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Script 72.6

Notes to broadcasters

The weed striga (Striga spp.) poses a terrible problem for millions of farmers. Women especially spend a lot of time pulling striga from the fields. Striga feeds on rice, maize, millet, sorghum, cowpeas and sugarcane, and can damage up to 70% of crops in a field. The key to managing striga, also known as witchweed, is to use a variety of control methods at one time. Crop rotation, intercropping, planting resistant cereal varieties, soil fertilization and hand weeding are all important methods that should be used together when managing striga. This script discusses crop rotation and intercropping in particular.

One section of the script refers to “desmodium”, a forage crop that has shown some success in reducing striga growth when interplanted between rows of maize. If possible, before you air this program, find out whether this crop grows locally in your area and/or how farmers might be able to obtain it.

Farmers in your listening audience may have successful methods of controlling striga. If possible, conduct interviews or gather additional local information to include in your program.

Script

Host 1:
On our program today, we’re going to talk about a weed that I know is plaguing many farmers in our region… in fact in much of Africa.

Host 2:
And the name of that weed is striga. Some people call it witchweed.

Host 1:
Whatever name you know it by, striga is causing serious damage to maize, millet, sorghum, upland rice and Napier throughout sub-Sahara Africa.

Host 2:
What’s more, striga does most of its damage before you can even see it above the ground. While still underground, striga plants attach themselves to the roots of the growing plants and suck nutrients and water out of the crops. The crops wither, and produce far less grain.

Host 1:
In our discussion, we will share some useful ways to control this nasty weed.

Host 2:
The first thing we should point out is that if you want to prevent striga from spreading, you must use several different control methods.

Host 1:
You mean it’s not enough to use just one method.

Host 2:
That’s exactly what I mean. The key is to use a variety of control methods at one time.

Host 1:
In an earlier program, we talked about the importance of carefully hand pulling and getting rid of striga weeds. Today, we’re going to talk about two other methods for striga control — crop rotation and intercropping.

Host 2:
Yes. Crop rotation is one effective technique for managing striga. In other words grow other crops which are not susceptible to striga before and after your maize or millet.

Host 1:
And avoid growing the same cereal crop year after year. If you grow the same cereal crop every year, striga will continue to feed on that crop and become well established. If you follow cereal crops with other crops that are not affected by striga, you make it more difficult for striga to survive.

Host 2:
But farmers may be wondering what kinds of crops they can plant before or after a cereal crop.

Host 1:
There are many possibilities, depending on where you live, what you like, and what’s available. Farmers can grow cereal crops in rotation with groundnuts, cowpeas, cotton, soybeans, sesame, sunnhemp, or linseed.

Host 2:
Striga doesn’t feed on and infect these crops because it can’t attach to their roots. So no striga plants will grow in those crops and no new striga seeds are produced. Next year there are fewer seeds in the soil… and therefore fewer weeds grow.

Host 1:
Some farmers who are listening to this program may be thinking: “Well that sounds like a good idea, but I can’t grow a different crop every other year – I need to grow cereal crops every year.” And that’s understandable. Because that cereal crop is probably an important food crop.

Host 2:
Well those farmers will be interested to know that there has been a lot of research on intercropping cereal crops with other crops. In this system you can mix two crops together in the same field. For example grow one row of maize, one row of soybeans, one row of maize, and so on. This can reduce damage from striga.

Host 1:
Can you give some examples of systems that farmers have already tried.

Host 2:
Well, yes. In West African countries, striga is a serious pest in pearl millet. Some experiments there showed that the damage was reduced by growing rows of cowpeas between rows of pearl millet. Farmers have also had success growing soybeans and sweet potatoes in between rows of cereals.

Host 1:
Anything else?

Host 2:
Yes. There are other experiments where farmers planted a forage crop called desmodium between rows of maize. For some reason striga doesn’t grow well next to desmodium. So, where farmers planted desmodium between rows of maize, striga didn’t grow very well and maize yield increased compared to fields where no desmodium was planted.

Host 1:
Very interesting indeed. It seems that there are many crops that can be grown with cereal crops to help protect them from striga damage.

Host 2:
Cowpea, soybean and groundnuts are just a few examples. It’s a question of doing your own experiments, seeing what other farmers are doing, and talking to extension agents.

FADE IN MUSIC.

Host 1:
Remember that your striga control program will only be successful if you use more than one method of control. The best defence against this weed is to use several methods at the same time! Just intercropping or rotating your crops is not enough. You must also fertilize the soil to keep your crops healthy and hand pull the weeds.

Host 2:
I’d like to remind our listeners to keep pulling the striga plants as long as you find them in your fields, even if you are intercropping and rotating your crops, or using other methods. If you leave them in the ground, they will continue to produce more seeds, and you will have even bigger problems.

Host 1:
Thanks for tuning in today.

FADE OUT MUSIC.

Acknowledgements

  • Contributed by Jennifer Pittet, researcher/writer, Thornbury, Canada.
  • Reviewed by Aad van Ast, Department of Plant Sciences, Crop and Weed Ecology Group, Wageningen University, Haarweg 333, 6709 RZ Wageningen, The Netherlands.

Information Sources