Pest and disease attacks on crops rising due to climate change: Scientist

Prasanna talks about some of the challenges that climate change poses to agriculture and ways to handle them

Agriculture is one of the sectors most vulnerable to the effects of climate change on weather patterns across different parts of the world. In an interview with Business Standard, B M Prasanna, distinguished scientist and regional director for Asia at the International Maize and Wheat Improvement Center (CIMMYT), talks about some of the challenges that climate change poses to agriculture and ways to handle them. Edited excerpts:

 

How severe is the climate change problem for the agriculture sector?

 

Climate change is undoubtedly a reality, and it is already influencing agri-food systems in several major ways, including the frequent incidence of devastating pests and diseases, which are also a result of changing climates—especially increases in temperature and erratic rainfall conditions. These conditions exacerbate the impact of some pathogens and insect pests.

 

It is a proven fact that drought, heat, and waterlogging not only reduce productivity, but also influence the biotic spectrum.

 

It is a complex reality. There are only two or three major ways we can solve this. One is improved genetic innovations—better varieties with tolerance to an array of abiotic and biotic stresses. The second is agronomic or climate-smart practices, which can help mitigate the impact of climate change. The third is enabling policies, especially regarding water, nutrient and user efficiency, and labour-saving technologies.

 

These three—improved genetics, improved agronomy, and enabling policies—must work in conjunction to effectively tackle the various threats imposed by changing climates.

 

How much have pest and disease attacks gone up globally? Which crops are most vulnerable?

 

A wide range of crops are hit by transboundary pests and diseases. For example, the fall armyworm in maize agri-food systems has been a constant factor in sub-Saharan Africa since 2017 and in India since 2018. It has very quickly spread across multiple countries in the Asia-Pacific region.

 

So, fall armyworm is, in your view, a prime example of the impact of climate change?

 

Yes, fall armyworm is a prime example of transboundary pests in maize. But it is not the only one.

 

For example, in the case of wheat, wheat blast disease occurred in Bangladesh. This is again a transboundary pathogen that came from Brazil. Similarly, there are post-flowering stalk rots increasingly seen in maize systems across South Asia, especially in India.

 

These diseases existed 30–40 years ago too, did they not? Then how can we say their incidence has increased due to climate change?

 

Absolutely. Some of them were present earlier but were far less prevalent. For example, fall armyworm was never reported in Africa or Asia.

 

It was confined to the US corn belt. It appeared in the fall season—hence the name fall armyworm—and migrated to warmer parts of the US and Latin America in winter.

 

But in 2016, we witnessed a major fall armyworm outbreak in sub-Saharan Africa, and in 2018, it appeared in maize fields in Asia. So, some diseases had not existed in these continents for decades.

 

Some minor pathogens have become major threats due to changes in climate.

 

Both phenomena are happening: diseases not previously seen in a region are emerging, and others have intensified due to factors like changing climates and international trade. These are major drivers behind transboundary pests and diseases.

 

Similarly, in the case of animals, there are diseases that were once confined to specific geographies or species and are now jumping to others.

 

What is the ideal solution to fight them?

 

Fighting these diseases requires a multi-pronged and sustainable approach. Plant health management must address several aspects.

 

First, we need to strengthen the capacity of national phytosanitary agencies in diagnostics, monitoring and surveillance—constantly, within our borders. This ensures that any new pathogen entering our territory is quickly identified, characterised, and either contained or eliminated. If elimination is not possible, a rapid response must follow. This is the first and most important step to prevent further damage.

 

If containment fails, the next best option is sustainable plant health management. That means identifying eco-friendly solutions.

 

Currently, when countries are hit by pests or diseases, the first response is to apply chemical pesticides.

 

These provide temporary relief, but many farmers are unaware of the correct way to use them.

 

Just like antibiotics require a certain dosage and duration, pesticides must also be used properly. Farmers must be trained on how, when, and how much to apply. Otherwise, pest populations can become resistant to the pesticide, making them more aggressive.

 

This is why the emphasis must now shift to nature-friendly or eco-friendly plant health management.

 

What role does genetics play in this?

 

Pest-resistant varieties are extremely important. For instance, in Africa, CIMMYT has for the first time developed and deployed native genetic resistance to fall armyworm. It is not transgenic.

 

We used germplasm developed in Mexico from landraces called Tuxpeños and Caribbean flints. The Caribbean is not just known for cricket—it is also home to maize landraces resistant to certain insect pests.

 

We bred that germplasm and introduced it in Africa, and more recently in Asia.

 

Now, Africa has adopted fall armyworm-tolerant hybrids that are completely non-transgenic. We have released them in six countries across Africa.

 

Similarly, in Asia, at our Hyderabad research centre, we are breeding yellow maize hybrids that are climate-resilient (drought- and heat-tolerant) and resistant to fall armyworm.

 

What role should governments play?

 

As I said earlier, in monitoring, surveillance, and diagnostics, governments must collaborate. If a problem arises in one country, it should not be suppressed or go unreported.