Script 45.9

Notes to broadcasters

To the broadcaster: This script (Package 45, #9) is part two of a 2-part series on understanding plant diseases.(Package 45, #8) talks about how plants get diseases, and how to recognize symptoms of disease. Your listeners’ understanding will be more complete if the two scripts are read together.


Today we are going to tell you about some simple ways you can stop diseases from damaging your crops. If you do these simple things, your plants will have a better chance to stay healthy and free of diseases.

Even if you don’t know the name of the disease that is hurting your plants, there are many things you can do to stop that disease from getting worse. And, there are many things you can do to stop your plants from getting diseases in the first place.

Good farming practices protect plants from disease

Let’s talk about ways you can prevent your plants from getting diseases.

First of all, don’t put your plants too close together. Most plants should have enough room around them so that their leaves can dry out after rain or watering. Cereals such as rice, millet or maize are usually planted closer together, but should not be overcrowded. If your plants are crowded together and can’t dry out, disease organisms will spread more easily and cause more harm.

It’s also important not to water your plants too much. Watering too much is a common cause of disease. You should thoroughly water your plants once or twice a week – but not more than that. It is best if you water them in the morning, before the air and sun get too hot. If you water in the middle of the day when the sun is hottest, you might burn the plant leaves. And if you water in the evening, more moisture will stay on the plants, instead of evaporating in the sunlight. This moisture will encourage diseases to grow and spread.

Third, it’s not a good idea to plant in soil that is very wet. Many disease organisms spread more quickly in wet soil. And try not to walk in your fields when the leaves are wet. When you walk among wet leaves, you can easily spread disease from one plant to another just by brushing against the leaves with your tools or your body.

It’s a good idea to rotate your crops. Here’s why. Some disease organisms like to feed on only one crop. If you plant a crop that they don’t like, they will have nothing to eat, and will die.

Rotating your crops means that each part of your field will have a different crop growing in it every year. For example, let’s say you have three crops in your field this year. You are growing maize on the south side of your field, root vegetables on the west side and lettuce on the east side. Next year, you should rotate your crops. For example, you might plant maize on the west side, root vegetables on the east side, and lettuce on the north side.

Another good practice is to plant a variety of crops in your fields, instead of only one or two. Here’s why. As you now know, many disease organisms can live in only one or a few crops. These organisms will not damage as many plants in a field with many crops they don’t like.

You might be able to find varieties of crops that are resistant to certain diseases. These plants do not get infected even when disease is present. Scientists are breeding resistant varieties of many crops. If you can find these plants, use them.

When you transplant seedlings, it’s important to plant only strong, healthy seedlings. It is less likely that disease will infect these healthy plants.

You have a better chance of having healthy plants if you have healthy soil.

There are several ways you can keep your soil healthy.

One way is to add lots of organic matter to your soil. Compost is a good source of organic matter. If you add compost to your soil, it will help in two ways. First, there will be larger spaces inside the soil. Water can drain away through these large spaces, and plant roots will not be standing in water. This is helpful because plant roots need air.

Second, organic matter provides lots of nutrients for your plants. It also encourages good soil creatures to live in your soil. These good creatures will eat many disease organisms.

It is also a good idea to cover the soil between your crops with straw, hay, grass or tree bark. This cover is called a ‘mulch’. A mulch will stop disease organisms that live in the soil from splashing up on to your leaves. It can also stop your soil from eroding.

Another good way to prevent your plants from getting diseases is to wash your tools before you move from one crop to another. If you keep your tools clean, you will be less likely to carry disease from plant to plant, or field to field.

Something you may not know is that, if you smoke tobacco, it is important to wash your hands thoroughly before you touch any crops. This is because many tobacco leaves carry a virus called tobacco mosaic virus. You can easily spread this virus to many crops when you touch them.

If your plants have caught a disease, you can help stop it from getting any worse.

If you see plants that look like they might have a disease, pick off the diseased part of the plant. If the plant is badly diseased, remove the whole thing, roots and all, from your fields. Burn it, or bury it deeply in the soil. This will prevent the disease from spreading.

These are just a few of the ways you can stop diseases from harming your plants. Many of you will know of other solutions. But if you follow these practices, and see which of them works best for your crops, you should have fewer plant disease problems.


  • This script was written by Vijay Cuddeford, a summer intern at the Developing Countries Farm Radio Network, and a student of sustainable agriculture at the University of Waterloo, Ontario, Canada.
  • It was reviewed Dr. Darrell Cox, Ecological Concerns for Hunger Organization, Fort Myers, Florida.

Information Sources

  • Fruit and vegetable soft rot, DCFRN script Package 8, #2.
  • “Developing a disease-free garden”, in Agriculture in action, March 1990, pp. 19-20. Barbados Agricultural Society, ‘The Grotto’, Beckles Road, St. Michael, Barbados, West Indies.
  • “How to avoid plant diseases”, in Food gardens foundation #79, Summer 95, pp. 2-3. Food Gardens Foundation, P.O. Box 41250, Craighall, Johannesburg, 2024, South Africa.
  • “Rural farmers explore causes of plant disease”, by Stephen Sherwood & Jeffery Bentley, ILEIA Newsletter, Mar 95, Vol. 11:1, pp. 20-22. Information Centre for Low-External-Input and Sustainable Agriculture (ILEIA), Kastanjelaan 5, P.O. Box 64, NL?3830 AB Leusden, The Netherlands.
  • “Non-chemical methods to reduce disease infection on vegetables”, Insect and Disease Control in the Home Garden, #64, 1979?80, 2 pages. Ontario Ministry of Food, 1 Stone Road West, Guelph, Ontario, Canada. N1G 4Y2.
  • Plant pathology, by George N. Agrios, 1978. New York: Academic Press.
  • What’s wrong with my plants? A guide to identifying plant diseases caused by pathogens by Rebecca de Guzman, 19 pages. International Rice Research Institute, P.O. Box 933, Manila 1099, Philippines.