RUST - A CANCEROUS DISEASE FOR WHEAT CROP

M.R. CHAUDHRY
Apr 21 - 27, 2008

Among the diseases affecting and damaging wheat crop, rusts are the most widely spread and destructive disease. Rust badly affects production and yield of wheat crop. Although such diseases can effectively be controlled through non-chemical treatment, majority of farmers do not afford to follow the recommended practices due to economic reasons or because of health or environmental hazards.

Only recently the UN's agriculture agency (FAO) has asked Pakistan and other major wheat producing countries, which fall east of Iran to be on "high alert" following the discovery of a dangerous new fungus that could destroy the entire wheat crop.

The rusts so far detected are of three types viz. black stem rust, leaf or orange rust and yellow or stripe rust. These rust fungi are highly specialized plant pathogens with narrow host ranges. Record shows that in the years 1906 to 1908 there had been severe attack of black stem rust in Mirpurkhas, Sindh and in 1978 there had been severe attacks of yellow or stripe and orange or leaf rust all over wheat growing areas.

The fungus causing black stem rust or stem rust possesses a long life-cycle with many pathogen races. This disease produces rust like orange coloured pustules on leaves, stems and leaf sheaths. At a later stage these pustules turn dark brown or black. When it is fully developed, it erupts through the epidermis of stems, leaf sheaths and blades, glumes and awns.

According to Bible Prophecy News, Britain's Observer newspaper reported that the disease called black stem rust has already wiped out harvests in Uganda, Kenya and Ethiopia. As wheat is not a staple crop in most of East Africa, it has not caused major food or social problems in these countries. The Observer (April 22, 2007) has expressed fears that millions of people face starvation following an outbreak of a deadly new strain of crop disease, which is spreading across the wheat fields of Africa and Asia. Researchers report that stem rust spores, blown across the Red Sea and reaching the Arabian peninsula have affected wheat fields in Yemen.

It is being observed that the disease could reach Egypt before the end of the year, which is heavily dependent on wheat as its staple food. Now studies of wind patterns suggest that the disease known as UG99 will soon spread to Saudi Arabia and the Near East. Eventually Syria, Lebanon, Turkey, Iran, Pakistan and Europe could be affected.

Rick Ward of the Global Rust Initiative, which has been set up with most of the funding from Canada, India and United States to counter this new threat said: "When an outbreak occurred, a field of ripening wheat would be turned into a mass of blackened vegetation." He is of the considered opinion that we urgently need to breed new wheat strains that are resistant to UG99. He warns that if we do not, then we must be prepared to face calamitous losses of wheat production. Therefore, we have to move quickly as there is no time to lose.

The international agriculture expert and Nobel prize-winner Norman Borlang waned: "This thing has immense potential for social and human destruction."

A spokesman of the Ministry of Food, Agriculture and Livestock (Minfal) in Islamabad on Friday, 7th March assured that although race UG-99 is now widespread in wheat growing areas of Kenya and Ethiopia causing colossal losses to the crop, the current wheat crop in Pakistan is in good shape and is without any major threat of the disease. He informed that Pakistan is an active partner of the global efforts to control rust threats to wheat and is involved in joint research activities being carried out by regional and international research institutions, both long term and short term strategies have been made to combat and control the threat of stem rust, found in southern part of the country. He assured that there was no major threat to the crop. He reiterated that efforts are being taken on the federal and provincial levels by "wheat research institutes" for development of wheat resistant varieties against stem rust UG-99. Some 27 fields in Nepal, India, Afghanistan and Pakistan have been planted with new varieties of wheat with a hope to extend the number of seeds without giving the fungus a chance to evolve new strategies and risks for circumventing resistance. Developing such varieties of wheat seed will, of course, take some time and then supplying them to farmers for cultivation and wheat production.

Almost simultaneously Dr. Majeeb Qazi of the Pakistan Agriculture Research Council (Parc) has clarified that the stem rust strain found in Sindh is a local strain and not UG99, which has caused devastation in Africa and is now damaging crops in our neighbouring country, Iran. He, however, emphasized that we cannot afford to be self-satisfied and oblivious to the threat, thinking that UG99 will not attack Pakistan. (That will be a self deception). We should not ignore FAO's warning in this regard. As already pointed out, the Food and Agriculture Organization of the United Nations has warned Pakistan against this rust attack. Dr. Qazi was of the opinion that Pakistan's current wheat crop would not be attacked by UG99 because it was not found in the country's environment. He stated that experimental tests of the local stem rust strain carried out in Sindh proved that it was not UG99.

Mr. Qazi said that the swift spread of the pathogens into Yemen and now into Iran within only one year had sent alarm bells. Pakistani researchers should expedite their efforts to develop locally wheat seed variety that may be immune and resistant to UG99.

Recapitulating the damage caused by the said stem rust, Dr. Qazi said that stem rust on wheat had caused international concerns due to its damage potential and systematic spread across wheat growing areas in several countries from Uganda to Kenya and Ethiopia from where it went into Yemen and has recently been reported to be in Iran. It is feared that its air borne spores spreading nature would threaten Pakistan wheat areas, especially where stem rust is to be a problem (Sindh and lower Punjab).

Recent rain, frosty nights and long cloudy weather during current wheat cropping season was favourable for spreading rusts.

It is the time for our Research Centres, Pakistan Research Council, NIAB, Punjab Agriculture University, MINFAL and all concerned in the Government to make intensive efforts on war footing for developing new rusts resistant varieties of wheat. Breeding for resistance varieties has been a successful research activity and is the best method to prevent the crop from diseases in the long term.

The growers should also ensure timely sowing of wheat or as early as possible because the crop sown early matures early and may remain safe and free from rust and other diseases. They should never hesitate to seek guidance from agriculture experts and Extension staff whenever they observe any sign and symptom of this fungus on their wheat or other crops. At the same time it is necessary for the agriculture extension staff to create awareness amongst the farmers with regard to this fungus, its adverse effects on wheat crop and how to cope with the situation including anticipatory measures and measures to be taken in the eventuality of attack of rust UG99. Till such time as our Researchers are able to introduce wheat seed varieties resistant to UG99, Seed Corporation should purchase wheat seed varieties from other countries, which have been able to produce wheat varieties resistant to this fungus, in sufficient quantities, so that our farmers and country may not suffer any loss for want of the proper seed varieties.