UG99 has potential to hit wheat crop, but there is no panic alarm: Ronnie Coffman

Q&A with International Professor of Plant Breeding, Cornell University

Almost 90% of the 130 million hectares in which wheat is grown across the globe faces the threat of deadly UG 99 stem rust which can destroy acres of fields in just a few days. Ronnie Coffman, International Professor of Plant Breeding At Cornell University, tells Sanjeeb Mukherjee that the rust has now reached Yemen in the last 5-6 years and if wind direction is favourable it could also hit India. Coffman is among the few plant scientists who did their doctorate under the legendary Noble Laureate Norman Borlaug and is now associated with the Borlaug Global Rust Initiative (BGRI). Excerpts:

We have been hearing about UG 99 since a long time, but how big is the treat to India's wheat production?

Well, if you ask me, no country where wheat is grown is outside the threat of UG 99, including India. But when it will come to India, depends upon the wind direction. At present, it is in Africa, and scientists along with those in BGRI are trying to stop 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 epidemic. Most of the wind currents suggest that the rust has the potential to come to India.

However, at the same time, we would like to very clearly state that there is not a panic alarm. If it comes to India and scientists are better prepared then there is no threat. And, I must mention that Indian government has done an excellent job in expanding the coverage of wheat seeds which are resistant to stem rust. ICAR has taken a lead in this field.

Which part of the country, do you think has the more chance of getting affected with the rust?

In north India, which is the country's main wheat growing belt, the risk is low, because of the heat in these parts during the crop growing stage. But, across the country, the way wheat is grown has changed since the 1960s. UG 99 has the potential of striking peninsular India. I feel of the 26 million hectares of land in which wheat is cultivated in India, which in peninsular India is most vulnerable as the rust germinates fast in moist climate.

What are wheat varieties which are most vulnerable to UG 99 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 UG 99. India did send some samples of this wheat variety to Kenya to test its resistance to UG 99, but it was found to be very vulnerable. But, once again I must say that Indian authorities have done an excellent job in preventing this rust from affecting India.

In the last 3-4 years, UG 99-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 UG 99-resistant varieties, what else did the Indian government do to stop this disease from affecting the fields?

Well, apart from spreading the UG 99-resistant varieties, India has an excellent surveillance mechanism, through IT, 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 it has a very well developed fungicides and pesticides and hence they are better prepared to react to the rust.

Globally, do you think there is need for a global surveillance over UG 99, because as you say almost the entire wheat area is under threat?

Well, there is a informal arrangement, but it could be strengthened. I feel apart from India, Nepal has vastly improved its surveillance, it's a global effort.

Apart from UG 99, 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, UG 99 is most potential threat and also there is 'yellow rust'. But 'yellow rust' does not destroy the field, it at best pulls down the per hectare yield by 10-15%. The biggest problem with UG 99 stem rust is it is difficult to predict the time when it will hit a certain area. Like in case of Ethiopia, UG 99 was detected in 2004, but is has not developed into an epidemic yet. In that case, my advice would be to remain in state of preparedness as well as develop and spread wheat varieties which are resistant to UG 99 as much as possible.