Script 58.3

Notes to broadcasters

In August 2000, farmers and scientists completed a large and important agricultural experiment in China.  The study confirmed that crop diversity — planting a mixture of different crops or crop varieties in the same space — helps prevent crop disease. The farmers and researchers were studying a disease called blast (Magnaporthe grisea) — a major fungal disease of rice. Farmers usually control blast by spraying fungicides.  The farmers involved in this experiment were able to stop using fungicides to control the disease within two years. The following is a fictional drama highlighting the idea that diversity in the field reduces the incidence of disease.  More details about the study in China are provided at the end of the script for those interested in writing their own radio programs about or related to the study.  It is important to note that randomly selecting any two varieties of rice will not necessarily provide protection against blast.



Program host

Mr. Kwanga:
An agricultural extension worker
Farmer Chuma

Farmer Suzgo

SOUND EFFECTS(Sounds of the countryside: roosters crowing, birds singing…).


Program host:
As we begin today’s story, Mr. Kwanga, an agricultural extension worker from town, is entering one of the villages in his assigned region. The first person to greet him along the way is Mr. Chuma, a rice farmer.

Mr. Kwanga:
Greetings, Mr. Chuma!

Farmer Chuma:
Greetings, Mr. Kwanga! What brings you to the village today?

Mr. Kwanga:
As you know, it will soon be time to spray your rice to prevent disease — especially blast. I’ve come to tell you about a new chemical that is now available. I urge you to try it — I feel that farmers in this region will benefit from using this spray and …

Farmer Chuma:
Sir, wait — stop right there. I appreciate that you have come, but I must tell you that these days I am feeling uneasy about using all these chemicals. On top of that I spend all my profits paying for them.

Mr. Kwanga:
I understand Mr. Chuma, but unfortunately we do not know any other ways to control diseases in rice.

Farmer Chuma:
With all due respect, that is where I think you might be wrong. I have heard that a farmer from the village of Galaha – one Mr. Suzgo — I have heard that he has found a way to prevent disease WITHOUT spraying.

Mr. Kwanga:
Do you know more about this Mr. Suzgo and his experiment? Perhaps his knowledge, combined with the scientific research that I know about, can be of help to you on your farm!

Farmer Chuma:
He doesn’t use any sprays. I think it has something to do with his planting method. All the farmers from Galaha are talking about it. Sir, you will have to excuse me. I see that my son needs help in the field. Good-bye, Sir.
Mr. Kwanga:
Good-bye, Mr. Chuma. Thank you for speaking with me.


Program host:
Farmer Chuma seems to believe that his fellow farmer, Mr. Suzgo, in the neighbouring village has found a way to control disease in rice. On the other hand, the extension worker is having trouble believing the story. But he is a curious man and he knows that farmers are clever people. He plans a trip to the village of Galaha where Mr. Suzgo lives, to discover the truth. What do you think he will find? Is it really possible to control a serious disease such as blast WITHOUT using chemicals?

FADE OUT MUSIC. FADE IN SOUND EFFECTS (Countryside sounds: roosters crowing, birds singing…)


Mr. Kwanga:
Good day, Sir — are you Mr. Suzgo?

Farmer Suzgo:
I am one and the same. And, if you don’t mind me asking, who are you, Sir?

Mr. Kwanga:
I am Mr. Kwanga, an extension worker from the Department of Agriculture. And if you are Mr. Suzgo, then you are the farmer that all the other farmers are talking about. Mr. Chuma in the next village told me that you have a special way to prevent blast without spraying chemicals. I was surprised and so I came to talk to you myself.

Farmer Suzgo:
You have come all this way to visit me? I am honoured. And yes, it is true that I don’t spray and yet I no longer see any disease in my rice. This is because I use a special planting method. I will take you to the field so you can see for yourself. Then I hope you will join me for tea.

MUSICAL BREAK(Five seconds).

FADE IN SOUND EFFECTS (Sound of footsteps as they walk together).


Farmer Suzgo:
That is my field over there. Do you notice anything different about my field compared with the other farmers’ fields?


Mr. Kwanga:
Well, I see that you have two types of rice growing together in one field. A tall variety and a short variety.

Farmer Suzgo:
Yes, I plant two kinds of rice in one field. You can see that the tall sticky rice is planted in a row next to the rows of hybrid rice.

Mr. Kwanga:
And why is this so important?

Farmer Suzgo:
This is important for these reasons. The tall sticky rice gets the disease easily. But the short hybrid rice that I have selected is not affected by the disease. And when the two are planted together there is no disease in the field — not even on the sticky rice. If you come back in four weeks you will see for yourself. By planting these two kinds of rice together — I prevent disease.

Mr. Kwanga:
Yes, I can understand now why this works. By planting these varieties of rice in your field the disease cannot spread. The disease can’t spread between the rows of sticky rice because the rows of hybrid rice block its way. I congratulate you, Mr. Suzgo, on your successful experiment! I hope you will allow me to bring some of the people from my office to meet you and learn about your achievement.

Farmer Suzgo:
Certainly! You would be most welcome, Sir. And now let’s go — we can discuss this more over a cup of tea.


Program host:
It seems the extension worker is very impressed with Mr. Suzgo’s experiment. He will go back to the Department of Agriculture and talk about it with his colleagues. Hopefully they can inform other farmers who will benefit from this knowledge. Mr. Suzgo has helped prove something that many of you already know — diversity helps to fight disease!



Contributed by: Jennifer Pittet, Researcher/writer, Toronto, Canada.

Reviewed by:  Christopher Mundt, Professor, Department of Botany and Plant Pathology, Oregon State University, USA.

Between the years 1998 and 2000 farmers and scientists carried out one of the largest agricultural experiments of its kind in the world. The study area covered 100,000 acres of farmland and involved thousands of farmers. It examined the effect of intercropping two varieties of rice on the incidence of blast (Magnaporthe grisea), a serious disease of rice.

Previous to the experiment, farmers were planting large areas of standard hybrid rice. They planted separate smaller plots exclusively with sticky rice, which is a valuable crop, but also very susceptible to blast.

In this experiment, farmers planted in a new way. They planted mixtures of the standard and sticky rice together. Four rows of standard rice were planted, then one row of sticky rice, then four more rows of standard rice, and so on. These fields were compared with fields where only sticky rice was planted. In these pure stands of sticky rice there was a 20% incidence of blast. In the fields where sticky rice was intercropped with standard rice, the incidence of blast was reduced to 1%.

The researchers concluded that in the intercropped fields where there were two kinds of rice, the standard rice plants blocked the spread of the blast fungus which spreads by spores in the wind. The difference in height between the two rice varieties was also a factor. The sticky rice plants are very tall and experienced drier, warmer conditions with their heads above the shorter standard rice plants. Disease is less likely to develop in these dry, warm conditions.

Information Sources

Chinese farmers fight crop disease with diversity,” Pesticide Action Network Updates Service, August 29, 2000. Pesticide Action Network.

Pesticide Action Network, BP 5938, Dakar-Fann, Dakar, Senegal. E-mail:

Pesticide Action Network Asia and the Pacific, PO Box 1170, 10850 Penang, Malaysia.  E-mail:

Red de Acción en Alternativas al uso de Agroquímicos, Apartado Postal 11-0581, Lima, Perú.  E-mail:

Simple method found to increase crop yields vastly,” C.K. Yoon, New York Times, August 22, 2000, D1-2.

“Genetic diversity and disease control in rice,” Y. Zhu et al., Nature, 406:718-722, August 17, 2000. Macmillan Publishers Ltd.