KHUJAND, April 29, 2009, Asia-Plus – Yellow rust has affected some wheat fields in Jabborrasulov and Zafarobod districts in northern Tajikistan, according to the Sughd agriculture directorate.
Specialists have monitored the affected areas and come to a conclusion that the affected grain fields should be treated by special chemical compounds. The affected fields are currently treated by fungicides, the source said.
According to the Sughd agriculture directorate, local farmers have planted cereals on 41,130 hectares of farmland to this date, which some 75 percent of the target.
Yellow rust is the disease of cereals is caused by Puccinia striiformis and different forms affect wheat and barley.
Puccinia striiformis requires living green plant material in order to survive. The fungus survives the winter as dormant mycelium or active sporulating lesions on volunteers or early autumn-sown crops. Set-aside provides an excellent source of yellow rust overwintering inoculum. Yellow rust within plant tissue can survive very low temperatures. Only if the wheat is killed by frost will the yellow rust fungus within the plant tissues die. In the spring, particularly in cool moist weather, the fungus starts to grow and produces active sporulating lesions. Temperatures of 10-15°C and a relative humidity of 100% are optimal for spore germination, penetration and production of new, wind-dispersed spores. The fungus is inhibited by temperatures over 20°C. The complete cycle from infection to the production of new spores can take as little as 7 days during ideal conditions. The disease cycle may therefore be repeated many times in one season.
