• by Omer Redi* (addis ababa)
• Saturday, May 29, 2010
• Inter Press Service

Aston Kirui’s worst experience with wheat stem rust was in 2009 when he lost most of his crop. The wheat farmer from Katakala village in Narok, west of Kenya’s capital Nairobi, is more fortunate this year as the disease has not struck. But his neighbour is not so lucky.

'I have a neighbour who is going to lose everything this year. His farm looks like a field in an arid area during drought.' (The wheat rust pathogen enters the stem of a wheat plant and destroys the vascular tissue. As a result, the plant collapses.)

Like Kirui and his neighbour, wheat farmers in Narok faced devastation of their crops in 2007 because of Ug99, a strain of wheat stem rust. First discovered in Uganda in 1999, and then later in Kenya, nearly 80 percent of wheat crops in Narok failed three years ago.

But now scientists have discovered two new mutations of Ug99. Discovered by Professor Zak Pretorius, a wheat pathologist at the University of the Free State in South Africa, the mutations are resistant to the two stem rust resistant genes (Sr24 and Sr31) used by wheat breeders to combat wheat stem rust.

Upon further study of the genome of the pathogen, Pretorius discovered it was a mutation of Ug99. 'It was alarming for us that one of the resistant genes was not effective anymore,' he said.

Pretorius’s findings will be presented at the 8th International Wheat Conference being held in St. Petersburg, Russia from Jun. 1-4.

Pretorius told IPS that the new strain of wheat rust pathogens were also able to migrate rapidly and could easily spread across Africa.

He added that while wheat stem rust can destroy wheat crops in weeks, three factors needed to be present for this to happen. The wheat had to be of a variety that was susceptible to the virulent pathogen; the environment needed to be ideal - moisture and heat are driving factors; and wind was needed to transport it.

He said South Africa had no cause for immediate concern as wheat was mostly farmed commercially and farmers were constantly updated about new developments and had access to the correct control methods (fungicides).

Pretorius added that smallholder farmers in Africa would be more at risk to the new strains.

Dr. Ronnie Coffman, Director of the Durable Rust Resistance in Wheat Project at Cornell University said the new mutations were a threat to all farmers. Ug99 has spread to Ethiopia, Sudan, Yemen and Iran and experts believe it is now migrating to South Asia.

He said while fungicides could be used to prevent the mutations from attacking wheat, smallholder farmers such as those in Ethiopia will not have the means to purchase this. 'There is no immediate emergency in Ethiopia. But if the mutant is present it could become epidemic.'

He said an ideal situation would be to produce a wheat resistant to the new mutations. 'In Ethiopia, the best hope is seed availability (of resistant wheat) to farmers,' Coffman said.

Peter Njau, a research scientist at the Kenya Agriculture Research Institute, and an expert in wheat breeding, said that in the 2003 Kenyan epidemic an anti-fungus chemical known as ‘Folicur’ was recommended, with hopes that the pathogen would vanish.

'But instead, it worsened because most farmers, especially smallholders, could not afford it,' he said.

The chemical cost 37 dollars a litre, which should be sprayed on one hector under wheat three times in a season. 'This, added to other costs of production, became unbearable for poor smallholder farmers,' Njau said.

The Lume Wereda rural district in Ethiopia has over 13,000 small scale farmers, and over 200,000 tonnes of wheat are expected from this area in the next harvest.

Ayichiluhim Mojo, a wheat farmer in the area has frequently lost his harvest over the past 10 years to wheat stem rust. 'But I don’t know anything about the new types of Wagg,' he told IPS, using Ug99’s local name.

Dellu Ayisanew, 58, a veteran farmer in Lume has not heard about the new rust races, but believes 'there is no cure to Wagg.'

Mentioning his harvest loses 11 years ago due to Wagg, Ayisanew told IPS that if another round of rust besieges his crops, he will give up farming wheat and consider another crop because he cannot afford the deterrent options.

Chemical usage is unaffordable for most farmers in Ethiopia who represent over 80 percent of the country’s above 80 million population.

According to Dr. Firdissa Eticha, Cereals Research Team Leader at the Ethiopian Agricultural Research Institute, there have been many incidents of wheat loses due to Ug99 in the past. 'But there are no indications of the latest races,' he said.

Head of the Wereda Agriculture Bureau, Negussie Gemechu, also said he has not yet heard about the mutant Ug99 and there have not been incidents of major wheat losses recently.

'The sowing season for wheat is yet to come. But in the incident of any Wagg, we will alert our farmers,' Gemechu told IPS. Almost all farmers in Ethiopia fall under the small scale category.

*Additional reporting by Nalisha Kalideen in Johannesburg and Isaiah Esipisu in Nairobi.

© Inter Press Service (2010) — All Rights Reserved. Original source: Inter Press Service

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