International partnership develops warning system for the risk of wheat blast

O Early Warning System (EWS), or Early Warning System in free translation, is a platform that simulates the risks of blast incidence based on the collection of meteorological data. The EWS is the result of a project led by the International Corn and Wheat Improvement Center (CIMMYT), in partnership with Embrapa and the University of Passo Fundo (UPF). 

The risks associated with the occurrence of blast are directly related to climatic conditions, especially during the wheat harvesting period. The occurrence of frequent rains, temperatures above 22ºC, plant wetness time above 10 hours, cloudy days and high relative humidity in the air form the ideal conditions for the proliferation of the disease. 

The EWS is capable of analyzing data collected by weather stations and predicting when these conditions may occur in regions with wheat crops. The system cross-references this information with the plants' stage of development and, in the event of a risk, sends an alert to producers so that they can take preventive actions.

As there is no cure, blast control must be preventative, with the application of fungicides before the fungus establishes itself on the plant. On average, the fungicide protects the plant from the disease for between 12 and 14 days. Therefore, to carry out more assertive control, it is necessary to check the weather forecasts, evaluating the best time and the real need to apply the pesticide. The platform Early Warning System assists precisely in this decision making. At the EWS website, the user chooses the country, state and nearest weather station to evaluate low, moderate and high risks on the map. 

Embrapa Trigo researcher José Maurício Fernandes explains that the disease is considered a global threat, as there are no varieties that are resistant to the fungus. “There is no resistant germplasm in most elite wheat genotypes worldwide and fungicide treatments are ineffective when disease intensity is high”, explains the scientist.

System usability

In Brazil, the EWS is still being supplied with data, considering the diversity of wheat growing environments in the country. “We are working on a more responsive interface, capable of running the site on different devices and with greater coverage”, says the researcher from UPF Willington Pavan. According to him, interactivity with registered users is also being tested, with the sending of alerts, in an experimental phase, to smartphones and emails.

Project partner in Bangladesh, researcher Tim Krupnik, national representative of CIMMYT, says that in the Asian country the EWS has been working since 2019, sending text messages and emails to the rural extension network that works with wheat . 

For now, the EWS is restricted to wheat-producing states in Brazil and Bagladesh, but in the future it should cover all wheat-growing regions in the world. 

Another anticipated advance is to expand the EWS database for Fusarium head blight, another important ear disease with frequent epidemics in different wheat crops in South America and Asia.

The disease that threatens wheat

Blast is one of the main diseases with an economic impact on wheat. The causal agent is the fungus magnaporthe oryzae which, when it attacks the rachis of the cob, results in deformed grains with a low specific weight, which implies a reduction in crop yield. The fungus that causes it is dispersed by wind and can attack more than 50 species of grasses, in addition to surviving in crop residues, seeds and volunteer plants.

The disease was first recorded in Brazil in the 1980s, in occasional epidemics in tropical areas, but within a short time it spread throughout South America, causing epidemics in Bolivia, Paraguay and Argentina. The arrival of the disease in Bangladesh, in 2016, in South Asia, and in Zambia, in Southern Africa, in the 2017/2018 harvest, raised awareness of the global threat that blast represents. 

In Brazil, blast is more important in the tropical region, more frequent in regions such as the north of Paraná, São Paulo, Minas Gerais, Goiás and the Federal District. The last blast epidemic in the country was observed in 2012, when damage above 40% compromised crops in the wheat heading phase in the north of Paraná, in Mato Grosso do Sul and in the south of São Paulo. 

Isolated cases of blast in RS have been detected since 2014, but epidemics of the disease have never been recorded. In 2019, climatic conditions at the beginning of the crop cycle led to blast fungus infection during plant tillering in Minas Gerais, Goiás and the Federal District.

Fernandes recalls that, although it does not yet pose a risk to wheat-producing countries in the Northern Hemisphere, the main cereal research centers are alert to the spread of the disease around the world, which could compromise food security, especially in poor Asian countries. and Africa. He explains that the climate of the Northern Hemisphere does not favor the survival of the fungus that causes blast under current conditions. However, climate change and even possible mutations in the microorganism could alter this scenario, hence the concern of all cereal producing countries.