varieties that are most vulnerable to UG99 and how has the Indian government responded to that?
Well, the most popular variety of wheat, which is grown in India is PBW-343 and it is vulnerable to UG99. India had sent some samples of this wheat variety to Kenya to test its resistance to UG99, but it was found to be very vulnerable. I must say that Indian authorities have done an excellent job in preventing this rust from affecting India.
In the last 3-4 years, UG99-resistant varieties of wheat is grown in half of the areas where the crop is grown. The government has gradually withdrawn the most popular variety from the fields. This has been possible due to joint efforts of the government, seed agencies, research institutes and private companies.
Apart from replacing the vulnerable seeds with UG99-resistant varieties, what else did the Indian government do to stop this disease from affecting the fields?
Apart from spreading the UG99-resistant varieties, India has an excellent surveillance mechanism, through information technology, mobile phones, etc. India has also been recognised as a Centre for Global Molecular Technology. In some other major wheat growing countries like Australia, the threat is not present as the country has well-developed fungicides and pesticides and it is better prepared to react to the rust.
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Do you think there is need for a global surveillance over UG99, because as you say almost the entire wheat area is under threat?
Well, there is an informal arrangement, but it could be strengthened. I feel apart from India, Nepal has vastly improved its surveillance. It is a global effort.
Apart from UG99, what are the other plant diseases that can impact world wheat production in the near future?
It is difficult to say because as of now, UG99 is the immediate threat. There is also this ‘yellow rust’, which does not destroy the entire crop; at best, it pulls down the per hectare yield by 10-15 per cent. The biggest problem with UG99 stem rust is that it is difficult to predict when exactly will it hit a certain area. Take, for instance, the case of Ethiopia. UG 99 was detected way back in 2004, but it has not developed into an epidemic as yet. In which case, my advice would be to remain in a state of preparedness as well as develop and spread wheat varieties that are resistant to UG99.