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Tag: fungi

Wheat blast spread globally under climate change modeled for the first time

Written by Julian Bañuelos-Uribe on . Posted in News, Press releases.

Climate change poses a threat to yields and food security worldwide, with plant diseases as one of the main risks. An international team of researchers, surrounding professor Senthold Asseng from the Technical University of Munich (TUM), has now shown that further spread of the fungal disease wheat blast could reduce global wheat production by 13% until 2050. The result is dramatic for global food security.

With a global cultivation area of 222 million hectares and a harvest volume of 779 million tons, wheat is an essential food crop. Like all plant species, it is also struggling with diseases that are spreading more rapidly compared to a few years ago because of climate change. One of these is wheat blast. In warm and humid regions, the fungus magnaporthe oryzae has become a serious threat to wheat production since it was first observed in 1985. It initially spread from Brazil to neighboring countries. The first cases outside of South America occurred in Bangladesh in 2016 and in Zambia in 2018. Researchers from Germany, Mexico, Bangladesh, the United States, and Brazil have now modeled for the first time how wheat blast will spread in the future.

Wheat fields affected by wheat blast fungal disease in Passo Fundo, Rio Grande do Sul, Brazil. (Photo: Paulo Ernani Peres Ferreira)

Regionally up to 75% of total wheat acreage affected

According to the researchers, South America, southern Africa, and Asia will be the regions most affected by the future spread of the disease. Up to 75% of the area under wheat cultivation in Africa and South America could be at risk in the future. According to the predictions, wheat blast will also continue to spread in countries that were previously only slightly impacted, including Argentina, Zambia, and Bangladesh. The fungus is also penetrating countries that were previously untouched. These include Uruguay, Central America, the southeastern US, East Africa, India, and eastern Australia. According to the model, the risk is low in Europe and East Asia—with the exception of Italy, southern France, Spain, and the warm and humid regions of southeast China. Conversely, where climate change leads to drier conditions with more frequent periods of heat above 35 °C, the risk of wheat blast may also decrease. However, in these cases, heat stress decreases the yield potential.

Wheat fields affected by wheat blast fungal disease in Passo Fundo, Rio Grande do Sul, Brazil. (Photo: Paulo Ernani Peres Ferreira)

Dramatic yield losses call for adapted management

The affected regions are among the areas most severely impacted by the direct consequences of climate change. Food insecurity is already a significant challenge in these areas and the demand for wheat continues to rise, especially in urban areas. In many regions, farmers will have to switch to more robust crops to avoid crop failures and financial losses. In the midwest of Brazil, for example, wheat is increasingly being replaced by maize. Another important strategy against future yield losses is breeding resistant wheat varieties. CIMMYT in collaboration with NARs partners have released several wheat blast-resistant varieties which have been helpful in mitigating the effect of wheat blast. With the right sowing date, wheat blast-promoting conditions can be avoided during the ear emergence phase. Combined with other measures, this has proven to be successful. In more specific terms, this means avoiding early sowing in central Brazil and late sowing in Bangladesh.

First study on yield losses due to wheat blast

Previous studies on yield changes due to climate change mainly considered the direct effects of climate change such as rising temperatures, changing precipitation patterns, and increased CO2 emissions in the atmosphere. Studies on fungal diseases have so far ignored wheat blast. For their study, the researchers focused on the influence of wheat blast on production by combining a simulation model for wheat growth and yield with a newly developed wheat blast model. Environmental conditions such as the weather are thus included in the calculations, as is data on plant growth. In this way, the scientists are modeling the disease pressure in the particularly sensitive phase when the ear matures. The study focused on the influence of wheat blast on production. Other consequences of climate change could further reduce yields.

Read the full article.

Further information:

The study was conducted by researchers from:

  • CIMMYT (Mexico and Bangladesh)
  • Technical University of Munich (Germany)
  • University of Florida (United States)
  • Brazilian Agricultural Research Corporation (Brazil)
  • International Fertilizer Development Center (United States)
  • International Food Policy Research Institute (United States)

Soybean rust threatens soybean production in Malawi and Zambia

Written by Julian Bañuelos-Uribe on . Posted in Blogs.

Healthy soybean fields. (Photo: Peter Setimela/CIMMYT)

Soybeans are a significant source of oil and protein, and soybean demand has been increasing over the last decade in Malawi and Zambia. Soybean contributes to human nutrition, is used in producing animal feed, and fetches a higher price per unit than maize, thus serving as a cash crop for smallholder farmers. These are among the main factors contributing to the growing adoption of soybean among smallholder producers. In addition, soybean is a vital soil-fertility improvement crop used in crop rotations because of its ability to fix atmospheric nitrogen. To a large extent, soybean demand outweighs supply, with the deficit covered by imports.

Soybean production in sub-Saharan Africa is expected to grow by over 2% per annum to meet the increasing demand. However, as production increases, significant challenges caused by diseases, pests, declining soil fertility, and other abiotic factors remain. According to official government statistics, Zambia produces about 450,000 tonnes of soybean per annum, with an estimated annual growth of 14%. According to FAOSTAT, this makes Zambia the second largest soybean producer in the southern African region. Although soybean was traditionally grown by large commercial farmers in Zambia, smallholders now account for over 60% of the total annual soybean production.

Production trends show that smallholder soybean production increased rapidly in the 2015–2016 season, a period that coincided with increased demand from local processing facilities. As smallholder production continued to increase, in 2020, total output by smallholder farmers outpaced that of large-scale farmers for the first time and has remained dominant over the last two seasons (Fig 1). However, soybean yields among smallholder farmers have remained low at around 1 MT/HA.

Figure 1. Soybean production trends by smallholders and large-scale farmers. (Photo: Hambulo Ngoma/Zambia Ministry of Agriculture, Crop Forecast Survey)

Soybean production in the region is threatened by soybean rust caused by the fungus Phakopsora pachyrhizi. The rust became prevalent in Africa in 1996; it was first confirmed in Uganda on experimental plots and subsequently on farmers’ fields throughout the country. Monitoring efforts in the U.S. have saved the soybean industry millions of dollars in fungicide costs due to the availability of accurate disease forecasting based on pathogen surveillance and environmental data.

Soybean rust disease is spread rapidly and easily by wind, and most available varieties grown by farmers are susceptible. The above-normal rainfall during the 2022–2023 season was conducive to the spread of the fungus. A recent survey of over 1,000 farm households shows that 55% and 39% of farmers in Zambia and Malawi, respectively, were affected by soybean rust during the 2022–2023 season. The lack of rust-tolerant varieties makes production expensive for smallholder farmers who cannot afford to purchase fungicides to control the pathogens. It is estimated that soybean rust can cause large yield losses of up to 90%, depending on crop stage and disease severity. Symptoms due to soybean rust infection may be observed at any developmental stage of the plant, but losses are mostly associated with infection from the flowering stage to the pod-filling stage.

Soybean plants affected by soy rust. (Photo: Peter Setimela)

Mitigation measures using resistant or tolerant varieties have been challenging because the fungus mutates very rapidly, creating genetic variability. Although a variety of fungicides effective against soybean rust are available, the use of such fungicides is limited due to the high cost of the product and its application, as well as to environmental concerns. Due to this restricted use of fungicide, an early monitoring system for detecting rust threats for steering fungicide might only be relevant for large-scale producers in eastern and southern Africa. With the massive increase in the area under soybean production, soybean rust is an important disease that cannot be ignored. Host-plant resistance provides a cheaper, more environmentally friendly, and much more sustainable approach for managing soybean rust in smallholder agriculture that characterizes the agricultural landscape of eastern and southern Africa.

To advance the use of rust-tolerant varieties, the Southern Africa Accelerated Innovation Delivery Initiative (AID-I) Rapid Delivery Hub, or MasAgro Africa, is presently concluding surveys to assess farmers’ demand and willingness to pay for rust-tolerant varieties in Malawi and Zambia. The results from this assessment will be valuable to seed companies and last-mile delivery partners to gain a better understanding of what farmers need and to better serve the farmers.  This coming season AID-I will include rust tolerant varieties in the mega-demonstrations to create awareness about new varieties that show some tolerance to rust.

Examining how insects spread toxic fungi

Written by Julian Bañuelos-Uribe on . Posted in Blogs, Explainers.

Maize grain heavily damaged by the larger grain borer and maize weevil. (Photo: Jessica González/CIMMYT)

According to the World Health Organization (WHO), 10% of the global population suffers from food poisoning each year. Aflatoxins, the main contributor to food poisoning around the world, contaminate cereals and nuts and humans, especially vulnerable groups like the young, elderly, or immune-compromised, and animals are susceptible to their toxic and potentially carcinogenic effects.

Fungi contamination occurs all along the production cycle, during and after harvest, so the mitigation of the mycotoxins challenge requires the use of an integrated approach, including the selection of farmer-preferred tolerant varieties, implementing good agricultural practices such as crop rotation or nitrogen management, reducing crop stress, managing pests and diseases, biological control of mycotoxigenic strains, and good post-harvest practices.

Monitoring of mycotoxins in food crops is important to identify places and sources of infestations as well as implementing effective agricultural practices and other corrective measures that can prevent outbreaks.

A bug problem

Insects can directly or indirectly contribute to the spread of fungi and the subsequent production of mycotoxins. Many insects associated with maize plants before and after harvest act as a vector by carrying fungal spores from one location to another.

International collaboration is key to managing the risks associated with the spread of invasive pests and preventing crop damage caused by the newly introduced pests. CIMMYT, through CGIAR’s Plant Health initiative, partners with the Center for Grain and Animal Health Research of the US Department of Agriculture (USDA) and Kansas State University are investigating the microbes associated with the maize weevil and the larger grain borer.

The experiment consisted of trapping insects in three different habitats, a prairie near CIMMYT facilities in El Batán, Texcoco, Mexico, a maize field, and a maize store at CIMMYT’s experimental station at El Batán, using Lindgren funnel traps and pheromones lures.

Hanging of the Lindgren funnel traps in a prairie near El Bátan, Texcoco, Mexico. (Photo: Jessica González/CIMMYT)

Preliminary results of this study were presented by Hannah Quellhorst from the Department of Entomology at Kansas State University during an online seminar hosted by CIMMYT.

The collected insect samples were cultured in agar to identify the microbial community associated with them. Two invasive pests, the larger grain bore and the maize weevil, a potent carcinogenic mycotoxin was identified and associated with the larger grain borer and the maize weevil.

The larger grain borer is an invasive pest, which can cause extensive damage and even bore through packaging materials, including plastics. It is native to Mexico and Central America but was introduced in Africa and has spread to tropical and subtropical regions around the world. Together with the maize weevil, post-harvest losses of up to 60% have been recorded in Mexico from these pests.

“With climate change and global warming, there are risks of these pests shifting their habitats to areas where they are not currently present like sub-Saharan Africa and North Africa,” said Quelhorst. “However, the monitoring of the movement of these pests at an international level is lacking and the microbial communities moving with these post-harvest insects are not well investigated.”

Inauguration of the international soil-borne pathogens research & development center in Ankara, Turkey

Written by Julian Bañuelos-Uribe on . Posted in News.

Staff of the International Soil Borne Pathogens Research and Development Center along with the Minister, deputy ministers, TAGEM’s DG, and high-level officials of the Ministry of Agriculture Forestry. (Photo: TAGEM)

Soil-borne pathogens (SBP) are a serious threat to Turkey’s food security, especially as climate extremes (temperature, precipitations) become more commonplace. SBP are an array of specific adverse effects, such as root rot, wilt, yellowing, and dwarfing caused by fungi, bacteria, viruses, and nematodes. These pathogens can cause 50-75% yield loss in crops.

On May 2, 2023, the International Maize and Wheat Improvement Center (CIMMYT) Country Representative in Turkey, Abdelfattah Dababat, joined the inauguration ceremony of the International Soil-Borne Pathogens Research & Development Center (ISBPRDC).

Vahit Kirişci, Turkish Minister of Agriculture and Forestry, inaugurated the Center, which is the first of its kind in the Central West Asia and North Africa (CWANA) region dedicated to advancing research on SBPs and developing innovative solutions to control and prevent their spread.

The opening ceremony took place at the Directorate of Plant Protection Central Institute working under the General Directorate of Agricultural Research and Policies (TAGEM), and it was attended by deputy ministers, TAGEM’s DG, and high-level officials of the Ministry of Agriculture and Forestry.

Serving under the auspices of the General Directorate of Agricultural Research and Policies (TAGEM), part of the Turkish Minister of Agriculture and Forestry, the ISBPRDC will meet international standards for sanitary conditions.

CGIAR and TAGEM mutually supported the SBP CIMMYT Turkey program by establishing and funding the ISBPRDC.

Bringing partners together

CIMMYT is signing a collaboration agreement with the ISBPRDC to facilitate knowledge exchange and technology transfer between the two institutions, which will support joint research and development activities aimed at improving crop health and productivity.

“The most effective way forward to battle against threats to food security is through cooperation,” said Dababat. “This collaboration is a great opportunity for Turkey’s seed industry to maintain its competitive advantage in foreign markets.”

Professor Vahit Kirişci, Turkish Minister of Agriculture and Forestry, TAGEM’s DG, CIMMYT’s Representative, and high-level officials from the Ministry of Agriculture and Forestry. (Photo: TAGEM)

Thirty-five scientists and technicians will work at the ISBPRDC and the institute will act as an umbrella for all SBP research in Turkey. Bahri Dağdaş International Agricultural Research Institute (BDIARI), the Transitional Zone Agricultural Research Institute (TZARI), and the Plant Protection Central Research Institute (PPCRI) with offices in Konya, Eskisehir, and Ankara, respectively, will support the ISBPRDC center and collaborate with the SBP program at CIMMYT to deliver high-yielding wheat germplasm that is resistant to SBP.

Among new programs at the center are the development of a robust surveillance system to track pathogens, a genebank for germplasm, and screening facilities for resistance against SBP.