ISLAMABAD: The Mexico-based International Maize and Wheat Improvement Centre (CIMMYT) has warned wheat growing farmers in Pakistan to keep a close eye on the spread of yellow rust disease which might evolve in new forms.

“When weather is good for wheat production, it is equally good for wheat yellow rust attack, and when appropriate measures are not in place to control the disease, the expected gain in production cannot be materialised due to losses from yellow rust and this is what happened in the previous wheat season,” said Dr Imtiaz Muhammad, Country Representative of CIMMYT in Pakistan, told Dawn on Wednesday.

He said that yellow rust was not a serious disease in Sindh province but in the last three to four years, the rust started to appear in Sindh where mega varieties are susceptible to yellow rust.

He advised farmers to remain vigilant till mid-February especially during rainy and humid days. Rusts can be better controlled when the crop is about 7 to 8 leaves or at stem elongation growth stage.

Fungicide spray at this stage can save up to 50 per cent yield losses. Vigilance and generation of knowledge through research are keys in rust management as Dr Norman Borlaug, pioneer of the green revolution, said “rust never sleeps,” Dr Imtiaz said.

Yellow rust also occurs in the central and northern districts of Khyber-Pakhtunkhwa from mid-February to mid-March. In Northern areas rust can occur even in late April.

This rust was mainly affecting wheat in central, northern Punjab and KP but in recent years it started affecting wheat crop in Sindh and southern Punjab due to climate and pathogen adaptability. Leaf rust occurs mostly in Punjab particularly in warmer areas. This can also occur in central districts like Nowshera, Mardan and Swabi.

Emphasising that scientists need to revise the strategy when developing varieties for Sindh, Dr Imtiaz stated that the combined efforts of US Department of Agriculture (USDA), CIMMYT and Pakistani scientists have resulted in the successful testing and release of 35 highly productive rust resistant wheat varieties that are capable of surviving even the destructive Ug-99 wheat fungal disease — a stem rust disease which is not yet reached Pakistan but was reported from neighbouring country like Iran.

If susceptible varieties are grown, worldwide effective fungicides application at appropriate growth stage play an important role in rust management, however, fungicides should be regarded as secondary option and not a substitute for resistant varieties.

Published in Dawn, February 6th, 2020