… situation not so serious as yet, officials say

YK Poudel 

Farmers are on high alert as the National Plant Protection Centre warns of imminent rice blast due to current weather conditions.

Rice blast is one of the most destructive diseases of rice, capable of decimating seedlings or plants in their early growth stages and beyond.

There has been no major rice blast outbreak since 1996 after farmers began growing more resistant varieties.

According to a notification from the Centre, except in a few cases where susceptible varieties are grown, no case of major outbreak was recorded. “Rice blast is a serious disease which can result in substantial yield loss up to total destruction as well. It can affect at different growth stages of paddy.”

Head of the Centre’s pathology programme, Dr Namgay Om, said that rice blast outbreak could occur if conditions are favourable, such as growing susceptible varieties, frequent and prolonged wet periods with cool temperature and high inputs of nitrogen fertilizer. “Measures are taken to prevent outbreaks. Rice blast is mainly managed through use of resistant varieties.”

Farmers, she added, now mostly grow resistant varieties and hence no outbreaks. “Further, we send out alerts and notifications when weather conditions are favourable [for the disease] to caution and remind field officers and farmers about scouting and monitoring fields for timely management of the disease.” 

Other management practices include using disease-free seeds, avoiding application of excess nitrogen fertilizer, high density planting, maintaining proper water level, and continuous monitoring of fields for early detection of the disease. 

Fungicide spray is necessary if susceptible varieties are grown and weather conditions are favourable for development of blast fungus. “Regular use of fungicide is not recommended due to the risk of development of resistance,” said Dr Namgay Om.

Agriculture officials have been told to monitor the fields in their respective gewogs and employ necessary interventions in the case of disease presence. 

Leaf blast can kill rice plants at seedling stage and cause yield losses in cases of severe infection. In case of neck blasts, brown to black spots or rings are formed on the rachis of the maturing inflorescence.

The 2022 Agriculture spatial information for paddy cultivation recorded 40,106.81 metric tonnes of paddy compared to 40,804.95 metric tonnes in 2020—a drop by 1.7 percent. 

Accounting for 53 percent of dietary energy, rice is the most important cereal crop in Bhutan. However, the country is only 37 percent self-sufficient.

Rice is grown from the tropical lowlands (200 masl) in the south up to warm and temperate regions in the north (2700 masl).