Robigalia Roundup LXXI

Aspergillus flavus is a saprophytic, opportunistic pathogen in Aspergillus section Flavi (Ascomycota, Trichocomaceae). It is the primary producer of aflatoxins B₁ and B₂ in food and feed crops, although atoxigenic strains lacking functional aflatoxin biosynthesis clusters also occur.

Aspergillus flavus is widely distributed in soil and decaying organic matter and colonises a broad range of plant hosts as an endophyte, pathogen, or saprobe. Agriculturally, it is most problematic on oilseed and starchy crops such as maize, groundnuts (peanuts), cottonseed, and tree nuts, with additional contamination reported in wheat, sorghum, and rice, particularly post‑harvest.

In maize, A. flavus causes ear rot characterised by green‑yellow sporulation on kernels, often linked to insect damage and drought stress, leading to aflatoxin accumulation in grain. In groundnuts and tree nuts, infection of developing or stored seeds is often asymptomatic or expressed as mouldy, shrivelled kernels, yet aflatoxin levels can far exceed regulatory limits.

Although A. flavus occurs worldwide, aflatoxin problems are most severe in warm, semi‑arid to tropical regions of Africa and Asia, and in hot, irrigated production zones such as parts of the southern United States and China. High temperatures, intermittent drought, and poor post‑harvest drying and storage promote sporulation and toxin production, particularly in smallholder systems.

Integrated management includes host‑resistance breeding (for ear‑rot and aflatoxin resistance in maize and groundnut), minimising drought and insect stress, and timely harvest. Pre‑harvest application of atoxigenic A. flavus biocontrol strains to competitively displace toxigenic populations is now widely adopted in several regions. Rapid drying to safe moisture levels, hygienic storage, removal of damaged kernels, and regular regulatory testing underpin post‑harvest risk reduction along value chains.

Keep reading to learn more about A. flavus and to meet a PhD researcher from the Colegio de Postgraduados in Mexico studying the pathogen.

_{*This week’s plant pathologist of the week}

This week, we meet Carlos Muñoz‑Zavala, a researcher pursuing his PhD in Plant Pathology at the Colegio de Postgraduados (COLPOS, Mexico).

Carlos is a plant pathology specialist with more than 20 years of experience in maize disease management at the International Maize and Wheat Improvement Center (CIMMYT, Mexico). He holds a Master of Science in Plant Protection from the Universidad Autónoma Chapingo (UACH, Mexico) and is now completing his PhD with the support of CIMMYT.

His doctoral research focuses on characterising the population distribution of toxigenic and atoxigenic Aspergillus flavus strains native to maize fields under hybrid and creole production systems in tropical and subtropical regions of Mexico. Carlos evaluates biological control strategies using native atoxigenic strains, as well as genetic control through maize varieties adapted to these regions, particularly those tolerant to drought and heat and with high carotenoid content, to mitigate aflatoxin contamination in grain.

Carlos is deeply grateful to CIMMYT for supporting his doctoral studies and to the collaborative network between COLPOS and national and private institutions working to improve maize production in Mexico, a global center of maize diversity.

He believes that meaningful scientific progress is built through collaboration. He is eager to connect with colleagues and research teams to explore maize diseases, develop integrated management strategies, and strengthen scientific exchange. Carlos is also interested in short research stays, international collaborations, scientific congresses, cultural exchange, and opportunities to further improve his English proficiency.

If you are working on or interested in maize‑related topics, you can contact Carlos via Carlos via LinkedIn or follow his research updates on ResearchGate. As he says, “always open to dialogue, just as many colleagues have supported me throughout my professional journey."

Have a job, scholarship, or event to advertise? List it in Robigalia. I’ll help promote your opportunity or event to a global network of over 10,000 plant pathologists for free.

See you next Monday!

P.S. Why Robigalia? The name originates from the Ancient Roman festival dedicated to crop protection. You can read all about the history here: